1
|
Luo Z, Liu Z, Tan Y, Yang J. Modeling and analysis of a multilayer solid tumour with cell physiological age and resource limitations. J Biol Dyn 2024; 18:2295492. [PMID: 38140711 DOI: 10.1080/17513758.2023.2295492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/08/2023] [Indexed: 12/24/2023]
Abstract
We study an avascular spherical solid tumour model with cell physiological age and resource constraints in vivo. We divide the tumour cells into three components: proliferating cells, quiescent cells and dead cells in necrotic core. We assume that the division rate of proliferating cells is nonlinear due to the nutritional and spatial constraints. The proportion of newborn tumour cells entering directly into quiescent state is considered, since this proportion can respond to the therapeutic effect of drug. We establish a nonlinear age-structured tumour cell population model. We investigate the existence and uniqueness of the model solution and explore the local and global stabilities of the tumour-free steady state. The existence and local stability of the tumour steady state are studied. Finally, some numerical simulations are performed to verify the theoretical results and to investigate the effects of different parameters on the model.
Collapse
Affiliation(s)
- Zhonghu Luo
- College of Mathematics and Statistics, Chongqing Jiaotong University, Chongqing, People's Republic of China
| | - Zijian Liu
- College of Mathematics and Statistics, Chongqing Jiaotong University, Chongqing, People's Republic of China
| | - Yuanshun Tan
- College of Mathematics and Statistics, Chongqing Jiaotong University, Chongqing, People's Republic of China
| | - Jin Yang
- College of Mathematics and Statistics, Chongqing Jiaotong University, Chongqing, People's Republic of China
| |
Collapse
|
2
|
Hamon LE, Youngsteadt E, Irwin RE, Sorenson CE. As prey and pollinators, insects increase reproduction and allow for outcrossing in the carnivorous plant Dionaea muscipula. Am J Bot 2024; 111:e16279. [PMID: 38290989 DOI: 10.1002/ajb2.16279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 02/01/2024]
Abstract
PREMISE Understanding the factors that limit reproductive success is a key component of plant biology. Carnivorous plants rely on insects as both nutrient sources and pollinators, providing a unique system for studying the effects of both resource and pollen limitation on plant reproduction. METHODS We conducted a field experiment using wild-growing Dionaea muscipula J. Ellis (Droseraceae) in which we manipulated prey and pollen in a factorial design and measured flower production, number of fruits, and number of seeds. Because understanding reproduction requires knowledge of a plant species' reproductive and pollination biology, we also examined the pollination system, per-visit pollinator effectiveness, and pollen-ovule (P/O) ratio of D. muscipula. RESULTS Plants that received supplemental prey produced more flowers than control plants. They also had a higher overall fitness estimate (number of flowers × fruit set (total fruits/total flowers) × seeds per fruit), although this benefit was significant only when prey supplementation occurred in the previous growing season. Neither pollen supplementation nor the interaction between pollen and prey supplementation significantly affected overall plant fitness. CONCLUSIONS This study reinforces the reliance of D. muscipula on adequate prey capture for flower, fruit, and seed production and a mobile pollen vector for reproduction, indicating the importance of considering insects as part of an effective conservation management plan for this species.
Collapse
Affiliation(s)
- Laura E Hamon
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695, USA
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Elsa Youngsteadt
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
- Center for Geospatial Analytics, North Carolina State University, Raleigh, North Carolina, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Clyde E Sorenson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695, USA
| |
Collapse
|
3
|
Vicente-Santos A, Willink B, Nowak K, Civitello DJ, Gillespie TR. Host-pathogen interactions under pressure: A review and meta-analysis of stress-mediated effects on disease dynamics. Ecol Lett 2023; 26:2003-2020. [PMID: 37804128 PMCID: PMC10874615 DOI: 10.1111/ele.14319] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 10/08/2023]
Abstract
Human activities have increased the intensity and frequency of natural stressors and created novel stressors, altering host-pathogen interactions and changing the risk of emerging infectious diseases. Despite the ubiquity of such anthropogenic impacts, predicting the directionality of outcomes has proven challenging. Here, we conduct a review and meta-analysis to determine the primary mechanisms through which stressors affect host-pathogen interactions and to evaluate the impacts stress has on host fitness (survival and fecundity) and pathogen infectivity (prevalence and intensity). We assessed 891 effect sizes from 71 host species (representing seven taxonomic groups) and 78 parasite taxa from 98 studies. We found that infected and uninfected hosts had similar sensitivity to stressors and that responses varied according to stressor type. Specifically, limited resources compromised host fecundity and decreased pathogen intensity, while abiotic environmental stressors (e.g., temperature and salinity) decreased host survivorship and increased pathogen intensity, and pollution increased mortality but decreased pathogen prevalence. We then used our meta-analysis results to develop susceptible-infected theoretical models to illustrate scenarios where infection rates are expected to increase or decrease in response to resource limitations or environmental stress gradients. Our results carry implications for conservation and disease emergence and reveal areas for future work.
Collapse
Affiliation(s)
- Amanda Vicente-Santos
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
| | - Beatriz Willink
- Department of Zoology, Stockholm University, Stockholm 106-91, Sweden
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
- School of Biology, University of Costa Rica, San José 11501-2060, Costa Rica
| | - Kacy Nowak
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - David J. Civitello
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Thomas R. Gillespie
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322, USA
| |
Collapse
|
4
|
García Y, Dow BS, Parachnowitsch AL. Water deficit changes patterns of selection on floral signals and nectar rewards in the common morning glory. AoB Plants 2023; 15:plad061. [PMID: 37899982 PMCID: PMC10601024 DOI: 10.1093/aobpla/plad061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/24/2023] [Indexed: 10/31/2023]
Abstract
Understanding whether and how resource limitation alters phenotypic selection on floral traits is key to predict the evolution of plant-pollinator interactions under climate change. Two important resources predicted to decline with our changing climate are pollinators and water in the form of increased droughts. Most work, however, has studied these selective agents separately and in the case of water deficit, studies are rare. Here, we use the common morning glory (Ipomoea purpurea) to investigate the effects of experimental reduction in pollinator access and water availability on floral signals and nectar rewards and their effects on phenotypic selection on these traits. We conducted a manipulative experiment in a common garden, where we grew plants in three treatments: (1) pollinator restriction, (2) water reduction and (3) unmanipulated control. Plants in pollinator restriction and control treatments were well-watered compared to water deficit. We found that in contrast to pollinator restriction, water deficit had strong effects altering floral signals and nectar rewards but also differed in the direction and strength of selection on these traits compared to control plants. Water deficit increased the opportunity for selection, and selection in this treatment favoured lower nectar volumes and larger floral sizes, which might further alter pollinator visitation. In addition, well-watered plants, both in control and pollinator deficit, showed similar patterns of selection to increase nectar volume suggesting non-pollinator-mediated selection on nectar. Our study shows that floral traits may evolve in response to reduction in water access faster than to declines in pollinators and reinforces that abiotic factors can be important agents of selection for floral traits. Although only few experimental selection studies have manipulated access to biotic and abiotic resources, our results suggest that this approach is key for understanding how pollination systems may evolve under climate change.
Collapse
Affiliation(s)
- Yedra García
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
| | - Benjamin S Dow
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
| | - Amy L Parachnowitsch
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
| |
Collapse
|
5
|
Adams BJ, Gora EM, Donaldson-Matasci MC, Robinson EJH, Powell S. Competition and habitat availability interact to structure arboreal ant communities across scales of ecological organization. Proc Biol Sci 2023; 290:20231290. [PMID: 37752835 PMCID: PMC10523074 DOI: 10.1098/rspb.2023.1290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/25/2023] [Indexed: 09/28/2023] Open
Abstract
Understanding how resource limitation and biotic interactions interact across spatial scales is fundamental to explaining the structure of ecological communities. However, empirical studies addressing this issue are often hindered by logistical constraints, especially at local scales. Here, we use a highly tractable arboreal ant study system to explore the interactive effects of resource availability and competition on community structure across three local scales: an individual tree, the nest network created by each colony and the individual ant nest. On individual trees, the ant assemblages are primarily shaped by availability of dead wood, a critical nesting resource. The nest networks within a tree are constrained by the availability of nesting resources but also influenced by the co-occurring species. Within individual nests, the distribution of adult ants is only affected by distance to interspecific competitors. These findings demonstrate that resource limitation exerts the strongest effects on diversity at higher levels of local ecological organization, transitioning to a stronger effect of species interactions at finer scales. Collectively, these results highlight that the process exerting the strongest influence on community structure is highly dependent on the scale at which we examine the community, with shifts occurring even across fine-grained local scales.
Collapse
Affiliation(s)
- Benjamin J. Adams
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Evan M. Gora
- Smithsonian Tropical Research Institute, Balboa, Panama
- Cary Institute of Ecosystem Studies, Millbrook, NY, USA
| | | | | | - Scott Powell
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| |
Collapse
|
6
|
Liu Z, Zhao M, Zhang H, Ren T, Liu C, He N. Divergent response and adaptation of specific leaf area to environmental change at different spatio-temporal scales jointly improve plant survival. Glob Chang Biol 2023; 29:1144-1159. [PMID: 36349544 DOI: 10.1111/gcb.16518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/23/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
Specific leaf area (SLA) is one of the most important plant functional traits. It integrates multiple functions and reflects strategies of plants to obtain resources. How plants employ different strategies (e.g., through SLA) to respond to dynamic environmental conditions remains poorly understood. This study aimed to explore the spatial variation in SLA and its divergent adaptation through the lens of biogeographic patterns, evolutionary history, and short-term responses. SLA data for 5424 plant species from 76 natural communities in China were systematically measured and integrated with meta-analysis of field experiments (i.e., global warming, drought, and nitrogen addition). The mean value of SLA across all species was 21.8 m2 kg-1 , ranging from 0.9 to 110.2 m2 kg-1 . SLA differed among different ecosystems, temperature zones, vegetation types, and functional groups. Phylogeny had a weak effect on SLA, but plant species evolved toward higher SLA. Furthermore, SLA responded nonlinearly to environmental change. Unexpectedly, radiation was one of the main factors determining the spatial variation in SLA on a large scale. Conversely, short-term manipulative experiments showed that SLA increased with increased resource availability and tended to stabilize with treatment duration. However, different species exhibited varying response patterns. Overall, variation in long-term adaptation of SLA to environmental gradients and its short-term response to resource pulses jointly improve plant adaptability to a changing environment. Overall SLA-environment relationships should be emphasized as a multidimensional strategy for elucidating environmental change in future research.
Collapse
Affiliation(s)
- Zhaogang Liu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Vegetation & Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Ming Zhao
- State Key Laboratory of Vegetation & Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Hongxiang Zhang
- Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Tingting Ren
- State Key Laboratory of Vegetation & Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Congcong Liu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Nianpeng He
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
7
|
Cote J, Dahirel M, Schtickzelle N, Altermatt F, Ansart A, Blanchet S, Chaine AS, De Laender F, De Raedt J, Haegeman B, Jacob S, Kaltz O, Laurent E, Little CJ, Madec L, Manzi F, Masier S, Pellerin F, Pennekamp F, Therry L, Vong A, Winandy L, Bonte D, Fronhofer EA, Legrand D. Dispersal syndromes in challenging environments: A cross-species experiment. Ecol Lett 2022; 25:2675-2687. [PMID: 36223413 PMCID: PMC9828387 DOI: 10.1111/ele.14124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 01/12/2023]
Abstract
Dispersal is a central biological process tightly integrated into life-histories, morphology, physiology and behaviour. Such associations, or syndromes, are anticipated to impact the eco-evolutionary dynamics of spatially structured populations, and cascade into ecosystem processes. As for dispersal on its own, these syndromes are likely neither fixed nor random, but conditional on the experienced environment. We experimentally studied how dispersal propensity varies with individuals' phenotype and local environmental harshness using 15 species ranging from protists to vertebrates. We reveal a general phenotypic dispersal syndrome across studied species, with dispersers being larger, more active and having a marked locomotion-oriented morphology and a strengthening of the link between dispersal and some phenotypic traits with environmental harshness. Our proof-of-concept metacommunity model further reveals cascading effects of context-dependent syndromes on the local and regional organisation of functional diversity. Our study opens new avenues to advance our understanding of the functioning of spatially structured populations, communities and ecosystems.
Collapse
Affiliation(s)
- Julien Cote
- Centre National de la Recherche Scientifique (CNRS)Université Paul Sabatier; UMR5174 EDB (Laboratoire Evolution & Diversité Biologique)Toulouse CedexFrance
| | - Maxime Dahirel
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, Biodiversité, Évolution)—UMR6553RennesFrance,Department of BiologyGhent UniversityGhentBelgium
| | - Nicolas Schtickzelle
- Univ. Catholique de LouvainEarth and Life Institute, Biodiversity Research CentreLouvain‐la‐NeuveBelgium
| | - Florian Altermatt
- Eawag: Department of Aquatic EcologySwiss Federal Institute of Aquatic Science and TechnologyDübendorfSwitzerland,Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZürichSwitzerland
| | - Armelle Ansart
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, Biodiversité, Évolution)—UMR6553RennesFrance
| | - Simon Blanchet
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Alexis S. Chaine
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance,Institute for Advanced Studies in Toulouse, Toulouse School of EconomicsToulouseFrance
| | - Frederik De Laender
- Research Unit in Environmental and Evolutionary Biology, Namur Institute of Complex Systems, and the Institute of Life, Earth, and EnvironmentUniversity of NamurNamurBelgium
| | - Jonathan De Raedt
- Research Unit in Environmental and Evolutionary Biology, Namur Institute of Complex Systems, and the Institute of Life, Earth, and EnvironmentUniversity of NamurNamurBelgium,Laboratory of Environmental Toxicology and Applied EcologyGhent UniversityGhentBelgium
| | - Bart Haegeman
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Staffan Jacob
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Oliver Kaltz
- ISEM, Univ MontpellierCNRS, EPHE, IRDMontpellierFrance
| | - Estelle Laurent
- Univ. Catholique de LouvainEarth and Life Institute, Biodiversity Research CentreLouvain‐la‐NeuveBelgium
| | - Chelsea J. Little
- Eawag: Department of Aquatic EcologySwiss Federal Institute of Aquatic Science and TechnologyDübendorfSwitzerland,Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZürichSwitzerland,School of Environmental ScienceSimon Fraser UniversityBurnabyBritish ColumbiaCanada
| | - Luc Madec
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, Biodiversité, Évolution)—UMR6553RennesFrance
| | - Florent Manzi
- ISEM, Univ MontpellierCNRS, EPHE, IRDMontpellierFrance,Department of Ecosystem ResearchLeibniz‐Institute of Freshwater Ecology and Inland FisheriesBerlinGermany
| | | | - Felix Pellerin
- Centre National de la Recherche Scientifique (CNRS)Université Paul Sabatier; UMR5174 EDB (Laboratoire Evolution & Diversité Biologique)Toulouse CedexFrance
| | - Frank Pennekamp
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZürichSwitzerland
| | - Lieven Therry
- Centre National de la Recherche Scientifique (CNRS)Université Paul Sabatier; UMR5174 EDB (Laboratoire Evolution & Diversité Biologique)Toulouse CedexFrance,Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Alexandre Vong
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Laurane Winandy
- Centre National de la Recherche Scientifique (CNRS)Université Paul Sabatier; UMR5174 EDB (Laboratoire Evolution & Diversité Biologique)Toulouse CedexFrance,Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| | - Dries Bonte
- Department of BiologyGhent UniversityGhentBelgium
| | - Emanuel A. Fronhofer
- Eawag: Department of Aquatic EcologySwiss Federal Institute of Aquatic Science and TechnologyDübendorfSwitzerland,Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZürichSwitzerland,ISEM, Univ MontpellierCNRS, EPHE, IRDMontpellierFrance
| | - Delphine Legrand
- Centre National de la Recherche Scientifique (CNRS)Station d'Ecologie Théorique et Expérimentale (UAR2029)MoulisFrance
| |
Collapse
|
8
|
Santini A, Messina A, Costantini E, Protti A, Cecconi M. COVID-19: dealing with ventilator shortage. Curr Opin Crit Care 2022; 28:652-9. [PMID: 36226709 DOI: 10.1097/MCC.0000000000001000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE OF REVIEW To describe different strategies adopted during coronavirus disease 2019 pandemic to cope with the shortage of mechanical ventilators. RECENT FINDINGS Short-term interventions aimed to increase ventilator supply and decrease demand. They included: redistributing and centralizing patients, repurposing operating rooms into intensive care units (ICUs) and boosting ventilator production and using stocks and back-ups; support by the critical care outreach team to optimize treatment of patients in the ward and permit early discharge from the ICU, ethical allocation of mechanical ventilators to patients who could benefit more from intensive treatment and short term ICU trials for selected patients with uncertain prognosis, respectively. Long-term strategies included education and training of non-ICU physicians and nurses to the care of critically-ill patients and measures to decrease viral spread among the population and the progression from mild to severe disease. SUMMARY The experience and evidence gained during the current pandemic is of paramount importance for physicians and law-makers to plan in advance an appropriate response to any future similar crisis. Intensive care unit, hospital, national and international policies can all be improved to build systems capable of treating an unexpectedly large number of patients, while keeping a high standard of safety.
Collapse
|
9
|
Vinton AC, Vasseur DA. Resource limitation determines realized thermal performance of consumers in trophodynamic models. Ecol Lett 2022; 25:2142-2155. [PMID: 36029291 DOI: 10.1111/ele.14086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 05/17/2022] [Accepted: 06/27/2022] [Indexed: 01/07/2023]
Abstract
Recent work has demonstrated that changes in resource availability can alter a consumer's thermal performance curve (TPC). When resources decline, the optimal temperature and breadth of thermal performance also decline, leading to a greater risk of warming than predicted by static TPCs. We investigate the effect of temperature on coupled consumer-resource dynamics, focusing on the potential for changes in the consumer TPC to alter extinction risk. Coupling consumer and resource dynamics generally reduces the potential for resource decline to exacerbate the effects of warming via changes to the TPC due to a reduction in top-down control when consumers near the limits of their thermal performance curve. However, if resources are more sensitive to warming, consumer TPCs can be reshaped by declining resources, leading to increased extinction risk. Our work elucidates the role of top-down and bottom-up regulation in determining the extent to which changes in resource density alter consumer TPCs.
Collapse
Affiliation(s)
- Anna C Vinton
- Department of Biology, University of Oxford, Oxford, UK.,Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
| | - David A Vasseur
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
| |
Collapse
|
10
|
Nair S, Li X, Arya GA, McDew-White M, Ferrari M, Anderson T. Nutrient Limitation Magnifies Fitness Costs of Antimalarial Drug Resistance Mutations. Antimicrob Agents Chemother 2022; 66:e0152921. [PMID: 35465723 PMCID: PMC9112896 DOI: 10.1128/aac.01529-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 02/22/2022] [Indexed: 12/15/2022] Open
Abstract
Drug resistance mutations tend to disrupt key physiological processes and frequently carry fitness costs, which are a central determinant of the rate of spread of these mutations in natural populations. Head-to-head competition assays provide a standard approach to measuring fitness for malaria parasites. These assays typically use a standardized culture medium containing RPMI 1640, which has a 1.4- to 5.5-fold higher concentration of amino acids than human blood. In this rich medium, we predict that fitness costs will be underestimated because resource competition is weak. We tested this prediction using an artemisinin-sensitive parasite edited to contain kelch-C580Y or R561H mutations conferring resistance to artemisinin or synonymous control mutations. We examined the impact of these single amino acid mutations on fitness, using replicated head-to-head competition experiments conducted in media containing (i) normal RPMI, (ii) modified RPMI with reduced amino acid concentration, (iii) RPMI containing only isoleucine, or (iv) 3-fold diluted RPMI. We found a significant 1.3- to 1.4-fold increase in fitness costs measured in modified and isoleucine-only media relative to normal media, while fitness costs were 2.5-fold higher in diluted media. We conclude that fitness costs are strongly affected by media composition and will be significantly underestimated in normal RPMI. Several components differed between media, including pABA and sodium bicarbonate concentrations, so we cannot directly determine which is responsible. Elevated fitness costs in nature will limit spread of artemisinin (ART) resistance but will also promote evolution of compensatory mutations that restore fitness and can be exploited to maximize selection in laboratory experiments.
Collapse
Affiliation(s)
- Shalini Nair
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Xue Li
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Grace A. Arya
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Marina McDew-White
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Marco Ferrari
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Tim Anderson
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| |
Collapse
|
11
|
Choi RT, Reed SC, Tucker CL. Multiple resource limitation of dryland soil microbial carbon cycling on the Colorado Plateau. Ecology 2022; 103:e3671. [PMID: 35233760 DOI: 10.1002/ecy.3671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/20/2021] [Accepted: 11/11/2021] [Indexed: 11/06/2022]
Abstract
Understanding interactions among biogeochemical cycles is increasingly important as anthropogenic alterations of global climate and of carbon (C), nitrogen (N), and phosphorus (P) cycles interactively affect the Earth system. Ecosystem processes in the dryland biome, which makes up over 40% of Earth's terrestrial surface, are often distinctively sensitive to small changes in resource availability, likely because levels of many resources are low. However, data also suggest that simultaneous changes in the availability of multiple resources may be necessary to affect a response in these low-resource systems, offering an opportunity to test patterns and controls of co-limitation, serial limitation, and individual limitation in soil environments. While drylands may play a governing role in key aspects of Earth's C cycle, and while an improved understanding of resource limitation could substantially improve our forecasts of dryland responses to change, our understanding of interacting controls on soil C cycle processes remains notably poor in these dry systems. Here, we address multiple fundamental hypotheses of resource controls over ecosystem function to test how water, C, N, and P regulate soil C cycling individually and interactively in a dryland ecosystem on the Colorado Plateau. Using a series of laboratory incubations, we found that while water, C, and N limited C cycling through serial limitation, water alone resulted in an extremely small respiratory response from target organisms, whereas water + C resulted in a dramatic increase in soil C cycling, suggesting a degree of functional co-limitation. Nitrogen additions alone resulted in no changes to soil C cycling, but when N was added in concert with water and C, N greatly increased soil C cycling rates relative to additions of water and C without N. Phosphorus additions had no effect on the C cycle either alone or synergistically. These patterns were consistent with the stoichiometry of the system, and interactions among resources were surprising in ways that inform our understanding of critical theories in ecology, such as the Transient Maxima Hypothesis, supporting the suggestion that multiple resource limitation explains pulse-dynamic C cycling in drylands better than water limitation alone.
Collapse
Affiliation(s)
- Ryan T Choi
- Department of Wildland Resources, Utah State University and the Ecology Center, Logan, UT, USA
| | - Sasha C Reed
- U.S. Geological Survey, Southwest Biological Science Center, Moab, UT, USA
| | - Colin L Tucker
- U.S. Geological Survey, Southwest Biological Science Center, Moab, UT, USA.,U.S.D.A Forest Service, Northern Research Station, Houghton, MI, USA
| |
Collapse
|
12
|
Recart W, Campbell DR. Water availability affects the relationship between pollen intensity and seed production. AoB Plants 2021; 13:plab074. [PMID: 34987746 PMCID: PMC8711293 DOI: 10.1093/aobpla/plab074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
Seed production can be affected by water availability and also depend on the amount (pollen intensity) and quality of pollen deposited. The way pollen receipt on the stigma translates into seeds produced follows that of a saturating dose-response. Not only can water availability and pollen intensity each influence seed production, these factors could interact in their effects on seed production. Changes to the relationship between seed production and pollen intensity can in turn influence pollinator effectiveness and pollinator-mediated selection. We asked how water availability affected indices of plant fitness (seed set, fruit set and seed mass) and the relationship between pollen intensity and seed production in Phacelia parryi. We conducted a greenhouse experiment where we manipulated water availability (either high- or low-water) to pollen recipient plants and hand-pollinated each plant with a range of pollen intensities. We conducted 703 hand-pollinations on 30 plants. For each hand-pollinated flower we measured pollen deposited, seed production and seed mass. We then generated a piecewise regression of the relationship between pollen intensity and seed production, and determined average effects of water on plant fitness measures. This experiment was paired with a field observational study aimed to document natural variation in pollen deposition. Average seed production per fruit was 21 % higher in the high-watered plants. The relationship between pollen intensity and seed production differed between the two water treatments. Plants under high-water exhibited a wider range in which pollen deposition increased seed production. Average natural pollen intensities fell within different regions of the piecewise regression for low- and high-water plants. Water availability can alter the efficiency by which pollen received is translated into seeds produced. Our greenhouse data suggest that only under certain pollen intensity environments will water availability affect how pollen received is translated into seeds produced.
Collapse
Affiliation(s)
- Wilnelia Recart
- Department of Biology, University of San Diego, 5998 Alcalá Park, San Diego, CA 92110, USA
| | - Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
| |
Collapse
|
13
|
Huxley PJ, Murray KA, Pawar S, Cator LJ. The effect of resource limitation on the temperature dependence of mosquito population fitness. Proc Biol Sci 2021; 288:20203217. [PMID: 33906411 PMCID: PMC8079993 DOI: 10.1098/rspb.2020.3217] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/31/2021] [Indexed: 12/27/2022] Open
Abstract
Laboratory-derived temperature dependencies of life-history traits are increasingly being used to make mechanistic predictions for how climatic warming will affect vector-borne disease dynamics, partially by affecting abundance dynamics of the vector population. These temperature-trait relationships are typically estimated from juvenile populations reared on optimal resource supply, even though natural populations of vectors are expected to experience variation in resource supply, including intermittent resource limitation. Using laboratory experiments on the mosquito Aedes aegypti, a principal arbovirus vector, combined with stage-structured population modelling, we show that low-resource supply in the juvenile life stages significantly depresses the vector's maximal population growth rate across the entire temperature range (22-32°C) and causes it to peak at a lower temperature than at high-resource supply. This effect is primarily driven by an increase in juvenile mortality and development time, combined with a decrease in adult size with temperature at low-resource supply. Our study suggests that most projections of temperature-dependent vector abundance and disease transmission are likely to be biased because they are based on traits measured under optimal resource supply. Our results provide compelling evidence for future studies to consider resource supply when predicting the effects of climate and habitat change on vector-borne disease transmission, disease vectors and other arthropods.
Collapse
Affiliation(s)
- Paul J. Huxley
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Kris A. Murray
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
- MRC Unit The Gambia at London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Samraat Pawar
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - Lauren J. Cator
- Department of Life Sciences, Imperial College London, Ascot, UK
| |
Collapse
|
14
|
Zhou Y, Wigley BJ, Case MF, Coetsee C, Staver AC. Rooting depth as a key woody functional trait in savannas. New Phytol 2020; 227:1350-1361. [PMID: 32306404 DOI: 10.1111/nph.16613] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/08/2020] [Indexed: 05/17/2023]
Abstract
Dimensions of tree root systems in savannas are poorly understood, despite being essential in resource acquisition and post-disturbance recovery. We studied tree rooting patterns in Southern African savannas to ask: how tree rooting strategies affected species responses to severe drought; and how potential rooting depths varied across gradients in soil texture and rainfall. First, detailed excavations of eight species in Kruger National Park suggest that the ratio of deep to shallow taproot diameters provides a reasonable proxy for potential rooting depth, facilitating extensive interspecific comparison. Detailed excavations also suggest that allocation to deep roots traded off with shallow lateral root investment, and that drought-sensitive species rooted more shallowly than drought-resistant ones. More broadly across 57 species in Southern Africa, potential rooting depths were phylogenetically constrained, with investment to deep roots evident among miombo Detarioids, consistent with results suggesting they green up before onset of seasonal rains. Soil substrate explained variation, with deeper roots on sandy, nutrient-poor soils relative to clayey, nutrient-rich ones. Although potential rooting depth decreased with increasing wet season length, mean annual rainfall had no systematic effect on rooting depth. Overall, our results suggest that rooting depth systematically structures the ecology of savanna trees. Further work examining other anatomical and physiological root traits should be a priority for understanding savanna responses to changing climate and disturbances.
Collapse
Affiliation(s)
- Yong Zhou
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| | - Benjamin J Wigley
- Department of Environmental Biology, Sapienza University of Rome, Ple A. Moro 5, Rome, Italy
- School of Natural Resource Management, Nelson Mandela University, George, 6529, South Africa
| | - Madelon F Case
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| | - Corli Coetsee
- School of Natural Resource Management, Nelson Mandela University, George, 6529, South Africa
- Scientific Services, Kruger National Park, Private Bag X402, Skukuza, 1350, South Africa
| | - Ann Carla Staver
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| |
Collapse
|
15
|
Vimercati L, Bueno de Mesquita CP, Schmidt SK. Limited Response of Indigenous Microbes to Water and Nutrient Pulses in High-Elevation Atacama Soils: Implications for the Cold-Dry Limits of Life on Earth. Microorganisms 2020; 8:E1061. [PMID: 32708721 PMCID: PMC7409055 DOI: 10.3390/microorganisms8071061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/07/2020] [Accepted: 07/09/2020] [Indexed: 01/05/2023] Open
Abstract
Soils on the world's highest volcanoes in the Atacama region represent some of the harshest ecosystems yet discovered on Earth. Life in these environments must cope with high UV flux, extreme diurnal freeze-thaw cycles, low atmospheric pressure and extremely low nutrient and water availability. Only a limited spectrum of bacterial and fungal lineages seems to have overcome the harshness of this environment and may have evolved the ability to function in situ. However, these communities may lay dormant for most of the time and spring to life only when enough water and nutrients become available during occasional snowfalls and aeolian depositions. We applied water and nutrients to high-elevation soils (5100 meters above sea level) from Volcán Llullaillaco, both in lab microcosms and in the field, to investigate how microbial communities respond when resource limitations are alleviated. The dominant taxon in these soils, the extremophilic yeast Naganishia sp., increased in relative sequence abundance and colony-forming unit counts after water + nutrient additions in microcosms, and marginally in the field after only 6 days. Among bacteria, only a Noviherbaspirillum sp. (Oxalobacteraceae) significantly increased in relative abundance both in the lab and field in response to water addition but not in response to water and nutrients together, indicating that it might be an oligotroph uniquely suited to this extreme environment. The community structure of both bacteria and eukaryotes changed significantly with water and water + nutrient additions in the microcosms and taxonomic richness declined with amendments to water and nutrients. These results indicate that only a fraction of the detected community is able to become active when water and nutrients limitations are alleviated in lab microcosms, and that water alone can dramatically change community structure. Our study sheds light on which extremophilic organisms are likely to respond when favorable conditions occur in extreme earthly environments and perhaps in extraterrestrial environments as well.
Collapse
Affiliation(s)
- Lara Vimercati
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA; (L.V.); (C.P.B.d.M.)
| | - Clifton P. Bueno de Mesquita
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA; (L.V.); (C.P.B.d.M.)
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309-0450, USA
| | - Steven K. Schmidt
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA; (L.V.); (C.P.B.d.M.)
| |
Collapse
|
16
|
Mola JM, Miller MR, O'Rourke SM, Williams NM. Wildfire reveals transient changes to individual traits and population responses of a native bumble bee Bombus vosnesenskii. J Anim Ecol 2020; 89:1799-1810. [PMID: 32358976 DOI: 10.1111/1365-2656.13244] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/19/2020] [Indexed: 12/14/2022]
Abstract
Fire-induced changes in the abundance and distribution of organisms, especially plants, can alter resource landscapes for mobile consumers driving bottom-up effects on their population sizes, morphologies and reproductive potential. We expect these impacts to be most striking for obligate visitors of plants, like bees and other pollinators, but these impacts can be difficult to interpret due to the limited information provided by forager counts in the absence of survival or fitness proxies. Increased bumble bee worker abundance is often coincident with the pulses of flowers that follow recent fire. However, it is unknown if observed postfire activity is due to underlying population growth or a stable pool of colonies recruiting more foragers to abundant resource patches. This distinction is necessary for determining the net impact of disturbance on bumble bees: are there population-wide responses or do just a few colonies reap the rewards? We estimated colony abundance before and after fire in burned and unburned areas using a genetic mark-recapture framework. We paired colony abundance estimates with measures of body size, counts of queens, and estimates of foraging and dispersal to assess changes in worker size, reproductive output, and landscape-scale movements. Higher floral abundance following fire not only increased forager abundance but also the number of colonies from which those foragers came. Importantly, despite a larger population size, we also observed increased mean worker size. Two years following fire, queen abundance was higher in both burned and unburned sites, potentially due to the dispersal of queens from burned into unburned areas. The effects of fire were transient; within two growing seasons, worker abundance was substantially reduced across the entire sampling area and body sizes were similar between burned and unburned sites. Our results reveal how disturbance can temporarily release populations from resource limitation, boosting the genetic diversity, body size, and reproductive output of populations. Given that the effects of fire on bumble bees acted indirectly through pulsed resource availability, it is likely our results are generalizable to other situations, such as habitat restorations, where resource density is enhanced within the landscape.
Collapse
Affiliation(s)
- John M Mola
- Fort Collins Science Center, U.S. Geological Survey, Ft Collins, CO, USA.,Graduate Group in Ecology, University of California, Davis, CA, USA
| | - Michael R Miller
- Graduate Group in Ecology, University of California, Davis, CA, USA.,Department of Animal Science, University of California, Davis, CA, USA
| | - Sean M O'Rourke
- Department of Animal Science, University of California, Davis, CA, USA
| | - Neal M Williams
- Graduate Group in Ecology, University of California, Davis, CA, USA.,Department of Entomology, University of California, Davis, CA, USA
| |
Collapse
|
17
|
Gyi AA, Nyein HL, Aung T, Mra R. Transplant Programs in APBMT: Blood and Marrow Transplant Activity Report from Myanmar APBMT Meeting 2018, Taiwan. Blood Cell Ther 2019; 2:54-57. [PMID: 37588102 PMCID: PMC10427229 DOI: 10.31547/bct-2019-008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/09/2019] [Indexed: 08/18/2023]
Abstract
Hematopoietic stem cell transplantation (HSCT) was introduced in Myanmar in 2014 and was first performed in a patient with multiple myeloma at the North Okkalapa General and Teaching Hospital. From 2014 to 2016,transplantation activities were in the preliminary stage of establishing the infrastructure and gradually developing capacity-building. In 2016, the Yangon General Hospital also commenced autologous transplantation for myeloma. Five autologous transplants were performed in Myanmar during 2016 in patients with myeloma, using high-dose melphalan and non-cryopreserved peripheral blood stem cell rescue. Despite the lack of a National Registry system, all cases were reported in the activity survey due to their small number. The National Marrow Donor Program has not been implemented in Myanmar yet. The major limitation in promoting HSCT in Myanmar is the unavailability of health insurance coverage for blood and marrow transplantation (BMT). The patients who received transplantation were partly supported by the government and partly by their families through out-of-pocket expenses. However, despite limited resources, there has been substantial progress in the human resource development for BMT in Myanmar. Under the leadership of The Asia Pacific Blood and Marrow Transplantation Group (APBMT), several transplant centers in the Asia-Pacific region have been supporting Myanmar to establish transplantation activities and capacity-building for promoting HSCT in patients from Myanmar.
Collapse
Affiliation(s)
- Aye Aye Gyi
- Department of Clinical Haematology, North Okkalapa General and Teaching Hospital, University of Medicine 2, Yangon,Myanmar
| | - Htun Lwin Nyein
- Department of Clinical Haematology, Yangon General Hospital, Yangon
| | | | - Rai Mra
- Myanmar Society of Haematology, Myanmar Medical Association
| |
Collapse
|
18
|
Abstract
The combination of individual-based selection with shared access to resources drives individuals to invest more than necessary in taking up their share of resources due to the threat of other individuals doing the same (competitive overinvestments). This evolutionary escalation of investment is common, from deer antlers and peacock feathers to tree height and plant roots. Because plant roots seem to be well intermingled belowground, the simplifying assumption that belowground resources are perfectly well mixed is often made in models-a condition that favours maximal fine-root overinvestments. Here, I develop simple models to investigate the role of space in determining the overlap among individuals belowground and resulting fine-root biomass. Without costs of growing roots through space, evolutionary optimization leads individuals to intermingle their fine roots perfectly and to invest just as much in these roots, whether there are two individuals competing or many. However, if there are any costs of sending roots through soil, investment in fine roots is constrained in amount and spatial extent. Dominant individuals are those that keep their roots in the soil closest to their own stem and the stems of their closest neighbours. These results highlight the importance of space in determining individual strategies as well as competitive networks.
Collapse
Affiliation(s)
- Caroline E Farrior
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| |
Collapse
|
19
|
Kamimura A, Kaneko K. Molecular Diversity and Network Complexity in Growing Protocells. Life (Basel) 2019; 9:E53. [PMID: 31226813 DOI: 10.3390/life9020053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 06/14/2019] [Accepted: 06/17/2019] [Indexed: 12/02/2022] Open
Abstract
A great variety of molecular components is encapsulated in cells. Each of these components is replicated for cell reproduction. To address the essential role of the huge diversity of cellular components, we studied a model of protocells that convert resources into catalysts with the aid of a catalytic reaction network. As the resources were limited, the diversity in the intracellular components was found to be increased to allow the use of diverse resources for cellular growth. A scaling relation was demonstrated between resource abundances and molecular diversity. In the present study, we examined how the molecular species diversify and how complex catalytic reaction networks develop through an evolutionary course. At some generations, molecular species first appear as parasites that do not contribute to the replication of other molecules. Later, the species turn into host species that contribute to the replication of other species, with further diversification of molecular species. Thus, a complex joint network evolves with this successive increase in species. The present study sheds new light on the origin of molecular diversity and complex reaction networks at the primitive stage of a cell.
Collapse
|
20
|
Møller AP, Laursen K. The ecological significance of extremely large flocks of birds. Ecol Evol 2019; 9:6559-6567. [PMID: 31236244 PMCID: PMC6580271 DOI: 10.1002/ece3.5234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/09/2019] [Accepted: 04/18/2019] [Indexed: 11/29/2022] Open
Abstract
Population size is generally limited by resource availability during and outside the breeding season. Therefore, maximum size of flocks may provide important information on population regulation and the influence of diet and trophic level on maximal degree of sociality. We hypothesized that (a) flock size should increase with nutrient availability; (b) flock size should decrease with latitude because productivity is higher at lower latitude; (c) aquatic habitats should have larger flocks than terrestrial habitats because the former are less accessible; (d) smaller species should have larger flocks because they require overall less food; (e) human-impacted species that live in perturbed habitats should have smaller flocks than other species; (f) flock size should decrease with increasing trophic level because there is a reduction in biomass due to conversion at each trophic level; and (g) flocks of species depending on ancestral landscapes should have decreased in size in recent years due to human impact (e.g., land-use). We obtained 1564 observations of flocks that exceeded 100,000 individuals in order to test the predictions listed above. Most effect sizes were small to medium accounting for 1%-9% of the variance, while large effects accounting for 25% or more were only found for total nitrogen used per km2 and area used for agriculture. Changes in large bird flocks were caused by habitat degradation and persecution, and temporal decline in size of large flocks revealed changes in nutrient use, reductions in nutrient cycling, and changes in flock size linked to trophic level.
Collapse
Affiliation(s)
- Anders Pape Møller
- Ecologie Systématique Evolution, Université Paris‐Sud, CNRS, AgroParisTechUniversité Paris‐SaclayOrsay CedexFrance
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life SciencesBeijing Normal UniversityBeijingChina
| | | |
Collapse
|
21
|
Weideli OC, Papastamatiou YP, Planes S. Size frequency, dispersal distances and variable growth rates of young sharks in a multi-species aggregation. J Fish Biol 2019; 94:789-797. [PMID: 30883741 DOI: 10.1111/jfb.13968] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/15/2019] [Indexed: 06/09/2023]
Abstract
During a mark-recapture survey from November 2014 until April 2017, 333 neonatal and juvenile blacktip reef sharks Carcharhinus melanopterus and 302 neonatal and juvenile sicklefin lemon sharks Negaprion acutidens were tagged and measured at the uninhabited and isolated St. Joseph Atoll (Republic of Seychelles). Both species demonstrated seasonal reproductive synchronicity and relatively large sizes at birth. Despite the extended times at liberty > 2.5 years, the majority of recaptures were found in close proximity to the initial tagging location (< 500 m). Annual growth rates of C. melanopterus (n = 24) and N. acutidens (n = 62) ranged from 6.6 to 31.7 cm year-1 (mean ± SE; 16.2 ± 1.2 cm year-1 ) and 0.2 to 32.2 cm year-1 (11.8 ± 1 cm year-1 ), respectively and are to date the most variable ever recorded in wild juvenile sharks. High abundances of both species coupled with long-term and repeated recaptures are indicative of a habitat where juveniles can reside for their first years of life. However, large variability in annual growth rates in both species may suggest high intra and interspecific competition induced by a possibly resource limited, isolated habitat.
Collapse
Affiliation(s)
- Ornella C Weideli
- PSL Research University: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France
- SOSF - D'Arros Research Centre (SOSF-DRC), Geneva, Switzerland
| | - Yannis P Papastamatiou
- Department of Biological Sciences, Marine Sciences Program, Florida International University, North Miami, Florida, USA
| | - Serge Planes
- PSL Research University: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France
- Laboratoire d'excellence 'CORAIL', EPHE, PSL Research University, UPVD, CNRS, USR 3278 CRIOBE, Papetoai, Moorea, French Polynesia
| |
Collapse
|
22
|
Spaan RS, Epps CW, Ezenwa VO, Jolles AE. Why did the buffalo cross the park? Resource shortages, but not infections, drive dispersal in female African buffalo ( Syncerus caffer). Ecol Evol 2019; 9:5651-5663. [PMID: 31160988 PMCID: PMC6540691 DOI: 10.1002/ece3.5145] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/06/2019] [Accepted: 03/13/2019] [Indexed: 12/04/2022] Open
Abstract
Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management implications, particularly with respect to disease spread. Although the role of adult dispersal in spreading disease has been documented, the potential influence of disease on dispersal has received little attention. African buffalo (Syncerus caffer) are wide-ranging and harbor many pathogens that can affect nearby livestock. Dispersal of adult buffalo has been described, but ecological and social drivers of buffalo dispersal are poorly understood. We investigated drivers of adult buffalo dispersal during a 4-year longitudinal study at Kruger National Park, South Africa. We monitored the spatial movement of 304 female buffalo in two focal areas using satellite and radio collars, capturing each buffalo every 6 months to assess animal traits and disease status. We used generalized linear mixed models to determine whether likelihood of dispersal for individual female buffalo was influenced by animal traits, herd identity, environmental variables, gastrointestinal parasites, or microparasite infections. The likelihood and drivers of buffalo dispersal varied by herd, area, and year. In the Lower Sabie herd, where resources were abundant, younger individuals were more likely to disperse, with most dispersal occurring in the early wet season and during an unusually dry year, 2009. In the resource-poor Crocodile Bridge area, buffalo in poor condition were most likely to disperse. Our findings suggest that dispersal of female buffalo is driven by either seasonal (Lower Sabie) or perhaps social (Crocodile Bridge) resource restriction, indicating resource limitation and dispersal decisions are tightly linked for this social ungulate. We found no direct effects of infections on buffalo dispersal, assuaging fears that highly infectious individuals might be more prone to dispersing, which could accelerate the spatial spread of infectious diseases.
Collapse
Affiliation(s)
- Robert S. Spaan
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon
| | - Clinton W. Epps
- Department of Fisheries and WildlifeOregon State UniversityCorvallisOregon
| | - Vanessa O. Ezenwa
- Department of Infectious Diseases, Odum School of EcologyUniversity of GeorgiaAthensGeorgia
| | - Anna E. Jolles
- Department of Biomedical SciencesOregon State UniversityCorvallisOregon
- Department of Integrative BiologyOregon State UniversityCorvallisOregon
| |
Collapse
|
23
|
Moreira X, Abdala-Roberts L, Pérez-Ramos IM, Knops JMH, Pesendorfer MB, Koenig WD, Mooney KA. Weather cues associated with masting behavior dampen the negative autocorrelation between past and current reproduction in oaks. Am J Bot 2019; 106:51-60. [PMID: 30633821 DOI: 10.1002/ajb2.1210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/17/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY The influence of weather conditions on masting and the ecological advantages of this reproductive behavior have been the subject of much interest. Weather conditions act as cues influencing reproduction of individual plants, and similar responses expressed across many individuals lead to population-level synchrony in reproductive output. In turn, synchrony leads to benefits from economies of scale such as enhanced pollination success and seed predator satiation. However, there may also be individual-level benefits from reproductive responses to weather cues, which may explain the origin of masting in the absence of economies of scale. In a previous study, we found support for a mechanism whereby individual responses to weather cues attenuate the negative autocorrelation between past and current annual seed production-a pattern typically attributed to resource limitation and reproductive tradeoffs among years. METHODS Here we provide a follow-up and more robust evaluation of this hypothesis in 12 species of oaks (Quercus spp.), testing for a negative autocorrelation (tradeoff) between past and current reproduction and whether responses to weather cues associated with masting reduce the strength of this negative autocorrelation. KEY RESULTS Our results showed a strong negative autocorrelation for 11 of the species, and that species-specific reproductive responses to weather cues dampened this negative autocorrelation in 10 of them. CONCLUSIONS This dampening effect presumably reflects a reduction in resource limitation or increased resource use associated with weather conditions, and suggests that responses to weather cues conferring these advantages should be selected for based on individual benefits.
Collapse
Affiliation(s)
- Xoaquín Moreira
- Misión Biológica de Galicia (MBG-CSIC), Apdo. 28, 36080, Pontevedra, Galicia, Spain
| | - Luis Abdala-Roberts
- Departamento de Ecología Tropical, Universidad Autónoma de Yucatán, Apartado Postal 4-116, Itzimna, 97000, Mérida, Yucatán, Mexico
| | - Ignacio M Pérez-Ramos
- Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), P.O. Box 1052, 41080, Sevilla, Andalucía, Spain
| | - Johannes M H Knops
- Department of Health and Environmental Sciences, Xi'an Jiaotong Liverpool University, Suzhou, 215123, China
| | - Mario B Pesendorfer
- Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York, 14850, USA
| | - Walter D Koenig
- Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York, 14850, USA
| | - Kailen A Mooney
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA, 92697
| |
Collapse
|
24
|
Rueger T, Barbasch TA, Wong MYL, Srinivasan M, Jones GP, Buston PM. Reproductive control via the threat of eviction in the clown anemonefish. Proc Biol Sci 2018; 285:20181295. [PMID: 30464062 PMCID: PMC6253369 DOI: 10.1098/rspb.2018.1295] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 11/01/2018] [Indexed: 11/12/2022] Open
Abstract
In social groups, high reproductive skew is predicted to arise when the reproductive output of a group is limited, and dominant individuals can suppress subordinate reproductive efforts. Reproductive suppression is often assumed to occur via overt aggression or the threat of eviction. It is unclear, however, whether the threat of eviction alone is sufficient to induce reproductive restraint by subordinates. Here, we test two assumptions of the restraint model of reproductive skew by investigating whether resource limitation generates reproductive competition and whether the threat of eviction leads to reproductive restraint in the clown anemonefish Amphiprion percula First, we use a feeding experiment to test whether reproduction is resource limited, which would create an incentive for the dominant pair to suppress subordinate reproduction. We show that the number of eggs laid increased in the population over the study period, but the per cent increase in fed groups was more than twice that in unfed groups (205% and 78%, respectively). Second, we use an eviction experiment to test whether the dominant pair evicts mature subordinates, which would create an incentive for the subordinates to forgo reproduction. We show that mature subordinates are seven times more likely to be evicted than immature subordinates of the same size. In summary, we provide experimental support for the assumptions of the restraint model by showing that resource limitation creates reproductive competition and a credible threat of eviction helps explain why subordinates forego reproduction. Transactional models of reproductive skew may apply well to this and other simple systems.
Collapse
Affiliation(s)
- T Rueger
- Department of Biology and Marine Program, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - T A Barbasch
- Department of Biology and Marine Program, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - M Y L Wong
- Centre for Sustainable Ecosystems Solutions, School of Biological Sciences, University of Wollongong, Wollongong 2522, New South Wales, Australia
| | - M Srinivasan
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia
| | - G P Jones
- College of Science and Engineering, James Cook University, Townsville 4811, Queensland, Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville 4811, Queensland, Australia
| | - P M Buston
- Department of Biology and Marine Program, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| |
Collapse
|
25
|
Maggio A, Bressan RA, Zhao Y, Park J, Yun DJ. It's Hard to Avoid Avoidance: Uncoupling the Evolutionary Connection between Plant Growth, Productivity and Stress "Tolerance". Int J Mol Sci 2018; 19:E3671. [PMID: 30463352 PMCID: PMC6274854 DOI: 10.3390/ijms19113671] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 11/06/2018] [Accepted: 11/15/2018] [Indexed: 12/03/2022] Open
Abstract
In the last 100 years, agricultural developments have favoured selection for highly productive crops, a fact that has been commonly associated with loss of key traits for environmental stress tolerance. We argue here that this is not exactly the case. We reason that high yield under near optimal environments came along with hypersensitization of plant stress perception and consequently early activation of stress avoidance mechanisms, such as slow growth, which were originally needed for survival over long evolutionary time periods. Therefore, mechanisms employed by plants to cope with a stressful environment during evolution were overwhelmingly geared to avoid detrimental effects so as to ensure survival and that plant stress "tolerance" is fundamentally and evolutionarily based on "avoidance" of injury and death which may be referred to as evolutionary avoidance (EVOL-Avoidance). As a consequence, slow growth results from being exposed to stress because genes and genetic programs to adjust growth rates to external circumstances have evolved as a survival but not productivity strategy that has allowed extant plants to avoid extinction. To improve productivity under moderate stressful conditions, the evolution-oriented plant stress response circuits must be changed from a survival mode to a continued productivity mode or to avoid the evolutionary avoidance response, as it were. This may be referred to as Agricultural (AGRI-Avoidance). Clearly, highly productive crops have kept the slow, reduced growth response to stress that they evolved to ensure survival. Breeding programs and genetic engineering have not succeeded to genetically remove these responses because they are polygenic and redundantly programmed. From the beginning of modern plant breeding, we have not fully appreciated that our crop plants react overly-cautiously to stress conditions. They over-reduce growth to be able to survive stresses for a period of time much longer than a cropping season. If we are able to remove this polygenic redundant survival safety net we may improve yield in moderately stressful environments, yet we will face the requirement to replace it with either an emergency slow or no growth (dormancy) response to extreme stress or use resource management to rescue crops under extreme stress (or both).
Collapse
Affiliation(s)
- Albino Maggio
- Department of Agricultural Science, University of Napoli Federico II, 80055 Portici, NA, Italy.
| | - Ray A Bressan
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-2010, USA.
| | - Yang Zhao
- Shanghai Center for Plant Stress Biology and CAS Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
| | - Junghoon Park
- Department of Biomedical Science and Engineering Konkuk University, Seoul 05029, Korea.
| | - Dae-Jin Yun
- Department of Biomedical Science and Engineering Konkuk University, Seoul 05029, Korea.
| |
Collapse
|
26
|
Rebolleda-Gómez M, Travisano M. The Cost of Being Big: Local Competition, Importance of Dispersal, and Experimental Evolution of Reversal to Unicellularity. Am Nat 2018; 192:731-744. [PMID: 30444659 DOI: 10.1086/700095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Multicellularity provides multiple benefits. Nonetheless, unicellularity is ubiquitous, and there have been multiple cases of evolutionary reversal to a unicellular organization. In this article, we explore some of the costs of multicellularity as well as the possibility and dynamics of evolutionary reversals to unicellularity. We hypothesize that recently evolved multicellular organisms would face a high cost of increased competition for local resources in spatially structured environments because of larger size and increased cell densities. To test this hypothesis we conducted competition assays, computer simulations, and selection experiments using isolates of Saccharomyces cerevisiae that recently evolved multicellularity. In well-mixed environments, multicellular isolates had lower growth rates relative to their unicellular ancestor because of limitations of space and resource acquisition. In structured environments with localized resources, cells in both multicellular and unicellular isolates grew at a similar rate. Despite similar growth, higher local density of cells in multicellular groups led to increased competition and higher fitness costs in spatially structured environments. In structured environments all of the multicellular isolates rapidly evolved a predominantly unicellular life cycle, while in well-mixed environments reversal was more gradual. Taken together, these results suggest that a lack of dispersal, leading to higher local competition, might have been one of the main constraints in the evolution of early multicellular forms.
Collapse
|
27
|
Abstract
Interspecific aggregations of prey may provide benefits by mitigating predation risk, but they can also create costs if they increase competition for resources or are more easily detectable by predators. Variation in predation risk and resource availability may influence the occurrence and fitness effects of aggregating in nature. Yet tests of such possibilities are lacking. Cavity-nesting birds provide an interesting test case. They compete aggressively for resources and experience low nest predation rates, which might predict dispersion, but across 19 years of study we found that they commonly aggregate by sharing nest trees. Tree sharing was more common when aspen were more abundant and was somewhat more common in years with higher nest predation risk. Nest success was higher in shared trees when nest predation risk was higher than average. Ultimately, the costs and benefits of aggregating (nest tree sharing) varied across years, and we outline hypotheses for future studies.
Collapse
|
28
|
Chinn SM, Monson DH, Tinker MT, Staedler MM, Crocker DE. Lactation and resource limitation affect stress responses, thyroid hormones, immune function, and antioxidant capacity of sea otters ( Enhydra lutris). Ecol Evol 2018; 8:8433-8447. [PMID: 30250713 PMCID: PMC6145021 DOI: 10.1002/ece3.4280] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/22/2018] [Accepted: 05/19/2018] [Indexed: 12/11/2022] Open
Abstract
Lactation is the most energetically demanding stage of reproduction in female mammals. Increased energetic allocation toward current reproduction may result in fitness costs, although the mechanisms underlying these trade-offs are not well understood. Trade-offs during lactation may include reduced energetic allocation to cellular maintenance, immune response, and survival and may be influenced by resource limitation. As the smallest marine mammal, sea otters (Enhydra lutris) have the highest mass-specific metabolic rate necessitating substantial energetic requirements for survival. To provide the increased energy needed for lactation, female sea otters significantly increase foraging effort, especially during late-lactation. Caloric insufficiency during lactation is reflected in the high numbers of maternal deaths due to End-Lactation Syndrome in the California subpopulation. We investigated the effects of lactation and resource limitation on maternal stress responses, metabolic regulation, immune function, and antioxidant capacity in two subspecies of wild sea otters (northern: E. l. nereis and southern: E. l. kenyoni) within the California, Washington, and Alaska subpopulations. Lactation and resource limitation were associated with reduced glucocorticoid responses to acute capture stress. Corticosterone release was lower in lactating otters. Cortisol release was lower under resource limitation and suppression during lactation was only evident under resource limitation. Lactation and resource limitation were associated with alterations in thyroid hormones. Immune responses and total antioxidant capacity were not reduced by lactation or resource limitation. Southern sea otters exhibited higher concentrations of antioxidants, immunoglobulins, and thyroid hormones than northern sea otters. These data provide evidence for allocation trade-offs during reproduction and in response to nutrient limitation but suggest self-maintenance of immune function and antioxidant defenses despite energetic constraints. Income-breeding strategists may be especially vulnerable to the consequences of stress and modulation of thyroid function when food resources are insufficient to support successful reproduction and may come at a cost to survival, and thereby influence population trends.
Collapse
Affiliation(s)
- Sarah M. Chinn
- Department of BiologySonoma State UniversityRohnert ParkCalifornia
| | | | - M. Tim Tinker
- U.S. Geological SurveyWestern Ecological Research CenterLong Marine LaboratorySanta CruzCalifornia
| | | | | |
Collapse
|
29
|
Dai C, Luo WJ, Gong YB, Liu F, Wang ZX. Resource reallocation patterns within Sagittaria trifolia inflorescences following differential pollination. Am J Bot 2018; 105:803-811. [PMID: 29710426 DOI: 10.1002/ajb2.1053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/29/2018] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Understanding resource allocation to reproduction, a key factor in life history tradeoffs, has long intrigued plant ecologists. Despite the recognized importance of understanding the movement of resources among flowers following variable pollination, the patterns of resource reallocation to plant reproductive organs have not been thoroughly addressed. In this study, we aimed to empirically explore how resources redistribute within inflorescences in response to differential pollination intensities. METHODS Using a common herb, Sagittaria trifolia, we conducted supplemental and controlled pollination for single, some, or all flowers in simple and complex inflorescences, and compared their resulting fruiting probabilities, seed production, and average seed masses. KEY RESULTS Pollen supplementation of a single flower significantly increased its fruiting probability; however, the same manipulation of an inflorescence did not increase its overall reproduction. Single pollen-supplemented flowers had a higher percentage fruit set than inflorescences receiving supplemental pollination. In complex inflorescences, supplemental pollination had no effect on the reproductive success of flowers on the lateral or main branches. CONCLUSIONS We provided evidence of resource reallocation from controlled to pollen-supplemented flowers in simple inflorescences; however, resources were unlikely to be reallocated between the main and lateral branches in the complex inflorescences, suggesting that flowering branches represent integrated physiological units in S. trifolia. The results also demonstrated that single-flower supplemental pollination would exaggerate pollen limitation and lead to a biased understanding of a plant's reproductive status.
Collapse
Affiliation(s)
- Can Dai
- School of Resources and Environmental Science, Hubei University, Wuhan, 430062, China
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Wuhan, 430062, China
- Hubei Key Laboratory of Regional Development and Environmental Response (Hubei University), Wuhan, 430062, China
| | - Wen-Jie Luo
- School of Resources and Environmental Science, Hubei University, Wuhan, 430062, China
| | - Yan-Bing Gong
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Fan Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China
| | - Zheng-Xiang Wang
- School of Resources and Environmental Science, Hubei University, Wuhan, 430062, China
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Wuhan, 430062, China
- Hubei Key Laboratory of Regional Development and Environmental Response (Hubei University), Wuhan, 430062, China
| |
Collapse
|
30
|
Kilgour RJ, McAdam AG, Betini GS, Norris DR. Experimental evidence that density mediates negative frequency-dependent selection on aggression. J Anim Ecol 2018; 87:1091-1101. [PMID: 29446094 DOI: 10.1111/1365-2656.12813] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/25/2018] [Indexed: 11/28/2022]
Abstract
Aggression can be beneficial in competitive environments if aggressive individuals are more likely to access resources than non-aggressive individuals. However, variation in aggressive behaviour persists within populations, suggesting that high levels of aggression might not always be favoured. The goal of this study was to experimentally assess the effects of population density and phenotypic frequency on selection on aggression in a competitive environment. We compared survival of two strains of Drosophila melanogaster that differ in aggression across three density treatments and five frequency treatments (single strain groups, equal numbers of each strain and strains mixed at 3:1 and 1:3 ratios) during a period of limited resources. While there was no difference in survival across single-strain treatments, survival was strongly density dependent, with declining survival as density increased. Furthermore, at medium and high densities, there was evidence of negative frequency-dependent selection, where rare strains experienced greater survival than common strains. However, there was no evidence of negative frequency-dependent selection at low density. Our results indicate that the benefits of aggression during periods of limited resources can depend on the interaction between the phenotypic composition of populations and population density, both of which are mechanisms that could maintain variation in aggressive behaviours within natural populations.
Collapse
Affiliation(s)
- R Julia Kilgour
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Andrew G McAdam
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Gustavo S Betini
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - D Ryan Norris
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| |
Collapse
|
31
|
Chen M, Zhao XY. Effect of pollen and resource limitation on reproduction of Zygophyllum xanthoxylum in fragmented habitats. Ecol Evol 2017; 7:9076-9084. [PMID: 29152199 PMCID: PMC5677495 DOI: 10.1002/ece3.3465] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/01/2017] [Indexed: 12/04/2022] Open
Abstract
Limitations on pollen and resources may significantly affect plant reproduction in fragmented habitats. In this study, phenology and pollinator frequency and activity were investigated to estimate the role of pollinators in Zygophyllum xanthoxylum reproduction, and this species is ecologically important in northwest China. In addition, the relative impact of restrictive amounts of pollen and resources on the seed set per flower was evaluated. It was found that adding pollen boosted the size of the seed set per flower, but had no significant effect on the number of flowers. By contrast, the addition of resources increased flower numbers as well as had a slight impact on the seed set per flower. These results indicate the amount of available pollen is a limiting factor for reproductive success. Moreover, Apis mellifera was identified as the most effective pollinator of Z. xanthoxylum, and there were more overall pollinators and visitations in the control than in the fragmented habitats. Furthermore, the limitations in pollen were more restrictive in the fragmented area than in the control. This was due to increased pollinator visitations in the control that could ameliorate the effects of lower pollen levels. When there is a limited availability of suitable pollinators, self‐pollination is critical in fragmented habitats. Z. xanthoxylum has reproductive strategies that aid in adapting to harsh environments, including protogyny and delayed selfing.
Collapse
Affiliation(s)
- Min Chen
- Northwest Institute of Eco-Environment and Resources CAS Lanzhou China
| | - Xue-Yong Zhao
- Northwest Institute of Eco-Environment and Resources CAS Lanzhou China
| |
Collapse
|
32
|
Zu P, Schiestl FP. The effects of becoming taller: direct and pleiotropic effects of artificial selection on plant height in Brassica rapa. Plant J 2017; 89:1009-1019. [PMID: 27889935 DOI: 10.1111/tpj.13440] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/07/2016] [Accepted: 11/18/2016] [Indexed: 06/06/2023]
Abstract
Plant height is an important trait for plant reproductive success. Plant height is often under pollinator-mediated selection, and has been shown to be correlated with various other traits. However, few studies have examined the evolutionary trajectory of plant height under selection and the pleiotropic effects of plant height evolution. We conducted a bi-directional artificial selection experiment on plant height with fast cycling Brassica rapa plants to estimate its heritability and genetic correlations, and to reveal evolutionary responses to artificial selection on height and various correlated traits. With the divergent lines obtained through artificial selection, we subsequently conducted pollinator-choice assays and investigated resource limitation of fruit production. We found that plant height variation is strongly genetically controlled (with a realized heritability of 41-59%). Thus, plant height can evolve rapidly under phenotypic selection. In addition, we found remarkable pleiotropic effects in phenology, morphology, floral scent, color, nectar and leaf glucosinolates. Most traits were increased in tall-line plants, but flower size, UV reflection and glucosinolates were decreased, indicating potential trade-offs. Pollinators preferred plants of the tall selection lines over the short selection lines in both greenhouse experiments with bumblebees and field experiment with natural pollinators. We did not detect any differences in resource limitation between plants of the different selection lines. Overall, our study predicts that increased height should evolve under positive pollinator-mediated directional selection with potential trade-offs in floral signals and herbivore defense.
Collapse
Affiliation(s)
- Pengjuan Zu
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Florian P Schiestl
- Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| |
Collapse
|
33
|
Burstahler CM, Roth JD, Gau RJ, Murray DL. Demographic differences in diet breadth of Canada lynx during a fluctuation in prey availability. Ecol Evol 2016; 6:6366-75. [PMID: 27648249 PMCID: PMC5016656 DOI: 10.1002/ece3.2115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 02/20/2016] [Accepted: 03/20/2016] [Indexed: 11/10/2022] Open
Abstract
Population dynamics of specialist carnivores are closely linked to prey availability, but the extent of variability in diet breadth of individual carnivores relative to natural variability in the abundance of their primary prey is not well understood. Canada lynx (Lynx canadensis) specialize on snowshoe hares (Lepus americanus) and exhibit cyclic fluctuations in abundance that lag 1–2 years behind those of snowshoe hares. Declining hare densities spur demographic changes in lynx, but it is unclear whether a corresponding increase in diet breadth occurs: (1) broadly across a lynx population; (2) only among individuals who are able to effectively switch to alternative prey; or (3) only among individuals who cannot capture sufficient primary prey. We measured stable isotope ratios of lynx muscle tissue spanning a cyclic increase and decline in hare density (1998–2001) in Fort Providence, NT, Canada. We found that lynx cohorts responded differently to hare population change, with yearling animals having broader diets at low hare densities, while adults and dependent juveniles maintained a constant diet through the initial decline in hare density. This result was consistent irrespective of lynx sex and indicates that yearling lynx likely are forced to adopt a broader diet when primary prey densities decline. Our results imply that select cohorts of specialist carnivores can exhibit high dietary plasticity in response to changes in primary prey abundance, prompting the need to determine whether increased diet breadth in young lynx is a successful strategy for surviving through periods of snowshoe hare scarcity. In this way, cohort‐specific niche expansion could strongly affect the dynamics of organisms exhibiting population cycles.
Collapse
Affiliation(s)
- Christa M Burstahler
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - James D Roth
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - Robert J Gau
- Department of Environment & Natural Resources Government of the Northwest Territories Yellowknife Northwest Territories Canada
| | - Dennis L Murray
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada; Department of Biology Trent University Peterborough Ontario Canada
| |
Collapse
|
34
|
Hove AA, Mazer SJ, Ivey CT. Seed set variation in wild Clarkia populations: teasing apart the effects of seasonal resource depletion, pollen quality, and pollen quantity. Ecol Evol 2016; 6:6524-6536. [PMID: 27777726 PMCID: PMC5058524 DOI: 10.1002/ece3.2372] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 06/13/2016] [Accepted: 07/11/2016] [Indexed: 12/02/2022] Open
Abstract
In habitats where resource availability declines during the growing season, selection may favor early‐flowering individuals. Under such ephemerally favorable conditions, late‐blooming species (and individuals) may be particularly vulnerable to resource limitation of seed production. In California, a region prone to seasonal drought, members of the annual genus Clarkia are among the last to flower in the spring. We compared pollen limitation (PL) of seed set and outcrossing rates between early‐ and late‐flowering individuals in two mixed‐mating Clarkia taxa to detect whether flowering time is associated with changes in seed set due to resource depletion, PL, or increased selfing. In 2008–2010, we hand‐pollinated one flower on a total of 1855 individual plants either Early (near the onset of flowering) or Late (near the end of flowering) in the flowering season and compared seed set to adjacent, open‐pollinated flowers on the same stem. To assess the contribution of pollen quality to reproduction, we first (2008) used allozymes to estimate outcrossing rates of seeds produced by Early and Late open‐pollinated flowers. Second (2009), we conducted an anther‐removal experiment to estimate self‐pollen deposition. Seed set in Clarkia unguiculata was not pollen‐limited. Clarkia xantiana ssp. xantiana was pollen‐limited in 2008 and 2010, but not 2009. PL did not differ between Early and Late treatments. In both taxa, seed set of Early flowers was greater than Late flowers, but not due to PL in the latter. Reproduction was generally pollinator‐dependent. Most pollen deposition was xenogamous, and outcrossing rates were >0.7 – and similar between Early and Late periods. These results suggest that pollen receipt and pollen quality remain seasonally consistent. By contrast, the resources necessary to provision seeds decline, reducing the fitness benefits associated with resource allocation to ovules.
Collapse
Affiliation(s)
- Alisa A Hove
- Biology Department Warren Wilson College PO Box 9000 Asheville NC 28815-6217
| | - Susan J Mazer
- Ecology, Evolution, and Marine Biology Department University of California Santa Barbara CA 93106
| | - Christopher T Ivey
- Department of Biological Sciences California State University Chico Chico CA 95929-0515
| |
Collapse
|
35
|
Hanly PJ, Haase AT. The Interactive Role of Immature Stage Competition, Cohort Overlap, and Resource Limitation on the Population Viability of the Treehole Mosquito Aedes triseriatus (Diptera: Culicidae). J Med Entomol 2016; 53:562-568. [PMID: 27026157 DOI: 10.1093/jme/tjw021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/20/2016] [Indexed: 06/05/2023]
Abstract
The size and success of epidemiologically significant adult mosquito populations are inherently tied to the conditions of the aquatic habitat in which juvenile stages grow until eclosion. While resource competition and quality are well-established controls to juvenile growth and survival, the implications to overall population rates of increase are less understood due to the large sample sizes needed to parameterize population models for all five juvenile life stages under multiple environmental and demographic conditions. Here, we present the results of >4,300 trials of wild-caught Aedes triseriatus (Say, 1823) larvae and pupae reared under varying resource quantity crossed by the presence or absence of competition within a single cohort as well as multiple overlapping cohorts. Demographic projection was used to make predictions of the realized growth rates of simulated Ae. triseriatus populations across the range of potential Ae. triseriatus fecundity. Further, to inform control efforts on juvenile habitat, we constructed a stochastic simulation to estimate the rates of successful emergence from habitats under different resource regimes and levels of cohort overlap. We found that while Ae. triseriatus populations were robust to low resource levels and competition within a cohort, the combination of these stressors with multiple cohort overlap led to self-limitation or complete collapse of mosquito populations. Despite this importance of intraspecific competition to population viability, the stochastic simulation revealed only a modest self-limitation of adult emergence, with the clear implication that high-resource habitats are a higher value control target.
Collapse
Affiliation(s)
- Patrick J Hanly
- W. K. Kellogg Biological Station, Hickory Corners, MI 49060 (; ),
- W. K. Kellogg Biological Station, Hickory Corners, MI 49060 (; )
- W. K. Kellogg Biological Station, Hickory Corners, MI 49060 (; )
| | - Amanda T Haase
- W. K. Kellogg Biological Station, Hickory Corners, MI 49060 (; )
- W. K. Kellogg Biological Station, Hickory Corners, MI 49060 (; )
| |
Collapse
|
36
|
Rodríguez-Pérez J, Traveset A. Effects of flowering phenology and synchrony on the reproductive success of a long-flowering shrub. AoB Plants 2016; 8:plw007. [PMID: 26839285 PMCID: PMC4793561 DOI: 10.1093/aobpla/plw007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/21/2016] [Indexed: 05/25/2023]
Abstract
Flowering phenology and synchrony with biotic and abiotic resources are crucial traits determining the reproductive success in insect-pollinated plants. In seasonal climates, plants flowering for long periods should assure reproductive success when resources are more predictable. In this work, we evaluated the relationship between flowering phenology and synchrony and reproductive success in Hypericum balearicum, a shrub flowering all year round but mainly during spring and summer. We studied two contrasting localities (differing mostly in rainfall) during 3 years, and at different biological scales spanning from localities to individual flowers and fruits. We first monitored (monthly) flowering phenology and reproductive success (fruit and seed set) of plants, and assessed whether in the locality with higher rainfall plants had longer flowering phenology and synchrony and relatively higher reproductive success within or outside the flowering peak. Secondly, we censused pollinators on H. balearicum individuals and measured reproductive success along the flowering peak of each locality to test for an association between (i) richness and abundance of pollinators and (ii) fruit and seed set, and seed weight. We found that most flowers (∼90 %) and the highest fruit set (∼70 %) were produced during the flowering peak of each locality. Contrary to expectations, plants in the locality with lower rainfall showed more relaxed flowering phenology and synchrony and set more fruits outside the flowering peak. During the flowering peak of each locality, the reproductive success of early-flowering individuals depended on a combination of both pollinator richness and abundance and rainfall; by contrast, reproductive success of late-flowering individuals was most dependent on rainfall. Plant species flowering for long periods in seasonal climates, thus, appear to be ideal organisms to understand how flowering phenology and synchrony match with biotic and abiotic resources, and how this ultimately influences plant reproductive success.
Collapse
Affiliation(s)
- Javier Rodríguez-Pérez
- Institut Mediterrani d'Estudis Avançats - IMEDEA (CSIC-UIB), Miquel Marqués, 21, E07190 Esporles, Mallorca, Balearic Islands, Spain Present address: Aranzadi Sciences Society, Zorroagagaina 11, E20014 Donostia-San Sebastián, Spain
| | - Anna Traveset
- Institut Mediterrani d'Estudis Avançats - IMEDEA (CSIC-UIB), Miquel Marqués, 21, E07190 Esporles, Mallorca, Balearic Islands, Spain Present address: Aranzadi Sciences Society, Zorroagagaina 11, E20014 Donostia-San Sebastián, Spain
| |
Collapse
|
37
|
Okamoto DK, Schmitt RJ, Holbrook SJ. Stochastic density effects on adult fish survival and implications for population fluctuations. Ecol Lett 2015; 19:153-162. [PMID: 26607838 DOI: 10.1111/ele.12547] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/28/2015] [Accepted: 10/16/2015] [Indexed: 11/29/2022]
Abstract
The degree to which population fluctuations arise from variable adult survival relative to variable recruitment has been debated widely for marine organisms. Disentangling these effects remains challenging because data generally are not sufficient to evaluate if and how adult survival rates are regulated by stochasticity and/or population density. Using unique time series for a largely unexploited reef fish, we found both population density and stochastic food supply impacted adult survival. The estimated effect of variable survival on adult abundance (both mean and variability) rivalled that of variable recruitment. Moreover, we show density-dependent adult survival can dampen impacts of stochastic recruitment. Thus, food variability may alter population fluctuations by simultaneously regulating recruitment and compensatory adult survival. These results provide an additional mechanism for why intensified density-independent mortality (via harvest or other means) amplifies population fluctuations and emphasises need for research evaluating the causes and consequences of variability in adult survival.
Collapse
Affiliation(s)
- Daniel K Okamoto
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara EEMB, Santa Barbara, CA, 93106-9610, USA
| | - Russell J Schmitt
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara EEMB, Santa Barbara, CA, 93106-9610, USA.,Marine Science Institute, University of California, Santa Barbara EEMB, Santa Barbara, CA, 93106-9610, USA
| | - Sally J Holbrook
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara EEMB, Santa Barbara, CA, 93106-9610, USA.,Marine Science Institute, University of California, Santa Barbara EEMB, Santa Barbara, CA, 93106-9610, USA
| |
Collapse
|
38
|
Ellis CN, Traverse CC, Mayo-Smith L, Buskirk SW, Cooper VS. Character displacement and the evolution of niche complementarity in a model biofilm community. Evolution 2015; 69:283-93. [PMID: 25494960 PMCID: PMC4335599 DOI: 10.1111/evo.12581] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/21/2014] [Indexed: 01/04/2023]
Abstract
Colonization of vacant environments may catalyze adaptive diversification and be followed by competition within the nascent community. How these interactions ultimately stabilize and affect productivity are central problems in evolutionary ecology. Diversity can emerge by character displacement, in which selection favors phenotypes that exploit an alternative resource and reduce competition, or by facilitation, in which organisms change the environment and enable different genotypes or species to become established. We previously developed a model of long-term experimental evolution in which bacteria attach to a plastic bead, form a biofilm, and disperse to a new bead. Here, we focus on the evolution of coexisting mutants within a population of Burkholderia cenocepacia and how their interactions affected productivity. Adaptive mutants initially competed for space, but later competition declined, consistent with character displacement and the predicted effects of the evolved mutations. The community reached a stable equilibrium as each ecotype evolved to inhabit distinct, complementary regions of the biofilm. Interactions among ecotypes ultimately became facilitative and enhanced mixed productivity. Observing the succession of genotypes within niches illuminated changing selective forces within the community, including a fundamental role for genotypes producing small colony variants that underpin chronic infections caused by B. cenocepacia.
Collapse
Affiliation(s)
- Crystal N Ellis
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, 212 Rudman Hall, Durham, New Hampshire, 03824; Current Address: Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114.
| | | | | | | | | |
Collapse
|
39
|
Zhang C, Willis CG, Burghardt LT, Qi W, Liu K, de Moura Souza-Filho PR, Ma Z, Du G. The community-level effect of light on germination timing in relation to seed mass: a source of regeneration niche differentiation. New Phytol 2014; 204:496-506. [PMID: 25081830 DOI: 10.1111/nph.12955] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 06/13/2014] [Indexed: 06/03/2023]
Abstract
Within a community, species may germinate at different times so as to mitigate competition and to take advantage of different aspects of the seasonal environment (temporal niche differentiation). We illustrated a hypothesis of the combined effects of abiotic and biotic competitive factors on germination timing and the subsequent upscale effects on community assembly. We estimated the germination timing (GT) for 476 angiosperm species of the eastern Tibetan Plateau grasslands under two light treatments in the field: high (i.e. natural) light and low light. We also measured the shift in germination timing (SGT) across treatments for all species. Furthermore, we used phylogenetic comparative methods to test if GT and SGT were associated with seed mass, an important factor in competitive interactions. We found a significant positive correlation between GT and seed mass in both light treatments. Additionally, small seeds (early germinating seeds) tended to germinate later and large seeds (late germinating seeds) tended to germinate earlier under low light vs high light conditions. Low light availability can reduce temporal niche differentiation by increasing the overlap in germination time between small and large seeds. In turn, reduced temporal niche differentiation may increase competition in the process of community assembly.
Collapse
Affiliation(s)
- Chunhui Zhang
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, 810008, China
| | - Charles G Willis
- Center for the Environment, Harvard University, Cambridge, MA, 02138, USA
| | | | - Wei Qi
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Kun Liu
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | | | - Zhen Ma
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, 810008, China
| | - Guozhen Du
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| |
Collapse
|
40
|
Affiliation(s)
- Caroline E Farrior
- Princeton Environmental Institute, Princeton University, 106 Guyot Hall, Princeton, NJ, 08544, USA
| |
Collapse
|
41
|
Lalubin F, Delédevant A, Glaizot O, Christe P. Natural malaria infection reduces starvation resistance of nutritionally stressed mosquitoes. J Anim Ecol 2014; 83:850-7. [PMID: 24286465 DOI: 10.1111/1365-2656.12190] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 11/24/2013] [Indexed: 11/26/2022]
Abstract
In disease ecology, there is growing evidence that environmental quality interacts with parasite and host to determine host susceptibility to an infection. Most studies of malaria parasites have focused on the infection costs incurred by the hosts, and few have investigated the costs on mosquito vectors. The interplay between the environment, the vector and the parasite has therefore mostly been ignored and often relied on unnatural or allopatric Plasmodium/vector associations. Here, we investigated the effects of natural avian malaria infection on both fecundity and survival of field-caught female Culex pipiens mosquitoes, individually maintained in laboratory conditions. We manipulated environmental quality by providing mosquitoes with different concentrations of glucose-feeding solution prior to submitting them to a starvation challenge. We used molecular-based methods to assess mosquitoes' infection status. We found that mosquitoes infected with Plasmodium had lower starvation resistance than uninfected ones only under low nutritional conditions. The effect of nutritional stress varied with time, with the difference of starvation resistance between optimally and suboptimally fed mosquitoes increasing from spring to summer, as shown by a significant interaction between diet treatment and months of capture. Infected and uninfected mosquitoes had similar clutch size, indicating no effect of infection on fecundity. Overall, this study suggests that avian malaria vectors may suffer Plasmodium infection costs in their natural habitat, under certain environmental conditions. This may have major implications for disease transmission in the wild.
Collapse
Affiliation(s)
- Fabrice Lalubin
- Department of Ecology and Evolution, Le Biophore, University of Lausanne, CH-1015, Lausanne, Switzerland.,Museum of Zoology, Place de la Riponne 6, CH-1014, Lausanne, Switzerland
| | - Aline Delédevant
- Department of Ecology and Evolution, Le Biophore, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Olivier Glaizot
- Department of Ecology and Evolution, Le Biophore, University of Lausanne, CH-1015, Lausanne, Switzerland.,Museum of Zoology, Place de la Riponne 6, CH-1014, Lausanne, Switzerland
| | - Philippe Christe
- Department of Ecology and Evolution, Le Biophore, University of Lausanne, CH-1015, Lausanne, Switzerland
| |
Collapse
|
42
|
Evans B, Borowicz V. Verbesina alternifolia Tolerance to the Holoparasite Cuscuta gronovii and the Impact of Drought. Plants (Basel) 2013; 2:635-49. [PMID: 27137396 PMCID: PMC4844395 DOI: 10.3390/plants2040635] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 09/25/2013] [Accepted: 10/09/2013] [Indexed: 11/17/2022]
Abstract
Holoparasites are nonphotosynthetic plants that acquire all resources from hosts. The holoparasite Cuscuta gronovii is native to much of the US with a broad host range including Verbesina alternifolia, an understory perennial. Both species grow in moderate to moist soils and occur in habitats that may experience prolonged or episodic drought. We applied the Wise-Abrahamson Limiting Resource Model (LRM) developed for plant-herbivore relations to examine the effects of pattern of drought stress on tolerance of V. alternifolia to parasitism by C. gronovii. Individual plants were assigned one of six treatments that were combinations of parasite (none or addition of parasite) and drought stress (well-watered, continuously-stressed, or pulse-stressed). After pulse-stressed plants had experienced two wet-dry cycles all plants were harvested. Parasitism strongly reduced both shoot and root mass and well-watered hosts exhibited the greatest decline, indicating reduced tolerance to parasitism when water was readily available. This is consistent with the LRM if parasitism limits photosynthates available to the host. However, parasitism increased allocation to shoot and this effect did not differ between well-watered and drought-stressed plants, indicating equal tolerance. This outcome is in accord with an alternative prediction of the LRM if hosts are not carbon limited. Total pot productivity was reduced by parasitism and drought stress, and this effect was greater for pulse-stressed than for continuously-stressed hosts. We discuss the applicability of the LRM for understanding the effects of drought on tolerance to parasitism.
Collapse
Affiliation(s)
- Bethany Evans
- BEES Section, 4120/School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
| | - Victoria Borowicz
- BEES Section, 4120/School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
| |
Collapse
|
43
|
Tonsor SJ, Elnaccash TW, Scheiner SM. Developmental instability is genetically correlated with phenotypic plasticity, constraining heritability, and fitness. Evolution 2013; 67:2923-35. [PMID: 24094343 DOI: 10.1111/evo.12175] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 05/02/2013] [Indexed: 11/29/2022]
Abstract
Although adaptive plasticity would seem always to be favored by selection, it occurs less often than expected. This lack of ubiquity suggests that there must be trade-offs, costs, or limitations associated with plasticity. Yet, few costs have been found. We explore one type of limitation, a correlation between plasticity and developmental instability, and use quantitative genetic theory to show why one should expect a genetic correlation. We test that hypothesis using the Landsberg erecta × Cape Verde Islands recombinant inbred lines (RILs) of Arabidopsis thaliana. RILs were grown at four different nitrogen (N) supply levels that span the range of N availabilities previously documented in North American field populations. We found a significant multivariate relationship between the cross-environment trait plasticity and the within-environment, within-RIL developmental instability across 13 traits. This genetic covariation between plasticity and developmental instability has two costs. First, theory predicts diminished fitness for highly plastic lines under stabilizing selection, because their developmental instability and variance around the optimum phenotype will be greater compared to nonplastic genotypes. Second, empirically the most plastic traits exhibited heritabilities reduced by 57% on average compared to nonplastic traits. This demonstration of potential costs in inclusive fitness and heritability provoke a rethinking of the evolutionary role of plasticity.
Collapse
Affiliation(s)
- Stephen J Tonsor
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.
| | | | | |
Collapse
|
44
|
Padmanabha H, Bolker B, Lord CC, Rubio C, Lounibos LP. Food availability alters the effects of larval temperature on Aedes aegypti growth. J Med Entomol 2011; 48:974-84. [PMID: 21936315 PMCID: PMC4226433 DOI: 10.1603/me11020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Variation in temperature and food availability in larval habitats can influence the abundance, body size, and vector competence of the mosquito Aedes aegypti. Although increased temperature has energetic costs for growing larvae, how food resources influence the developmental response of this mosquito species to thermal conditions is unknown. We explored how rearing temperature and food affect allometric scaling between wing size and epidermal cell size in Ae. aegypti. Mosquitoes were reared at 22 and 28 degrees C across a gradient of field-collected detritus designed to simulate commonly observed natural larval food resources. Overall, reduced temperature and increased food level increased wing size, but only temperature affected cell size. Females fed the least food had the longest time to maturation, and their increases in wing size induced by cold temperature were associated with larger, rather than more, cells. By contrast, males fed the most food had the shortest time to maturation, and their increases in wing size induced by cold temperature were associated with more, rather than larger, cells. Therefore, food levels can alter the underlying physiological mechanisms generating temperature-size patterns in mosquitoes, suggesting that the control of development is sensitive to the combination of nutrient and thermal conditions, rather than each independently. Conditions prolonging development time may favor increased cell division over growth. We suggest that understanding the effects of climate change on Ae. aegypti vectorial capacity requires an improved knowledge of how water temperature interacts with limited food resources and competition in aquatic container habitats.
Collapse
Affiliation(s)
- H Padmanabha
- Instituto Nacional de Salud de Colombia, Vigilancia y Control en Salud Publica, Bogota, Colombia.
| | | | | | | | | |
Collapse
|
45
|
Lay CR, Linhart YB, Diggle PK. The good, the bad and the flexible: plant interactions with pollinators and herbivores over space and time are moderated by plant compensatory responses. Ann Bot 2011; 108:749-63. [PMID: 21724655 PMCID: PMC3170155 DOI: 10.1093/aob/mcr152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 05/10/2011] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Plants are sessile organisms that face selection by both herbivores and pollinators. Herbivores and pollinators may select on the same traits and/or mediate each others' effects. Erysimum capitatum (Brassicaceae) is a widespread and variable plant species with generalized pollination that is attacked by a number of herbivores. The following questions were addressed. (a) Are pollinators and herbivores attracted by similar plant traits? (b) Does herbivory affect pollinator preferences? (c) Do pollinators and/or herbivores affect fitness and select on plant traits? (d) Do plant compensatory responses affect the outcome of interactions among plants, pollinators and herbivores? (e) Do interactions among E. capitatum and its pollinators and herbivores differ among sites and years? METHODS In 2005 and 2006, observational and experimental studies were combined in four populations at different elevations to examine selection by pollinators and herbivores on floral traits of E. capitatum. KEY RESULTS Pollinator and herbivore assemblages varied spatially and temporally, as did their effects on plant fitness and selection. Both pollinators and herbivores preferred plants with more flowers, and herbivory sometimes reduced pollinator visitation. Pollinators did not select on plant traits in any year or population and E. capitatum was not pollen limited; however, supplemental pollen resulted in altered plant resource allocation. Herbivores reduced fitness and selected for plant traits in some populations, and these effects were mediated by plant compensatory responses. CONCLUSIONS Individuals of Erysimum capitatum are visited by diverse groups of pollinators and herbivores that shift in abundance and importance in time and space. Compensatory reproductive mechanisms mediate interactions with both pollinators and herbivores and may allow E. capitatum to succeed in this complex selective environment.
Collapse
Affiliation(s)
- C. R. Lay
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | | | | |
Collapse
|
46
|
Viola DV, Mordecai EA, Jaramillo AG, Sistla SA, Albertson LK, Gosnell JS, Cardinale BJ, Levine JM. Competition-defense tradeoffs and the maintenance of plant diversity. Proc Natl Acad Sci U S A 2010; 107:17217-22. [PMID: 20855605 PMCID: PMC2951440 DOI: 10.1073/pnas.1007745107] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ecologists have long observed that consumers can maintain species diversity in communities of their prey. Many theories of how consumers mediate diversity invoke a tradeoff between species' competitive ability and their ability to withstand predation. Under this constraint, the best competitors are also most susceptible to consumers, preventing them from excluding other species. However, empirical evidence for competition-defense tradeoffs is limited and, as such, the mechanisms by which consumers regulate diversity remain uncertain. We performed a meta-analysis of 36 studies to evaluate the prevalence of the competition-defense tradeoff and its role in maintaining diversity in plant communities. We quantified species' responses to experimental resource addition and consumer removal as estimates of competitive ability and resistance to consumers, respectively. With this analysis, we found mixed empirical evidence for a competition-defense tradeoff; in fact, competitive ability tended to be weakly positively correlated with defense overall. However, when present, negative relationships between competitive ability and defense influenced species diversity in the manner predicted by theory. In the minority of communities for which a tradeoff was detected, species evenness was higher, and resource addition and consumer removal reduced diversity. Our analysis reframes the commonly held notion that consumers structure plant communities through a competition-defense tradeoff. Such a tradeoff can maintain diversity when present, but negative correlations between competitive ability and defense were less common than is often assumed. In this respect, this study supports an emerging theoretical paradigm in which predation interacts with competition to both enhance and reduce species diversity.
Collapse
Affiliation(s)
- David V Viola
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Holmes GD, James EA, Hoffmann AA. Limitations to reproductive output and genetic rescue in populations of the rare shrub Grevillea repens (Proteaceae). Ann Bot 2008; 102:1031-41. [PMID: 18922849 PMCID: PMC2712411 DOI: 10.1093/aob/mcn195] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS When conserving rare plant species, managers are often faced with small and/or isolated populations displaying low levels of sexual reproduction and genetic variation. One option for reinvigorating these populations is the introduction of genetic material from other sites, but in some cases fitness may be reduced as a result of outbreeding depression. Here the pollination biology of the rare shrub Grevillea repens is studied across its natural range and reproductive responses following cross-pollination among populations are examined to determine factors that may be limiting sexual reproduction and the potential for genetic rescue. METHODS Pollen manipulation treatments (self-, autogamous self-, cross- and open pollination) were applied to flowers to examine the breeding system and fruit and seed production in five populations of G. repens. Pollen production, presentation and viability were investigated and interpopulation crosses of increasing genetic distance performed among the populations. KEY RESULTS The study species is self-incompatible and displayed very low natural seed set over two seasons, due partly to low pollen viability in one of the populations. Within-population crossing increased fruit and seed production at some sites, indicating pollinator limitation. Interpopulation crosses further increased reproductive output in one population, suggesting mate limitation, and for this site there was a positive relationship between genetic distance among populations and the size of genetic rescue benefits. However, in other populations there was a decrease in fruit and seed set with increasing genetic distance. CONCLUSIONS The results highlight that management strategies involving interpopulation crosses can improve reproductive output in small, isolated populations of rare plants, but guidelines need to be developed on a population by population basis.
Collapse
Affiliation(s)
- G D Holmes
- Centre for Environmental Stress and Adaptation Research (CESAR), Department of Genetics, Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia.
| | | | | |
Collapse
|
48
|
Abstract
Coinfection of a host by multiple parasite species has important epidemiological and clinical implications. However, the direction and magnitude of effects vary considerably among systems, and, until now, there has been no general framework within which to explain this variation. Community ecology has great potential for application to such problems in biomedicine. Here, metaanalysis of data from 54 experiments on laboratory mice reveals that basic ecological rules govern the outcome of coinfection across a broad spectrum of parasite taxa. Specifically, resource-based ("bottom-up") and predator-based ("top-down") control mechanisms combined to determine microparasite population size in helminth-coinfected hosts. Coinfection imposed bottom-up control (resulting in decreased microparasite density) when a helminth that causes anemia was paired with a microparasite species that requires host red blood cells. At the same time, coinfection impaired top-down control of microparasites by the immune system: the greater the helminth-induced suppression of the inflammatory cytokine interferon (IFN)-gamma, the greater the increase in microparasite density. These results suggest that microparasite population growth will be most explosive when underlying helminths do not impose resource limitations but do strongly modulate IFN-gamma responses. Surprisingly simple rules and an ecological framework within which to analyze biomedical data thus emerge from analysis of this dataset. Through such an interdisciplinary lens, predicting the outcome of coinfection may become tractable.
Collapse
Affiliation(s)
- Andrea L Graham
- Institute of Evolution, School of Biological Sciences, University of Edinburgh, King's Buildings, Ashworth Laboratories, Edinburgh EH9 3JT, Scotland.
| |
Collapse
|
49
|
Abstract
• Staminate flowers of andromonoecious species are thought to be produced to increase reproductive success through enhancing male function or diverting resources from unneeded pistils to fruits. This does not explain why andromonoecy occurs within genera with monoecy, since staminate flowers of monoecious plants can also serve these functions. • Here the male allocation of staminate and perfect flowers was measured in the annual herb Sagittaria guyanensis ssp. lappula , an andromonoecious species in a predominantly monoecious genus. Staminate flowers contained anthers that were larger and more numerous than those of perfect flowers, and their petals were also larger. This contrasts with most investigations where staminate flowers typically have equal or lower investment in male structures than perfect flowers. • Seed set was not significantly different between bagged and open-pollinated flowers. Pollinator observation and a pollen-dyeing experiment indicated visits to the flowers rarely occurred. • The presence of functional stamens in perfect flowers could be selected to allow reproductive assurance in case of inadequate pollination in andromonoecious species, rather than as a mechanism for optimal resource allocation.
Collapse
|