151
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Bush A, Mokany K, Catullo R, Hoffmann A, Kellermann V, Sgrò C, McEvey S, Ferrier S. Incorporating evolutionary adaptation in species distribution modelling reduces projected vulnerability to climate change. Ecol Lett 2016; 19:1468-1478. [DOI: 10.1111/ele.12696] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/01/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Alex Bush
- CSIRO Land and Water; Canberra Australia
| | | | - Renee Catullo
- CSIRO Land and Water; Canberra Australia
- Biological Sciences; Macquarie University; Sydney Australia
- School of Science and Health; Western Sydney University; Australia
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152
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Allen JL, Chown SL, Janion-Scheepers C, Clusella-Trullas S. Interactions between rates of temperature change and acclimation affect latitudinal patterns of warming tolerance. CONSERVATION PHYSIOLOGY 2016; 4:cow053. [PMID: 27933165 PMCID: PMC5142048 DOI: 10.1093/conphys/cow053] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 10/11/2016] [Accepted: 10/17/2016] [Indexed: 05/26/2023]
Abstract
Critical thermal limits form an increasing component of the estimation of impacts of global change on ectotherms. Whether any consistent patterns exist in the interactive effects of rates of temperature change (or experimental ramping rates) and acclimation on critical thermal limits and warming tolerance (one way of assessing sensitivity to climate change) is, however, far from clear. Here, we examine the interacting effects of ramping rate and acclimation on the critical thermal maxima (CTmax) and minima (CTmin) and warming tolerance of six species of springtails from sub-tropical, temperate and polar regions. We also provide microhabitat temperatures from 26 sites spanning 5 years in order to benchmark environmentally relevant rates of temperature change. Ramping rate has larger effects than acclimation on CTmax, but the converse is true for CTmin. Responses to rate and acclimation effects are more consistent among species for CTmax than for CTmin. In the latter case, interactions among ramping rate and acclimation are typical of polar species, less marked for temperate ones, and reduced in species from the sub-tropics. Ramping rate and acclimation have substantial effects on estimates of warming tolerance, with the former being more marked. At the fastest ramping rates (>1.0°C/min), tropical species have estimated warming tolerances similar to their temperate counterparts, whereas at slow ramping rates (<0.4°C/min) the warming tolerance is much reduced in tropical species. Rates of temperate change in microhabitats relevant to the springtails are typically <0.05°C/min, with rare maxima of 0.3-0.5°C/min depending on the site. These findings emphasize the need to consider the environmental setting and experimental conditions when assessing species' vulnerability to climate change using a warming tolerance approach.
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Affiliation(s)
- Jessica L Allen
- Centre for Invasion Biology, Department of Botany and Zoology,
Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, VIC 3800,
Australia
| | | | - Susana Clusella-Trullas
- Centre for Invasion Biology, Department of Botany and Zoology,
Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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153
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Xing S, Bonebrake TC, Tang CC, Pickett EJ, Cheng W, Greenspan SE, Williams SE, Scheffers BR. Cool habitats support darker and bigger butterflies in Australian tropical forests. Ecol Evol 2016; 6:8062-8074. [PMID: 27878078 PMCID: PMC5108258 DOI: 10.1002/ece3.2464] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/17/2016] [Accepted: 08/24/2016] [Indexed: 02/04/2023] Open
Abstract
Morphology mediates the relationship between an organism's body temperature and its environment. Dark organisms, for example, tend to absorb heat more quickly than lighter individuals, which could influence their responses to temperature. Therefore, temperature‐related traits such as morphology may affect patterns of species abundance, richness, and community assembly across a broad range of spatial scales. In this study, we examined variation in color lightness and body size within butterfly communities across hot and cool habitats in the tropical woodland–rainforest ecosystems of northeast Queensland, Australia. Using thermal imaging, we documented the absorption of solar radiation relative to color lightness and wingspan and then built a phylogenetic tree based on available sequences to analyze the effects of habitat on these traits within a phylogenetic framework. In general, darker and larger individuals were more prevalent in cool, closed‐canopy rainforests than in immediately adjacent and hotter open woodlands. In addition, darker and larger butterflies preferred to be active in the shade and during crepuscular hours, while lighter and smaller butterflies were more active in the sun and midday hours—a pattern that held after correcting for phylogeny. Our ex situ experiment supported field observations that dark and large butterflies heated up faster than light and small butterflies under standardized environmental conditions. Our results show a thermal consequence of butterfly morphology across habitats and how environmental factors at a microhabitat scale may affect the distribution of species based on these traits. Furthermore, this study highlights how butterfly species might differentially respond to warming based on ecophysiological traits and how thermal refuges might emerge at microclimatic and habitat scales.
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Affiliation(s)
- Shuang Xing
- School of Biological Sciences The University of Hong Kong Hong Kong China
| | | | - Chin Cheung Tang
- School of Science and Technology The Open University of Hong Kong Hong Kong China
| | - Evan J Pickett
- School of Biological Sciences The University of Hong Kong Hong Kong China
| | - Wenda Cheng
- School of Biological Sciences The University of Hong Kong Hong Kong China
| | - Sasha E Greenspan
- College of Marine and Environmental Science James Cook University Townsville QLD Australia
| | - Stephen E Williams
- College of Marine and Environmental Science James Cook University Townsville QLD Australia
| | - Brett R Scheffers
- Department of Wildlife Ecology and Conservation University of Florida Gainesville FL 32611 USA
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154
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Bujan J, Yanoviak SP, Kaspari M. Desiccation resistance in tropical insects: causes and mechanisms underlying variability in a Panama ant community. Ecol Evol 2016; 6:6282-91. [PMID: 27648242 PMCID: PMC5016648 DOI: 10.1002/ece3.2355] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/05/2016] [Accepted: 07/11/2016] [Indexed: 02/04/2023] Open
Abstract
Desiccation resistance, the ability of an organism to reduce water loss, is an essential trait in arid habitats. Drought frequency in tropical regions is predicted to increase with climate change, and small ectotherms are often under a strong desiccation risk. We tested hypotheses regarding the underexplored desiccation potential of tropical insects. We measured desiccation resistance in 82 ant species from a Panama rainforest by recording the time ants can survive desiccation stress. Species' desiccation resistance ranged from 0.7 h to 97.9 h. We tested the desiccation adaptation hypothesis, which predicts higher desiccation resistance in habitats with higher vapor pressure deficit (VPD) - the drying power of the air. In a Panama rainforest, canopy microclimates averaged a VPD of 0.43 kPa, compared to a VPD of 0.05 kPa in the understory. Canopy ants averaged desiccation resistances 2.8 times higher than the understory ants. We tested a number of mechanisms to account for desiccation resistance. Smaller insects should desiccate faster given their higher surface area to volume ratio. Desiccation resistance increased with ant mass, and canopy ants averaged 16% heavier than the understory ants. A second way to increase desiccation resistance is to carry more water. Water content was on average 2.5% higher in canopy ants, but total water content was not a good predictor of ant desiccation resistance or critical thermal maximum (CT max), a measure of an ant's thermal tolerance. In canopy ants, desiccation resistance and CT max were inversely related, suggesting a tradeoff, while the two were positively correlated in understory ants. This is the first community level test of desiccation adaptation hypothesis in tropical insects. Tropical forests do contain desiccation-resistant species, and while we cannot predict those simply based on their body size, high levels of desiccation resistance are always associated with the tropical canopy.
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Affiliation(s)
- Jelena Bujan
- Department of BiologyGraduate Program in Ecology and Evolutionary BiologyUniversity of OklahomaNormanOklahoma
| | - Stephen P. Yanoviak
- Department of BiologyUniversity of LouisvilleLouisvilleKentucky
- Smithsonian Tropical Research InstituteBalboaRepublic of Panama
| | - Michael Kaspari
- Department of BiologyGraduate Program in Ecology and Evolutionary BiologyUniversity of OklahomaNormanOklahoma
- Smithsonian Tropical Research InstituteBalboaRepublic of Panama
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155
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Yanoviak SP, Silveri C, Stark AY, Van Stan JT, Levia DF. Surface roughness affects the running speed of tropical canopy ants. Biotropica 2016. [DOI: 10.1111/btp.12349] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Stephen P. Yanoviak
- Department of Biology University of Louisville 139 Life Sciences Building Louisville KY 40292 U.S.A
- Smithsonian Tropical Research Institute Apartado Postal 0843‐03092 Panamá Republic of Panama
| | - Cheryl Silveri
- Department of Biological Sciences University of Arkansas Fayetteville AR 72701 U.S.A
| | - Alyssa Y. Stark
- Department of Biology University of Louisville 139 Life Sciences Building Louisville KY 40292 U.S.A
| | - John T. Van Stan
- Department of Geology and Geography Georgia Southern University Statesboro GA 30460 U.S.A
| | - Delphis F. Levia
- Departments of Geography and Plant & Soil Sciences University of Delaware Newark DE 19716 U.S.A
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156
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Sagata K, Gibb H. The Effect of Temperature Increases on an Ant-Hemiptera-Plant Interaction. PLoS One 2016; 11:e0155131. [PMID: 27434232 PMCID: PMC4951116 DOI: 10.1371/journal.pone.0155131] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 04/25/2016] [Indexed: 11/18/2022] Open
Abstract
Global temperature increases are significantly altering species distributions and the structure of ecological communities. However, the impact of temperature increases on multi- species interactions is poorly understood. We used an ant-Hemiptera-plant interaction to examine the potential outcomes of predicted temperature increases for each partner and for the availability of honeydew, a keystone resource in many forest ecosystems. We re-created this interaction in growth cabinets using predicted mean summer temperatures for Melbourne, Australia, for the years 2011 (23°C), 2050 (25°C) and 2100 (29°C), respectively, under an unmitigated greenhouse gas emission scenario. Plant growth and ant foraging activities increased, while scale insect growth, abundance and size, honeydew standing crop per tree and harvesting by ants decreased at 29°C, relative to lower temperatures (23 and 25°C). This led to decreased scale insect infestations of plants and reduced honeydew standing crop per tree at the highest temperature. At all temperatures, honeydew standing crop was lower when ants harvested the honeydew from scale insects, but the impact of ant harvesting was particularly significant at 29°C, where combined effects of temperature and ants reduced honeydew standing crop to below detectable levels. Although temperature increases in the next 35 years will have limited effects on this system, by the end of this century, warmer temperatures may cause the availability of honeydew to decline. Decline of honeydew may have far-reaching trophic effects on honeydew and ant-mediated interactions. However, field-based studies that consider the full complexity of ecosystems may be required to elucidate these impacts.
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Affiliation(s)
- Katayo Sagata
- Department of Zoology, La Trobe University, Melbourne, VIC 3086, Australia
- Papua New Guinea Institute of Biological Research, Goroka, Eastern Highlands Province, Papua New Guinea
| | - Heloise Gibb
- Department of Zoology, La Trobe University, Melbourne, VIC 3086, Australia
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157
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Buckley LB, Huey RB. How Extreme Temperatures Impact Organisms and the Evolution of their Thermal Tolerance. Integr Comp Biol 2016; 56:98-109. [PMID: 27126981 DOI: 10.1093/icb/icw004] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
SynopsisUnderstanding the biological impacts of extreme temperatures requires translating meteorological estimates into organismal responses, but that translation is complex. In general, the physiological stress induced by a given thermal extreme should increase with the extreme's magnitude and duration, though acclimation may buffer that stress. However, organisms can differ strikingly in their exposure to and tolerance of a given extreme temperatures. Moreover, their sensitivity to extremes can vary during ontogeny, across seasons, and among species; and that sensitivity and its variation should be subject to selection. We use a simple quantitative genetic model and demonstrate that thermal extremes-even when at low frequency-can substantially influence the evolution of thermal sensitivity, particularly when the extremes cause mortality or persistent physiological injury, or when organisms are unable to use behavior to buffer exposure to extremes. Thermal extremes can drive organisms in temperate and tropical sites to have similar thermal tolerances despite major differences in mean temperatures. Indeed, the model correctly predicts that Australian Drosophila should have shallower latitudinal gradients in thermal tolerance than would be expected based only on gradients in mean conditions. Predicting responses to climate change requires understanding not only how past selection to tolerate thermal extremes has helped establish existing geographic gradients in thermal tolerances, but also how increasing the incidence of thermal extremes will alter geographic gradients in the future.
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Affiliation(s)
- Lauren B Buckley
- Department of Biology, University of Washington, Seattle, WA 981951800, USA
| | - Raymond B Huey
- Department of Biology, University of Washington, Seattle, WA 981951800, USA
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158
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Pincebourde S, Suppo C. The Vulnerability of Tropical Ectotherms to Warming Is Modulated by the Microclimatic Heterogeneity. Integr Comp Biol 2016; 56:85-97. [DOI: 10.1093/icb/icw014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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159
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Ortega Z, Mencía A, Pérez-Mellado V. Behavioral buffering of global warming in a cold-adapted lizard. Ecol Evol 2016; 6:4582-90. [PMID: 27386098 PMCID: PMC4931003 DOI: 10.1002/ece3.2216] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/10/2016] [Accepted: 05/12/2016] [Indexed: 02/04/2023] Open
Abstract
Alpine lizards living in restricted areas might be particularly sensitive to climate change. We studied thermal biology of Iberolacerta cyreni in high mountains of central Spain. Our results suggest that I. cyreni is a cold‐adapted thermal specialist and an effective thermoregulator. Among ectotherms, thermal specialists are more threatened by global warming than generalists. Alpine lizards have no chance to disperse to new suitable habitats. In addition, physiological plasticity is unlikely to keep pace with the expected rates of environmental warming. Thus, lizards might rely on their behavior in order to deal with ongoing climate warming. Plasticity of thermoregulatory behavior has been proposed to buffer the rise of environmental temperatures. Therefore, we studied the change in body and environmental temperatures, as well as their relationships, for I. cyreni between the 1980s and 2012. Air temperatures have increased more than 3.5°C and substrate temperatures have increased by 6°C in the habitat of I. cyreni over the last 25 years. However, body temperatures of lizards have increased less than 2°C in the same period, and the linear relationship between body and environmental temperatures remains similar. These results show that alpine lizards are buffering the potential impact of the increase in their environmental temperatures, most probably by means of their behavior. Body temperatures of I. cyreni are still cold enough to avoid any drop in fitness. Nonetheless, if warming continues, behavioral buffering might eventually become useless, as it would imply spending too much time in shelter, losing feeding, and mating opportunities. Eventually, if body temperature exceeds the thermal optimum in the near future, fitness would decrease abruptly.
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Affiliation(s)
- Zaida Ortega
- Department of Animal Biology University of Salamanca Campus Miguel de Unamuno 37007 Salamanca Spain
| | - Abraham Mencía
- Department of Animal Biology University of Salamanca Campus Miguel de Unamuno 37007 Salamanca Spain
| | - Valentín Pérez-Mellado
- Department of Animal Biology University of Salamanca Campus Miguel de Unamuno 37007 Salamanca Spain
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160
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Wendt CF, Verble-Pearson R. Critical thermal maxima and body size positively correlate in red imported fire ants,Solenopsis invicta. SOUTHWEST NAT 2016. [DOI: 10.1894/0038-4909-61.1.79] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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161
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Cavieres G, Bogdanovich JM, Bozinovic F. Ontogenetic thermal tolerance and performance of ectotherms at variable temperatures. J Evol Biol 2016; 29:1462-8. [DOI: 10.1111/jeb.12886] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/24/2016] [Accepted: 04/19/2016] [Indexed: 02/03/2023]
Affiliation(s)
- G. Cavieres
- Departamento de Ecología and Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - J. M. Bogdanovich
- Departamento de Ecología and Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
| | - F. Bozinovic
- Departamento de Ecología and Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
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162
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Pincebourde S, Murdock CC, Vickers M, Sears MW. Fine-Scale Microclimatic Variation Can Shape the Responses of Organisms to Global Change in Both Natural and Urban Environments. Integr Comp Biol 2016; 56:45-61. [PMID: 27107292 DOI: 10.1093/icb/icw016] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
When predicting the response of organisms to global change, models use measures of climate at a coarse resolution from general circulation models or from downscaled regional models. Organisms, however, do not experience climate at such large scales. The climate heterogeneity over a landscape and how much of that landscape an organism can sample will determine ultimately the microclimates experienced by organisms. This past few decades has seen an important increase in the number of studies reporting microclimatic patterns at small scales. This synthesis intends to unify studies reporting microclimatic heterogeneity (mostly temperature) at various spatial scales, to infer any emerging trends, and to discuss the causes and consequences of such heterogeneity for organismal performance and with respect to changing land use patterns and climate. First, we identify the environmental drivers of heterogeneity across the various spatial scales that are pertinent to ectotherms. The thermal heterogeneity at the local and micro-scales is mostly generated by the architecture or the geometrical features of the microhabitat. Then, the thermal heterogeneity experienced by individuals is modulated by behavior. Second, we survey the literature to quantify thermal heterogeneity from the micro-scale up to the scale of a landscape in natural habitats. Despite difficulties in compiling studies that differ much in their design and aims, we found that there is as much thermal heterogeneity across micro-, local and landscape scales, and that the temperature range is large in general (>9 °C on average, and up to 26 °C). Third, we examine the extent to which urban habitats can be used to infer the microclimatic patterns of the future. Urban areas generate globally drier and warmer microclimatic patterns and recent evidence suggest that thermal traits of ectotherms are adapted to them. Fourth, we explore the interplay between microclimate heterogeneity and the behavioral thermoregulatory abilities of ectotherms in setting their overall performance. We used a random walk framework to show that the thermal heterogeneity allows a more precise behavioral thermoregulation and a narrower temperature distribution of the ectotherm compared to less heterogeneous microhabitats. Finally, we discuss the potential impacts of global change on the fine scale mosaics of microclimates. The amplitude of change may differ between spatial scales. In heterogeneous microhabitats, the amplitude of change at micro-scale, caused by atmospheric warming, can be substantial while it can be limited at the local and landscape scales. We suggest that the warming signal will influence species performance and biotic interactions by modulating the mosaic of microclimates.
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Affiliation(s)
- Sylvain Pincebourde
- *Institut de Recherche sur la Biologie de l'Insecte (IRBI, CNRS UMR 7261), Université François Rabelais, Faculté des Sciences et Techniques, Tours, 37200, France
| | - Courtney C Murdock
- Department of Infectious Diseases, College of Veterinary Medicine, Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Mathew Vickers
- Station d'Ecologie Théorique Expérimentale, UMR 5321, CNRS et Université Paul Sabatier, 2 route du CNRS, Moulis, 09200, France
| | - Michael W Sears
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634
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163
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Kaspari M, Clay NA, Lucas J, Revzen S, Kay A, Yanoviak SP. Thermal adaptation and phosphorus shape thermal performance in an assemblage of rainforest ants. Ecology 2016; 97:1038-47. [DOI: 10.1890/15-1225.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Michael Kaspari
- Graduate Program in Ecology and Evolution Department of Biology University of Oklahoma Norman OK 73019 USA
- Smithsonian Tropical Research Institute Balboa Republic of Panama
| | - Natalie A. Clay
- Graduate Program in Ecology and Evolution Department of Biology University of Oklahoma Norman OK 73019 USA
- Smithsonian Tropical Research Institute Balboa Republic of Panama
| | - Jane Lucas
- Graduate Program in Ecology and Evolution Department of Biology University of Oklahoma Norman OK 73019 USA
- Smithsonian Tropical Research Institute Balboa Republic of Panama
| | - Shai Revzen
- Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109 USA
| | - Adam Kay
- Department of Biology University of St. Thomas St. Paul MN 55105 USA
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164
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Nguyen AD, Gotelli NJ, Cahan SH. The evolution of heat shock protein sequences, cis-regulatory elements, and expression profiles in the eusocial Hymenoptera. BMC Evol Biol 2016; 16:15. [PMID: 26787420 PMCID: PMC4717527 DOI: 10.1186/s12862-015-0573-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/19/2015] [Indexed: 01/22/2023] Open
Abstract
Background The eusocial Hymenoptera have radiated across a wide range of thermal environments, exposing them to significant physiological stressors. We reconstructed the evolutionary history of three families of Heat Shock Proteins (Hsp90, Hsp70, Hsp40), the primary molecular chaperones protecting against thermal damage, across 12 Hymenopteran species and four other insect orders. We also predicted and tested for thermal inducibility of eight Hsps from the presence of cis-regulatory heat shock elements (HSEs). We tested whether Hsp induction patterns in ants were associated with different thermal environments. Results We found evidence for duplications, losses, and cis-regulatory changes in two of the three gene families. One member of the Hsp90 gene family, hsp83, duplicated basally in the Hymenoptera, with shifts in HSE motifs in the novel copy. Both copies were retained in bees, but ants retained only the novel HSE copy. For Hsp70, Hymenoptera lack the primary heat-inducible orthologue from Drosophila melanogaster and instead induce the cognate form, hsc70-4, which also underwent an early duplication. Episodic diversifying selection was detected along the branch predating the duplication of hsc70-4 and continued along one of the paralogue branches after duplication. Four out of eight Hsp genes were heat-inducible and matched the predictions based on presence of conserved HSEs. For the inducible homologues, the more thermally tolerant species, Pogonomyrmex barbatus, had greater Hsp basal expression and induction in response to heat stress than did the less thermally tolerant species, Aphaenogaster picea. Furthermore, there was no trade-off between basal expression and induction. Conclusions Our results highlight the unique evolutionary history of Hsps in eusocial Hymenoptera, which has been shaped by gains, losses, and changes in cis-regulation. Ants, and most likely other Hymenoptera, utilize lineage-specific heat inducible Hsps, whose expression patterns are associated with adaptive variation in thermal tolerance between two ant species. Collectively, our analyses suggest that Hsp sequence and expression patterns may reflect the forces of selection acting on thermal tolerance in ants and other social Hymenoptera. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0573-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrew D Nguyen
- Department of Biology, University of Vermont, Burlington, VT, 05405, USA.
| | - Nicholas J Gotelli
- Department of Biology, University of Vermont, Burlington, VT, 05405, USA.
| | - Sara Helms Cahan
- Department of Biology, University of Vermont, Burlington, VT, 05405, USA.
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165
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Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction. Proc Natl Acad Sci U S A 2016; 113:680-5. [PMID: 26729867 DOI: 10.1073/pnas.1507681113] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The critical thermal maximum (CTmax), the temperature at which motor control is lost in animals, has the potential to determine if species will tolerate global warming. For insects, tolerance to high temperatures decreases with latitude, suggesting that similar patterns may exist along elevational gradients as well. This study explored how CTmax varies among species and populations of a group of diverse tropical insect herbivores, the rolled-leaf beetles, across both broad and narrow elevational gradients. Data from 6,948 field observations and 8,700 museum specimens were used to map the elevational distributions of rolled-leaf beetles on two mountains in Costa Rica. CTmax was determined for 1,252 individual beetles representing all populations across the gradients. Initial morphological identifications suggested a total of 26 species with populations at different elevations displaying contrasting upper thermal limits. However, compared with morphological identifications, DNA barcodes (cytochrome oxidase I) revealed significant cryptic species diversity. DNA barcodes identified 42 species and haplotypes across 11 species complexes. These 42 species displayed much narrower elevational distributions and values of CTmax than the 26 morphologically defined species. In general, species found at middle elevations and on mountaintops are less tolerant to high temperatures than species restricted to lowland habitats. Species with broad elevational distributions display high CTmax throughout their ranges. We found no significant phylogenetic signal in CTmax, geography, or elevational range. The narrow variance in CTmax values for most rolled-leaf beetles, especially high-elevation species, suggests that the risk of extinction of insects may be substantial under some projected rates of global warming.
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166
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Arnan X, Blüthgen N, Molowny-Horas R, Retana J. Thermal Characterization of European Ant Communities Along Thermal Gradients and Its Implications for Community Resilience to Temperature Variability. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00138] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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167
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Duffy GA, Coetzee BW, Janion-Scheepers C, Chown SL. Microclimate-based macrophysiology: implications for insects in a warming world. CURRENT OPINION IN INSECT SCIENCE 2015; 11:84-89. [PMID: 28285764 DOI: 10.1016/j.cois.2015.09.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/30/2015] [Indexed: 06/06/2023]
Abstract
Understanding the influence of microclimates is an increasing focus of investigations of global change risks to insects. Here we review recent advances in this area in the context of macrophysiological forecasts of the impacts of warming. Some studies have suggested that risk estimates may be inaccurate owing to microclimate variation or behavioural responses. Using modelled microclimatic data we illustrate this problem, demonstrating that soil microclimates on the Australian continent will warm in concert with global climate change such that the upper thermal tolerance limits of many insects will be exceeded across much of the continent. Deeper microclimates will be cooler and more hospitable, emphasising the importance of behavioural adaptation and movement amongst microclimates as a response to environmental warming.
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Affiliation(s)
- Grant A Duffy
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
| | - Bernard Wt Coetzee
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | | | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
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168
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Dowd WW, King FA, Denny MW. Thermal variation, thermal extremes and the physiological performance of individuals. J Exp Biol 2015; 218:1956-67. [DOI: 10.1242/jeb.114926] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
ABSTRACT
In this review we consider how small-scale temporal and spatial variation in body temperature, and biochemical/physiological variation among individuals, affect the prediction of organisms' performance in nature. For ‘normal’ body temperatures – benign temperatures near the species' mean – thermal biology traditionally uses performance curves to describe how physiological capabilities vary with temperature. However, these curves, which are typically measured under static laboratory conditions, can yield incomplete or inaccurate predictions of how organisms respond to natural patterns of temperature variation. For example, scale transition theory predicts that, in a variable environment, peak average performance is lower and occurs at a lower mean temperature than the peak of statically measured performance. We also demonstrate that temporal variation in performance is minimized near this new ‘optimal’ temperature. These factors add complexity to predictions of the consequences of climate change. We then move beyond the performance curve approach to consider the effects of rare, extreme temperatures. A statistical procedure (the environmental bootstrap) allows for long-term simulations that capture the temporal pattern of extremes (a Poisson interval distribution), which is characterized by clusters of events interspersed with long intervals of benign conditions. The bootstrap can be combined with biophysical models to incorporate temporal, spatial and physiological variation into evolutionary models of thermal tolerance. We conclude with several challenges that must be overcome to more fully develop our understanding of thermal performance in the context of a changing climate by explicitly considering different forms of small-scale variation. These challenges highlight the need to empirically and rigorously test existing theories.
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Affiliation(s)
- W. Wesley Dowd
- Loyola Marymount University, Department of Biology, Los Angeles, CA 90045, USA
| | - Felicia A. King
- Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA
| | - Mark W. Denny
- Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA
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169
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Verble-Pearson RM, Gifford ME, Yanoviak SP. Variation in thermal tolerance of North American ants. J Therm Biol 2014; 48:65-8. [PMID: 25660632 DOI: 10.1016/j.jtherbio.2014.12.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 11/04/2014] [Accepted: 12/12/2014] [Indexed: 11/17/2022]
Abstract
Changing climates are predicted to alter the distribution of thermal niches. Small ectotherms such as ants may be particularly vulnerable to heat injury and death. We quantified the critical thermal maxima of 92 ant colonies representing 14 common temperate ant species. The mean CTmax for all measured ants was 47.8 °C (±0.27; range=40.2-51.2 °C), and within-colony variation was lower than among-colony variation. Critical thermal maxima differed among species and were negatively correlated with body size. Results of this study illustrate the importance of accounting for mass, among and within colony variation, and interspecific differences in diel activity patterns, which are often neglected in studies of ant thermal physiology.
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Affiliation(s)
| | - Matthew E Gifford
- University of Louisville, 139 Life Sciences Building, Louisville, KY 40292, USA.
| | - Stephen P Yanoviak
- University of Central Arkansas, 201 Donaghey Ave., LSC 180, Conway, AR 72035, USA.
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