1
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Dickel L, Arcese P, Keller LF, Nietlisbach P, Goedert D, Jensen H, Reid JM. Multigenerational Fitness Effects of Natural Immigration Indicate Strong Heterosis and Epistatic Breakdown in a Wild Bird Population. Am Nat 2024; 203:411-431. [PMID: 38358807 DOI: 10.1086/728669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
AbstractThe fitness of immigrants and their descendants produced within recipient populations fundamentally underpins the genetic and population dynamic consequences of immigration. Immigrants can in principle induce contrasting genetic effects on fitness across generations, reflecting multifaceted additive, dominance, and epistatic effects. Yet full multigenerational and sex-specific fitness effects of regular immigration have not been quantified within naturally structured systems, precluding inference on underlying genetic architectures and population outcomes. We used four decades of song sparrow (Melospiza melodia) life history and pedigree data to quantify fitness of natural immigrants, natives, and their F1, F2, and backcross descendants and test for evidence of nonadditive genetic effects. Values of key fitness components (including adult lifetime reproductive success and zygote survival) of F1 offspring of immigrant-native matings substantially exceeded their parent mean, indicating strong heterosis. Meanwhile, F2 offspring of F1-F1 matings had notably low values, indicating surprisingly strong epistatic breakdown. Furthermore, magnitudes of effects varied among fitness components and differed between female and male descendants. These results demonstrate that strong nonadditive genetic effects on fitness can arise within weakly structured and fragmented populations experiencing frequent natural immigration. Such effects will substantially affect the net degree of effective gene flow and resulting local genetic introgression and adaptation.
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2
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Fitzpatrick SW, Mittan-Moreau C, Miller M, Judson JM. Genetic rescue remains underused for aiding recovery of federally listed vertebrates in the United States. J Hered 2023; 114:354-366. [PMID: 36975379 PMCID: PMC10287150 DOI: 10.1093/jhered/esad002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 02/13/2023] [Indexed: 03/29/2023] Open
Abstract
Restoring gene flow among fragmented populations is discussed as a potentially powerful management strategy that could reduce inbreeding depression and cause genetic rescue. Yet, examples of assisted migration for genetic rescue remain sparse in conservation, prompting several outspoken calls for its increased use in genetic management of fragmented populations. We set out to evaluate the extent to which this strategy is underused and to determine how many imperiled species would realistically stand to benefit from genetic rescue, focusing on federally threatened or endangered vertebrate species in the United States. We developed a "genetic rescue suitability index (GR index)" based on concerns about small population problems relative to risks associated with outbreeding depression and surveyed the literature for 222 species. We found that two-thirds of these species were good candidates for consideration of assisted migration for the purpose of genetic rescue according to our suitability index. Good candidate species spanned all taxonomic groups and geographic regions, though species with more missing data tended to score lower on the suitability index. While we do not recommend a prescriptive interpretation of our GR index, we used it here to establish that assisted migration for genetic rescue is an underused strategy. For example, we found in total, "genetic rescue" was only mentioned in 11 recovery plans and has only been implemented in 3 of the species we surveyed. A potential way forward for implementation of this strategy is incorporating genetic rescue as a priority in USFWS recovery documentation. In general, our results suggest that although not appropriate for all imperiled species, many more species stand to benefit from a conservation strategy of assisted migration for genetic rescue than those for which it has previously been considered or implemented.
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Affiliation(s)
- Sarah W Fitzpatrick
- W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, United States
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, United States
| | - Cinnamon Mittan-Moreau
- W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, United States
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, United States
| | - Madison Miller
- Savannah River Ecology Lab, University of Georgia, Aiken, SC, United States
- Division of Forestry and Natural Resources, West Virginia University, Morgantown, WV, United States
| | - Jessica M Judson
- W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, United States
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, United States
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3
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Jørgensen DB, Ørsted M, Kristensen TN. Sustained positive consequences of genetic rescue of fitness and behavioural traits in inbred populations of Drosophila melanogaster. J Evol Biol 2022; 35:868-878. [PMID: 35532930 PMCID: PMC9325394 DOI: 10.1111/jeb.14015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/10/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022]
Abstract
One solution to alleviate the detrimental genetic effects associated with reductions in population size and fragmentation is to introduce immigrants from other populations. While the effects of this genetic rescue on fitness traits are fairly well known, it is less clear to what extent inbreeding depression and subsequent genetic rescue affect behavioural traits. In this study, replicated crosses between inbred lines of Drosophila melanogaster were performed in order to investigate the effects of inbreeding and genetic rescue on egg-to-adult viability and negative geotaxis behaviour-a locomotor response used to measure, e.g. the effects of physiological ageing. Transgenerational effects of outcrossing were investigated by examining the fitness consequences in both the F1 and F4 generation. The majority of inbred lines showed evidence for inbreeding depression for both egg-to-adult viability and behavioural performance (95% and 66% of lines, respectively), with inbreeding depression being more pronounced for viability compared with the locomotor response. Subsequent outcrossing with immigrants led to an alleviation of the negative effects for both viability and geotaxis response resulting in inbred lines being similar to the outbred controls, with beneficial effects persisting from F1 to F4 . Overall, the results clearly show that genetic rescue can provide transgenerational rescue of small, inbred populations by rapidly improving population fitness components. Thus, we show that even the negative effects of inbreeding on behaviour, similar to that of neurodegeneration associated with physiological ageing, can be reversed by genetic rescue.
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Affiliation(s)
| | - Michael Ørsted
- Department of Chemistry and Bioscience, Aalborg University, Aalborg E, Denmark.,Department of Biology, Aarhus University, Aarhus C, Denmark
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4
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MacPherson A, Wang S, Yamaguchi R, Rieseberg L, Otto S. Parental Population Range Expansion Before Secondary Contact Promotes Heterosis. Am Nat 2022; 200:E1-E15. [DOI: 10.1086/719656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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5
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Ottenburghs J. The genic view of hybridization in the Anthropocene. Evol Appl 2021; 14:2342-2360. [PMID: 34745330 PMCID: PMC8549621 DOI: 10.1111/eva.13223] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 03/10/2021] [Accepted: 03/10/2021] [Indexed: 12/24/2022] Open
Abstract
Human impact is noticeable around the globe, indicating that a new era might have begun: the Anthropocene. Continuing human activities, including land-use changes, introduction of non-native species and rapid climate change, are altering the distributions of countless species, often giving rise to human-mediated hybridization events. While the interbreeding of different populations or species can have detrimental effects, such as genetic extinction, it can be beneficial in terms of adaptive introgression or an increase in genetic diversity. In this paper, I first review the different mechanisms and outcomes of anthropogenic hybridization based on literature from the last five years (2016-2020). The most common mechanisms leading to the interbreeding of previously isolated taxa include habitat change (51% of the studies) and introduction of non-native species (34% intentional and 19% unintentional). These human-induced hybridization events most often result in introgression (80%). The high incidence of genetic exchange between the hybridizing taxa indicates that the application of a genic view of speciation (and introgression) can provide crucial insights on how to address hybridization events in the Anthropocene. This perspective considers the genome as a dynamic collection of genetic loci with distinct evolutionary histories, giving rise to a heterogenous genomic landscape in terms of genetic differentiation and introgression. First, understanding this genomic landscape can lead to a better selection of diagnostic genetic markers to characterize hybrid populations. Second, describing how introgression patterns vary across the genome can help to predict the likelihood of negative processes, such as demographic and genetic swamping, as well as positive outcomes, such as adaptive introgression. It is especially important to not only quantify how much genetic material introgressed, but also what has been exchanged. Third, comparing introgression patterns in pre-Anthropocene hybridization events with current human-induced cases might provide novel insights into the likelihood of genetic swamping or species collapse during an anthropogenic hybridization event. However, this comparative approach remains to be tested before it can be applied in practice. Finally, the genic view of introgression can be combined with conservation genomic studies to determine the legal status of hybrids and take appropriate measures to manage anthropogenic hybridization events. The interplay between evolutionary and conservation genomics will result in the constant exchange of ideas between these fields which will not only improve our knowledge on the origin of species, but also how to conserve and protect them.
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Affiliation(s)
- Jente Ottenburghs
- Wildlife Ecology and ConservationWageningen University & ResearchWageningenThe Netherlands
- Forest Ecology and Forest ManagementWageningen University & ResearchWageningenThe Netherlands
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6
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Kucera KF, Fant JB, Jensen S, Landeen M, Orr E, Kramer AT. Genetic variation and structure change when producing and using mixed‐source seed lots for restoration. Restor Ecol 2021. [DOI: 10.1111/rec.13521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Katherine F. Kucera
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL U.S.A
- Plant Biology and Conservation Program Northwestern University Evanston IL U.S.A
| | - Jeremie B. Fant
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL U.S.A
- Plant Biology and Conservation Program Northwestern University Evanston IL U.S.A
| | - Scott Jensen
- Shrub Sciences Lab USDA Forest Service Provo UT U.S.A
| | - Melissa Landeen
- Utah Division of Wildlife Resources, Great Basin Research Center Ephraim UT U.S.A
| | - Emily Orr
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL U.S.A
| | - Andrea T. Kramer
- Negaunee Institute for Plant Conservation Science and Action Chicago Botanic Garden Glencoe IL U.S.A
- Plant Biology and Conservation Program Northwestern University Evanston IL U.S.A
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7
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Gargiulo R, Adamo M, Cribb PJ, Bartolucci F, Sarasan V, Alessandrelli C, Bona E, Ciaschetti G, Conti F, Di Cecco V, Di Martino L, Gentile C, Juan A, Magrini S, Mucciarelli M, Perazza G, Fay MF. Combining current knowledge of
Cypripedium calceolus
with a new analysis of genetic variation in Italian populations to provide guidelines for conservation actions. CONSERVATION SCIENCE AND PRACTICE 2021. [DOI: 10.1111/csp2.513] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
| | - Martino Adamo
- Department of Life Sciences and Systems Biology Università di Torino Torino Italy
| | | | - Fabrizio Bartolucci
- Floristic Research Center of the Apennine (University of Camerino – Gran Sasso and Laga Mountains National Park) Barisciano (L'Aquila) Italy
| | | | | | - Enzo Bona
- Centro Studi Naturalistici Bresciani, Museo di Scienze Naturali Brescia (BS) Italy
| | - Giampiero Ciaschetti
- Maiella National Park – Office for Plant Biodiversity Monitoring and Conservation Sulmona (AQ) Italy
| | - Fabio Conti
- Floristic Research Center of the Apennine (University of Camerino – Gran Sasso and Laga Mountains National Park) Barisciano (L'Aquila) Italy
| | - Valter Di Cecco
- Maiella National Park – Office for Plant Biodiversity Monitoring and Conservation Sulmona (AQ) Italy
| | - Luciano Di Martino
- Maiella National Park – Office for Plant Biodiversity Monitoring and Conservation Sulmona (AQ) Italy
| | - Carmelo Gentile
- Abruzzo, Lazio and Molise National Park viale Santa Lucia Pescasseroli (AQ) Italy
| | - Ana Juan
- Ciencias Ambientales y Recursos Naturales University of Alicante Alicante Spain
| | - Sara Magrini
- Tuscia Germplasm Bank, Tuscia University, largo dell'Università blocco C Viterbo Italy
| | - Marco Mucciarelli
- Department of Life Sciences and Systems Biology Università di Torino Torino Italy
| | | | - Michael F. Fay
- Royal Botanic Gardens, Kew Richmond United Kingdom
- School of Plant Biology, University of Western Australia Crawley Western Australia Australia
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8
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Genomic Approaches for Conservation Management in Australia under Climate Change. Life (Basel) 2021; 11:life11070653. [PMID: 34357024 PMCID: PMC8304512 DOI: 10.3390/life11070653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/02/2021] [Accepted: 07/03/2021] [Indexed: 12/28/2022] Open
Abstract
Conservation genetics has informed threatened species management for several decades. With the advent of advanced DNA sequencing technologies in recent years, it is now possible to monitor and manage threatened populations with even greater precision. Climate change presents a number of threats and challenges, but new genomics data and analytical approaches provide opportunities to identify critical evolutionary processes of relevance to genetic management under climate change. Here, we discuss the applications of such approaches for threatened species management in Australia in the context of climate change, identifying methods of facilitating viability and resilience in the face of extreme environmental stress. Using genomic approaches, conservation management practices such as translocation, targeted gene flow, and gene-editing can now be performed with the express intention of facilitating adaptation to current and projected climate change scenarios in vulnerable species, thus reducing extinction risk and ensuring the protection of our unique biodiversity for future generations. We discuss the current barriers to implementing conservation genomic projects and the efforts being made to overcome them, including communication between researchers and managers to improve the relevance and applicability of genomic studies. We present novel approaches for facilitating adaptive capacity and accelerating natural selection in species to encourage resilience in the face of climate change.
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9
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Evolutionary history and genetic connectivity across highly fragmented populations of an endangered daisy. Heredity (Edinb) 2021; 126:846-858. [PMID: 33608651 PMCID: PMC8102499 DOI: 10.1038/s41437-021-00413-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 01/24/2021] [Accepted: 01/25/2021] [Indexed: 01/31/2023] Open
Abstract
Conservation management can be aided by knowledge of genetic diversity and evolutionary history, so that ecological and evolutionary processes can be preserved. The Button Wrinklewort daisy (Rutidosis leptorrhynchoides) was a common component of grassy ecosystems in south-eastern Australia. It is now endangered due to extensive habitat loss and the impacts of livestock grazing, and is currently restricted to a few small populations in two regions >500 km apart, one in Victoria, the other in the Australian Capital Territory and nearby New South Wales (ACT/NSW). Using a genome-wide SNP dataset, we assessed patterns of genetic structure and genetic differentiation of 12 natural diploid populations. We estimated intrapopulation genetic diversity to scope sources for genetic management. Bayesian clustering and principal coordinate analyses showed strong population genetic differentiation between the two regions, and substantial substructure within ACT/NSW. A coalescent tree-building approach implemented in SNAPP indicated evolutionary divergence between the two distant regions. Among the populations screened, the last two known remaining Victorian populations had the highest genetic diversity, despite having among the lowest recent census sizes. A maximum likelihood population tree method implemented in TreeMix suggested little or no recent gene flow except potentially between very close neighbours. Populations that were more genetically distinctive had lower genetic diversity, suggesting that drift in isolation is likely driving population differentiation though loss of diversity, hence re-establishing gene flow among them is desirable. These results provide background knowledge for evidence-based conservation and support genetic rescue within and between regions to elevate genetic diversity and alleviate inbreeding.
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10
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Kyriazis CC, Wayne RK, Lohmueller KE. Strongly deleterious mutations are a primary determinant of extinction risk due to inbreeding depression. Evol Lett 2021; 5:33-47. [PMID: 33552534 PMCID: PMC7857301 DOI: 10.1002/evl3.209] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 11/10/2020] [Accepted: 11/21/2020] [Indexed: 11/08/2022] Open
Abstract
Human-driven habitat fragmentation and loss have led to a proliferation of small and isolated plant and animal populations with high risk of extinction. One of the main threats to extinction in these populations is inbreeding depression, which is primarily caused by recessive deleterious mutations becoming homozygous due to inbreeding. The typical approach for managing these populations is to maintain high genetic diversity, increasingly by translocating individuals from large populations to initiate a "genetic rescue." However, the limitations of this approach have recently been highlighted by the demise of the gray wolf population on Isle Royale, which declined to the brink of extinction soon after the arrival of a migrant from the large mainland wolf population. Here, we use a novel population genetic simulation framework to investigate the role of genetic diversity, deleterious variation, and demographic history in mediating extinction risk due to inbreeding depression in small populations. We show that, under realistic models of dominance, large populations harbor high levels of recessive strongly deleterious variation due to these mutations being hidden from selection in the heterozygous state. As a result, when large populations contract, they experience a substantially elevated risk of extinction after these strongly deleterious mutations are exposed by inbreeding. Moreover, we demonstrate that, although genetic rescue is broadly effective as a means to reduce extinction risk, its effectiveness can be greatly increased by drawing migrants from small or moderate-sized source populations rather than large source populations due to smaller populations harboring lower levels of recessive strongly deleterious variation. Our findings challenge the traditional conservation paradigm that focuses on maximizing genetic diversity in small populations in favor of a view that emphasizes minimizing strongly deleterious variation. These insights have important implications for managing small and isolated populations in the increasingly fragmented landscape of the Anthropocene.
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Affiliation(s)
- Christopher C. Kyriazis
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaLos AngelesCalifornia90095
| | - Robert K. Wayne
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaLos AngelesCalifornia90095
| | - Kirk E. Lohmueller
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaLos AngelesCalifornia90095
- Interdepartmental Program in BioinformaticsUniversity of CaliforniaLos AngelesCalifornia90095
- Department of Human Genetics, David Geffen School of MedicineUniversity of CaliforniaLos AngelesCalifornia90095
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11
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Increased Genetic Diversity via Gene Flow Provides Hope for Acacia whibleyana, an Endangered Wattle Facing Extinction. DIVERSITY 2020. [DOI: 10.3390/d12080299] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this paper we apply a conservation genomics approach to make evidence-based management recommendations for Acacia whibleyana, an endangered shrub endemic to Eyre Peninsula, South Australia. We used population genomic analysis to assess genetic connectivity, diversity, and historical inbreeding across all known stands of the species sampling remnant stands, revegetated stands of unknown origin, and a post-fire seedling cohort. Our results indicate a degree of historical connectivity across the landscape, but habitat loss and/or pollinator community disruption are potential causes of strong genetic structure across the remnant stands. Remnant stands had low genetic diversity and showed evidence of historical inbreeding, but only low levels of intra-stand relatedness indicating that risks of contemporary inbreeding are low. Analysis of a post-fire first generation cohort of seedlings showed they likely resulted from intra-stand matings, resulting in reduced genetic diversity compared to the parents. However, admixed seedlings in this cohort showed an increase in heterozygosity relative to likely sources and the non-admixed seedlings of the same stand. Assisted inter-stand gene flow may prove an effective management strategy to boost heterozygosity and corresponding increases in adapting capacity in this endangered species.
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12
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Effect of acclimated temperature on thermal tolerance, immune response and expression of HSP genes in Labeo rohita, Catla catla and their intergeneric hybrids. J Therm Biol 2020; 89:102570. [PMID: 32364999 DOI: 10.1016/j.jtherbio.2020.102570] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 03/03/2020] [Accepted: 03/16/2020] [Indexed: 11/23/2022]
Abstract
The ability of a species and population to respond to a decrease or an increase in temperature depends on their adaptive potential. Here, the critical thermal tolerance (CTmax and CTmin) of four populations: Labeo rohita, Catla catla, and their reciprocal hybrids L. rohita♀× C. catla♂ (RC) and C. catla♀ × L. rohita♂ (CR) being acclimatized at four acclimation temperatures (22, 26, 30 and 34 °C) were determined. All populations indicated substantial variations (P < 0.05) in CTmax and CTmin values. L. rohita displayed, comparatively the highest CTmax with largest total and intrinsic polygon zones as well as the upper and lower acquired thermal tolerance zones followed by RC and CR hybrids, while C. catla showed significantly the highest CTmin value and the smallest intrinsic and acquired thermal tolerance zones. Both hybrids illustrated low parent heterosis (≤11%). Additionally, the highest expression of Hsp70 and Hsp90 (heat shock proteins) genes, serum lysozyme level, respiratory burst activity and lowest lipid peroxidation level under lower and higher temperature shock further illustrated strong physiological mechanism of L. rohita in contrast to C. catla, to deal with acute temperature, while hybrids, especially F1 RC hybrid appeared as a good option to replace C. catla in relatively higher and lower temperature areas.
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13
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Li J, Qi C, Gu J, Jin Z. Effect of sire population on the genetic diversity and fitness of F1 progeny in the endangered Chinese endemic Sinocalycanthus chinensis. Ecol Evol 2020; 10:4091-4103. [PMID: 32489633 PMCID: PMC7244809 DOI: 10.1002/ece3.6179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 11/23/2022] Open
Abstract
Sinocalycanthus chinensis Cheng et S. Y. Chang (Calycanthaceae), which has a unique systematic status, is listed as a national second-class protected plant of China. In this study, the genetic diversity, performance, and fitness of F1 progeny from crosses between the Damingshan (DMS) population of S. chinensis and pollen parents from the Daleishan (DLS) and Longxushan (LXS) populations were examined. The DLS population has a relatively small population size, low genetic diversity, and considerable geographical and genetic distances from the DMS population relative to the LXS population. Compared with naturally occurring seeds, DLS-sired seeds had the highest thousand-seed weight, starch content, fat content, germination rate, germination index, and emergence rate, but the lowest protein content. Naturally occurring, open-pollinated seeds had the lowest thousand-seed weight, starch content, and fat content, but the highest protein content. Compared with natural F1 progeny, DMS × DLS seedlings had the highest genetic diversity, photosynthetic parameters, and growth characteristics, except for leaf mass ratio and stem mass ratio. Under strong light, DMS × DLS seedlings exhibited a F v/F m value of 0.75, while the other two seedling types exhibited F v/F m values of 0.65. DLS-sired seeds had the most vigorous growth characteristics except for leaf mass ratio and stem mass ratio. These results suggest that genetic rescue by transplanting seedlings from the DLS population or hand pollination with pollen from the DLS population would be effective methods to reduce inbreeding depression and obtain strong offspring with high genetic diversity and fitness in the DMS population.
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Affiliation(s)
- Junmin Li
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
| | - Caihong Qi
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Traffic Patrol Headquarters of Public Security Bureau of Chongqing CityVehicle Management InstituteChongqinChina
| | - Jingjing Gu
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
- Xianju Branch of Ecological Environment Bureau of Taizhou CityTaizhouChina
| | - Zexin Jin
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and ConservationTaizhou UniversityTaizhouChina
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14
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St. Clair AB, Dunwiddie PW, Fant JB, Kaye TN, Kramer AT. Mixing source populations increases genetic diversity of restored rare plant populations. Restor Ecol 2020. [DOI: 10.1111/rec.13131] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Adrienne Basey St. Clair
- Program in Plant Biology and ConservationNorthwestern University 2205 Tech Drive Evanston IL 60208 U.S.A
- Negaunee Institute for Plant Conservation Science and ActionNegaunee Institute for Plant Conservation Science and Action Botanic Garden 1000 Lake Cook Road Chicago IL 60022 U.S.A
| | | | - Jeremie B. Fant
- Negaunee Institute for Plant Conservation Science and ActionNegaunee Institute for Plant Conservation Science and Action Botanic Garden 1000 Lake Cook Road Chicago IL 60022 U.S.A
| | - Thomas N. Kaye
- Institute for Applied Ecology 563 SW Jefferson Avenue Corvallis OR 97333 U.S.A
- Department of Botany and Plant PathologyOregon State University Corvallis OR 97331 U.S.A
| | - Andrea T. Kramer
- Negaunee Institute for Plant Conservation Science and ActionNegaunee Institute for Plant Conservation Science and Action Botanic Garden 1000 Lake Cook Road Chicago IL 60022 U.S.A
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15
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Kerk M, Onorato DP, Hostetler JA, Bolker BM, Oli MK. Dynamics, Persistence, and Genetic Management of the Endangered Florida Panther Population. WILDLIFE MONOGRAPHS 2019. [DOI: 10.1002/wmon.1041] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Madelon Kerk
- Department of Wildlife Ecology and Conservation University of Florida 110 Newins‐Ziegler Hall Gainesville FL 32611‐0430 USA
| | - David P. Onorato
- Fish and Wildlife Research Institute Florida Fish and Wildlife Conservation Commission 298 Sabal Palm Road Naples FL 34114 USA
| | - Jeffrey A. Hostetler
- Fish and Wildlife Research Institute Florida Fish and Wildlife Conservation Commission 100 8th Avenue SE St. Petersburg FL 33701 USA
| | - Benjamin M. Bolker
- Departments of Mathematics and Statistics and Biology McMaster University 314 Hamilton Hall Hamilton ON L8S 4K1 Canada
| | - Madan K. Oli
- Department of Wildlife Ecology and Conservation University of Florida 110 Newins‐Ziegler Hall Gainesville FL 32611‐0430 USA
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16
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Genetic rescue insights from population- and family-level hybridization effects in brook trout. CONSERV GENET 2019. [DOI: 10.1007/s10592-019-01179-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Using population genetics and demographic reconstruction to predict outcomes of genetic rescue for an endangered songbird. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1050-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Jensen C, Ørsted M, Kristensen TN. Effects of genetic distance on heterosis in a Drosophila melanogaster model system. Genetica 2018; 146:345-359. [PMID: 29761415 DOI: 10.1007/s10709-018-0026-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 05/08/2018] [Indexed: 11/27/2022]
Abstract
Habitat fragmentation and small population sizes can lead to inbreeding and loss of genetic variation, which can potentially cause inbreeding depression and decrease the ability of populations to adapt to altered environmental conditions. One solution to these genetic problems is the implementation of genetic rescue, which re-establishes gene flow between separated populations. Similar techniques are being used in animal and plant breeding to produce superior production animals and plants. To optimize fitness benefits in genetic rescue programs and to secure high yielding domestic varieties in animal and plant breeding, knowledge on the genetic relatedness of populations being crossed is imperative. In this study, we conducted replicated crosses between isogenic Drosophila melanogaster lines from the Drosophila Genetic Reference Panel. We grouped lines in two genetic distance groups to study the effect of genetic divergence between populations on the expression of heterosis in two fitness components; starvation resistance and reproductive output. We further investigated the transgenerational effects of outcrossing by investigating the fitness consequences in both the F1- and the F3-generations. High fitness enhancements were observed in hybrid offspring compared to parental lines, especially for reproductive output. However, the level of heterosis declined from the F1- to the F3-generation. Generally, genetic distance did not have strong impact on the level of heterosis detected, although there were exceptions to this pattern. The best predictor of heterosis was performance of parental lines with poorly performing parental lines showing higher hybrid vigour when crossed, i.e. the potential for heterosis was proportional to the level of inbreeding depression. Overall, our results show that outcrossing can have very strong positive fitness consequences for genetically depauperate populations.
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Affiliation(s)
- Charlotte Jensen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg E, Denmark
| | - Michael Ørsted
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg E, Denmark.
| | - Torsten Nygaard Kristensen
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg E, Denmark.,Section of Genetics, Ecology and Evolution, Institute of Bioscience, Aarhus University, Ny Munkegade 114, 8000, Aarhus C, Denmark
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19
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Shi J, Joshi J, Tielbörger K, Verhoeven KJF, Macel M. Costs and benefits of admixture between foreign genotypes and local populations in the field. Ecol Evol 2018; 8:3675-3684. [PMID: 29686848 PMCID: PMC5901173 DOI: 10.1002/ece3.3946] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 01/29/2018] [Accepted: 01/30/2018] [Indexed: 12/11/2022] Open
Abstract
Admixture is the hybridization between populations within one species. It can increase plant fitness and population viability by alleviating inbreeding depression and increasing genetic diversity. However, populations are often adapted to their local environments and admixture with distant populations could break down local adaptation by diluting the locally adapted genomes. Thus, admixed genotypes might be selected against and be outcompeted by locally adapted genotypes in the local environments. To investigate the costs and benefits of admixture, we compared the performance of admixed and within-population F1 and F2 generations of the European plant Lythrum salicaria in a reciprocal transplant experiment at three European field sites over a 2-year period. Despite strong differences between site and plant populations for most of the measured traits, including herbivory, we found limited evidence for local adaptation. The effects of admixture depended on experimental site and plant population, and were positive for some traits. Plant growth and fruit production of some populations increased in admixed offspring and this was strongest with larger parental distances. These effects were only detected in two of our three sites. Our results show that, in the absence of local adaptation, admixture may boost plant performance, and that this is particularly apparent in stressful environments. We suggest that admixture between foreign and local genotypes can potentially be considered in nature conservation to restore populations and/or increase population viability, especially in small inbred or maladapted populations.
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Affiliation(s)
- Jun Shi
- Institute of Evolution and Ecology Plant Ecology Group University of Tübingen Tübingen Germany.,Ningbo Academy of Agricultural Sciences Ningbo China
| | - Jasmin Joshi
- Biodiversity Research/Systematic Botany Institute of Biochemistry and Biology University of Potsdam Potsdam Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB) Institute of Biology Freie Universität Berlin Berlin Germany
| | - Katja Tielbörger
- Institute of Evolution and Ecology Plant Ecology Group University of Tübingen Tübingen Germany
| | - Koen J F Verhoeven
- Department of Terrestrial Ecology Netherlands Institute of Ecology (NIOO-KNAW) Wageningen the Netherlands
| | - Mirka Macel
- Institute of Evolution and Ecology Plant Ecology Group University of Tübingen Tübingen Germany.,Molecular Interaction Ecology Department of Plant Science Radboud University Nijmegen Nijmegen the Netherlands.,Plant Ecology and Phytochemistry Leiden Institute of Biology Leiden the Netherlands
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20
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Hamilton JA, Royauté R, Wright JW, Hodgskiss P, Ledig FT. Genetic conservation and management of the California endemic, Torrey pine ( Pinus torreyana Parry): Implications of genetic rescue in a genetically depauperate species. Ecol Evol 2017; 7:7370-7381. [PMID: 28944023 PMCID: PMC5606898 DOI: 10.1002/ece3.3306] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 06/04/2017] [Accepted: 07/13/2017] [Indexed: 01/15/2023] Open
Abstract
Rare species present a challenge under changing environmental conditions as the genetic consequences of rarity may limit species ability to adapt to environmental change. To evaluate the evolutionary potential of a rare species, we assessed variation in traits important to plant fitness using multigenerational common garden experiments. Torrey pine, Pinus torreyana Parry, is one of the rarest pines in the world, restricted to one mainland and one island population. Morphological differentiation between island and mainland populations suggests adaptation to local environments may have contributed to trait variation. The distribution of phenotypic variances within the common garden suggests distinct population-specific growth trajectories underlay genetic differences, with the island population exhibiting substantially reduced genetic variance for growth relative to the mainland population. Furthermore, F1 hybrids, representing a cross between mainland and island trees, exhibit increased height accumulation and fecundity relative to mainland and island parents. This may indicate genetic rescue via intraspecific hybridization could provide the necessary genetic variation to persist in environments modified as a result of climate change. Long-term common garden experiments, such as these, provide invaluable resources to assess the distribution of genetic variance that may inform conservation strategies to preserve evolutionary potential of rare species, including genetic rescue.
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Affiliation(s)
- Jill A. Hamilton
- Department of Biological SciencesNorth Dakota State UniversityFargoNDUSA
| | - Raphaël Royauté
- Department of Biological SciencesNorth Dakota State UniversityFargoNDUSA
| | | | - Paul Hodgskiss
- Pacific Southwest Research StationUSDA‐Forest ServiceDavisCAUSA
| | - F. Thomas Ledig
- Department of Plant ScienceUniversity of CaliforniaDavisCAUSA
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21
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Wells ZRR, McDonnell LH, Chapman LJ, Fraser DJ. Limited variability in upper thermal tolerance among pure and hybrid populations of a cold-water fish. CONSERVATION PHYSIOLOGY 2016; 4:cow063. [PMID: 27990291 PMCID: PMC5156897 DOI: 10.1093/conphys/cow063] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 10/31/2016] [Accepted: 11/07/2016] [Indexed: 05/29/2023]
Abstract
As climate warming threatens the persistence of many species and populations, it is important to forecast their responses to warming thermal regimes. Climate warming often traps populations in smaller habitat fragments, not only changing biotic parameters, but potentially decreasing adaptive potential by decreasing genetic variability. We examined the ability of six genetically distinct and different-sized populations of a cold-water fish (brook trout, Salvelinus fontinalis) to tolerate acute thermal warming and whether this tolerance could be altered by hybridizing populations. Critical thermal maximum (CTmax) assays were conducted on juveniles from each population to assess thermal tolerance, and the agitation temperature was recorded for assessing behavioural changes to elevated temperatures. An additional metric, which we have called the 'CTmax-agitation window' (CTmax minus agitation temperature), was also assessed. The CTmax differed between five out of 15 population pairs, although the maximal CTmax difference was only 0.68°C (29.11-29.79°C). Hybridization between one large population and two small populations yielded no obvious heterosis in mean CTmax, and no differences in agitation temperature or CTmax-agitation window were detected among pure populations or hybrids. Summer variation in temperature within each stream was negatively correlated with mean CTmax and mean CTmax-agitation window, although the maximal difference was small. Despite being one of the most phenotypically divergent and plastic north temperate freshwater fishes, our results suggest that limited variability exists in CTmax among populations of brook trout, regardless of their population size, standing genetic variation and differing natural thermal regimes (temperature variation, minimum and maximum). This study highlights the level to which thermal tolerance is conserved between isolated populations of a vertebrate species, in the face of climate warming.
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Affiliation(s)
- Zachery R. R. Wells
- Department of Biology, Concordia University, Montreal, Quebec, Canada H4B 1R6
| | - Laura H. McDonnell
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Lauren J. Chapman
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Dylan J. Fraser
- Department of Biology, Concordia University, Montreal, Quebec, Canada H4B 1R6
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22
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Espeland EK, Emery NC, Mercer KL, Woolbright SA, Kettenring KM, Gepts P, Etterson JR. Evolution of plant materials for ecological restoration: insights from the applied and basic literature. J Appl Ecol 2016. [DOI: 10.1111/1365-2664.12739] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Erin K. Espeland
- USDA-ARS Pest Management Research Unit; 1500 N. Central Avenue Sidney MT 59270 USA
| | - Nancy C. Emery
- Department of Ecology and Evolutionary Biology; RAMY 0334, University of Colorado; Boulder CO 80309 USA
| | - Kristin L. Mercer
- Department of Horticulture and Crop Science; 2021 Coffey Road, Ohio State University; Columbus OH 43210 USA
| | - Scott A. Woolbright
- Department of Biological Sciences; University of Arkansas at Little Rock 2801 S. University Avenue; Little Rock AR 72204 USA
| | - Karin M. Kettenring
- Ecology Center and Department of Watershed Sciences; 5210 Old Main Hill, Utah State University; Logan UT 84322 USA
| | - Paul Gepts
- Department of Plant Sciences/MS1; University of California; 1 Shields Avenue, Davis CA 95616 USA
| | - Julie R. Etterson
- Department of Biology; University of Minnesota Duluth; 1049 University Drive Duluth MN 55812 USA
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23
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Harrisson KA, Pavlova A, Gonçalves da Silva A, Rose R, Bull JK, Lancaster ML, Murray N, Quin B, Menkhorst P, Magrath MJL, Sunnucks P. Scope for genetic rescue of an endangered subspecies though re-establishing natural gene flow with another subspecies. Mol Ecol 2016; 25:1242-58. [PMID: 26820991 DOI: 10.1111/mec.13547] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/24/2015] [Accepted: 01/19/2016] [Indexed: 12/24/2022]
Abstract
Genetic diversity is positively linked to the viability and evolutionary potential of species but is often compromised in threatened taxa. Genetic rescue by gene flow from a more diverse or differentiated source population of the same species can be an effective strategy for alleviating inbreeding depression and boosting evolutionary potential. The helmeted honeyeater Lichenostomus melanops cassidix is a critically endangered subspecies of the common yellow-tufted honeyeater. Cassidix has declined to a single wild population of ~130 birds, despite being subject to intensive population management over recent decades. We assessed changes in microsatellite diversity in cassidix over the last four decades and used population viability analysis to explore whether genetic rescue through hybridization with the neighbouring Lichenostomus melanops gippslandicus subspecies constitutes a viable conservation strategy. The contemporary cassidix population is characterized by low genetic diversity and effective population size (N(e) < 50), suggesting it is vulnerable to inbreeding depression and will have limited capacity to evolve to changing environments. We find that gene flow from gippslandicus to cassidix has declined substantially relative to pre-1990 levels and argue that natural levels of gene flow between the two subspecies should be restored. Allowing gene flow (~4 migrants per generation) from gippslandicus into cassidix (i.e. genetic rescue), in combination with continued annual release of captive-bred cassidix (i.e. demographic rescue), should lead to positive demographic and genetic outcomes. Although we consider the risk of outbreeding depression to be low, we recommend that genetic rescue be managed within the context of the captive breeding programme, with monitoring of outcomes.
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Affiliation(s)
- Katherine A Harrisson
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia
| | - Alexandra Pavlova
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia
| | - Anders Gonçalves da Silva
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Vic., 3000, Australia
| | - Rebecca Rose
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia
| | - James K Bull
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia
| | | | - Neil Murray
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Vic., 3086, Australia
| | - Bruce Quin
- Department of Environment, Land, Water and Planning, Symes Road, Woori Yallock, Vic., 3139, Australia
| | - Peter Menkhorst
- Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, Heidelberg, Vic., 3084, Australia
| | - Michael J L Magrath
- Department of Wildlife Conservation and Science, Zoos Victoria, Parkville, Vic., 3052, Australia
| | - Paul Sunnucks
- School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia
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24
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Todesco M, Pascual MA, Owens GL, Ostevik KL, Moyers BT, Hübner S, Heredia SM, Hahn MA, Caseys C, Bock DG, Rieseberg LH. Hybridization and extinction. Evol Appl 2016; 9:892-908. [PMID: 27468307 PMCID: PMC4947151 DOI: 10.1111/eva.12367] [Citation(s) in RCA: 333] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/28/2016] [Indexed: 01/29/2023] Open
Abstract
Hybridization may drive rare taxa to extinction through genetic swamping, where the rare form is replaced by hybrids, or by demographic swamping, where population growth rates are reduced due to the wasteful production of maladaptive hybrids. Conversely, hybridization may rescue the viability of small, inbred populations. Understanding the factors that contribute to destructive versus constructive outcomes of hybridization is key to managing conservation concerns. Here, we survey the literature for studies of hybridization and extinction to identify the ecological, evolutionary, and genetic factors that critically affect extinction risk through hybridization. We find that while extinction risk is highly situation dependent, genetic swamping is much more frequent than demographic swamping. In addition, human involvement is associated with increased risk and high reproductive isolation with reduced risk. Although climate change is predicted to increase the risk of hybridization‐induced extinction, we find little empirical support for this prediction. Similarly, theoretical and experimental studies imply that genetic rescue through hybridization may be equally or more probable than demographic swamping, but our literature survey failed to support this claim. We conclude that halting the introduction of hybridization‐prone exotics and restoring mature and diverse habitats that are resistant to hybrid establishment should be management priorities.
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Affiliation(s)
- Marco Todesco
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Mariana A Pascual
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Gregory L Owens
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Katherine L Ostevik
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Brook T Moyers
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada; Department of Bioagricultural Sciences and Pest Management Colorado State University Ft Collins CO USA
| | - Sariel Hübner
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Sylvia M Heredia
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Min A Hahn
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Celine Caseys
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Dan G Bock
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada; Department of Biology Indiana University Bloomington IN USA
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25
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Hamilton JA, Miller JM. Adaptive introgression as a resource for management and genetic conservation in a changing climate. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2016; 30:33-41. [PMID: 26096581 DOI: 10.1111/cobi.12574] [Citation(s) in RCA: 170] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 06/15/2015] [Accepted: 06/17/2015] [Indexed: 05/22/2023]
Abstract
Current rates of climate change require organisms to respond through migration, phenotypic plasticity, or genetic changes via adaptation. We focused on questions regarding species' and populations' ability to respond to climate change through adaptation. Specifically, the role adaptive introgression, movement of genetic material from the genome of 1 species into the genome of another through repeated interbreeding, may play in increasing species' ability to respond to a changing climate. Such interspecific gene flow may mediate extinction risk or consequences of limited adaptive potential that result from standing genetic variation and mutation alone, enabling a quicker demographic recovery in response to changing environments. Despite the near dismissal of the potential benefits of hybridization by conservation practitioners, we examined a number of case studies across different taxa that suggest gene flow between sympatric or parapatric sister species or within species that exhibit strong ecotypic differentiation may represent an underutilized management option to conserve evolutionary potential in a changing environment. This will be particularly true where advanced-generation hybrids exhibit adaptive traits outside the parental phenotypic range, a phenomenon known as transgressive segregation. The ideas presented in this essay are meant to provoke discussion regarding how we maintain evolutionary potential, the conservation value of natural hybrid zones, and consideration of their important role in adaptation to climate.
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Affiliation(s)
- Jill A Hamilton
- Department of Evolution and Ecology, University of California, Davis, CA, 95616, U.S.A..
- Department of Biological Sciences, North Dakota State University, Fargo, ND, 58102, U.S.A..
| | - Joshua M Miller
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
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26
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Unger GM, Heuertz M, Vendramin GG, Robledo-Arnuncio JJ. Assessing early fitness consequences of exotic gene flow in the wild: a field study with Iberian pine relicts. Evol Appl 2016; 9:367-80. [PMID: 26834830 PMCID: PMC4721076 DOI: 10.1111/eva.12333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 09/27/2015] [Indexed: 12/14/2022] Open
Abstract
Gene flow from plantations of nonlocal (genetically exotic) tree provenances into natural stands of the same species is probably a widespread phenomenon, but its effects remain largely unexamined. We investigated early fitness consequences of intraspecific exotic gene flow in the wild by assessing differences in survival among native, nonlocal, and F1 intraspecific hybrid seedlings naturally established within two native pine relicts (one of Pinus pinaster and the other of P. sylvestris) surrounded by nonlocal plantations. We obtained broad‐scale temporally sequential genotypic samples of a cohort of recruits in each pine relict, from seeds before dispersal to established seedlings months after emergence, tracking temporal changes in the estimated proportion of each parental cross‐type. Results show significant proportions of exotic male gametes before seed dispersal in the two pine relicts. Subsequently to seedling establishment, the frequency of exotic male gametes became nonsignificant in P. pinaster, and dropped by half in P. sylvestris. Exotic zygotic gene flow was significantly different from zero among early recruits for P. sylvestris, decreasing throughout seedling establishment. Seedling mortality resulted in small late sample sizes, and temporal differences in exotic gene flow estimates were not significant, so we could not reject the null hypothesis of invariant early viability across parental cross types in the wild.
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Affiliation(s)
- Gregor M Unger
- Department of Forest Ecology & Genetics INIA-CIFOR Madrid Spain
| | - Myriam Heuertz
- Department of Forest Ecology & Genetics INIA-CIFOR Madrid Spain; INRA UMR 1202 BIOGECO Cestas France; University of Bordeaux UMR 1202 BIOGECO Talence France
| | - Giovanni G Vendramin
- Institute of Biosciences and Bioresources National Research Council Sesto Fiorentino (FI) Italy
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27
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Ottewell KM, Bickerton DC, Byrne M, Lowe AJ. Bridging the gap: a genetic assessment framework for population-level threatened plant conservation prioritization and decision-making. DIVERS DISTRIB 2015. [DOI: 10.1111/ddi.12387] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Kym M. Ottewell
- Australian Centre for Evolutionary Biology and Biodiversity; School of Earth and Environmental Sciences; University of Adelaide; North Terrace Adelaide SA 5005 Australia
- Science and Conservation Division; Department of Parks and Wildlife; Government of Western Australia; Locked Bag 104, Bentley Delivery Centre Perth WA 6152 Australia
| | - Doug C. Bickerton
- Department of Environment, Water and Natural Resources; Government of South Australia; GPO Box 1047 Adelaide SA 5001 Australia
| | - Margaret Byrne
- Science and Conservation Division; Department of Parks and Wildlife; Government of Western Australia; Locked Bag 104, Bentley Delivery Centre Perth WA 6152 Australia
| | - Andrew J. Lowe
- Australian Centre for Evolutionary Biology and Biodiversity; School of Earth and Environmental Sciences; University of Adelaide; North Terrace Adelaide SA 5005 Australia
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28
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Abstract
Setting aside high-quality large areas of habitat to protect threatened populations is becoming increasingly difficult as humans fragment and degrade the environment. Biologists and managers therefore must determine the best way to shepherd small populations through the dual challenges of reductions in both the number of individuals and genetic variability. By bringing in additional individuals, threatened populations can be increased in size (demographic rescue) or provided with variation to facilitate adaptation and reduce inbreeding (genetic rescue). The relative strengths of demographic and genetic rescue for reducing extinction and increasing growth of threatened populations are untested, and which type of rescue is effective may vary with population size. Using the flour beetle (Tribolium castaneum) in a microcosm experiment, we disentangled the genetic and demographic components of rescue, and compared them with adaptation from standing genetic variation (evolutionary rescue in the strictest sense) using 244 experimental populations founded at either a smaller (50 individuals) or larger (150 individuals) size. Both types of rescue reduced extinction, and those effects were additive. Over the course of six generations, genetic rescue increased population sizes and intrinsic fitness substantially. Both large and small populations showed evidence of being able to adapt from standing genetic variation. Our results support the practice of genetic rescue in facilitating adaptation and reducing inbreeding depression, and suggest that demographic rescue alone may suffice in larger populations even if only moderately inbred individuals are available for addition.
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29
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Genetic and fitness consequences of interpopulation mating in Dianthus guliae Janka: conservation implications for severely depleted and isolated plant populations. CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0727-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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30
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Whiteley AR, Fitzpatrick SW, Funk WC, Tallmon DA. Genetic rescue to the rescue. Trends Ecol Evol 2015; 30:42-9. [DOI: 10.1016/j.tree.2014.10.009] [Citation(s) in RCA: 355] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 01/26/2023]
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31
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Weisenberger LA, Weller SG, Sakai AK. Remnants of populations provide effective source material for reintroduction of an endangered Hawaiian plant, Schiedea kaalae (Caryophyllaceae). AMERICAN JOURNAL OF BOTANY 2014; 101:1954-1962. [PMID: 25366860 DOI: 10.3732/ajb.1400271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
PREMISE OF THE STUDY Reintroductions may be essential to prevent extinction of many critically endangered species. Ideally, reintroduction efforts rely on adjacent source populations, but limited source material may necessitate crossing individuals from different and possibly distant populations. To determine the consequences of integrating multiple populations in reintroductions, we investigated levels of inbreeding depression, outbreeding depression, and heterosis for populations of Schiedea kaalae (Caryophyllaceae), an endangered species endemic to the Wai'anae and Ko'olau Mountains of O'ahu, Hawai'i. The possibility of gene flow among plants was explored through pollinator observations. METHODS Individuals from ex situ living collections of nine populations were hand-pollinated with pollen from the same plant, plants from the same population (for three populations only), or plants from different populations. Progeny were outplanted into two common gardens, one in each mountain range on O'ahu. Cumulative fitness was estimated using several independent life history stages. KEY RESULTS Inbreeding depression was minimal, and no outbreeding depression was detected. In contrast, strong heterosis was evident in progeny from between-population crosses, which had higher relative fitness than progeny from self-pollinations or within-population crosses. Observations of floral visitors provided the first evidence that biotic pollination may be important for this species. CONCLUSIONS Results demonstrate the ability to conduct genetic rescue of rare species and suggest that reintroductions may be most successful using heterotic individuals from crosses between populations and at sites where pollinators are present and promote outcrossing.
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Affiliation(s)
- Lauren A Weisenberger
- University of Hawai'i, Department of Botany, 3190 Maile Way, 408 St. John Hall, Honolulu, Hawaii 96822 USA
| | - Stephen G Weller
- University of California Irvine, Department of Ecology & Evolutionary Biology, 321 Steinhaus Hall, Irvine, California 92697 USA
| | - Ann K Sakai
- University of California Irvine, Department of Ecology & Evolutionary Biology, 321 Steinhaus Hall, Irvine, California 92697 USA
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32
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Pannell JR, Fields PD. Evolution in subdivided plant populations: concepts, recent advances and future directions. THE NEW PHYTOLOGIST 2014; 201:417-432. [PMID: 24111698 DOI: 10.1111/nph.12495] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 08/07/2013] [Indexed: 05/14/2023]
Abstract
Research into the evolution of subdivided plant populations has long involved the study of phenotypic variation across plant geographic ranges and the genetic details underlying that variation. Genetic polymorphism at different marker loci has also allowed us to infer the long- and short-term histories of gene flow within and among populations, including range expansions and colonization-extinction dynamics. However, the advent of affordable genome-wide sequences for large numbers of individuals is opening up new possibilities for the study of subdivided populations. In this review, we consider what the new tools and technologies may allow us to do. In particular, we encourage researchers to look beyond the description of variation and to use genomic tools to address new hypotheses, or old ones afresh. Because subdivided plant populations are complex structures, we caution researchers away from adopting simplistic interpretations of their data, and to consider the patterns they observe in terms of the population genetic processes that have given rise to them; here, the genealogical framework of the coalescent will continue to be conceptually and analytically useful.
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Affiliation(s)
- John R Pannell
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland
| | - Peter D Fields
- Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA, 22904-4328, USA
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