1
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Mathur S, Mason AJ, Bradburd GS, Gibbs HL. Functional genomic diversity is correlated with neutral genomic diversity in populations of an endangered rattlesnake. Proc Natl Acad Sci U S A 2023; 120:e2303043120. [PMID: 37844221 PMCID: PMC10614936 DOI: 10.1073/pnas.2303043120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 09/19/2023] [Indexed: 10/18/2023] Open
Abstract
Theory predicts that genetic erosion in small, isolated populations of endangered species can be assessed using estimates of neutral genetic variation, yet this widely used approach has recently been questioned in the genomics era. Here, we leverage a chromosome-level genome assembly of an endangered rattlesnake (Sistrurus catenatus) combined with whole genome resequencing data (N = 110 individuals) to evaluate the relationship between levels of genome-wide neutral and functional diversity over historical and future timescales. As predicted, we found positive correlations between genome-wide estimates of neutral genetic diversity (π) and inferred levels of adaptive variation and an estimate of inbreeding mutation load, and a negative relationship between neutral diversity and an estimate of drift mutation load. However, these correlations were half as strong for projected future levels of neutral diversity based on contemporary effective population sizes. Broadly, our results confirm that estimates of neutral genetic diversity provide an accurate measure of genetic erosion in populations of a threatened vertebrate. They also provide nuance to the neutral-functional diversity controversy by suggesting that while these correlations exist, anthropogenetic impacts may have weakened these associations in the recent past and into the future.
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Affiliation(s)
- Samarth Mathur
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH48824
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH43210
| | - Andrew J. Mason
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH48824
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH43210
| | - Gideon S. Bradburd
- Evolution and Behavior Program, Department of Integrative Biology, Ecology, Michigan State University, East Lansing, MI48824
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI48109
| | - H. Lisle Gibbs
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH48824
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH43210
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2
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Heighton SP, Allio R, Murienne J, Salmona J, Meng H, Scornavacca C, Bastos ADS, Njiokou F, Pietersen DW, Tilak MK, Luo SJ, Delsuc F, Gaubert P. Pangolin Genomes Offer Key Insights and Resources for the World's Most Trafficked Wild Mammals. Mol Biol Evol 2023; 40:msad190. [PMID: 37794645 PMCID: PMC10551234 DOI: 10.1093/molbev/msad190] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023] Open
Abstract
Pangolins form a group of scaly mammals that are trafficked at record numbers for their meat and purported medicinal properties. Despite their conservation concern, knowledge of their evolution is limited by a paucity of genomic data. We aim to produce exhaustive genomic resources that include 3,238 orthologous genes and whole-genome polymorphisms to assess the evolution of all eight extant pangolin species. Robust orthologous gene-based phylogenies recovered the monophyly of the three genera and highlighted the existence of an undescribed species closely related to Southeast Asian pangolins. Signatures of middle Miocene admixture between an extinct, possibly European, lineage and the ancestor of Southeast Asian pangolins, provide new insights into the early evolutionary history of the group. Demographic trajectories and genome-wide heterozygosity estimates revealed contrasts between continental versus island populations and species lineages, suggesting that conservation planning should consider intraspecific patterns. With the expected loss of genomic diversity from recent, extensive trafficking not yet realized in pangolins, we recommend that populations be genetically surveyed to anticipate any deleterious impact of the illegal trade. Finally, we produce a complete set of genomic resources that will be integral for future conservation management and forensic endeavors for pangolins, including tracing their illegal trade. These comprise the completion of whole-genomes for pangolins through the hybrid assembly of the first reference genome for the giant pangolin (Smutsia gigantea) and new draft genomes (∼43x-77x) for four additional species, as well as a database of orthologous genes with over 3.4 million polymorphic sites.
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Affiliation(s)
- Sean P Heighton
- Laboratoire Evolution et Diversité Biologique (EDB)— IRD-UPS-CNRS, Université Toulouse III, Toulouse, France
| | - Rémi Allio
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Jérôme Murienne
- Laboratoire Evolution et Diversité Biologique (EDB)— IRD-UPS-CNRS, Université Toulouse III, Toulouse, France
| | - Jordi Salmona
- Laboratoire Evolution et Diversité Biologique (EDB)— IRD-UPS-CNRS, Université Toulouse III, Toulouse, France
| | - Hao Meng
- The State Key Laboratory of Protein and Plant Gene Research of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Céline Scornavacca
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Armanda D S Bastos
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
| | - Flobert Njiokou
- Laboratoire de Parasitologie et Ecologie, Faculté des Sciences, Université de Yaoundé I, Yaoundé, Cameroon
| | - Darren W Pietersen
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
| | - Marie-Ka Tilak
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Shu-Jin Luo
- The State Key Laboratory of Protein and Plant Gene Research of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Frédéric Delsuc
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Philippe Gaubert
- Laboratoire Evolution et Diversité Biologique (EDB)— IRD-UPS-CNRS, Université Toulouse III, Toulouse, France
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade 16 do Porto, Terminal de Cruzeiros do Porto de Leixões, Porto, Portugal
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3
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Thacker AJ, Hileman ET, Keenlance P, McCluskey EM, Swinehart A, Kovach J, Moore JA. Modeling Occupancy and Detection Probabilities to Update the Status of Threatened Eastern Massasauga Rattlesnake Populations. Glob Ecol Conserv 2023. [DOI: 10.1016/j.gecco.2023.e02422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023] Open
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4
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Martin SA, Peterman WE, Lipps GJ, Gibbs HL. Inferring population connectivity in eastern massasauga rattlesnakes (Sistrurus catenatus) using landscape genetics. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2793. [PMID: 36482809 DOI: 10.1002/eap.2793] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 10/18/2022] [Accepted: 10/25/2022] [Indexed: 06/17/2023]
Abstract
Assessing the environmental factors that influence the ability of a threatened species to move through a landscape can be used to identify conservation actions that connect isolated populations. However, direct observations of species' movement are often limited, making the development of alternate approaches necessary. Here we use landscape genetic analyses to assess the impact of landscape features on the movement of individuals between local populations of a threatened snake, the eastern massasauga rattlesnake (Sistrurus catenatus). We linked connectivity data with habitat information from two landscapes of similar size: a large region of unfragmented habitat and a previously studied fragmented landscape consisting of isolated patches of habitat. We used this analysis to identify features of the landscape where modification or acquisition would enhance population connectivity in the fragmented region. We found evidence that current connectivity was impacted by both contemporary land-cover features, especially roads, and inherent landscape features such as elevation. Next, we derived estimates of expected movement ability using a recently developed pedigree-based approach and least-cost paths through the unfragmented landscape. We then used our pedigree and resistance map to estimate resistance polygons of the potential extent for S. catenatus movement in the fragmented landscape. These polygons identify possible sites for future corridors connecting currently isolated populations in this landscape by linking the impact of future habitat modification or land acquisition to dispersal ability in this species. Overall, our study shows how modeling landscape resistance across differently fragmented landscapes can identify habitat features that affect contemporary movement in threatened species in fragmented landscapes and how this information can be used to guide mitigation actions whose goal is to connect isolated populations.
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Affiliation(s)
- Scott A Martin
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
| | - William E Peterman
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
- School of Environmental and Natural Resources, The Ohio State University, Columbus, Ohio, USA
| | - Gregory J Lipps
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
| | - H Lisle Gibbs
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
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5
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Nikolic N, Devloo-Delva F, Bailleul D, Noskova E, Rougeux C, Delord C, Borsa P, Liautard-Haag C, Hassan M, Marie AD, Feutry P, Grewe P, Davies C, Farley J, Fernando D, Biton-Porsmoguer S, Poisson F, Parker D, Leone A, Aulich J, Lansdell M, Marsac F, Arnaud-Haond S. Stepping up to genome scan allows stock differentiation in the worldwide distributed blue shark Prionace glauca. Mol Ecol 2023; 32:1000-1019. [PMID: 36511846 DOI: 10.1111/mec.16822] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/15/2022]
Abstract
The blue shark Prionace glauca is a top predator with one of the widest geographical distributions of any shark species. It is classified as Critically Endangered in the Mediterranean Sea, and Near Threatened globally. Previous genetic studies did not reject the null hypothesis of a single global population. The blue shark was proposed as a possible archetype of the "grey zone of population differentiation," coined to designate cases where population structure may be too recent or too faint to be detected using a limited set of markers. Here, blue shark samples collected throughout its global range were sequenced using a specific RAD method (DArTseq), which recovered 37,655 genome-wide single nucleotide polymorphisms (SNPs). Two main groups emerged, with Mediterranean Sea and northern Atlantic samples (Northern population) differentiated significantly from the Indo-west Pacific samples (Southern population). Significant pairwise FST values indicated further genetic differentiation within the Atlantic Ocean, and between the Atlantic Ocean and the Mediterranean Sea. Reconstruction of recent demographic history suggested divergence between Northern and Southern populations occurred about 500 generations ago and revealed a drastic reduction in effective population size from a large ancestral population. Our results illustrate the power of genome scans to detect population structure and reconstruct demographic history in highly migratory marine species. Given that the management plans of the blue shark (targeted or bycatch) fisheries currently assume panmictic regional stocks, we strongly recommend that the results presented here be considered in future stock assessments and conservation strategies.
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Affiliation(s)
- Natacha Nikolic
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France.,INRAE, Ecobiop, AQUA, Saint-Pée-sur-Nivelle, France.,ARBRE, Agence de Recherche pour la Biodiversité à la Réunion, Saint-Gilles, France
| | - Floriaan Devloo-Delva
- CSIRO Environment, Hobart, Tasmania, Australia.,School of Natural Sciences-Quantitative Marine Science, University of Tasmania, Hobart, Tasmania, Australia
| | - Diane Bailleul
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France
| | - Ekaterina Noskova
- Computer Technologies Laboratory, ITMO University, St Petersburg, Russia
| | | | - Chrystelle Delord
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France
| | - Philippe Borsa
- Institut de recherche pour le développement, UMR ENTROPIE, Montpellier, France
| | | | - Mohamad Hassan
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France.,Animal Production Department, Tishreen University, Latakia, Syria
| | - Amandine D Marie
- ARBRE, Agence de Recherche pour la Biodiversité à la Réunion, Saint-Gilles, France
| | | | - Peter Grewe
- CSIRO Environment, Hobart, Tasmania, Australia
| | | | | | | | | | - François Poisson
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France
| | - Denham Parker
- Department of Forestry, Fisheries and the Environment, (DFFE), Cape Town, South Africa.,Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - Agostino Leone
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France
| | | | | | - Francis Marsac
- UMR MARBEC, University of Montpellier, IRD, Ifremer, CNRS, Sète, France
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6
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Yu X, Chen F, Chen Z, Wei P, Song X, Liu C, Liu T, Li X, Liu X. Genetic diversity and gene expression diversity shape the adaptive pattern of the aquatic plant Batrachium bungei along an altitudinal gradient on the Qinghai-Tibet plateau. PLANT MOLECULAR BIOLOGY 2023; 111:275-290. [PMID: 36534297 DOI: 10.1007/s11103-022-01326-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 11/24/2022] [Indexed: 05/22/2023]
Abstract
It is an intriguing issue of evolutionary biology how genetic diversity and gene expression diversity shape the adaptive patterns. Comparative transcriptomic studies of wild populations in extreme environments provide critical insights into the relative contribution of genetic and expressive components. In this study, we analyzed the genetic diversity and gene expression diversity of 20 populations of the aquatic plant Batrachium bungei along elevations ranging from 2690 to 4896 m on the Qinghai-Tibet plateau (QTP). Based on single nucleotide polymorphisms (SNPs) and gene expression data from 100 individuals of B. bungei, we found that variation in genetic sequence was more sensitive to detect weak differentiation than gene expression. Using 292,613 high-quality SNPs, we documented a significant phylogeographical structure, a low within-population genetic diversity, and a high inter-population genetic differentiation in B. bungei populations. Analysis of relationship between geographic distance, genetic distance, and gene expression similarity showed that geographic isolation shaped gene flow patterns but not gene expression patterns. We observed a negative relationship between genetic diversity and gene expression diversity within and among B. bungei populations, and we demonstrated that as environmental conditions worsen with increasing altitude, genetic diversity played an increased role in maintaining the stability of populations, while the corresponding role of gene expression diversity decreased. These results suggested that genetic diversity and gene expression diversity might act as a complementary mechanism contributing to the long-term survival of B. bungei in extreme environments.
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Affiliation(s)
- Xiaolei Yu
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China
| | - Feifei Chen
- Laboratory of Extreme Environmental Biological Resources and Adaptive Evolution, Research Center for Ecology, School of Sciences, Tibet University, Lhasa, 850000, Tibet, China
| | - Zhuyifu Chen
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China
| | - Pei Wei
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China
| | - Xiaoli Song
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China
| | - Chenlai Liu
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China
| | - Tailong Liu
- Laboratory of Extreme Environmental Biological Resources and Adaptive Evolution, Research Center for Ecology, School of Sciences, Tibet University, Lhasa, 850000, Tibet, China
| | - Xiaoyan Li
- Biology Experimental Teaching Center, School of Life Science, Wuhan University, Wuhan, 430072, Hubei, China.
| | - Xing Liu
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China.
- Laboratory of Extreme Environmental Biological Resources and Adaptive Evolution, Research Center for Ecology, School of Sciences, Tibet University, Lhasa, 850000, Tibet, China.
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7
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Evaluation of Genetic Diversity in Dog Breeds Using Pedigree and Molecular Analysis: A Review. DIVERSITY 2022. [DOI: 10.3390/d14121054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Domestic dogs are important for many economic and social reasons, and they have become a well-known model species for human disease. According to research, dog breeds exhibit significant levels of inbreeding and genetic diversity loss, decreasing the population’s ability to adapt in certain conditions, and indicating the need of conservation strategies. Before the development of molecular markers, pedigree information was used for genetic diversity management. In recent years, genomic tools are frequently applied for accurate estimation of genetic diversity and improved genetic conservation due to incomplete pedigrees and pedigree errors. The most frequently used molecular markers include PCR-based microsatellite markers (STRs) and DNA sequencing-based single-nucleotide polymorphism markers (SNP). The aim of this review was to highlight genetic diversity studies on dog breeds conducted using pedigree and molecular markers, as well as the importance of genetic diversity conservation in increasing the adaptability and survival of dog breed populations.
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8
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Hoey JA, Able KW, Pinsky ML. Genetic decline and recovery of a demographically rebuilt fishery species. Mol Ecol 2022; 31:5684-5698. [PMID: 36114805 PMCID: PMC9828022 DOI: 10.1111/mec.16697] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/09/2022] [Accepted: 09/15/2022] [Indexed: 01/13/2023]
Abstract
The demographic history of a population is important for conservation and evolution, but this history is unknown for many populations. Methods that use genomic data have been developed to infer demography, but they can be challenging to implement and interpret, particularly for large populations. Thus, understanding if and when genetic estimates of demography correspond to true population history is important for assessing the performance of these genetic methods. Here, we used double-digest restriction-site associated DNA (ddRAD) sequencing data from archived collections of larval summer flounder (Paralichthys dentatus, n = 279) from three cohorts (1994-1995, 1997-1998 and 2008-2009) along the U.S. East coast to examine how contemporary effective population size and genetic diversity responded to changes in abundance in a natural population. Despite little to no detectable change in genetic diversity, coalescent-based demographic modelling from site frequency spectra revealed that summer flounder effective population size declined dramatically in the early 1980s. The timing and direction of change corresponded well with the observed decline in spawning stock census abundance in the late 1980s from independent fish surveys. Census abundance subsequently recovered and achieved the prebottleneck size. Effective population size also grew following the bottleneck. Our results for summer flounder demonstrate that genetic sampling and site frequency spectra can be useful for detecting population dynamics, even in species with large effective sizes.
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Affiliation(s)
- Jennifer A. Hoey
- Ecology, Evolution, & Natural ResourcesRutgers UniversityNew BrunswickNew JerseyUSA,Institute for Biodiversity Science and SustainabilityCalifornia Academy of SciencesSan FranciscoCaliforniaUSA
| | - Kenneth W. Able
- Marine Field Station, Department of Marine and Coastal Sciences, Rutgers UniversityTuckertonNew JerseyUSA
| | - Malin L. Pinsky
- Ecology, Evolution, & Natural ResourcesRutgers UniversityNew BrunswickNew JerseyUSA
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Campbell DC, Camak DT, Piller KR. Islands in the desert: assessing fine scale population genomic variation of a group of imperiled desert fishes. CONSERV GENET 2022. [DOI: 10.1007/s10592-022-01457-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Bauza Nowotny E, Lyons PJ, Gonzalez-Socoloske D. Identification of the Eastern Massasauga Rattlesnake (Sistrurus catenatus) through genetic analysis of shed skin. CONSERV GENET RESOUR 2022. [DOI: 10.1007/s12686-022-01274-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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11
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Limited gene flow and pronounced population genetic structure of Eastern Massasauga (Sistrurus catenatus) in a Midwestern prairie remnant. PLoS One 2022; 17:e0265666. [PMID: 35324968 PMCID: PMC8947261 DOI: 10.1371/journal.pone.0265666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 03/04/2022] [Indexed: 11/19/2022] Open
Abstract
As anthropogenic changes continue to ecologically stress wildlife, obtaining measures of gene flow and genetic diversity are crucial for evaluating population trends and considering management and conservation strategies for small, imperiled populations. In our study, we conducted a molecular assessment to expand on previous work to elucidate patterns of diversity and connectivity in the remaining disjunct Eastern Massasauga Rattlesnake (Sistrurus catenatus) hibernacula in Illinois. We assayed genetic data for 327 samples collected during 1999–2015 from the Carlyle Lake study area across 21 microsatellite loci. We found hibernacula formed distinct genetic clusters corresponding to the three main study areas (Dam Recreation Areas, Eldon Hazlet State Park, and South Shore State Park). Genetic structuring and low estimates of dispersal indicated that connectivity among these study areas is limited and each is demographically independent. Hibernacula exhibited moderate levels of heterozygosity (0.60–0.73), but estimates of effective population size (5.2–41.0) were low and track census sizes generated via long-term mark-recapture data. Hibernacula at Carlyle Lake, which represent the only Eastern Massasauga remaining in Illinois, are vulnerable to future loss of genetic diversity through lack of gene flow as well as demographic and environmental stochastic processes. Our work highlights the need to include population-level genetic data in recovery planning and suggests that recovery efforts should focus on managing the three major study areas as separate conservation units in order to preserve and maintain long-term adaptive potential of these populations. Specific management goals should include improving connectivity among hibernacula, maintaining existing wet grassland habitat, and minimizing anthropogenic sources of mortality caused by habitat management (e.g., mowing, prescribed fire) and recreational activities. Our molecular study provides additional details about demographic parameters and connectivity at Carlyle Lake that can be used to guide recovery of Eastern Massasauga in Illinois and throughout its range.
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12
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Lettoof DC, Thomson VA, Cornelis J, Bateman PW, Aubret F, Gagnon MM, von Takach B. Bioindicator snake shows genomic signatures of natural and anthropogenic barriers to gene flow. PLoS One 2021; 16:e0259124. [PMID: 34714831 PMCID: PMC8555784 DOI: 10.1371/journal.pone.0259124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/12/2021] [Indexed: 11/18/2022] Open
Abstract
Urbanisation alters landscapes, introduces wildlife to novel stressors, and fragments habitats into remnant 'islands'. Within these islands, isolated wildlife populations can experience genetic drift and subsequently suffer from inbreeding depression and reduced adaptive potential. The Western tiger snake (Notechis scutatus occidentalis) is a predator of wetlands in the Swan Coastal Plain, a unique bioregion that has suffered substantial degradation through the development of the city of Perth, Western Australia. Within the urban matrix, tiger snakes now only persist in a handful of wetlands where they are known to bioaccumulate a suite of contaminants, and have recently been suggested as a relevant bioindicator of ecosystem health. Here, we used genome-wide single nucleotide polymorphism (SNP) data to explore the contemporary population genomics of seven tiger snake populations across the urban matrix. Specifically, we used population genomic structure and diversity, effective population sizes (Ne), and heterozygosity-fitness correlations to assess fitness of each population with respect to urbanisation. We found that population genomic structure was strongest across the northern and southern sides of a major river system, with the northern cluster of populations exhibiting lower heterozygosities than the southern cluster, likely due to a lack of historical gene flow. We also observed an increasing signal of inbreeding and genetic drift with increasing geographic isolation due to urbanisation. Effective population sizes (Ne) at most sites were small (< 100), with Ne appearing to reflect the area of available habitat rather than the degree of adjacent urbanisation. This suggests that ecosystem management and restoration may be the best method to buffer the further loss of genetic diversity in urban wetlands. If tiger snake populations continue to decline in urban areas, our results provide a baseline measure of genomic diversity, as well as highlighting which 'islands' of habitat are most in need of management and protection.
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Affiliation(s)
- Damian C. Lettoof
- Behavioural Ecology Lab, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Vicki A. Thomson
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Jari Cornelis
- Behavioural Ecology Lab, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Philip W. Bateman
- Behavioural Ecology Lab, School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Fabien Aubret
- Station d’Ecologie Théorique et Expérimentale, CNRS, Moulis, France
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Marthe M. Gagnon
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Brenton von Takach
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
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13
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Gallego-García N, Caballero S, Shaffer HB. Are genomic updates of well-studied species worth the investment for conservation? A case study of the Critically Endangered Magdalena River turtle. J Hered 2021; 112:575-589. [PMID: 34628509 DOI: 10.1093/jhered/esab063] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
As genomic-scale data sets become economically feasible for most organisms, a key question for conservation biology is whether the increased resolution offered by new genomic approaches justifies repeating earlier studies based on traditional markers, rather than investing those same time and monetary resources in less-known species. Genomic studies offer clear advantages when the objective is to identify adaptive loci that may be critical to conservation policy-makers. However, the answer is far less certain for the population and landscape studies based on neutral loci that dominate the conservation genetics research agenda. We used RADseq to revisit earlier molecular studies of the IUCN Critically Endangered Magdalena River turtle (Podocnemis lewyana), documenting the conservation insights gained by increasing the number of neutral markers by several orders of magnitude. Earlier research indicated that P. lewyana has the lowest genetic diversity known for any chelonian, and little or no population differentiation among independent rivers. In contrast, the RADseq data revealed discrete population structure with isolation-by-distance within river segments and identified precise population breaks clearly delineating management units. It also confirmed that the species does not have extremely low heterozygosity and that effective population sizes are probably sufficient to maintain long-term evolutionary potential. Contrary to earlier inferences from more limited population genetic markers, our genomic data suggest that management strategies should shift from active genetic rescue to more passive protection without extreme interventions. We conclude with a list of examples of conservation studies in other vertebrates indicating that for many systems a genomic update is worth the investment.
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Affiliation(s)
- Natalia Gallego-García
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA.,Departamento de Ciencias Biológicas, Laboratorio de Ecología Molecular de Vertebrados Acuáticos LEMVA, Universidad de los Andes, Bogotá, Colombia
| | - Susana Caballero
- Departamento de Ciencias Biológicas, Laboratorio de Ecología Molecular de Vertebrados Acuáticos LEMVA, Universidad de los Andes, Bogotá, Colombia
| | - H Bradley Shaffer
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA.,La Kretz Center for California Conservation Science, and Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
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14
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Ochoa A, Gibbs HL. Genomic signatures of inbreeding and mutation load in a threatened rattlesnake. Mol Ecol 2021; 30:5454-5469. [PMID: 34448259 DOI: 10.1111/mec.16147] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/04/2021] [Accepted: 08/16/2021] [Indexed: 11/28/2022]
Abstract
Theory predicts that threatened species living in small populations will experience high levels of inbreeding that will increase their genetic load, but recent work suggests that the impact of load may be minimized by purging resulting from long-term population bottlenecks. Empirical studies that examine this idea using genome-wide estimates of inbreeding and genetic load in threatened species are limited. Here we use individual genome resequencing data to compare levels of inbreeding, levels of genetic load (estimated as mutation load) and population history in threatened Eastern massasauga rattlesnakes (Sistrurus catenatus), which exist in small isolated populations, and closely related yet outbred Western massasauga rattlesnakes (Sistrurus tergeminus). In terms of inbreeding, S. catenatus genomes had a greater number of runs of homozygosity of varying sizes, indicating sustained inbreeding through repeated bottlenecks when compared to S. tergeminus. At the species level, outbred S. tergeminus had higher genome-wide levels of mutation load in the form of greater numbers of derived deleterious mutations compared to S. catenatus, presumably due to long-term purging of deleterious mutations in S. catenatus. In contrast, mutations that escaped species-level drift effects within S. catenatus populations were in general more frequent and more often found in homozygous genotypes than in S. tergeminus, suggesting a reduced efficiency of purifying selection in smaller S. catenatus populations for most mutations. Our results support an emerging idea that the historical demography of a threatened species has a significant impact on the type of genetic load present, which impacts implementation of conservation actions such as genetic rescue.
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Affiliation(s)
- Alexander Ochoa
- Department of Evolution, Ecology, and Organismal Biology, Ohio Biodiversity Conservation Partnership, Ohio State University, Columbus, Ohio, USA
| | - H Lisle Gibbs
- Department of Evolution, Ecology, and Organismal Biology, Ohio Biodiversity Conservation Partnership, Ohio State University, Columbus, Ohio, USA
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15
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Kudla N, McCluskey EM, Lulla V, Grundel R, Moore JA. Intact landscape promotes gene flow and low genetic structuring in the threatened Eastern Massasauga Rattlesnake. Ecol Evol 2021; 11:6276-6288. [PMID: 34141217 PMCID: PMC8207425 DOI: 10.1002/ece3.7480] [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: 09/07/2020] [Revised: 12/07/2020] [Accepted: 02/01/2021] [Indexed: 11/07/2022] Open
Abstract
Genetic structuring of wild populations is dependent on environmental, ecological, and life-history factors. The specific role environmental context plays in genetic structuring is important to conservation practitioners working with rare species across areas with varying degrees of fragmentation. We investigated fine-scale genetic patterns of the federally threatened Eastern Massasauga Rattlesnake (Sistrurus catenatus) on a relatively undisturbed island in northern Michigan, USA. This species often persists in habitat islands throughout much of its distribution due to extensive habitat loss and distance-limited dispersal. We found that the entire island population exhibited weak genetic structuring with spatially segregated variation in effective migration and genetic diversity. The low level of genetic structuring contrasts with previous studies in the southern part of the species' range at comparable fine scales (~7 km), in which much higher levels of structuring were documented. The island population's genetic structuring more closely resembles that of populations from Ontario, Canada, that occupy similarly intact habitats. Intrapopulation variation in effective migration and genetic diversity likely corresponds to the presence of large inland lakes acting as barriers and more human activity in the southern portion of the island. The observed genetic structuring in this intact landscape suggests that the Eastern Massasauga is capable of sufficient interpatch movements to reduce overall genetic structuring and colonize new habitats. Landscape mosaics with multiple habitat patches and localized barriers (e.g., large water bodies or roads) will promote gene flow and natural colonization for this declining species.
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Affiliation(s)
- Nathan Kudla
- Biology DepartmentGrand Valley State UniversityAllendaleMIUSA
| | | | - Vijay Lulla
- Department of GeographyIUPUIIndianapolis, INUSA
| | - Ralph Grundel
- Great Lakes Science CenterU.S. Geological SurveyChestertonINUSA
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16
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Ogbonna AC, Braatz de Andrade LR, Mueller LA, de Oliveira EJ, Bauchet GJ. Comprehensive genotyping of a Brazilian cassava (Manihot esculenta Crantz) germplasm bank: insights into diversification and domestication. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2021; 134:1343-1362. [PMID: 33575821 PMCID: PMC8081687 DOI: 10.1007/s00122-021-03775-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/11/2021] [Indexed: 05/03/2023]
Abstract
KEY MESSAGE Brazilian cassava diversity was characterized through population genetics and clustering approaches, highlighting contrasted genetic groups and spatial genetic differentiation. Cassava (Manihot esculenta Crantz) is a major staple root crop of the tropics, originating from the Amazonian region. In this study, 3354 cassava landraces and modern breeding lines from the Embrapa Cassava Germplasm Bank (CGB) were characterized. All individuals were subjected to genotyping-by-sequencing (GBS), identifying 27,045 single-nucleotide polymorphisms (SNPs). Identity-by-state and population structure analyses revealed a unique set of 1536 individuals and 10 distinct genetic groups with heterogeneous linkage disequilibrium (LD). On this basis, a density of 1300-4700 SNP markers were selected for large-effect quantitative trait loci (QTL) detection. Identified genetic groups were further characterized for population genetics parameters including minor allele frequency (MAF), observed heterozygosity [Formula: see text], effective population size estimate [Formula: see text]) and polymorphism information content (PIC). Selection footprints and introgressions of M. glaziovii were detected. Spatial population structure analysis revealed five ancestral populations related to distinct Brazilian ecoregions. Estimation of historical relationships among identified populations suggests an early population split from Amazonian to Atlantic forest and Caatinga ecoregions and active gene flows. This study provides a thorough genetic characterization of ex situ germplasm resources from cassava's center of origin, South America, with results shedding light on Brazilian cassava characteristics and its biogeographical landscape. These findings support and facilitate the use of genetic resources in modern breeding programs including implementation of association mapping and genomic selection strategies.
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Affiliation(s)
- Alex C Ogbonna
- Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute for Plant Research, Ithaca, NY, USA
| | | | - Lukas A Mueller
- Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute for Plant Research, Ithaca, NY, USA
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17
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Ogbonna AC, Braatz de Andrade LR, Mueller LA, de Oliveira EJ, Bauchet GJ. Comprehensive genotyping of a Brazilian cassava (Manihot esculenta Crantz) germplasm bank: insights into diversification and domestication. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2021; 134:1343-1362. [PMID: 33575821 DOI: 10.1101/2020.07.13.200816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/11/2021] [Indexed: 05/25/2023]
Abstract
Brazilian cassava diversity was characterized through population genetics and clustering approaches, highlighting contrasted genetic groups and spatial genetic differentiation. Cassava (Manihot esculenta Crantz) is a major staple root crop of the tropics, originating from the Amazonian region. In this study, 3354 cassava landraces and modern breeding lines from the Embrapa Cassava Germplasm Bank (CGB) were characterized. All individuals were subjected to genotyping-by-sequencing (GBS), identifying 27,045 single-nucleotide polymorphisms (SNPs). Identity-by-state and population structure analyses revealed a unique set of 1536 individuals and 10 distinct genetic groups with heterogeneous linkage disequilibrium (LD). On this basis, a density of 1300-4700 SNP markers were selected for large-effect quantitative trait loci (QTL) detection. Identified genetic groups were further characterized for population genetics parameters including minor allele frequency (MAF), observed heterozygosity [Formula: see text], effective population size estimate [Formula: see text]) and polymorphism information content (PIC). Selection footprints and introgressions of M. glaziovii were detected. Spatial population structure analysis revealed five ancestral populations related to distinct Brazilian ecoregions. Estimation of historical relationships among identified populations suggests an early population split from Amazonian to Atlantic forest and Caatinga ecoregions and active gene flows. This study provides a thorough genetic characterization of ex situ germplasm resources from cassava's center of origin, South America, with results shedding light on Brazilian cassava characteristics and its biogeographical landscape. These findings support and facilitate the use of genetic resources in modern breeding programs including implementation of association mapping and genomic selection strategies.
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Affiliation(s)
- Alex C Ogbonna
- Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute for Plant Research, Ithaca, NY, USA
| | | | - Lukas A Mueller
- Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute for Plant Research, Ithaca, NY, USA
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18
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Bradke DR, Altobelli JT, Russell AL, Jaeger CP, Moore JA. Low Bottleneck Detection in Long-Lived Species Despite Lost Genetic Diversity: A Case Study of Tuatara and Eastern Massasauga Rattlesnakes. J Hered 2021; 112:346-356. [PMID: 33908605 DOI: 10.1093/jhered/esab025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/21/2021] [Indexed: 11/12/2022] Open
Abstract
Population bottlenecks can reduce genetic diversity and may lead to inbreeding depression. However, some studies have provided evidence that long lifespans buffer negative genetic effects of bottlenecks. Others have cautioned that longevity might merely mask the effects of genetic drift, which will still affect long-term population viability. We used microsatellite data from actual populations of tuatara (Sphenodon punctatus) and eastern massasaugas (Sistrurus catenatus) as a starting point for simulated population declines to evaluate the performance of bottleneck tests under a range of scenarios. We quantified losses in genetic diversity for each scenario and assessed the power of commonly used tests (i.e., M-ratio, heterozygosity excess, and mode-shift) to detect known bottlenecks in these moderate- to long-lived species. Declines in genetic diversity were greater in bottlenecks simulated for eastern massasaugas, the shorter-lived species, and mode-shift and heterozygosity excess tests were more sensitive to population declines in this species. Conversely, M-ratio tests were more sensitive to bottlenecks simulated in tuatara. Despite dramatic simulated population declines, heterozygosity excess and mode-shift tests often failed to detect bottlenecks in both species, even when large losses in genetic diversity had occurred (both allelic diversity and heterozygosity). While not eliminating type II error, M-ratio tests generally performed best and were most reliable when a critical value (Mc) of 0.68 was used. However, in tuatara simulations, M-ratio tests had high rates of type I error when Mc was calculated assuming θ = 10. Our results suggest that reliance on these tests could lead to misguided species management decisions.
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Affiliation(s)
- Danielle R Bradke
- Biology Department, Grand Valley State University, Allendale, MI, USA
| | - Joseph T Altobelli
- Biology Department, Grand Valley State University, Allendale, MI, USA.,Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Amy L Russell
- Biology Department, Grand Valley State University, Allendale, MI, USA
| | - Collin P Jaeger
- Department of Biology, McHenry County College, Crystal Lake, IL, USA
| | - Jennifer A Moore
- Biology Department, Grand Valley State University, Allendale, MI, USA
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19
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Martin SA, Lipps GJ, Gibbs HL. Pedigree-based assessment of recent population connectivity in a threatened rattlesnake. Mol Ecol Resour 2021; 21:1820-1832. [PMID: 33738927 DOI: 10.1111/1755-0998.13383] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/25/2021] [Indexed: 12/18/2022]
Abstract
Managing endangered species in fragmented landscapes requires estimating dispersal rates between populations over contemporary timescales. Here, we developed a new method for quantifying recent dispersal using genetic pedigree data for close and distant kin. Specifically, we describe an approach that infers missing shared ancestors between pairs of kin in habitat patches across a fragmented landscape. We then applied a stepping-stone model to assign unsampled individuals in the pedigree to probable locations based on minimizing the number of movements required to produce the observed locations in sampled kin pairs. Finally, we used all pairs of reconstructed parent-offspring sets to estimate dispersal rates between habitat patches under a Bayesian model. Our approach measures connectivity over the timescale represented by the small number of generations contained within the pedigree and so is appropriate for estimating the impacts of recent habitat changes due to human activity. We used our method to estimate recent movement between newly discovered populations of threatened Eastern Massasauga rattlesnakes (Sistrurus catenatus) using data from 2996 RAD-based genetic loci. Our pedigree analyses found no evidence for contemporary connectivity between five genetic groups, but, as validation of our approach, showed high dispersal rates between sample sites within a single genetic cluster. We conclude that these five genetic clusters of Eastern Massasauga rattlesnakes have small numbers of resident snakes and are demographically isolated conservation units. More broadly, our methodology can be widely applied to determine contemporary connectivity rates, independent of bias from shared genetic similarity due to ancestry that impacts other approaches.
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Affiliation(s)
- Scott A Martin
- Department of Evolution, Ecology, and Organismal Biology and Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH, USA
| | - Gregory J Lipps
- Department of Evolution, Ecology, and Organismal Biology and Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH, USA
| | - H Lisle Gibbs
- Department of Evolution, Ecology, and Organismal Biology and Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, OH, USA
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20
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Bassitta M, Brown RP, Pérez-Cembranos A, Pérez-Mellado V, Castro JA, Picornell A, Ramon C. Genomic signatures of drift and selection driven by predation and human pressure in an insular lizard. Sci Rep 2021; 11:6136. [PMID: 33731784 PMCID: PMC7971075 DOI: 10.1038/s41598-021-85591-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/02/2021] [Indexed: 01/27/2023] Open
Abstract
Genomic divergence was studied in 10 small insular populations of the endangered Balearic Islands lizard (Podarcis lilfordi) using double digest restriction-site associated DNA sequencing. The objectives were to establish levels of divergence among populations, investigate the impact of population size on genetic variability and to evaluate the role of different environmental factors on local adaptation. Analyses of 72,846 SNPs supported a highly differentiated genetic structure, being the populations with the lowest population size (Porros, Foradada and Esclatasang islets) the most divergent, indicative of greater genetic drift. Outlier tests identified ~ 2% of loci as candidates for selection. Genomic divergence-Enviroment Association analyses were performed using redundancy analyses based on SNPs putatively under selection, detecting predation and human pressure as the environmental variables with the greatest explanatory power. Geographical distributions of populations and environmental factors appear to be fundamental drivers of divergence. These results support the combined role of genetic drift and divergent selection in shaping the genetic structure of these endemic island lizard populations.
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Affiliation(s)
- Marta Bassitta
- Laboratori de Genètica, Departament de Biologia, Universitat de les Illes Balears, Crta. de Valldemossa, km 7.5, 07122, Palma de Mallorca, Spain.
| | - Richard P Brown
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Ana Pérez-Cembranos
- Departamento de Biología Animal, Edificio de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Valentín Pérez-Mellado
- Departamento de Biología Animal, Edificio de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - José A Castro
- Laboratori de Genètica, Departament de Biologia, Universitat de les Illes Balears, Crta. de Valldemossa, km 7.5, 07122, Palma de Mallorca, Spain
| | - Antònia Picornell
- Laboratori de Genètica, Departament de Biologia, Universitat de les Illes Balears, Crta. de Valldemossa, km 7.5, 07122, Palma de Mallorca, Spain
| | - Cori Ramon
- Laboratori de Genètica, Departament de Biologia, Universitat de les Illes Balears, Crta. de Valldemossa, km 7.5, 07122, Palma de Mallorca, Spain
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21
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Ochoa A, Broe M, Moriarty Lemmon E, Lemmon AR, Rokyta DR, Gibbs HL. Drift, selection and adaptive variation in small populations of a threatened rattlesnake. Mol Ecol 2020; 29:2612-2625. [PMID: 32557885 DOI: 10.1111/mec.15517] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/09/2020] [Accepted: 05/21/2020] [Indexed: 01/22/2023]
Abstract
An important goal of conservation genetics is to determine if the viability of small populations is reduced by a loss of adaptive variation due to genetic drift. Here, we assessed the impact of drift and selection on direct measures of adaptive variation (toxin loci encoding venom proteins) in the eastern massasauga rattlesnake (Sistrurus catenatus), a threatened reptile that exists in small isolated populations. We estimated levels of individual polymorphism in 46 toxin loci and 1,467 control loci across 12 populations of this species, and compared the results with patterns of selection on the same loci following speciation of S. catenatus and its closest relative, the western massasauga (S. tergeminus). Multiple lines of evidence suggest that both drift and selection have had observable impacts on standing adaptive variation. In support of drift effects, we found little evidence for selection on toxin variation within populations and a significant positive relationship between current levels of adaptive variation and long- and short-term estimates of effective population size. However, we also observed levels of directional selection on toxin loci among populations that are broadly similar to patterns predicted from interspecific selection analyses that pre-date the effects of recent drift, and that functional variation in these loci persists despite small short-term effective sizes. This suggests that much of the adaptive variation present in populations may represent an example of "drift debt," a nonequilibrium state where present-day levels of variation overestimate the amount of functional genetic diversity present in future populations.
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Affiliation(s)
- Alexander Ochoa
- Ohio Biodiversity Conservation Partnership and Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, USA
| | - Michael Broe
- Ohio Biodiversity Conservation Partnership and Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, USA
| | | | - Alan R Lemmon
- Department of Scientific Computing, Florida State University, Tallahassee, FL, USA
| | - Darin R Rokyta
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - H Lisle Gibbs
- Ohio Biodiversity Conservation Partnership and Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, USA
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22
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Schmidt DA, Govindarajulu P, Larsen KW, Russello MA. Genotyping-in-Thousands by sequencing reveals marked population structure in Western Rattlesnakes to inform conservation status. Ecol Evol 2020; 10:7157-7172. [PMID: 32760519 PMCID: PMC7391313 DOI: 10.1002/ece3.6416] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/13/2020] [Accepted: 05/04/2020] [Indexed: 01/06/2023] Open
Abstract
Delineation of units below the species level is critical for prioritizing conservation actions for species at-risk. Genetic studies play an important role in characterizing patterns of population connectivity and diversity to inform the designation of conservation units, especially for populations that are geographically isolated. The northernmost range margin of Western Rattlesnakes (Crotalus oreganus) occurs in British Columbia, Canada, where it is federally classified as threatened and restricted to five geographic regions. In these areas, Western Rattlesnakes hibernate (den) communally, raising questions about connectivity within and between den complexes. At present, Western Rattlesnake conservation efforts are hindered by a complete lack of information on genetic structure and degree of isolation at multiple scales, from the den to the regional level. To fill this knowledge gap, we used Genotyping-in-Thousands by sequencing (GT-seq) to genotype an optimized panel of 362 single nucleotide polymorphisms (SNPs) from individual samples (n = 461) collected across the snake's distribution in western Canada and neighboring Washington (USA). Hierarchical STRUCTURE analyses found evidence for population structure within and among the five geographic regions in BC, as well as in Washington. Within these regions, 11 genetically distinct complexes of dens were identified, with some regions having multiple complexes. No significant pattern of isolation-by-distance and generally low levels of migration were detected among den complexes across regions. Additionally, snakes within dens generally were more related than those among den complexes within a region, indicating limited movement. Overall, our results suggest that the single, recognized designatable unit for Western Rattlesnakes in Canada should be re-assessed to proactively focus conservation efforts on preserving total genetic variation detected range-wide. More broadly, our study demonstrates a novel application of GT-seq for investigating patterns of diversity in wild populations at multiple scales to better inform conservation management.
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Affiliation(s)
- Danielle A. Schmidt
- Department of BiologyUniversity of British ColumbiaOkanagan CampusKelownaBCCanada
| | - Purnima Govindarajulu
- British Columbia Ministry of Environment and Climate Change StrategyVictoriaBCCanada
| | - Karl W. Larsen
- Department of Natural Resource SciencesThompson Rivers UniversityKamloopsBCCanada
| | - Michael A. Russello
- Department of BiologyUniversity of British ColumbiaOkanagan CampusKelownaBCCanada
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23
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Matthee CA. The influence of host dispersal on the gene flow and genetic diversity of generalist and specialist ectoparasites. AFRICAN ZOOLOGY 2020. [DOI: 10.1080/15627020.2020.1762512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Conrad A Matthee
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
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24
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Loureiro LO, Engstrom MD, Lim BK. Comparative phylogeography of mainland and insular species of Neotropical molossid bats ( Molossus). Ecol Evol 2020; 10:389-409. [PMID: 31993120 PMCID: PMC6972955 DOI: 10.1002/ece3.5903] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 01/01/2023] Open
Abstract
Historical events, habitat preferences, and geographic barriers might result in distinct genetic patterns in insular versus mainland populations. Comparison between these two biogeographic systems provides an opportunity to investigate the relative role of isolation in phylogeographic patterns and to elucidate the importance of evolution and demographic history in population structure. Herein, we use a genotype-by-sequencing approach (GBS) to explore population structure within three species of mastiff bats (Molossus molossus, M. coibensis, and M. milleri), which represent different ecological histories and geographical distributions in the genus. We tested the hypotheses that oceanic straits serve as barriers to dispersal in Caribbean bats and that isolated island populations are more likely to experience genetic drift and bottlenecks in comparison with highly connected ones, thus leading to different phylogeographic patterns. We show that population structures vary according to general habitat preferences, levels of population isolation, and historical fluctuations in climate. In our dataset, mainland geographic barriers played only a small role in isolation of lineages. However, oceanic straits posed a partial barrier to the dispersal for some populations within some species (M. milleri), but do not seem to disrupt gene flow in others (M. molossus). Lineages on distant islands undergo genetic bottlenecks more frequently than island lineages closer to the mainland, which have a greater exchange of haplotypes.
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Affiliation(s)
- Livia O. Loureiro
- Department of Natural HistoryRoyal Ontario MuseumTorontoONCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Mark D. Engstrom
- Department of Natural HistoryRoyal Ontario MuseumTorontoONCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Burton K. Lim
- Department of Natural HistoryRoyal Ontario MuseumTorontoONCanada
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25
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Lu RS, Chen Y, Tamaki I, Sakaguchi S, Ding YQ, Takahashi D, Li P, Isaji Y, Chen J, Qiu YX. Pre-quaternary diversification and glacial demographic expansions of Cardiocrinum (Liliaceae) in temperate forest biomes of Sino-Japanese Floristic Region. Mol Phylogenet Evol 2019; 143:106693. [PMID: 31778814 DOI: 10.1016/j.ympev.2019.106693] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/11/2019] [Accepted: 11/22/2019] [Indexed: 11/27/2022]
Abstract
The Sino-Japanese Floristic Region (SJFR) in East Asia is one of the most diverse temperate floras in the world. However, the relative influence of Neogene palaeogeographical changes and Quaternary climatic fluctuations as causal mechanisms on species diversification remains largely controversial, because most divergence time estimates were inferred from single-locus data and have limited geographic or taxonomic sampling. To evaluate these influences, we use SNP markers from restriction site-associated DNA sequencing (RAD-Seq) loci and expressed sequence tags-simple sequence repeat (EST-SSR) markers to investigate the levels of genetic variation, speciation and demographic history of the temperate-deciduous forest (TDF) endemic Cardiocrinum (Endlicher) Lindley (Liliaceae), a genus comprising three species in China (C. giganteum, C. cathayanum) and Japan (C. cordatum). Phylogenomic and population genomic coalescent-based analyses demonstrated that Late Neogene tectonic/climatic events triggered speciation of Cardiocrinum, and Pleistocene climatic fluctuations had limited influence on its divergence history. Population demographic inference using Approximate Bayesian Computation from EST-SSRs and palaeoclimatic niche models both indicated that all three Cardiocrinum species experienced population expansions during the transition from the LIG to the LGM. We also discussed the implications of these results on the conservation of montane TDF species in the SJFR under ongoing environmental change. Our results improve our understanding of how the constituents of montane TDF across the SJFR responded to previous periods of rapid climate and environmental change in terms of speciation and population demographic processes.
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Affiliation(s)
- Rui-Sen Lu
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yang Chen
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ichiro Tamaki
- Gifu Academy of Forest Science and Culture, 88 Sodai, Mino, Gifu 501-3714, Japan
| | - Shota Sakaguchi
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yan-Qian Ding
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Daiki Takahashi
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Pan Li
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yuji Isaji
- Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Jun Chen
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ying-Xiong Qiu
- Systematic & Evolutionary Botany and Biodiversity Group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
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