1
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Dehasque M, Morales HE, Díez-Del-Molino D, Pečnerová P, Chacón-Duque JC, Kanellidou F, Muller H, Plotnikov V, Protopopov A, Tikhonov A, Nikolskiy P, Danilov GK, Giannì M, van der Sluis L, Higham T, Heintzman PD, Oskolkov N, Gilbert MTP, Götherström A, van der Valk T, Vartanyan S, Dalén L. Temporal dynamics of woolly mammoth genome erosion prior to extinction. Cell 2024:S0092-8674(24)00577-4. [PMID: 38942016 DOI: 10.1016/j.cell.2024.05.033] [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: 10/02/2023] [Revised: 02/08/2024] [Accepted: 05/17/2024] [Indexed: 06/30/2024]
Abstract
A number of species have recently recovered from near-extinction. Although these species have avoided the immediate extinction threat, their long-term viability remains precarious due to the potential genetic consequences of population declines, which are poorly understood on a timescale beyond a few generations. Woolly mammoths (Mammuthus primigenius) became isolated on Wrangel Island around 10,000 years ago and persisted for over 200 generations before becoming extinct around 4,000 years ago. To study the evolutionary processes leading up to the mammoths' extinction, we analyzed 21 Siberian woolly mammoth genomes. Our results show that the population recovered quickly from a severe bottleneck and remained demographically stable during the ensuing six millennia. We find that mildly deleterious mutations gradually accumulated, whereas highly deleterious mutations were purged, suggesting ongoing inbreeding depression that lasted for hundreds of generations. The time-lag between demographic and genetic recovery has wide-ranging implications for conservation management of recently bottlenecked populations.
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Affiliation(s)
- Marianne Dehasque
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden.
| | - Hernán E Morales
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - David Díez-Del-Molino
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
| | - Patrícia Pečnerová
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden; Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - J Camilo Chacón-Duque
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden; Department of Archaeology and Classical Studies, Stockholm University, Lilla Frescativägen 7, 11418 Stockholm, Sweden
| | - Foteini Kanellidou
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
| | - Héloïse Muller
- Master de Biologie, Ecole Normale Superieure de Lyon, Universite Claude Bernard Lyon I, Universite de Lyon, 69007 Lyon, France
| | - Valerii Plotnikov
- Academy of Sciences of Sakha Republic, Lenin Avenue 33, Yakutsk, Republic of Sakha (Yakutia), Russia
| | - Albert Protopopov
- Academy of Sciences of Sakha Republic, Lenin Avenue 33, Yakutsk, Republic of Sakha (Yakutia), Russia
| | - Alexei Tikhonov
- Zoological Institute of Russian Academy of Sciences, Saint-Petersburg, Russia
| | - Pavel Nikolskiy
- Geological Institute of the Russian Academy of Sciences, Moscow, Russia
| | - Gleb K Danilov
- Peter the Great Museum of Anthropology and Ethnography, Kunstkamera, Russian Academy of Sciences, 3 University Embankment, Box 199034, Saint-Petersburg, Russia
| | - Maddalena Giannì
- Department of Evolutionary Anthropology, Faculty of Life Sciences, University of Vienna, Vienna, Austria; Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria
| | - Laura van der Sluis
- Department of Evolutionary Anthropology, Faculty of Life Sciences, University of Vienna, Vienna, Austria; Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria
| | - Tom Higham
- Department of Evolutionary Anthropology, Faculty of Life Sciences, University of Vienna, Vienna, Austria; Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria
| | - Peter D Heintzman
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Nikolay Oskolkov
- Department of Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Lund University, Lund, Sweden
| | - M Thomas P Gilbert
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark; University Museum, NTNU, Trondheim, Norway
| | - Anders Götherström
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Archaeology and Classical Studies, Stockholm University, Lilla Frescativägen 7, 11418 Stockholm, Sweden
| | - Tom van der Valk
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden; SciLifeLab, Stockholm, Sweden
| | - Sergey Vartanyan
- North-East Interdisciplinary Scientific Research Institute N.A.N.A. Shilo, Far East Branch, Russian Academy of Sciences, Magadan, Russia
| | - Love Dalén
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, 10691 Stockholm, Sweden; Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden; Department of Zoology, Stockholm University, 10691 Stockholm, Sweden.
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2
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Melepat B, Li T, Vinkler M. Natural selection directing molecular evolution in vertebrate viral sensors. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 154:105147. [PMID: 38325501 DOI: 10.1016/j.dci.2024.105147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 12/30/2023] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
Diseases caused by pathogens contribute to molecular adaptations in host immunity. Variety of viral pathogens challenging animal immunity can drive positive selection diversifying receptors recognising the infections. However, whether distinct virus sensing systems differ across animals in their evolutionary modes remains unclear. Our review provides a comparative overview of natural selection shaping molecular evolution in vertebrate viral-binding pattern recognition receptors (PRRs). Despite prevailing negative selection arising from the functional constraints, multiple lines of evidence now suggest diversifying selection in the Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs) and oligoadenylate synthetases (OASs). In several cases, location of the positively selected sites in the ligand-binding regions suggests effects on viral detection although experimental support is lacking. Unfortunately, in most other PRR families including the AIM2-like receptor family, C-type lectin receptors (CLRs), and cyclic GMP-AMP synthetase studies characterising their molecular evolution are rare, preventing comparative insight. We indicate shared characteristics of the viral sensor evolution and highlight priorities for future research.
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Affiliation(s)
- Balraj Melepat
- Charles University, Faculty of Science, Department of Zoology, Viničná 7, 128 43, Prague, EU, Czech Republic
| | - Tao Li
- Charles University, Faculty of Science, Department of Zoology, Viničná 7, 128 43, Prague, EU, Czech Republic
| | - Michal Vinkler
- Charles University, Faculty of Science, Department of Zoology, Viničná 7, 128 43, Prague, EU, Czech Republic.
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3
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Femerling G, van Oosterhout C, Feng S, Bristol RM, Zhang G, Groombridge J, P Gilbert MT, Morales HE. Genetic Load and Adaptive Potential of a Recovered Avian Species that Narrowly Avoided Extinction. Mol Biol Evol 2023; 40:msad256. [PMID: 37995319 DOI: 10.1093/molbev/msad256] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 10/26/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023] Open
Abstract
High genetic diversity is a good predictor of long-term population viability, yet some species persevere despite having low genetic diversity. Here we study the genomic erosion of the Seychelles paradise flycatcher (Terpsiphone corvina), a species that narrowly avoided extinction after having declined to 28 individuals in the 1960s. The species recovered unassisted to over 250 individuals in the 1990s and was downlisted from Critically Endangered to Vulnerable in the International Union for the Conservation of Nature Red List in 2020. By comparing historical, prebottleneck (130+ years old) and modern genomes, we uncovered a 10-fold loss of genetic diversity. Highly deleterious mutations were partly purged during the bottleneck, but mildly deleterious mutations accumulated. The genome shows signs of historical inbreeding during the bottleneck in the 1960s, but low levels of recent inbreeding after demographic recovery. Computer simulations suggest that the species long-term small Ne reduced the masked genetic load and made the species more resilient to inbreeding and extinction. However, the reduction in genetic diversity due to the chronically small Ne and the severe bottleneck is likely to have reduced the species adaptive potential to face environmental change, which together with a higher load, compromises its long-term population viability. Thus, small ancestral Ne offers short-term bottleneck resilience but hampers long-term adaptability to environmental shifts. In light of rapid global rates of population decline, our work shows that species can continue to suffer the effect of their decline even after recovery, highlighting the importance of considering genomic erosion and computer modeling in conservation assessments.
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Affiliation(s)
- Georgette Femerling
- Section for Hologenomics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, México
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | | | - Shaohong Feng
- Center for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
- Innovation Center of Yangtze River Delta, Zhejiang University, Jiashan, China
| | - Rachel M Bristol
- Mahe, Seychelles
- Division of Human and Social Sciences, Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
| | - Guojie Zhang
- Center for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
- Innovation Center of Yangtze River Delta, Zhejiang University, Jiashan, China
| | - Jim Groombridge
- Division of Human and Social Sciences, Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
| | - M Thomas P Gilbert
- Section for Hologenomics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
- University Museum, NTNU, Trondheim, Norway
| | - Hernán E Morales
- Section for Hologenomics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
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4
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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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5
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Dussex N, Morales HE, Grossen C, Dalén L, van Oosterhout C. Purging and accumulation of genetic load in conservation. Trends Ecol Evol 2023; 38:961-969. [PMID: 37344276 DOI: 10.1016/j.tree.2023.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 05/11/2023] [Accepted: 05/12/2023] [Indexed: 06/23/2023]
Abstract
Our ability to assess the threat posed by the genetic load to small and declining populations has been greatly improved by advances in genome sequencing and computational approaches. Yet, considerable confusion remains around the definitions of the genetic load and its dynamics, and how they impact individual fitness and population viability. We illustrate how both selective purging and drift affect the distribution of deleterious mutations during population size decline and recovery. We show how this impacts the composition of the genetic load, and how this affects the extinction risk and recovery potential of populations. We propose a framework to examine load dynamics and advocate for the introduction of load estimates in the management of endangered populations.
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Affiliation(s)
- Nicolas Dussex
- Department of Natural History, NTNU University Museum, Erling Skakkes Gate 47A, 7012 Trondheim, Norway.
| | - Hernán E Morales
- Center for Evolutionary Hologenomics, Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christine Grossen
- WSL Swiss Federal Research Institute, CH-8903 Birmensdorf, Switzerland
| | - Love Dalén
- Centre for Palaeogenetics, Svante Arrhenius väg 20C, SE-106 91 Stockholm, Sweden
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, UK
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6
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Jackson HA, Percival‐Alwyn L, Ryan C, Albeshr MF, Venturi L, Morales HE, Mathers TC, Cocker J, Speak SA, Accinelli GG, Barker T, Heavens D, Willman F, Dawson D, Ward L, Tatayah V, Zuël N, Young R, Concannon L, Whitford H, Clavijo B, Bunbury N, Tyler KM, Ruhomaun K, Grace MK, Bruford MW, Jones CG, Tollington S, Bell DJ, Groombridge JJ, Clark M, Van Oosterhout C. Genomic erosion in a demographically recovered bird species during conservation rescue. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2022; 36:e13918. [PMID: 35554972 PMCID: PMC9546124 DOI: 10.1111/cobi.13918] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 01/07/2022] [Accepted: 01/13/2022] [Indexed: 06/15/2023]
Abstract
The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400-480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993-2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.
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Affiliation(s)
- Hazel A. Jackson
- Durrell Institute of Conservation and Ecology, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | | | - Camilla Ryan
- School of Environmental SciencesUniversity of East AngliaNorwichUK
- The Earlham InstituteNorwichUK
| | - Mohammed F. Albeshr
- School of Biological SciencesUniversity of East AngliaNorwichUK
- Department of Zoology, Faculty of ScienceKing Saud UniversityRiyadhSaudi Arabia
| | - Luca Venturi
- Department of Life SciencesThe Natural History MuseumLondonUK
| | | | | | - Jonathan Cocker
- The Earlham InstituteNorwichUK
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | - Samuel A. Speak
- School of Environmental SciencesUniversity of East AngliaNorwichUK
| | | | | | | | - Faye Willman
- Durrell Institute of Conservation and Ecology, School of Anthropology and ConservationUniversity of KentCanterburyUK
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Deborah Dawson
- NERC Biomolecular Analysis Facility, Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | - Lauren Ward
- Durrell Institute of Conservation and Ecology, School of Anthropology and ConservationUniversity of KentCanterburyUK
- NERC Biomolecular Analysis Facility, Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | | | - Nicholas Zuël
- Mauritian Wildlife FoundationVacoas‐PhoenixMauritius
| | - Richard Young
- Durrell Wildlife Conservation TrustJerseyChannel Islands
| | | | | | | | - Nancy Bunbury
- Seychelles Islands FoundationVictoriaSeychelles
- Centre for Ecology and ConservationUniversity of ExeterPenrynUK
| | - Kevin M. Tyler
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
| | - Kevin Ruhomaun
- National Parks and Conservation Service, Ministry of EnvironmentGovernment of MauritiusRéduitMauritius
| | - Molly K. Grace
- Molly K. Grace, Department of ZoologyUniversity of OxfordOxfordUK
| | | | - Carl G. Jones
- Mauritian Wildlife FoundationVacoas‐PhoenixMauritius
- Durrell Wildlife Conservation TrustJerseyChannel Islands
| | - Simon Tollington
- Durrell Institute of Conservation and Ecology, School of Anthropology and ConservationUniversity of KentCanterburyUK
- NERC Biomolecular Analysis Facility, Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
- North of England Zoological SocietyChester ZooChesterUK
| | - Diana J. Bell
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | - Jim J. Groombridge
- Durrell Institute of Conservation and Ecology, School of Anthropology and ConservationUniversity of KentCanterburyUK
| | - Matt Clark
- The Earlham InstituteNorwichUK
- Department of Life SciencesThe Natural History MuseumLondonUK
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7
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Minias P, Vinkler M. Selection balancing at innate immune genes: adaptive polymorphism maintenance in Toll-like receptors. Mol Biol Evol 2022; 39:6586215. [PMID: 35574644 PMCID: PMC9132207 DOI: 10.1093/molbev/msac102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Balancing selection is a classic mechanism for maintaining variability in immune genes involved in host–pathogen interactions. However, it remains unclear how widespread the mechanism is across immune genes other than the major histocompatibility complex (MHC). Although occasional reports suggest that balancing selection (heterozygote advantage, negative frequency-dependent selection, and fluctuating selection) may act on other immune genes, the current understanding of the phenomenon in non-MHC immune genes is far from solid. In this review, we focus on Toll-like receptors (TLRs), innate immune genes directly involved in pathogen recognition and immune response activation, as there is a growing body of research testing the assumptions of balancing selection in these genes. After reviewing infection- and fitness-based evidence, along with evidence based on population allelic frequencies and heterozygosity levels, we conclude that balancing selection maintains variation in TLRs, though it tends to occur under specific conditions in certain evolutionary lineages rather than being universal and ubiquitous. Our review also identifies key gaps in current knowledge and proposes promising areas for future research. Improving our understanding of host–pathogen interactions and balancing selection in innate immune genes are increasingly important, particularly regarding threats from emerging zoonotic diseases.
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8
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Barr K, Beichman AC, Kalhori P, Rajbhandary J, Bay RA, Ruegg K, Smith TB. Persistent panmixia despite extreme habitat loss and population decline in the threatened tricolored blackbird ( Agelaius tricolor). Evol Appl 2021; 14:674-684. [PMID: 33767743 PMCID: PMC7980274 DOI: 10.1111/eva.13147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/18/2020] [Accepted: 10/01/2020] [Indexed: 01/25/2023] Open
Abstract
Habitat loss and alteration has driven many species into decline, often to the point of requiring protection and intervention to avert extinction. Genomic data provide the opportunity to inform conservation and recovery efforts with details about vital evolutionary processes with a resolution far beyond that of traditional genetic approaches. The tricolored blackbird (Agelaius tricolor) has suffered severe losses during the previous century largely due to anthropogenic impacts on their habitat. Using a dataset composed of a whole genome paired with reduced representation libraries (RAD-Seq) from samples collected across the species' range, we find evidence for panmixia using multiple methods, including PCA (no geographic clustering), admixture analyses (ADMIXTURE and TESS conclude K = 1), and comparisons of genetic differentiation (average FST = 0.029). Demographic modeling approaches recovered an ancient decline that had a strong impact on genetic diversity but did not detect any effect from the known recent decline. We also did not detect any evidence for selection, and hence adaptive variation, at any site, either geographic or genomic. These results indicate that species continues to have high vagility across its range despite population decline and habitat loss and should be managed as a single unit.
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Affiliation(s)
- Kelly Barr
- Center for Tropical ResearchInstitute of the Environment and SustainabilityUniversity of California, Los AngelesLos AngelesCAUSA
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCAUSA
| | - Annabel C. Beichman
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCAUSA
| | - Pooneh Kalhori
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCAUSA
| | - Jasmine Rajbhandary
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCAUSA
| | - Rachael A. Bay
- Department of Evolution and EcologyUniversity of California, DavisDavisCAUSA
| | - Kristen Ruegg
- Department of BiologyColorado State UniversityFort CollinsCOUSA
| | - Thomas B. Smith
- Center for Tropical ResearchInstitute of the Environment and SustainabilityUniversity of California, Los AngelesLos AngelesCAUSA
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCAUSA
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9
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Smallbone W, Ellison A, Poulton S, van Oosterhout C, Cable J. Depletion of MHC supertype during domestication can compromise immunocompetence. Mol Ecol 2020; 30:736-746. [PMID: 33274493 PMCID: PMC7898906 DOI: 10.1111/mec.15763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 11/23/2020] [Accepted: 11/26/2020] [Indexed: 12/27/2022]
Abstract
The major histocompatibility complex (MHC) plays an important role in infectious disease resistance. The presence of certain MHC alleles and functionally similar groups of MHC alleles (i.e., supertypes) has been associated with resistance to particular parasite species. Farmed and domesticated fish stocks are often depleted in their MHC alleles and supertype diversity, possibly as a consequence of artificial selection for desirable traits, inbreeding (loss of heterozygosity), genetic drift (loss of allelic diversity) and/or reduced parasite biodiversity. Here we quantify the effects of depletion of MHC class II genotype and supertype variation on resistance to the parasite Gyrodactylus turnbulli in guppies (Poecilia reticulata). Compared to the descendants of wild‐caught guppies, ornamental fish had a significantly reduced MHC variation (i.e., the numbers of MHC alleles and supertypes per individual, and per population). In addition, ornamental fish were significantly more susceptible to G. turnbulli infections, accumulating peak intensity 10 times higher than that of their wildtype counterparts. Four out of 13 supertypes were associated with a significantly reduced parasite load, and the presence of some supertypes had a dramatic effect on the intensity of infection. Remarkably, the ornamental and wildtype fish differed in the supertypes that were associated with parasite resistance. Analysis with a genetic algorithm showed that resistance‐conferring supertypes of the wildtype and ornamental fish shared two unique amino acids in the peptide‐binding region of the MHC that were not found in any other alleles. These data show that the supertype demarcation captures some, but not all, of the variation in the immune function of the alleles. This study highlights the importance of managing functional MHC diversity in livestock, and suggests there might be some immunological redundancy among MHC supertypes.
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Affiliation(s)
| | - Amy Ellison
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Simon Poulton
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Joanne Cable
- School of Biosciences, Cardiff University, Cardiff, UK
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10
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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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11
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Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull. Immunogenetics 2020; 72:251-262. [PMID: 31996941 PMCID: PMC7182547 DOI: 10.1007/s00251-020-01156-8] [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: 11/11/2019] [Accepted: 01/14/2020] [Indexed: 11/01/2022]
Abstract
Nonspecific innate immune response is activated by toll-like receptors (TLRs), which recognize conserved molecular motifs characteristic for a broad spectrum of pathogens. In this study, we examined nucleotide substitution patterns and allelic diversity at five TLR genes in a wild nonpasserine bird, the black-headed gull Chroicocephalus ridibundus. We hypothesized that balancing selection can maintain high allelic diversity of TLR genes in the black-headed gull because of its ecological characteristics, coloniality, and migratoriness, which are associated with increased exposure and transmission of pathogens. Although we found moderately high levels of sequence polymorphism (8-49 haplotypes retrieved per locus within a sample of 60 individuals), most of these haplotypes were recorded at low frequencies within our study population. At the same time, we found no convincing evidence for the role of balancing selection in the maintenance of this variation (Tajima's D < 0.5), and sites with a significant excess of nonsynonymous mutations (dN/dS > 1) were recorded only at two loci (TLR5 and TLR7). This pattern is consistent with relaxation of selective constraints, where most mutations are slightly deleterious and usually removed by purifying selection. No differences in the diversity and nucleotide substitution rates were found between endosomal loci responsible for viral RNA sensing and loci responsible for the recognition of extracellular pathogens. Our study provides the first information on evolutionary mechanisms shaping polymorphism of TLRs in a species from Lari suborder (gulls and allies) and suggests that TLR genes may be poorly responsive to ecological and life-history characteristics of hosts.
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12
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Chapman JR, Hill T, Unckless RL. Balancing Selection Drives the Maintenance of Genetic Variation in Drosophila Antimicrobial Peptides. Genome Biol Evol 2019; 11:2691-2701. [PMID: 31504505 PMCID: PMC6764478 DOI: 10.1093/gbe/evz191] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2019] [Indexed: 12/19/2022] Open
Abstract
Genes involved in immune defense against pathogens provide some of the most well-known examples of both directional and balancing selection. Antimicrobial peptides (AMPs) are innate immune effector genes, playing a key role in pathogen clearance in many species, including Drosophila. Conflicting lines of evidence have suggested that AMPs may be under directional, balancing, or purifying selection. Here, we use both a linear model and control-gene-based approach to show that balancing selection is an important force shaping AMP diversity in Drosophila. In Drosophila melanogaster, this is most clearly observed in ancestral African populations. Furthermore, the signature of balancing selection is even more striking once background selection has been accounted for. Balancing selection also acts on AMPs in Drosophila mauritiana, an isolated island endemic separated from D. melanogaster by about 4 Myr of evolution. This suggests that balancing selection may be broadly acting to maintain adaptive diversity in Drosophila AMPs, as has been found in other taxa.
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Affiliation(s)
| | - Tom Hill
- Department of Molecular Biosciences, University of Kansas
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13
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McLennan EA, Wright BR, Belov K, Hogg CJ, Grueber CE. Too much of a good thing? Finding the most informative genetic data set to answer conservation questions. Mol Ecol Resour 2019; 19:659-671. [DOI: 10.1111/1755-0998.12997] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Elspeth A. McLennan
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
| | - Belinda R. Wright
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
| | - Katherine Belov
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
| | - Carolyn J. Hogg
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
| | - Catherine E. Grueber
- School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
- San Diego Zoo Global San Diego California
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14
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DeCandia AL, Brzeski KE, Heppenheimer E, Caro CV, Camenisch G, Wandeler P, Driscoll C, vonHoldt BM. Urban colonization through multiple genetic lenses: The city-fox phenomenon revisited. Ecol Evol 2019; 9:2046-2060. [PMID: 30847091 PMCID: PMC6392345 DOI: 10.1002/ece3.4898] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/11/2018] [Accepted: 12/13/2018] [Indexed: 12/31/2022] Open
Abstract
Urbanization is driving environmental change on a global scale, creating novel environments for wildlife to colonize. Through a combination of stochastic and selective processes, urbanization is also driving evolutionary change. For instance, difficulty in traversing human-modified landscapes may isolate newly established populations from rural sources, while novel selective pressures, such as altered disease risk, toxicant exposure, and light pollution, may further diverge populations through local adaptation. Assessing the evolutionary consequences of urban colonization and the processes underlying them is a principle aim of urban evolutionary ecology. In the present study, we revisited the genetic effects of urbanization on red foxes (Vulpes vulpes) that colonized Zurich, Switzerland. Through use of genome-wide single nucleotide polymorphisms and microsatellite markers linked to the major histocompatibility complex (MHC), we expanded upon a previous neutral microsatellite study to assess population structure, characterize patterns of genetic diversity, and detect outliers associated with urbanization. Our results indicated the presence of one large evolutionary cluster, with substructure evident between geographic sampling areas. In urban foxes, we observed patterns of neutral and functional diversity consistent with founder events and reported increased differentiation between populations separated by natural and anthropogenic barriers. We additionally reported evidence of selection acting on MHC-linked markers and identified outlier loci with putative gene functions related to energy metabolism, behavior, and immunity. We concluded that demographic processes primarily drove patterns of diversity, with outlier tests providing preliminary evidence of possible urban adaptation. This study contributes to our overall understanding of urban colonization ecology and emphasizes the value of combining datasets when examining evolutionary change in an increasingly urban world.
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Affiliation(s)
- Alexandra L. DeCandia
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
| | - Kristin E. Brzeski
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
- School of Forest Resources and Environmental ScienceMichigan Technological UniversityHoughtonMichigan
| | | | - Catherine V. Caro
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
| | - Glauco Camenisch
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | | | - Carlos Driscoll
- Laboratory of Comparative Behavioral GenomicsNational Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthRockvilleMaryland
| | - Bridgett M. vonHoldt
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
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