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Low neutral and immunogenetic diversity in northern fringe populations of the green toad Bufotes viridis: implications for conservation. CONSERV GENET 2021. [DOI: 10.1007/s10592-021-01407-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractGenetic variation is often lower at high latitudes, which may compromise the adaptability and hence survival of organisms. Here we show that genetic variability is negatively correlated with northern latitude in European green toads (Bufotes viridis). The result holds true for both putatively neutral microsatellite variation and supposedly adaptive MHC Class IIB variation. In particular, our findings have bearing on the conservation status of this species in Sweden, on the northern limit of its distribution where local populations are small and fragmented. These genetically impoverished populations are closely related to other populations found around the Baltic Sea basin. The low neutral and adaptive variation in these fringe populations compared to population at central ranges confirms a pattern shared across all other amphibians so far studied. In Sweden, the situation of green toads is of concern as the remaining populations may not have the evolutionary potential to cope with present and future environmental challenges.
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Plasil M, Wijkmark S, Elbers JP, Oppelt J, Burger PA, Horin P. The major histocompatibility complex of Old World camelids: Class I and class I-related genes. HLA 2020; 93:203-215. [PMID: 30828986 DOI: 10.1111/tan.13510] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/14/2019] [Accepted: 02/27/2019] [Indexed: 12/30/2022]
Abstract
The genomic structure of the Major Histocompatibility Complex (MHC) region and variation in selected MHC class I related genes in Old World camels, Camelus bactrianus and Camelus dromedaries were studied. The overall genomic organization of the camel MHC region follows a general pattern observed in other mammalian species and individual MHC loci appear to be well conserved. Selected MHC class I genes B-67 and BL3-7 exhibited unexpectedly low variability, even when compared to other camel MHC class I related genes MR1 and MICA. Interspecific SNP and allele sharing are relatively common, and frequencies of heterozygotes are usually low. Such a low variation in a genomic region generally considered as one of the most polymorphic in vertebrate genomes is unusual. Evolutionary relationships between MHC class I related genes and their counterparts from other species seem to be rather complex. Often, they do not follow the general evolutionary history of the species concerned. Close evolutionary relationships of individual MHC class I loci between camels, humans and dogs were observed. Based on the results of this study and on our data on MHC class II genes, the extent and the pattern of polymorphism of the MHC region of Old World camelids differed from most mammalian groups studied so far. Camels thus seem to be an important model for our understanding of the role of genetic diversity in immune functions, especially in the context of unique features of their immunoglobulin and T-cell receptor genes.
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Affiliation(s)
- Martin Plasil
- Department of Animal Genetics, Veterinary and Pharmaceutical University, Brno, Czech Republic.,Ceitec VFU, RG Animal Immunogenomics, Brno, Czech Republic
| | - Sofia Wijkmark
- Department of Animal Genetics, Veterinary and Pharmaceutical University, Brno, Czech Republic
| | - Jean P Elbers
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, Vienna, Austria
| | - Jan Oppelt
- Ceitec MU, Masaryk University, Brno, Czech Republic.,Faculty of Science, National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic
| | - Pamela A Burger
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, Vienna, Austria
| | - Petr Horin
- Department of Animal Genetics, Veterinary and Pharmaceutical University, Brno, Czech Republic.,Ceitec VFU, RG Animal Immunogenomics, Brno, Czech Republic
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Cortázar-Chinarro M, Meyer-Lucht Y, Van der Valk T, Richter-Boix A, Laurila A, Höglund J. Antimicrobial peptide and sequence variation along a latitudinal gradient in two anurans. BMC Genet 2020; 21:38. [PMID: 32228443 PMCID: PMC7106915 DOI: 10.1186/s12863-020-00839-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 03/06/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While there is evidence of both purifying and balancing selection in immune defense genes, large-scale genetic diversity in antimicrobial peptides (AMPs), an important part of the innate immune system released from dermal glands in the skin, has remained uninvestigated. Here we describe genetic diversity at three AMP loci (Temporin, Brevinin and Palustrin) in two ranid frogs (Rana arvalis and R. temporaria) along a 2000 km latitudinal gradient. We amplified and sequenced part of the Acidic Propiece domain and the hypervariable Mature Peptide domain (~ 150-200 bp) in the three genes using Illumina Miseq and expected to find decreased AMP genetic variation towards the northern distribution limit of the species similarly to studies on MHC genetic patterns. RESULTS We found multiple loci for each AMP and relatively high gene diversity, but no clear pattern of geographic genetic structure along the latitudinal gradient. We found evidence of trans-specific polymorphism in the two species, indicating a common evolutionary origin of the alleles. Temporin and Brevinin did not form monophyletic clades suggesting that they belong to the same gene family. By implementing codon evolution models we found evidence of strong positive selection acting on the Mature Peptide. We also found evidence of diversifying selection as indicated by divergent allele frequencies among populations and high Theta k values. CONCLUSION Our results suggest that AMPs are an important source of adaptive diversity, minimizing the chance of microorganisms developing resistance to individual peptides.
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Affiliation(s)
- Maria Cortázar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
| | - Yvonne Meyer-Lucht
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.,Centre for Paleogenetics Svante Arrhenius väg 20C, SE-106 91, Stockholm, Sweden
| | - Tom Van der Valk
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Alex Richter-Boix
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
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Talarico L, Babik W, Marta S, Mattoccia M. Genetic drift shaped MHC IIB diversity of an endangered anuran species within the Italian glacial refugium. J Zool (1987) 2018. [DOI: 10.1111/jzo.12617] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- L. Talarico
- Department of Biology University of Tor Vergata Rome Italy
| | - W. Babik
- Institute of Environmental Sciences Jagiellonian University Kraków Poland
| | - S. Marta
- Department of Biology University of Tor Vergata Rome Italy
- Institute of Ecosystem Studies National Research Council Rome Italy
- Department of Environmental Sciences and Policy University of Milan Milan Italy
| | - M. Mattoccia
- Department of Biology University of Tor Vergata Rome Italy
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Genetic variation and selection of MHC class I loci differ in two congeneric frogs. Genetica 2018; 146:125-136. [PMID: 29450668 DOI: 10.1007/s10709-018-0016-0] [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: 08/18/2017] [Accepted: 02/09/2018] [Indexed: 10/18/2022]
Abstract
Major histocompatibility complex (MHC) genes encode proteins in the acquired immune response pathway that often show distinctive selection-driven patterns in wild vertebrate populations. We examined genetic variation and signatures of selection in the MHC class I alpha 1 (A1)- and alpha 2 (A2)-domain encoding exons of two frog congeners [Agalychnis callidryas (n = 20) and A. lemur (n = 20)] from a single locality in Panama. We also investigated how historical demographic processes may have impacted MHC genetic diversity by analyzing a neutral mitochondrial marker. We found that both MHC domains were highly variable in both species, with both species likely expressing three loci. Our analyses revealed different signatures of selection between the two species, most notably that the A. callidryas A2 domain had experienced positive selection while the A2 domain of A. lemur had not. Diversifying selection acted on the same number of A1 and A2 allelic lineages, but on a higher percentage of A1 sites compared to A2 sites. Neutrality tests of mitochondrial haplotypes predominately indicated that the two species were at genetic equilibrium when the samples were collected. In addition, two historical tests of demography indicated both species have had relatively stable population sizes over the past 100,000 years; thus large population size changes are unlikely to have greatly influenced MHC diversity in either species during this time period. In conclusion, our results suggest that the impact of selection on MHC diversity varied between these two closely related species, likely due to a combination of distinct ecological conditions and past pathogenic pressures.
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Grogan KE, Sauther ML, Cuozzo FP, Drea CM. Genetic wealth, population health: Major histocompatibility complex variation in captive and wild ring-tailed lemurs ( Lemur catta). Ecol Evol 2017; 7:7638-7649. [PMID: 29043021 PMCID: PMC5632616 DOI: 10.1002/ece3.3317] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 12/24/2022] Open
Abstract
Across species, diversity at the major histocompatibility complex (MHC) is critical to individual disease resistance and, hence, to population health; however, MHC diversity can be reduced in small, fragmented, or isolated populations. Given the need for comparative studies of functional genetic diversity, we investigated whether MHC diversity differs between populations which are open, that is experiencing gene flow, versus populations which are closed, that is isolated from other populations. Using the endangered ring-tailed lemur (Lemur catta) as a model, we compared two populations under long-term study: a relatively "open," wild population (n = 180) derived from Bezà Mahafaly Special Reserve, Madagascar (2003-2013) and a "closed," captive population (n = 121) derived from the Duke Lemur Center (DLC, 1980-2013) and from the Indianapolis and Cincinnati Zoos (2012). For all animals, we assessed MHC-DRB diversity and, across populations, we compared the number of unique MHC-DRB alleles and their distributions. Wild individuals possessed more MHC-DRB alleles than did captive individuals, and overall, the wild population had more unique MHC-DRB alleles that were more evenly distributed than did the captive population. Despite management efforts to maintain or increase genetic diversity in the DLC population, MHC diversity remained static from 1980 to 2010. Since 2010, however, captive-breeding efforts resulted in the MHC diversity of offspring increasing to a level commensurate with that found in wild individuals. Therefore, loss of genetic diversity in lemurs, owing to small founder populations or reduced gene flow, can be mitigated by managed breeding efforts. Quantifying MHC diversity within individuals and between populations is the necessary first step to identifying potential improvements to captive management and conservation plans.
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Affiliation(s)
- Kathleen E. Grogan
- University Program in EcologyDuke UniversityDurhamNCUSA
- Department of Evolutionary AnthropologyDuke UniversityDurhamNCUSA
| | | | - Frank P. Cuozzo
- Lajuma Research CentreLouis Trichardt (Makhado)0920South Africa
| | - Christine M. Drea
- University Program in EcologyDuke UniversityDurhamNCUSA
- Department of Evolutionary AnthropologyDuke UniversityDurhamNCUSA
- Department of BiologyDuke UniversityDurhamNCUSA
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Cortázar-Chinarro M, Lattenkamp EZ, Meyer-Lucht Y, Luquet E, Laurila A, Höglund J. Drift, selection, or migration? Processes affecting genetic differentiation and variation along a latitudinal gradient in an amphibian. BMC Evol Biol 2017; 17:189. [PMID: 28806900 PMCID: PMC5557520 DOI: 10.1186/s12862-017-1022-z] [Citation(s) in RCA: 32] [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] [Received: 04/17/2017] [Accepted: 07/26/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Past events like fluctuations in population size and post-glacial colonization processes may influence the relative importance of genetic drift, migration and selection when determining the present day patterns of genetic variation. We disentangle how drift, selection and migration shape neutral and adaptive genetic variation in 12 moor frog populations along a 1700 km latitudinal gradient. We studied genetic differentiation and variation at a MHC exon II locus and a set of 18 microsatellites. RESULTS Using outlier analyses, we identified the MHC II exon 2 (corresponding to the β-2 domain) locus and one microsatellite locus (RCO8640) to be subject to diversifying selection, while five microsatellite loci showed signals of stabilizing selection among populations. STRUCTURE and DAPC analyses on the neutral microsatellites assigned populations to a northern and a southern cluster, reflecting two different post-glacial colonization routes found in previous studies. Genetic variation overall was lower in the northern cluster. The signature of selection on MHC exon II was weaker in the northern cluster, possibly as a consequence of smaller and more fragmented populations. CONCLUSION Our results show that historical demographic processes combined with selection and drift have led to a complex pattern of differentiation along the gradient where some loci are more divergent among populations than predicted from drift expectations due to diversifying selection, while other loci are more uniform among populations due to stabilizing selection. Importantly, both overall and MHC genetic variation are lower at northern latitudes. Due to lower evolutionary potential, the low genetic variation in northern populations may increase the risk of extinction when confronted with emerging pathogens and climate change.
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Affiliation(s)
- Maria Cortázar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
| | - Ella Z Lattenkamp
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
- Present address: Department of Neurogenetics of Vocal Communication, Max Planck Institute of Psycholinguistics, Box 310, 6500, Nijmegen, Netherlands
| | - Yvonne Meyer-Lucht
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Emilien Luquet
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
- Present address: Université Claude Bernard - Lyon I, CNRS, UMR 5023 - LEHNA, 3-6, rue Raphaël Dubois - Bâtiments Darwin C and Forel, 69622 Villeurbanne Cedex 43, Boulevard du 11 novembre, 1918, Lyon, France
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
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Savage AE, Mulder KP, Torres T, Wells S. Lost but not forgotten: MHC genotypes predict overwinter survival despite depauperate MHC diversity in a declining frog. CONSERV GENET 2017. [DOI: 10.1007/s10592-017-1001-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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9
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Santonastaso T, Lighten J, van Oosterhout C, Jones KL, Foufopoulos J, Anthony NM. The effects of historical fragmentation on major histocompatibility complex class II β and microsatellite variation in the Aegean island reptile, Podarcis erhardii. Ecol Evol 2017; 7:4568-4581. [PMID: 28690787 PMCID: PMC5496512 DOI: 10.1002/ece3.3022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 03/16/2017] [Accepted: 03/27/2017] [Indexed: 01/29/2023] Open
Abstract
The major histocompatibility complex (MHC) plays a key role in disease resistance and is the most polymorphic gene region in vertebrates. Although habitat fragmentation is predicted to lead to a loss in MHC variation through drift, the impact of other evolutionary forces may counter this effect. Here we assess the impact of selection, drift, migration, and recombination on MHC class II and microsatellite variability in 14 island populations of the Aegean wall lizard Podarcis erhardii. Lizards were sampled from islands within the Cyclades (Greece) formed by rising sea levels as the last glacial maximum approximately 20,000 before present. Bathymetric data were used to determine the area and age of each island, allowing us to infer the corresponding magnitude and timing of genetic bottlenecks associated with island formation. Both MHC and microsatellite variation were positively associated with island area, supporting the hypothesis that drift governs neutral and adaptive variation in this system. However, MHC but not microsatellite variability declined significantly with island age. This discrepancy is likely due to the fact that microsatellites attain mutation‐drift equilibrium more rapidly than MHC. Although we detected signals of balancing selection, recombination and migration, the effects of these evolutionary processes appeared negligible relative to drift. This study demonstrates how land bridge islands can provide novel insights into the impact of historical fragmentation on genetic diversity as well as help disentangle the effects of different evolutionary forces on neutral and adaptive diversity.
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Affiliation(s)
- Trent Santonastaso
- Department of Biological Sciences University of New Orleans New Orleans LA USA
| | - Jackie Lighten
- School of Environmental 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
| | - Kenneth L Jones
- Department of Biochemistry and Molecular Genetics University of Colorado Denver School of Medicine Denver CO USA
| | - Johannes Foufopoulos
- School of the Environment and Sustainability University of Michigan Ann Arbor MI USA
| | - Nicola M Anthony
- Department of Biological Sciences University of New Orleans New Orleans LA USA
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Roth S, Jehle R. High genetic diversity of common toad (Bufo bufo) populations under strong natural fragmentation on a Northern archipelago. Ecol Evol 2016; 6:1626-36. [PMID: 27087930 PMCID: PMC4801968 DOI: 10.1002/ece3.1957] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 02/02/2023] Open
Abstract
The last decades have shown a surge in studies focusing on the interplay between fragmented habitats, genetic variation, and conservation. In the present study, we consider the case of a temperate pond-breeding anuran (the common toad Bufo bufo) inhabiting a naturally strongly fragmented habitat at the Northern fringe of the species' range: islands offshore the Norwegian coast. A total of 475 individuals from 19 populations (three mainland populations and 16 populations on seven adjacent islands) were genetically characterized using nine microsatellite markers. As expected for a highly fragmented habitat, genetic distances between populations were high (pairwise F st values ranging between 0.06 and 0.33), with however little differences between populations separated by ocean and populations separated by terrestrial habitat (mainland and on islands). Despite a distinct cline in genetic variation from mainland populations to peripheral islands, the study populations were characterized by overall high genetic variation, in line with effective population sizes derived from single-sample estimators which were on average about 20 individuals. Taken together, our results reinforce the notion that spatial and temporal scales of fragmentation need to be considered when studying the interplay between landscape fragmentation and genetic erosion.
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Affiliation(s)
- Steffen Roth
- The Natural History Collections University Museum of Bergen Bergen N-5020 Norway
| | - Robert Jehle
- School of Environment and Life Sciences University of Salford Salford M5 4WT UK
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