Avian β-defensin variation in bottlenecked populations: the Seychelles warbler and other congeners

Gilroy, Danielle, van Oosterhout, Cock ORCID: https://orcid.org/0000-0002-5653-738X, Komdeur, Jan and Richardson, David S. ORCID: https://orcid.org/0000-0001-7226-9074 (2016) Avian β-defensin variation in bottlenecked populations: the Seychelles warbler and other congeners. Conservation Genetics, 17 (3). pp. 661-674. ISSN 1566-0621

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Abstract

β-defensins are important components of the vertebrate innate immune system responsible for encoding a variety of anti-microbial peptides. Pathogen-mediated selection is thought to act on immune genes and potentially maintain allelic variation in the face of genetic drift. The Seychelles warbler, Acrocephalus sechellensis, is an endemic passerine that underwent a recent bottleneck in its last remaining population, resulting in a considerable reduction in genome-wide variation. We genotyped avian β-defensin (AvBD) genes in contemporary (2000–2008) and museum samples (1876–1940) of the Seychelles warbler to investigate whether immunogenetic variation was lost through this bottleneck, and examined AvBD variation across four other Acrocephalus species with varying demographic histories. No variation was detected at four of the six AvBD loci screened in the post-bottleneck population of Seychelles warbler, but two silent nucleotide polymorphisms were identified at AvBD8 and one potentially functional amino-acid variation was observed at AvBD11. Variation in the Seychelles warbler was significantly lower than in the mainland migratory congeneric species investigated, but it similar to that found in other bottlenecked species. In addition, screening AvBD7 in 15 museum specimens of Seychelles warblers sampled prior to the bottleneck (1877–1905) revealed that this locus possessed two alleles previously, compared to the single allele in the contemporary population. Overall, the results show that little AvBD variation remains in the Seychelles warbler, probably as a result of having low AvBD diversity historically rather than the loss of variation due to drift associated with past demographic history. Given the limited pathogen fauna, this lack of variation at the AvBD loci may currently not pose a problem for this isolate population of Seychelles warblers, but it may be detrimental to the species’ long-term survival if new pathogens reach the population in the future.

Item Type:	Article
Additional Information:	This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creative commons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Data Accession Statement: GenBank do not accept sequences which are <200 bp, therefore, the authors have provided all sequences originating from this study in the supplementary material (Table S5) for easy and full access. Acknowledgments: Nature Seychelles kindly facilitate and support our long-term Seychelles warbler study on Cousin Island. The Seychelles Bureau of Standards and the Department of Environment gave permission for sampling and fieldwork. We thank Prof Terry Burke for the use of the NERC Biomolecular Analysis Facility at the University of Sheffield, and also would like to thank a number of collaborators for providing Acrocephalus DNA samples: Dr Deborah Dawson, Dr Juan Carlos Illera, Andrew Dixon, Dr Bengt Hansson, Dr Michael Brooke and Dr Ian Hartley. This work was funded by a VH-C Dean’s PhD Studentship at the University of East Anglia awarded to DLG, by a Natural Environmental Research Council grant to DSR (NE/F02083X/1) and by an additional contribution provided by JK from the University of Groningen. CvO is funded by the Earth and Life Systems Alliance (ELSA).
Uncontrolled Keywords:	seychelles warbler,avian β-defensins,bottleneck,demographic processes,genetic drift,selection
Faculty \ School:	Faculty of Science > School of Biological Sciences Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation Faculty of Science > Research Groups > Organisms and the Environment
Depositing User:	Pure Connector
Date Deposited:	17 Feb 2016 16:01
Last Modified:	24 Sep 2024 11:33
URI:	https://ueaeprints.uea.ac.uk/id/eprint/57152
DOI:	10.1007/s10592-016-0813-x

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