Abstract
Island populations are at higher risk of extinction than mainland populations. Therefore, understanding the factors that facilitate connectivity is particularly pressing for the conservation of island taxa. Sceloporus occidentalis becki, the Island Fence Lizard, is an endemic taxon restricted to the Northern Channel Islands, part of a nearshore archipelago in Southern California, USA. Since the Last Glacial Maximum, fence lizard habitat on the Northern Channel Islands has decreased with rising sea levels and increasing temperatures that have reduced the availability of woody vegetation. More recently, the introduction (and subsequent removal) of invasive ungulates over the last 170 years and recovery of vegetation has resulted in further dramatic habitat modification. Given the potential for genetic bottlenecks, the history of habitat alteration, and topographic and landscape complexity, we used landscape and population genetic approaches to characterize patterns of genetic diversity and structure of Island Fence Lizards on Santa Cruz Island, the largest of the Northern Channel Islands. Our analyses revealed shallow population structure across the island, low effective population size (Ne = ~ 200), and evidence for a recent genetic bottleneck. Landscape genetic analyses showed that connectivity is facilitated by tree canopy cover and shrubland, as well as by intermediate temperatures, emphasizing the importance of woody vegetation and habitats with variable thermal regimes as the climate warms. Combined, these population and landscape genetic analyses suggest that the Island Fence Lizard is of greater conservation concern than currently appreciated, and increased conservation management focus is warranted for this island endemic.
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Data availability
Genotype and individual locality data submitted to Dryad, https://doi.org/10.5061/dryad.3xsj3txf5.
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Acknowledgements
We thank the following people for help with fieldwork on Santa Cruz Island: C. Ghalambor, S. Fitzpatrick, E. Fischer, K. Hytten, J. McKenzie, M. Mouselli, E. Sanabria, S. Sillett, L. Quiroga, and J. Warner. We thank the Santa Cruz Island Reserve, especially Director L. Laughrin, for use of facilities. Research was supported by our Park Service sponsor K. Faulkner and The Nature Conservancy sponsors S. Morrison and C. Boser. Lab research was conducted, in part, by California State University, Northridge (CSUN) students in the 2015 Molecular Markers in Ecology and Evolution course (BIOL511). Thanks to S. Sillett and the members of the R. Espinoza and J. Robertson labs for valuable feedback on earlier drafts of the manuscript. Research permits were granted by the California Department of Fish and Wildlife (SCP 12495). Research protocols were approved by the Institutional Animal Care and Use Committee of CSUN (1314-005a). Our research was supported by the Department of Biology and Office of Research and Graduate Studies, CSUN (JMR), Southern California Research Learning Center research and learning grants (JMR, WCF, GBP), and the Natural History Museum of Los Angeles County (GBP).
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Department of Biology and Office of Research and Graduate Studies, CSUN, Southern California Research Learning Center research and learning grants, and the Natural History Museum of Los Angeles County.
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Trumbo, D.R., Funk, W.C., Pauly, G.B. et al. Conservation genetics of an island-endemic lizard: low Ne and the critical role of intermediate temperatures for genetic connectivity. Conserv Genet 22, 783–797 (2021). https://doi.org/10.1007/s10592-021-01362-1
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DOI: https://doi.org/10.1007/s10592-021-01362-1