Population expansion, divergence, and persistence in western fence lizards (Sceloporus occidentalis) at the northern extreme of their distributional range
Population dynamics within species at the edge of their distributional range, including the formation of genetic structure during range expansion, are difficult to study when they have had limited time to evolve. Western Fence Lizards (Sceloporus occidentalis) have a patchy distribution at the north...
| Main Authors: | , , , |
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| Format: | Software |
| Language: | unknown |
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2022
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| Subjects: | |
| Online Access: | https://zenodo.org/record/6321420 https://doi.org/10.5281/zenodo.6321420 |
| Summary: | Population dynamics within species at the edge of their distributional range, including the formation of genetic structure during range expansion, are difficult to study when they have had limited time to evolve. Western Fence Lizards (Sceloporus occidentalis) have a patchy distribution at the northern edge of their range around the Puget Sound, Washington, where they almost exclusively occur on imperiled coastal habitats. The entire region was covered by Pleistocene glaciation as recently as 16,000 years ago, suggesting that populations must have colonized these habitats relatively recently. We tested for population differentiation across this landscape using genome-wide SNPs and morphological data. A time-calibrated species tree supports the hypothesis of a post-glacial establishment and subsequent population expansion into the region. Despite a strong signal for fine-scale population genetic structure across the Puget Sound with as many as 8–10 distinct subpopulations supported by the SNP data, there is minimal evidence for morphological differentiation at this same spatiotemporal scale. Historical demographic analyses suggest that populations expanded and diverged across the region as the Cordilleran Ice Sheet receded. Population isolation, lack of dispersal corridors, and strict habitat requirements are the key drivers of population divergence in this system. These same factors may prove detrimental to the future persistence of populations as they cope with increasing shoreline development associated with urbanization. Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: NSF-SBS-2023723 We extracted genomic DNA from liver biopsies using salt-extraction and then conducted double digest restriction-site associated DNA sequencing (ddRADseq). We double-digested each sample using the digestion enzymes SbfI and MspI in CutSmart Buffer (New England Biolabs) for 7 hours at 37 C. For fragment purification, we used Sera-Mag SpeedBeads. We ... |
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