Sampling across 20 years (1996–2017) reveals loss of diversity and genetic connectivity in the Coachella Valley fringe-toed lizard (Uma inornata)
October 10, 2019
The Coachella Valley fringe-toed lizard (Uma inornata) is a federally threatened, aeolian sand dune obligate, endemic to the Coachella Valley, California. Historically, U. inornata is thought to have formed a large interconnected metapopulation across the valley, with local dune habitat and population size fluctuations linked to stochastic droughts and flooding. Since the 1950s, aeolian habitat in Coachella Valley has declined by 91–95 percent. What remains is highly fragmented by highways and development in the urban communities of the Coachella Valley, raising concerns that fringe-toed lizard movement and gene flow among remaining habitat fragments is limited or nonexistent. We examined population genetic structure across three sample periods (1996, 2008, and 2017). Over that time, this species has shifted from a panmictic condition (1996) with little or no genetic structure between sites to the current (2017) condition where there are now genetically distinct populations. Two severe droughts (2000–04 and 2012–16) may have accelerated this shift through drought-related population declines and subsequent genetic bottlenecks. Using a combination of microsatellite loci and single nucleotide polymorphisms, we found patterns of decreasing genetic connectivity and diversity over time. These patterns are consistent with reduced fringe-toed lizard movement and gene flow among isolated sand dune systems. Low effective population sizes were recovered in some sites, suggesting genetic drift in smaller and fluctuating populations is likely responsible for loss of genetic diversity. A U.S. Fish and Wildlife Service recovery objective for this species is to maintain genetic diversity; however, evidence of fragmentation suggests that genetic cohesiveness has been altered and that the diversity maintained in individual fragments is lower than in the total metapopulation. Management actions that increase genetic diversity could be implemented, including translocation. We modeled increasing gene flow between 1–10 percent, which showed that allelic richness could increase rapidly if translocated individuals can survive and reproduce. Establishing translocation protocols could help to avoid the high mortality that has occurred with other reptile translocations. Successful translocations could be a useful strategy to replenish lost genetic diversity after bottlenecks and could mitigate the loss of natural gene flow among populations.
Citation Information
Publication Year | 2019 |
---|---|
Title | Sampling across 20 years (1996–2017) reveals loss of diversity and genetic connectivity in the Coachella Valley fringe-toed lizard (Uma inornata) |
DOI | 10.3133/ofr20191105 |
Authors | Amy G. Vandergast, Dustin A. Wood, Mark Fisher, Cameron W. Barrows, Anna Mitelberg, Julia G. Smith |
Publication Type | Report |
Publication Subtype | USGS Numbered Series |
Series Title | Open-File Report |
Series Number | 2019-1105 |
Index ID | ofr20191105 |
Record Source | USGS Publications Warehouse |
USGS Organization | Western Ecological Research Center |
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This dataset includes location, field measurements, and descriptions of 330 Uma inornata sampled for the research study entitled "Sampling Across 20 Years (1996-2017) Reveals Loss of Diversity and Genetic Connectivity in the Coachella Valley Fringe-Toed Lizard (Uma inornata)". Field sampling occurred between March and September of 2017 and between April and June of 2018. Lizards were located by vi
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