Conservation genomics of California vernal pool endemics

Campuses: UC Merced

PI(s): Dawson

Background:  Vernal pools are a highly understudied set of aquatic ecosystems that house a unique flora and fauna uniquely adapted to their ephemeral nature.  It is currently estimated that 50 – 90% of vernal pool habitat from California’s Great Central Valley has been lost to anthropogenic factors.  As a result many vernal pool organisms endemic to this region are currently listed as threatened or endangered by federal and state entities.  Currently little is known about the geographic distribution of genetic variation for vernal pool endemic flora and fauna, information that would assist in establishing regional conservation priorities and guide ongoing restoration efforts.

We will use California’s Central Valley to test hypotheses regarding local and regional genetic diversification in vernal pool crustaceans and plants.  Specifically we will test hypotheses of gene flow at local scales using a landscape genomics approach.  These studies will take into account peculiarities of these species life-histories (e.g. resting egg/seed bank, passive dispersal) that contribute to the complex patterns that have been observed.  This work will provide unique insight into the factors that govern the geographic distribution of genetic variation for passively dispersed aquatic invertebrates and plants in a geographically confined, but environmentally diverse, landscape and provide a framework for restoration guidelines.

Approach:  This project has three main facets.  First, landscape level genomic variation will be assessed for a vernal pool crustacean using reduced representation library sequencing.  This will require the construction and sequencing of RADseq libraries for ~200 Branchinecta lynchi, a federally threatened species, that have been collected from some of the largest intact vernal pool habitats in eastern Merced County. Second, similar landscape genetics approaches will be applied to Collusa grass (Neostapfia colusana) and its close relatives (species within the monophyletic grass tribe Orcuttieae: Orcuttia inaequalis, O. pilosa, Tuctoria greenei), all of which are state or federal threatened or endangered species.  Third, a comparative population genomic analysis will be done on a time series of restored vernal pool habitat.  These will include pools that contain the focal species and will allow us to determine the relative impacts of drift, immigration and local adaptation on restored habitats that can be used to inform future conservation strategies.