gene flow

Jill Hamilton, North Dakota State University

Species evolutionary potential is tightly linked to both the amount and distribution of genetic variation available through which natural selection may act. Rare species present particular challenges under rapidly changing conditions where the genetic consequences of rarity may limit species ability to adapt to ongoing change. Thus in a rapidly changing environment, maintenance of genetic variation within and across populations becomes an increasingly important target for species conservation. Here, I examine the role genetic rescue may play in the maintenance of a rare species' evolutionary potential. Exhibiting exceptionally low levels of genetic variation, endangered Torrey pine, one of the rarest pines in the world and endemic to California, may represent a candidate for genetic rescue. Restricted to just one island and one mainland population, preliminary evaluation of fitness traits in Torrey pine indicate F1 hybrids, representing a cross between mainland and island trees, are more fit relative to parental populations when grown in a common environment. This suggests that in the short-term, gene flow between populations may provide necessary genetic variation to persist in changing conditions. However, there remain gaps in our understanding of the long-term consequences of genetic rescue. Torrey pine, a poster child for rarity in forest trees, provides an ideal system for which to track the short and long-term consequences of genetic rescue.

Date Recorded: 
Wednesday, September 11, 2019

Kyle L. Gunther, Sula Vanderplank, Jon P. Rebman, Andres Orduño Cruz, & Lluvia Flores-Rentería, San Diego State University, San Diego Natural History Museum, San Diego Zoo Global, Centro de Investigaciones Biológicas del Noroeste

California and the Baja peninsula are home to high levels of floral abundance, diversity, and endemism. Much of this region is part of a biodiversity hotspot and therefore a conservation priority. The Mission Manzanita (Xylococcus bicolor) is endemic to this area, an ecologically and ethnobotanically important shrub, and the sole member of a monotypic genus within Ericaceae. Xylococcus bicolor is narrowly distributed from the middle of Baja California to the Los Angeles area, and has been predicted to experience up to 88% habitat loss due to climate change and development. However, little is known about its population structure, demographics, and genetic diversity, which may be useful information for conservation purposes. In order to fill this gap in knowledge, we are studying these aspects from a genetic perspective. Using a genome skimming technique to reveal thousands of single nucleotide polymorphisms, we are analyzing the population structure, genetic diversity, gene flow, and effective population sizes across the X. bicolor distribution. Preliminary results suggest the presence of intraspecific divergence and population structure, while niche models show loss of suitable habitat using climate change scenarios. We hope our study will provide useful information for land management and conservation decisions.

Date Recorded: 
Wednesday, September 11, 2019