Preserving evolutionary potential in the face of rapidly changing conditions: the role of genetic rescue

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.