Applying genomic tools to aid the conservation of Torrey pines in the face of bark beetle threats

Dr. Stephanie Steele, San Diego Zoo Global 

The Torrey pine (Pinus torreyana) is a rare, iconic species that occurs naturally in only two locations in Southern California: in coastal San Diego County and on Santa Rosa Island. The species is of particular conservation concern due to prolonged drought which has increased susceptibility of trees to attack by the bark beetle Ips paraconfusus. The Ips beetle has posed a significant challenge for trees in the mainland population in recent years. While Torrey pines harbor a remarkably low level of genetic diversity, it is possible that genetic variation underlies resistance to beetles and thus determines, at least partially, which trees survive. To test this, we are using RNA-Seq to survey functional genetic diversity in Torrey pines that either succumb to mortality by bark beetles or remain asymptomatic. We aim to 1) characterize functional genetic diversity in the species, particularly in defense-related genes, 2) test for genetic differentiation between affected and asymptomatic trees, and 3) identify whether specific genetic variants are associated with survival. This work will offer insight into the adaptive potential of Torrey pines to respond to continued bark beetle outbreaks and will inform future restoration efforts for this iconic species.