Principal Investigators: Athena Lam, Chris Grinter, David J. Bettman, Matthew Van Dam, and Durrell D. Kapan, Center for Comparative Genomics and the Department of Entomology, California Academy of Sciences
The Xerces Blue, a small charismatic butterfly native to San Francisco’s dunes, was one of the first documented invertebrates to go extinct due to human-caused habitat destruction. This team seeks to identify a suitable ecological replacement for Xerces in San Francisco’s Presidio dunes, as part of a larger habitat restoration project led by the Presidio Trust.
To identify candidate replacements for Xerces, the team will extract DNA from and sequence genomes of 80-to-100-year-old museum specimens of the extinct Xerces Blue* and its close relative, the Silvery Blue (Glaucopsyche lygdamus). The first Silvery Blue specimens to be sequenced will be from populations ecologically and geographically closest to Xerces: adapted to foggy coastal scrub and feeding on Xerces’ pea-plant host Deerweed (Acmispon glaber). Other Silvery Blues from populations more geographically and ecologically distant across a range of microclimates and host plants will also be sequenced. This will provide a genomic ‘measuring stick’ with which to localize Xerces amongst its closest living relatives and to identify one or more suitable candidate Silvery Blue populations for reintroduction.
Just as important as restoring food-web connections between native plants and butterflies, bringing back a ‘stand-in’ for the Xerces Blue is intended to spark our collective imagination, to generate a sense of hope, pride, and agency that humans can revive extinct ecosystem functions that are so critical to regenerating the planet.
*Xerces has been variously considered as a separate species (Glaucopsyche xerces) or as a subspecies of the Silvery Blue (Glaucopsyche lygdamus xerces), a question that this project will help resolve.