Mutualism faces the heat

Joshua trees, which are cultural icons and ecological keystones of the Mojave Desert, are exclusively pollinated by highly specialized moths. The moths lay eggs in Joshua tree flowers, then deliberately apply pollen to fertilize the flowers so that, when the flowers develop into fruit, the moths' larvae can eat some of the seeds inside. This unique and mutually beneficial relationship is under threat by changes in land use and climate across the Mojave, and the Yoder Lab is one of several research groups working to understand how Joshua trees and their pollinators can survive for future generations.

Joshua Trees are visited by two different moth species, and trees visited by the different moths show parallel divergence in multiple traits, and on a genetic level. Following the sequencing and assembly of a Joshua tree reference genome, we will work to understand what genes underlie Joshua tree’s adaptation to the extreme climates in which it grows, from the margins of Death Valley to the high desert. We can use this information to understand whether adaptation to specialized pollinators helps or hinders adaptation to climate, and whether pollinators or climate have done more to shape the diversity of Joshua tree populations.

There are many lines of ongoing research on Joshua trees and their pollinators, and interested students may be able to help with

- developing a new, high-resolution range map for Joshua tree, to better understand the climates in which they grow,
- coordinating surveys of Joshua tree populations by citizen scientists from Mojave regional conservation organizations, and
- genetic analysis to help with the assembly and annotation of the Joshua tree reference genome, and surveys of Joshua tree populations to characterize their genomic diversity and relate it to climate adaptation