The Joshua tree (Yucca brevifolia) is a cultural icon and an ecological keystone of the Mojave Desert. The trees occupy challenging drought and temperature regimes across the Mojave. However, climate projections broadly agree that increasing temperatures and shifting rainfall will render most of the Joshua tree’s current range unsuitable by the end of this century.
Professor Jeremy Yoder at California State University-Northridge has spent his career studying the unique ecology and evolution of Joshua trees across their range. Recently, his work pivoted to the species’ vulnerabilities to climate change and, more importantly, the genetic potential for adaptation.
“We have very little idea what traits may help them weather droughts and stand up to heatwaves,” Dr. Yoder explains, “As the threats posed by climate change became more apparent, we became more interested in understanding Joshua trees’ adaptations to desert climates, and how we can harness those adaptations to help the trees survive.”
Professor Jeremy Yoder poses with the flower of a Joshua tree (Yucca brevifolia) | Credit: Colin MacDonald
Joshua trees encounter extreme climatic conditions across their range, and certain populations may harbor genetic variation that can support adaptation to warmer, drier conditions. To expand his team’s understanding of genetic variation across populations, Dr. Yoder applied to the Wild Genomes program at Revive & Restore for a new project to sequence 300 Joshua trees across the species’ range. Wild Genomes funds the development of genomic tools for applied conservation projects.
“A genomic inventory of Joshua trees is exciting scientifically, because there are not a lot of species for which we have whole-genome data across the entire geographic range,” Dr. Yoder explains. “And it’s exciting personally because it’s an opportunity to apply that really intensive data collection to protecting a species I’ve spent a lot of my career with.”
Dr. Yoder and colleagues will strategically sample populations across density, phenotypic, and climatic diversity. The resulting genomic dataset can reveal which genetic variants predict Joshua tree resilience to climate change and can help prioritize key populations for protection. This genomic insight can also inform conservation projects to restore Joshua tree populations by matching seed sources to projected future climates.
Sun setting behind a Joshua tree in Joshua Tree National Park. Credit: Joshua Earle, Unsplash+
“With this dataset, we may be able to help populations adapt instead of going locally extinct, and we may be able to shepherd the trees into a climate-changed future with a lot of their genetic diversity intact.”
Dr. Jeremy Yoder
Professor at California State University Northridge