The Joshua Tree Genome Project

Hi all! This is Olivia. I am part of a 4 person intern team here on the Mojave Desert, NV working with the USGS on the Joshua Tree Genome Project.

(Check the JTGP out here:

The mighty Joshua Tree (Yucca brevifolia)

This project is in collaboration with a handful of academic partners from all over the States and our mentors here in Nevada are among the Principle Investigators because they were some of the first scientists to ever investigate the life cycle, reproduction,
demography, and the effects of climate change on Joshua Trees!

So, Why the JTGP?:

JTs are an icon of the Mojave, provide food for a large range of desert organisms, and have an incredible relationship with their obligate moth pollinators. Both organisms have a long co-evolutionary history together which is known to result in JT population differentiation. Given the changes in climate that are projected for the Mojave and surrounding areas, the JT is now also going to be facing selection based on abiotic factors.
Therefore, the JT Genome Project was created with the goal of examining the JT’s local adaptation to climate, with the purpose of exploring the primary source of selection across populations (climate [abiotic] vs. pollinator driven population differentiation [biotic]). This will be done by identify ecophysiological traits that determine seedling tolerance to climate change and the genes that structure these traits (Project Proposal, 2020). Crazy cool! It is a multi-year study and we have the good fortune of being here right at the start. Oh, and of course, this project also involves sequencing, for the first time, the JT genome.

Our role as CLM interns:

Here at the USGS, we will handle all logistical and practical matters related to the establishment and monitoring of the JTs. This means planting and growing more than 3,000 JTs in our local greenhouse which will then be replanted at four different
common garden sites throughout the Mojave. These four sites represent both the extremes and norms of climate existing across the Mojave. We will then have the opportunity to collect preliminary data and even do some experimental work.
These common garden JTs will be the subjects in genetic analyses and physiological assessments that will be occurring in later years of the study. The work of the USGS and our role as CLM interns is paramount to the establishment and future success of this amazing project.

Fruit of a Joshua Tree

Kicking it off:

This week (among orientations and wrapping up paperwork) we worked on counting and cleaning JT seed collected from a multitude of populations and individuals. This counting and sorting of seed is necessary for the next step: planting!

An opened JT fruit-some aren’t is this nice of a condition. Predation by the moth larvae and other grub is common.
Myself (left) and my co-intern Michele (right) working on seed cleaning and counting!

Counting seed was a great opportunity to see the range of populations we will be working with and the number of individual trees that are a part of this study.
We are so excited to start planting and working in the greenhouse next week-those 3,000 JTs are calling us!

The black seeds are mature and full while the white/tan ones have been aborted and are empty. Some fruits had 500+ seeds while others only had 20!

Until next time,
Olivia T.