We study adaptation in a swiftly changing world

The Sexton lab studies the many factors that determine species distributions. Specifically, we are interested in plant adaptation and the processes that lead to both local adaptation and speciation. We use a great variety of methods, from genomics to distribution modeling to field and lab experiments. We also conduct research in a broad set of ecosystems, from deserts to vernal pools to mountains, and at a wide variety of scales, from genes to plant endophytes (e.g., bacteria and fungi) to plant communities. Our current research projects occur in California, Mexico, and Australia and are focused on the effects of environmental change on species range limits, the determinants of specialization (niche breadth), and the role of gene flow on adaptation. We are also focused on understanding vulnerabilities and adaptive responses of plants in the face of global change and we actively engage in interdisciplinary collaborations in order to develop solutions for conserving biodiversity.



Fall 2017

A review of ours about how species come to expand their ability to use resources (i.e., niche breadth evolution) will be published in this year’s volume of Annual Reviews in Ecology, Evolution, and Systematics.


Summer 2017

We will be attending/presenting research at the Evolution Meetings. Hope to see you there.

A paper first-authored by Megan Hirst that tests whether rare plant species can tolerate the same range of environments as widespread species has been published in the journal Ecology.


Spring 2017

Brandon Hendrickson and Lillie Pennington will be joining our group as graduate students in Fall 2017.  Welcome!

We had a good time “bioblitzing” for environmental DNA on the Vernal Pools Grassland Reserve.  See story.

We received a Cooperative Ecosystem Studies Units (CESU) agreement grant with the Bureau of Reclamation and the USFWS entitled, “Genetic investigation of listed vernal pool plants and their communities in Merced County.

Dannise Ruiz-Ramos has joined the lab as a postdoctoral fellow through the UC Conservation Genomics Consortium and will be spearheading our CALeDNA project to study eDNA in vernal pool ecosystems and to sequence the Colusa grass genome, a rare grass found only in vernal pools.


Fall 2016

Join us at the Northern California Botanists Symposium in Chico in January 2017.

Erin Dickman has graduated with her Master’s degree! Congratulations!

See a news story featuring Yazmin Lommel related to our collaboration with Yosemite National Park to better understand the giant sequoia seedling niche.

Some of us will be attending/presenting research at the Sequoia and Kings Canyon Science Symposium. Hope to see you there.

We enjoyed a few weeks of writing and analysis fun with Visiting Scientist, Rachel Slatyer.

Join us at the Species in the Age of Discordance conference in Salt Lake City in March 2017.



Summer 2016
First greenhouses are arriving at UC Merced soon!  Read more.
A study first-authored by Megan Hirst on population variation in Australian alpine daisies has been published in the journal Ecology and Evolution.
Jackie Shay will be joining our group as a graduate student in Fall 2016.  Welcome!


Spring 2016
We were awarded a grant from DOE’s Joint Genome Institute Community Science Program in collaboration with Mark Sistrom and Carolin Frank to study the effects of drought stress on the monkeyflower microbiome.
The UC Merced Phenology Project has launched!  Congratulations to the Yosemite Leadership Program fellows, including our own Jenna Heckel.


Our lab is collaborating in the newly awarded UC Catalyst Grant to develop new strategies and solutions in conservation genomics. Read more.

A paper of ours revealing patterns of gene flow and genetic variation across the species range of a specialized Sierran monkeyflower has been published in Molecular Ecology. Read more.


A paper of ours on local and geographic plant population limits has just been published as part of a special issue on Evolutionary Insights from Studies of Geographic Variation in American Journal of Botany. Read more. And more.


Fall 2015
We received an NSF IOS grant entitled, “Mechanisms of malleability and resilience of flowering responses to current and future variability in seasonal cues in a geographically-widespread species,” in collaboration with Ben Blackman, Nic Kooyers, and Daniel Runcie.
Congratulations to Molly Stephens on a grant from the Yosemite Conservancy to study the giant sequoia seedling niche in collaboration with Yosemite NP.


Jorge Montiel has joined the lab as a graduate student.  Welcome!
We say a fond farewell to Melissa Anderson who did an awesome job on her REU project on high-elevation monkeyflower pollination. Cheers!


Summer 2015
Melissa Anderson has joined us for her summer Yosemite research experience for undergrads (REU).  Welcome!


The book, “Biodiversity in a Changing Climate,” in which we have a chapter on evolutionary considerations for conservation with climate change was published this June.


Spring 2015
Daniel Toews will be joining our group as a graduate student in Fall 2015.  Welcome!


Congratulations to Erin Babich for receiving a VESR Grad Student Grant and a UC Merced Natural Reserve System Scholarship!


Fall 2014

We welcome Molly Stephens to the lab as a Project Scientist!

Summer 2014
A study led by Katie Ferris providing clues to the evolution of new species in monkeyflowers has been published at Philosophical Transactions of the Royal Society B. Read more.


Farewell to our 2014 summer REU students Lillie and Laurel. Both had exemplary presentations and made great contributions to the scientific community (along with their fellow REU accomplices). We all were impressed by their significant accomplishments in a mere ten week experience. We wish them the best of luck at their home institutes, but will miss them dearly!


Spring 2014 – Our lab begins, a brief article.