Hello!
I am a Biology PhD candidate in the Schumer lab at Stanford University, and I'm broadly interested in adaptive evolution and molecular ecology. Currently, I study the genetic basis of thermal tolerance, and how hybridization can facilitate adaptation to environmental stress, like rising temperatures. Previously, I was a bioinformatician in the Palumbi lab at Hopkins Marine Station (HMS), and received my B.S. in marine biology, with a minor in computer science, from UC San Diego.
The fishes
Introducing swordtails (AKA Xiphophorus)! Flamboyant, charismatic, and easy to raise! They're an aquarium jewel, a biomedical model, and are simultaneously a cultural symbol. For me, one of the most amazing things about this group is that pairs of closely-related swordtail species naturally hybridize in rivers flowing through the Sierra Madre Oriental in central México, resulting in parallel and independent hybrid zones throughout this region.
The ecology
I'm broadly interested in the adaptations that equip populations to withstand
environmental stress and change. I am especially fascinated by thermal
adaptations, and how populations are evolving as a result of climate change.
Two species of swordtail are particularly interesting to me because their
thermal tolerance, or ability to withstand high temperatures, is
significantly different. In the wild, they inhabit the same
rivers - X. malinche
live at high elevations in cooler mountain headwaters, while
X. birchmanni lives at low elevations in the warmer valleys.
Perhaps as expected, X. birchmanni can withstand higher environmental
temperatures than X. malinche, even when controlling for temperature
acclimation in a common lab environment.
This suggests that there is a
genetic basis for thermal tolerance in swordtails.
These species overlap where their thermal habitat overlaps, typically
in the middle of these rivers. And, due to chemical runoff that
impairs their ability to recognize members of their own species, these
species have historically hybridized. Over time hybrids have mated with
individuals from their parent species and with eachother,
resulting in a gradient of high X. malinche ancestry in high elevation
populations to high X. birchmanni ancestry in low elevation populations.
As you might have guessed, this ancestry gradient (or ancestry cline) along
each river
corresponds with a thermal gradient, from cool temperatures to warmer
temperatures, AND a thermal tolerance gradient, from less thermal tolerant
populations to tolerant populations (as shown by
Culumber et al 2012)!
The question
So what underlies thermal tolerance in this system? If you're familiar with the molecular basis of stress responses, you know that the answer to this question is insanely complex. But, using a combination of genetic tools and functional assays, I'm starting to detangle major explanatory genes and molecular pathways that contribute to evolved species-level differences in thermal tolerance in this system - and which may also show signal of adaptive movement from one species to the other.
The support
Grad school is hard, and requires solid support. Introducing my trustworthy companion, Cheb! She is extremely lazy and lounges on her hammock all day. She enjoys bugs and dislikes veggies.
