INVESTIGATING THE GENETIC BASIS OF CAVEFISH EVOLUTION

We use the Mexican tetra, Astyanax mexicanus, to study genetic changes that underlie morphological and physiological evolution

Cave-dwelling populations of Astyanax mexicanus have adapted to a dramatically different environment than their river-dwelling ancestors. Over 200,000 years ago, these fish colonized the perpetual darkness of underground limestone caves in northeastern Mexico. With food sources scarce, they evolved to survive on bat droppings and seasonal flood debris, while their surface relatives thrived on a diet rich in plants and insects.

Cavefish look strikingly different from their surface-dwelling relatives, despite being the same species. The most noticeable differences are their lack of eyes and reduced pigmentation. They have also evolved an insatiable appetite and a unique metabolism that allows them to store more fat than surface fish—an advantage in their food-scarce environment. Interestingly, some of their adaptations, like insulin resistance, are harmful in humans but help cavefish survive. There are multiple independent cavefish populations that can be utilized as natural replicates in the study of evolution.

The Mexican tetra has become an important model system due to the increasing availability of tools for studying gene function. Our research uses quantitative trait loci (QTL) mapping to identify genomic regions associated with metabolic changes. To pinpoint the genetic changes driving cavefish adaptations, we integrate comparative genomics, transcriptomics, and gene editing techniques.

Current projects are aimed at uncovering how evolution has modified:

Vitamin A metabolism
Microbiome composition
Gastrointestinal homeostasis
Development and function of the enteric nervous system

Our Team

We are a group of scientists from diverse backgrounds, united by a shared passion for advancing our understanding of the natural world. Our lab's mission is to conduct research that makes a lasting impact on our knowledge of life, and create an environment where members can learn, grow, and build a strong community.

Lab members

Misty Riddle PhD

Principle Investigator

Misty earned her bachelor's degree from Westminster College, studying the brine shrimp microbiome, and her Ph.D. from UC Santa Barbara, researching cell fate determination in C. elegans. Driven by an interest in natural variation and development, she joined Clifford Tabin's lab at Harvard Medical School, where she established her research on Eco-Evo-Devo in the Mexican tetra. She is now an assistant professor in the Biology Department.

email: mistyriddle@unr.edu

David Peréz Guerra

PhD candidate in Ecology, Evolution, and Conservation Biology (EECB)

David earned his Biology degree from the Autonomous University of Mexico and an M.S. from Midwestern State University, studying morphological plasticity and hypoxia effects in squamates. In the Riddle Lab, he investigates the genetics and physiological consequences of carotenoid metabolism in Astyanax mexicanus. His main interest is evolutionary development and phenotypic plasticity influenced by extreme environmental pressures.

Email: dperezguerra@unr.edu

Pavani Perera Ponnimbaduge

PhD candidate in Molecular Biosciences

Pavani is an international student. She earned her B.Sc (hon) in Zoology with a first class at the University of Colombo, Sri Lanka. As an undergraduate, Pavani became passionate about studying cave ecosystems and the adaptive plasticity of vertebrates in extreme environments. Now, as a graduate student in the Riddle Lab, Pavani studies the evolutionary development of the enteric nervous system using the unique model system, Mexican cavefish (Astyanax mexicanus).

Email: pavaniperera@nevada.unr.edu

LinkedIn: /in/pavani-perera

Twitter: @/pavi_dilsh

Bethany Ponte

PhD candidate in Integrative Neuroscience

Bethany has a BS degree in Psychology with an Emphasis in Biology from UC Davis. She joined the integrative neuroscience program to learn more about neuroscience and conduct laboratory research. In Dr. Riddle’s lab, she is investigating the evolution of oocyte maturation in A. mexicanus with an emphasis on the role of the neuronal network that surrounds the ovaries.

Email: bethanyponte@nevada.unr.edu

Maeve Nave

PhD candidate in Molecular Biosciences

Maeve received her BS in Biology from University of California, Santa Cruz in 2020, and continued as a research assistant in the COVID Molecular Diagnostic Lab there at UCSC post grad. She then went on to working for the Miura lab at UNR studying 3’UTR effects on glutamatergic neurons differentiation. In the Riddle lab, she investigates the genetic basis of microbiome composition in A. mexicanus with a keen interest in understanding how host-microbiome interactions influence physiology, metabolism, and evolution.

Email: mnave@nevada.unr.edu

Kaitlyn Webster PhD

Postdoc at Harvard Medical School

Kaitlyn collaborates closely with the Riddle lab. She is a postdoctoral fellow with experience in germ cells and models of male infertility. Kaitlyn is interested in understanding the developmental biology and genetics of gonadal sex differentiation in teleosts, particularly zebrafish and Astyanax mexicanus.

Email: kaitlyn_webster@hms.harvard.edu

Publications

Link to My Bibliography: https://www.ncbi.nlm.nih.gov/myncbi/misty.riddle.1/bibliography/public/