By: Cassidy Delamarter, University Communications and Marketing
Researchers at the 麻豆蜜桃AV are uncovering new clues about how animals evolve by studying rattlesnake venom 鈥� and what they鈥檝e found could help us better protect wildlife in a world increasingly shaped by human activity.
In their latest study, they found that some rattlesnakes are producing simpler venom that contains fewer and more focused toxin families than the more common complex venom. It鈥檚 a surprising discovery that challenges long-held ideas about how living alongside a variety of other species influences evolution.
Mark Margres, assistant professor in the Department of Integrative Biology, and doctoral student Samuel Hirst explored 11 uninhabited islands in the Gulf of California 鈥� a large inlet between the Mexican state of Baja California and the northwest coast of Mexico鈥檚 mainland. The researchers pitched tents along the beach and explored the islands with head lamps after sunset when it was cool enough for the snakes to come out. With help from scientists in Mexico and California, the team collected venom from 83 rattlesnakes 鈥� some stretching up to four feet in length 鈥� to study how the makeup of their venom reflects what they eat and how they survive in the wild.
鈥淭he Baja California islands are pristine and largely untouched by human activity, making them an extraordinary place to study evolutionary processes in isolation,鈥� Hirst said. 鈥淲e initially hypothesized that larger islands, which support greater biodiversity and prey diversity, would be associated with more complex venoms, which are better suited for more diverse prey. However, we found the opposite pattern. This unexpected result suggests that factors such as competition or ecological specialization may be at play, opening exciting avenues for future research.鈥�
Baja California Rattlesnake, Crotalus enyo, from Isla Espiritu Santo, Baja California Sur, Mexico. | Photo credit: Ricardo Ram铆rez Chaparro
Speckled Rattlesnake, Crotalus mitchellii, from Isla Espiritu Santo, Baja California Sur, Mexico. | Photo credit: Ricardo Ram铆rez Chaparro
Speckled Rattlesnake, Crotalus mitchellii, from Isla San Jos茅, Baja California Sur, Mexico. | Photo credit: Ricardo Ram铆rez Chaparro
The study found that on islands with more space and more competition, rattlesnake venom becomes more specialized. As animals adapt to reduced competition, rattlesnakes may evolve venom that鈥檚 finely tuned to specific prey. This challenges long-standing ideas about evolution and offers fresh insight into how species and their traits adapt in fragmented environments.
"Habitat fragmentation is like breaking apart a completed puzzle. A healthy, intact ecosystem is like a 1,000-piece puzzle where every piece is in place 鈥� you can clearly see the full picture,鈥� Margres said. 鈥淏ut when you start fragmenting it, pieces go missing or get rearranged, and the image becomes distorted. That distortion represents the disruption of ecosystem function."
This research offers a rare, measurable example of the effects of rapid changes in biodiversity 鈥� the variety of all living things in a particular area, including animals, plants, insects and even microscopic organisms. These changes, often driven by human activity, can affect not just which species live in an area, but how their bodies work on a molecular level. Because venom plays a key role in survival, hunting and reproduction, it鈥檚 a valuable tool for studying broader evolutionary trends.
Hirst handling a Red Diamond Rattlesnake, Crotalus ruber. Snakes are safely secured in long plastic tubes during venom extraction to protect both the researcher and the animal. | Photo credit: Ricardo Ram铆rez Chaparro
鈥淭his isn鈥檛 just about rattlesnakes 鈥� it鈥檚 about understanding the fundamental ways life evolves when isolation and biodiversity start to shift,鈥� said Margres, who also studies rattlesnakes in coastal areas of the eastern United States, including Honeymoon and Caladesi Islands in Pinellas County.
The study has provided an extensive amount of data, allowing Margres and Hirst to continue their research and further explore how island systems can inform habitat fragmentation and its effects on genetic diversity. They鈥檙e also working to test how well antivenoms neutralize the unique venom found on these islands -- a necessary step toward making sure that if someone is bitten, local hospitals have the correct antivenom to treat them effectively.
鈥淩ight now, we don鈥檛 know how well existing antivenoms work against these island venoms 鈥� but our research is helping to change that,鈥� Margres said
This study was funded and supported by the National Geographic Society and done in collaboration with Mexico鈥檚 Secretar铆a de Medio Ambiente y Recursos Naturales and Comisi贸n Nacional de 脕reas Naturales Protegidas.