Damselfishes are one of the largest fish families in the world, with at least 422 different species, including one of the most instantly recognizable fish of all, the clownfish of Finding Nemo fame. These small, colorful fish mostly live around coral reefs in tropical and temperate waters and make popular pets for aquariums.
They’re also a very diverse group of fish, with different body sizes, feeding habits, and unique behaviors. Some species, like the three-spot damselfish in Florida and the Caribbean, are territorial and aggressively defend their habitats. Others, like the longfin damselfish in Belize, tend to patches of algae like farmers, herding and protecting shrimp that fertilize the “crops” with their excrement.
Because of this fascinating diversity, damselfish are of keen interest to evolutionary biologists. Mark Westneat, Professor of Organismal Biology and Anatomy and director of the Integrative Biology PhD Program, has been studying them for more than 25 years, SCUBA diving and collecting samples around the world from the Florida Keys to French Polynesia.
“The damselfishes are a case study in how we can tackle an important group that's ecologically important and evolutionarily interesting, building a tree of life and studying traits to yield some insight into how their history has been shaped over the years," Westneat explained.
In a study published in October 2021, Dr. Westneat (Integrative Biology and Evolutionary Biology) continued his study of damselfish by building a new phylogney or tree of life that shows how different species are evolutionarily related to each other, for 345 of the 422 known species of damselfishes. The study is an academic multigenerational effort, with a team consisting of all former or current UChicago graduate students: lead author Charlene McCord (Integrative Biology PhD 2014) now an Assistant Professor at California State University, Dominguez Hills, and co-authors W. James Cooper (Integrative Biology PhD 2006), now Assistant Professor of Biology at Western Washington University, and current Evolutionary Biology student, Chloe Nash.
Using the newly completed tree of life, the team used computational and statistical methods to look for clues that could be driving the diversification of different damselfish species over time, since the group first emerged about 55 million years ago. In particular, they wanted to study the associations between body size and feeding habits with patterns of species diversification.
Damselfishes, like all the creatures in the sea, are affected by climate change, especially since they live around coral reefs that are undergoing rapid bleaching and die-offs. Developing such a complete and detailed phylogeny will be important for understanding how new conditions might impact their ability to thrive.
Read more in the full story by Matt Wood "New tree of life details the rich diversity and fascinating feeding habits of damselfishes" December 22, 2021