about dave

Dave Matthews is a scientist from Massachusetts who is getting his PhD in Organismal and Evolutionary Biology at Harvard University. As a kid, he was always asking about the animals around him in Massachusetts and watching documentaries about the animals that were too far away for him to see with his own eyes. In high school, Dave became really interested in marine life and got scuba certified. Ever since, he has spent a lot of his free time teaching scuba diving and taking pictures of local animals (both below and above the water). Dave’s interest in science stems from this, as there were so many cool things that he saw animals doing and he decided that he never wanted to stop learning about them.

A few years ago, Dave published a paper about the relationship between genetics, face shape, and feeding performance in a group of fish called cichlids (pronounced “sick-lids”). Cichlids live in east Africa, and are known for their tendency to split into new species often and rapidly. It’s estimated that there are 2000 species of cichlids living in three large lakes and a series of smaller lakes and rivers. A lot of the morphological diversity (differences in the way organisms look) in cichlid species is centered around their jaw shape, and jaw shape has a big impact on what and how animals eat. There’s often a relationship between what an animal’s jaw looks like, and how successful it is at foraging (hunting or gathering food) in particular settings.

In this study, Dave was looking not only at craniofacial morphology (the way that the bones of the face and jaw look) and feeding performance, but also at the genes that determine how the cichlids’ faces develop. Often, genetics get overlooked in studies like this so Dave thought it would shed new light on the topic. To test this, he and his partner took slow-motion video of several species of cichlids feeding, made measurements of their facial geometry, and sequenced their genes. In general, they found that there were a few facial traits that led to better feeding performance, but there weren’t any particularly strong trends when they looked solely at the relationship between face shape and feeding performance.

However, when they applied their understanding of the genetic makeup of the fish, trends became clearer. There is one particular gene, called sox9, that is well-known to influence face development in the womb in many groups of animals (fish, birds, mammals). In cichlids, there are two versions of this gene. Among the fish that had version 1, the shape of their face had a big impact on how successful they were at hunting. On the other hand, there wasn’t a strong connection between different face shapes and feeding performance in the fish with version 2. Sometimes, an animal’s morphology can become so specialized that it has a hard time switching between different ways of eating or hunting. On the other hand, “generalists” are more successful at more kinds of feeding. This has been observed in nature by countless scientists, but Dave thinks that his findings about the versions of sox9 can tell us exactly how some animals become feeding generalists or specialists.