Dr. Todd Streelman
Several months ago, I came across some studies on African cichlids that I thought were intriguing and I thought you, the reader, might also be interested. I reached out to the man behind this research and asked him if he would be willing to do an interview for the blog. Thankfully, he agreed.
Dr. Todd Streelman is Professor and Chair of the School of Biological Sciences at Georgia Institute of Technology (Georgia Tech as it’s more commonly known). With degrees from Bucknell and University of South Florida, Dr. Streelman did his post-doc work at the University of New Hampshire. His research focuses on the relationship between genotype and phenotype in wild vertebrates, using African cichlids as a research model.
For more information, visit the Streelman lab website.
Can you describe your lab’s fish room for the readers?
Our fish room was redesigned as part of a new building on Georgia Tech’s campus in 2015. The room currently consists of ~70 40-gallon tanks and 6 20-gallon tanks (all on a recirculating system) and a separate brood rack. Custom design by Tecniplast. The cichlid room sits within a larger animal facility.
What has your research shown are some of the most influential environmental factors affecting social behavior, in general?
Well, right now we are studying social behaviors (e.g., bower building, aggression) with a strong genetic component. It’s been surprising actually how little changes in the local environment affect these behaviors.
One of your lab’s model species for research is the Cynotilapia afra, an mbuna from Lake Malawi that is quite popular among cichlid keepers. What makes you want to study this particular species?
C. afra is a very aggressive species. So that’s one reason. It is also one of the few mbuna species to possess unicuspid teeth. Dentitions are another one of our favorite traits.
You were a co-author on a recent paper that studied the relationship between courtship and bower building of Malawi cichlids. Can you summarize that research for the hobbyist and perhaps describe how an artificial environment (a fish tank) might affect this relationship when compared to a natural one (a lake)?
That paper established that major bower building types (which we defined as pits or castles) evolved multiple times in Lake Malawi cichlids. This might not be much of a surprise for the hobbyist because there are Malawi genera containing species that exhibit both behaviors. We’re now trying to understand the genetic and neural bases of bower behavior. Good question about the natural vs lab environment. One of the big differences between the lab and the wild is that in the wild males tend to build bowers on leks — that is, surrounded by other males. In the lab, our animals build bowers in specific tanks designed to focus on the actions of a single male, when paired with multiple females. In the lab of course we have much more control over the environment, can modify it accordingly, and can make an array of automated measures of behavior.
For those unfamiliar with bower building by cichlids, can you describe what these are, how the fish create them, and perhaps comment on the differences between the bower types?
Bowers are structures fashioned from sand to attract females for mating, and to mitigate male-male aggression. Sand-dwelling males construct bowers by moving sand with their mouths. We differentiate between bower types called (i) pits — where a male digs a concavity in the sand, and (ii) castles, where a male builds a structure that looks like a mini volcano (picture attached). Males that have been born in captivity — who have never seen sand before and who have never seen other males construct bowers — will perform species-specific bower behaviors when housed with gravid females. One of the neat things we’re doing now is automating our analysis of structures made by males using the Kinect to measure sand change over time in 3D.
Regarding courtship, have you identified any physical trait predictors for mate selection in your model species? If so, what are they?
This is not something we’ve studied directly, but the literature would suggest that size, nuptial coloration, sound production, etc., all may affect mate selection. To date in our bower project, we’ve focused solely on male behavior. The picture from the female side is likely to be just as exciting — but we’re not there yet.
There are lots of opinions among hobbyists about the most humane way to euthanize a fish. Can you share your expert opinion on this?
Not sure about expert opinion, but we are mandated by law to euthanize by overdose of anesthesia. In certain circumstances for neuroscience experiments, we are authorized to use rapid decapitation.
For a perspective student out there reading this, what would you like to tell them about Georgia Tech’s School of Biological Sciences or your lab in particular?
This is probably preaching to the choir, but the diversity of Malawi cichlids offers so many possible questions for study. We try to be as creative as possible in our selection of projects, focusing on big questions that can’t always be addressed well in other systems.