Q. What award did you receive and when?
I received the AES Gruber Award this year at the annual meeting in New Orleans.
Q. What degree are you seeking, from what institution, under whose guidance?
I just finishing my doctorate in Ecology and Evolutionary Biology at the University of Toronto. My advisor is Dr. Nathan Lovejoy.
Q. What is the most important (actual or potential) finding of your research? Give us a little background on the subject.
Having a background in biomechanics, I was interested in how some elasmobranchs (sharks and rays) have evolved similar appearances (evolutionary convergence) as a result of their eating similar prey. Not just any prey, some species eat food which are not typical for most elasmobranchs – things like clams, snails, insects, and crabs. Animals which eat these sorts of ‘hard’ prey are coined durophagous (literally ‘hard-eating’ in Greek) – and for a long time durophagous predators have been lumped together into this similar category. The problem is, many of these predators look nothing alike, and anyone who has tried to smash a snail versus something like a cockroach know that the two behaviors are very different, right?
So I was working with a weird group of freshwater stingrays (Potamotrygonidae) – rays which are common in South American rivers – and I realized that their dietary diversity is pretty extensive. Some species only eat mollusks, others only eat insect, and still other species specialize on eating only fish. Now think of a shark or stingray that eats insects – can you think of any? I’m guessing not – I could not find any other examples of stingrays or sharks that feed exclusively on insects, yet some of these freshwater Potamotrygon only eat aquatic insect larvae, throughout their entire life. The anatomy of these insect-eaters was radically different from relatives who ate only crabs or mollusks – the former have very kinetic or mobile skulls and jaws, while mollusk-eaters have jaws which are rigid and fused. I filmed insect-feeders while they fed on different kinds of prey, including insects, and found that these stingrays effectively chew their prey in a manner similar to mammals, and that this chewing was exaggerated for prey like insects.
These insect-eaters use these very flexible, very mobile skulls and jaws to chew apart insects which require shearing or tearing to consume. Mollusk-eaters need to produce high forces to outright crush prey, while resisting these forces themselves. So durophagy as it has been defined in the literature is mostly an artificial and unrealistic paradigm – at least when comparing things like insects and mollusks. In addition, I learned that while these stingrays might chew like mammals, the lack of sophisticated teeth in stingrays suggests to us something about the evolution of chewing in vertebrates: highly mobile jaws and chewing behaviors are sufficient for chewing – these complex teeth in mammals might be necessary given that mammal jaws are not very flexible or kinetic.
Q. How is the award going to help you complete the project?
The award is going to help me communicate my research more effectively, by helping me attend the meeting, meet with colleagues, and through opportunities like this – just simply getting the word out.
Q. What are your other research goals?
I want to examine just how widespread these chewing behaviors are in potamotrygonid freshwater rays – so I recently raised funding through Experiment.com to examine other species, insect-feeding specialists, mollusk-eating specialists, and a series of omnivorous taxa too. This funding is serving as some of the first for my post-doctoral position at Friday Harbor labs. The last chapter of my dissertation examined how the evolution of these novel dietary modes (insectivory, molluscivory, piscivory) have changed the tempo of evolution for the whole potamotrygonid family – my next goal is to examine other examples of freshwater ray species, in SE Asia and Africa – and see if these animals look and behave similarly to S American freshwater rays. Hear more updates through my website: http://mattkolmann.jimdo.com/ or through Twitter @KolmannMA!
Q. How did you get started in research/shark bio/science?
My undergraduate advisor, Dr. Dan Huber, got me interested in sharks as a fascinating study system for understanding evolution; he uses biomechanical approaches to understand the mechanical function of shark cartilage from ecological and evolutionary perspectives. Dan’s enthusiasm and question-driven approach to research really engaged me, we published my undergraduate thesis on development of feeding performance in horn sharks, and the rest is history!