Collin Lab

Directory of Calyptraeid Researchers

Dr. Kathryn A. McDonald

Kathryn A. McDonald

Smithsonian Tropical Research Institute, Panama

Presently I’m working with calyptraeid snails because they offer an excellent system to test hypotheses about the development of swimming function in larvae, which includes consequences of changes in morphology and in behavior during ontogenesis.   Larvae of most invertebrate groups have evolved specialized ciliary arrays to fulfill different functions, including feeding and sensation.  Swimming can have extensive consequences for their ecology and survivability, however, which is why I am interested in understanding how species differ in characteristics that contribute to swimming function, and how those differences impact transport and settlement processes in nature.  Calyptraeids interest me mainly because some direct-developing clades include species which appear to have re-evolved planktotrophy (i.e., feeding, swimming larval development).  Are these species different from other planktotrophs in morphology and behavior?  Do these differences, if they exist, contribute to functional differences—for instance, in pattern and speed of swimming?  How do differences in function among planktotrophic species translate into performance differences in nature?  To address the first two questions, I use a combination of morphometrics, high-speed video-recording of ciliary activity, and observations of swimming in fluid flow.  The last question requires a modelling approach.  These studies will increase our understanding of the functional basis for evolutionary transitions in mode of development: a development environment permissive of differences in larval performance, and/or a developmental program that permits changes in growth allometries (cilium length vs. velum size, velum size vs. shell mass) should favor rapid and unbiased changes in mode of development.   

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