Research Training Program

Arden Ashley
Macalester College
St. Paul, Minnesota

Dave Pawson, Ph.D.
Supervising Scientist
Invertebrate Zoology

"It is a great privilige to be part of
this community of scientists. The energy
of this museum is generated by the intense
passion of the people who are most
intimately associated with it."

Intergeneric Hybridization between the sand dollars Encope michelini and Mellita isometra (Echinodermata: Echinoidea: Mellitidae)

Sand dollars are invertebrate animals closely related to sea stars (starfish). Sand dollars are important to the ocean ecosystem and many species can be found throughout the world. Along the coast of Florida, species in the genus Encope and the genus Mellita live in the same area. These genera (pl. of genus) are very different from one another in appearance and lifestyle. Nevertheless, several individuals of what appear to be hybrids between these genera were found in the 1970s near Fort Pierce, FL. To determine whether these sand dollars are the result of reproduction between Mellita isometra and Encope michelini, measurements of various characteristics of the proposed hybrids and their parents were taken and compared with one another. For several characteristics, the data of the proposed hybrids was intermediate between the data of Mellita and Encope. Hybrids are important ecologically because they possess different competetive abilities from their parents and they can therefore fill different roles in the environment or compete with their parent species. While the evidence strongly supports the Mellita isometra x Encope michelini hybridization hypothesis, more studies need to be conducted in order to rule out other possibilities - including the presence of an undescribed species.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-0243512.

Letter of gratitude