Meeting Abstract

P3.18  Saturday, Jan. 5  Molecular phylogenetics and egg size evolution in the sand dollar genus Mellita ZIGLER, K.S.*; MOOI, R.J.; LESSIOS, H.A.; Sewanee: The University of the South; California Academy of Sciences; Smithsonian Tropical Research Institute kzigler@sewanee.edu

Mellita consists of seven recognized species of sand dollars found in shallow waters along the coasts of the Americas. Four species (M. grantii, M. kanakoffi, M. longifissa, and M. notabilis) are found along the Pacific coast, from Mexico to Ecuador, whereas the other species (M. tenuis, M. isometra, and M. quinquiesperforata) are found along the Atlantic coast, from Massachusetts to Brazil. We undertook a molecular phylogenetic and population genetic study of nearly ninety specimens representing six of the seven species in the genus, lacking only M. notabilis. We sampled from North Carolina, both coasts of Florida, Texas, the Caribbean coast of Panama, Trinidad, Brazil, the Pacific coast of Panama and the Gulf of California. We sequenced more than 1200 bp of the mitochondrial cytochrome oxidase I gene, as well as 600 bp of the mitochondrial 16S gene. Our phylogenetic analyses were rooted with sequences from Leodia sexiesperforata, the closest extant relative of the genus Mellita. Our molecular results are compared to an earlier phylogenetic study that was based on morphological characters. In addition, we report egg size measurements for M. longifissa, M. kanakoffi, M. quinquiesperforata, and L. sexiesperforata and combine these measurements with those already published for other members of Mellita to compare egg size evolution in Mellita with other transisthmian genera of echinoderms.