Meeting Abstract

68.2  Tuesday, Jan. 6  Divergence in trophic morphology and diet within a young radiation of Cyprinodon pupfishes on San Salvador Island, Bahamas MARTIN, Christopher H.*; WAINWRIGHT, Peter C.; University of California, Davis; University of California, Davis chmartin@ucdavis.edu

Evolutionary transitions to new adaptive peaks, such as the invasion of a new niche or the origination of a key innovation, are still poorly understood. Unfortunately, very few clades containing novel traits are sufficiently young to observe the context in which these transitions occur. One exception is a radiation of four sympatric Cyprinodon pupfish species inhabiting inland saline lakes on San Salvador Island. This may be the youngest known radiation (< 6,000 years old, the age of the lakes) and, in contrast to the algivorous diet of almost all other Cyprinodon species, it contains at least two species which have invaded novel trophic niches. A specialized scale-biter and a large piscivore each exhibit distinct morphology, diet, behavior, and breeding coloration from their putative sister species C. variegatus. Furthermore, a third species exhibits a unique swelling of the anterior nasal and lacrimal tissues overgrowing the premaxilla, which may function in species recognition. Here I will compare the jaw morphology of these four species from cleared and stained specimens, including differences in adductor mandibulae mass. I will also quantify dietary breadth and diversity among species. These results will be contrasted with the only other known Cyprinodon radiation from Laguna Chichancanab, Mexico.