Meeting Abstract

P2.125  Saturday, Jan. 5  Mouthbrooding does not constrain craniofacial diversity in Lake Tanganyika cichlids BORSTEIN, SR*; MCGEE, MD; WAINWRIGHT, PC; California State University, Sacramento; University of California, Davis; University of California, Davis sam@borstein.com

Mouthbrooding, the parental care strategy in which the eggs or larvae are incubated in the mouth, may constrain craniofacial diversity in teleost fishes. In this study, we examined mouthbrooding and morphological diversity in cichlid fishes from East Africa’s Lake Tanganyika. This radiation is approximately 5-6 million years old and consists of nearly 200 species. Ancestral state reconstruction reveals that there is a deep split between a clade of substrate-spawning cichlids (Lamprologini) and a clade of mouthbrooding cichlids. We used geometric morphometric methods with the TPS family of programs to digitize a set of 25 sliding semi-landmarks along the dorsal and ventral outline of the head for every described cichlid species endemic to Lake Tanganyika. We generated a morphospace of relative warps, retaining three axes that explained more variation than would be expected by chance. Head elongation or deepening was the major axis of diversity and accounted for 60 percent of variation. The other two axes explained 16 and 12 percent of variation and were driven by mouth angle and mouth size, respectively. We then examined patterns of diversity in the mouthbrooding and non-mouthbrooding sister lineages using the program Morphospace Disparity Analysis to generate 10,000 bootstrapped samples of the mean Euclidean pairwise distance, a common measure of morphological diversity. Surprisingly, mouthbrooding species exhibit nearly three times the average pairwise distance of non-mouthbrooders (3.1 in mouthbrooders vs 1.3 in non-mouthbrooders, p<0.01). Our results demonstrate that, contrary to expectations, mouthbrooding does not constrain craniofacial diversity in Tanganyikan cichlids.