Meeting Abstract

40.3  Tuesday, Jan. 5  Are extant cetaceans the product of an adaptive radation? SLATER, G.J.; PRICE, S.A.*; SANTINI, F.; ALFARO, M.E.; University of California, Los Angeles; University of California, Davis; University of California, Los Angeles; University of California, Los Angeles gslater@ucla.edu

The transition from land to the sea represents a major shift in adaptive zone for cetaceans but it is not known whether the patterns of body size disparity and species richness in modern cetaceans reflect an initially rapid radiation into this habitat or whether more recent geologic and paleoclimatic factors are better explanations for their biodiversity. We constructed a molecular timescale for the evolution of extant cetaceans and used it to investigate diversification rates and patterns of body size evolution. Cetaceans did not undergo an early pulse of lineage diversification, as expected in an adaptively-radiating clade. However, a series of morphological analyses show that body size evolution does bear the signature of adaptive diversification. Body size has a strong influence on feeding behavior in cetaceans and early phylogenetic partitioning of niche space seems to be responsible for the current distribution of feeding behaviors. The evolution of extant cetaceans was adaptive, but not an adaptive radiation.