Meeting Abstract

P1-101   -   Multiparametric Comparative Analysis on Structure and Cellular Composition of Cetacean Brains. Souza, K*; Mota, B; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. kamillaa.bio@gmail.com

Cetaceans (whales, dolphins and porpoises) are exclusively aquatic animals that diverged from their terrestrial relatives approximately 50myr ago (Fordyce, 2013), evolving significant neuromorphological changes in the process. Modern cetaceans include species with the largest and most folded brains observed to date. It is plausible that the evolution of these and other aspects of brain morphology was influenced by the environment in which they evolved. This work is part of a systematic project to analyze diverse and complementary aspects of cetacean cortical and cerebellar morphology, both intra- and inter-specific. We are particularly interested in differences between freshwater and marine species, and between cetaceans and artiodactyls –its sister group-. For this, I have created a collection network for stranded cetacean brains along Brazil's coastline. Currently, we have 35 specimens from 9 species, including animals never anatomically described in the literature. We use MRI scans and the isotropic fractionator histological method (Herculano-Houzel, 2005) to study morphology and cellular composition, derive correlations and allometric regularities, and characterize their origins as 1)Physical: universally applicable rules due to underlying physical principles or measurable parameters; 2)Convergent: rules arising from similar characteristics and forms towards similar evolutive pressures; and 3)Contingent: Common characteristics due to common ancestry. In this context, we have identified at least one mathematical relationship of type 1 (Mota, 2015), leading to a universal scaling relationship empirically verified for a broad range of species. We will investigate whether the gyrification in cetaceans follows terrestrial mammals’ relationship, or if, as we have postulated, it will be affected by the hydrostatic pressure difference that cetaceans are typically subjected to.