Disparity and macroevolutionary aspects of the endocast of Tyrannides (Aves, Passeriformes)

DEMMEL FERREIRA, MARÍA MANUELA; DEGRANGE, FEDERICO JAVIER; TIRAO, GERMÁN ALFREDO

Congreso; Primer Congreso Latinoamericano de Evolución; 2021

Sociedad Chilena de Evolución, Sociedad Argentina de Biología Evolutiva y Asociación Colombiana de Biología Evolutiva

Tyrannides or New World suboscines is an infraorder of Passeriformes that includes one of the greatest endemic vertebrate radiations of South America with more than 1200 species. However, some aspects of its evolution are still unknown. Based on the premise that brain morphology reflects the versatility of the species to exploit the habitat, we aimed to explore the macroevolution of endocranial morphology of the Tyrannides, and to establish morphological differences between the Furnariidae and Tyrannidae. Fifteen skulls of adult specimens of these two families were microCT-scanned and 3D models of the endocast were generated. Linear and surface measurements were taken from the models. Phylogenetically corrected regression analysis shows that only Syndactyla rufosuperciliata (Furnariidae) has a larger brain than expected for its body mass, whereas the rest of the furnarids and all tyrannids have smaller brains. Phylogenetical signal was low in all the features tested (brain volume, wulsts, optic lobe, cerebellum, telencephalic and olfactory ratios). Phylomorphospace of linear measurements shows a greater disparity among Tyrannidae, although both morphospaces overlap greatly. The surface measurements? phylomorphospaces explain more variability with both morphospaces less overlapped. Separation between both families is explained mainly by vision-related brain structures: Furnariidae shows greater wulsts than the Tyrannidae, whereas this last family shows larger optic lobes, as corroborated by the density map of trait change plot. These results provide significant information that allows a better understanding of the Tyrannides radiation, and subsequently of the evolution of the largest order of birds, the Passeriformes.