Positive selection on the growth hormone and its association with size evolution in Platyrrhini

Author(s)

Elytania Veiga Menezes

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2008-08-06

Examining board members

Gabriel Henrique Marroig Zambonato; Claudia Augusta de Moraes Russo; Denise Selivon Scheepmaker; Wilson Araújo da Silva Junior; Anita Wajntal

• Advisor: Gabriel Henrique Marroig Zambonato

Abstract

The molecular bases of phenotipic diversity within and between species are of great interest to evolutionary biologists because the adaptive morphological evolution depends on the selection of genetics variants. However, there are few examples of phenotypic variation whose molecular basis is understood, especially among vertebrates, while most biologists agree that the natural selection process is the predominant source of morphological diversification. Is has been previously documented that there is adaptive diversification of cranial morphology among the higher taxa of Platyrrhini and also in species in most genera that apparently diversified in skull morphology by natural selection. The Growth Hormone (GH) is a multifunctional hormone, mainly produced by the pituitary gland of all vertebrates to modulate the metabolism and promote linear postnatal growth. The molecular evolution of GH has been extensively studied in a large number of vertebrate species, including primates. The rapid GH gene evolution on primates, especially on sites that are functionally important, suggest positive Darwinian selection. However, the hypothesis of purifying selection relaxation after multiple duplications of the GH locus cannot be ruled out either. The aim of this study was to investigate the molecular evolution of the GH gene on neotropical primates, trying to identify potential and functional differences between taxa. The analyses of Maximum likelihood of this work has shown that the ratio dN/dS in the GH1 gene of Neotropical primates are different among genera, demonstrating that the evolution of the GH1 in the Platyrrhini is not compatible with the neutral model of molecular evolution. These results suggest that the GH1 gene suffered positive selection at some sites inside the protein during the process of diversification of the Neotropical primates. (AU)