Os determinantes da evolução da coloração de Micrurus Ibiboboca (Merrem, 1820) (Squamata: Elapidae)

Abstract

The snake genus Micrurus is well known for its aposematic warning coloration, which generally presents some form of variation including black, white, yellow, and red; hence, they are often used as model organisms for studies investigating mimicry. Despite this, the factors that influence phenotypic evolution in the genus are still poorly known, particularly in terms of color evolution. The present work aimed at investigating the environmental determinants of color evolution in Micrurus ibiboboca. This species is mainly found in the Caatinga and in transition areas of the Biome, and to obtain the data we used specimens deposited in the main Brazilian zoological museums. We tested two main hypotheses, the thermal melanism hypothesis and Gloger's simple rule, to verify whether environmental factors, such as humidity and temperature increase or decrease, have a relationship with the melanic and white parts of the individuals. Therefore, we used generalized linear models to test which environmental factors correlated with the proportion of black, white and red rings of the triads. Our main hypotheses were corroborated since the proportion of white rings was associated with decreasing humidity (thermal melanism and Gloger's rule), while the proportion of black rings was associated with increasing temperature and humidity (Gloger's rule). Finally, the proportion of red rings showed no correlation with any environmental variable, since this coloration pattern is associated with aposematism, and therefore warning signals to other organisms.