Tropidurus semitaeniatus from Rio Grande do Norte, Brazil

Characterization of sexual dimorphism and male colour morphs of Tropidurus semitaeniatus (Spix, 1825) in three populations from northeast of Brazil

Andre Carreira Bruinjé, Peterson Trevisan Leivas, Gabriel Correa Costa

Abstract


Sexual dimorphism, including dichromatism, is a strong indicative of past or ongoing processes of sexual selection, which can also promote discrete variants within a sex. These variants can be either in terms of morphology, colouration, physiology, and behaviour, such as colour morphs with alternative mating tactics. However, as sexual selection acts in a populational level, distinct populations might be under different selection pressures conferring distinct levels of dimorphism and distinct number, and frequencies, of morphs in the cases in which it occurs. The Striped Lava Lizard, Tropidurus semitaeniatus, is a small (≤14g) flat lizard inhabitant of rocky outcrops distributed throughout all the semi-arid Caatinga biome in Brazil. Two discrete colour morphs were described within adult males from a single population, but their function, presence, frequencies, and morphological differences are still unexplored, especially among populations. Here, with a sample of 343 individuals, we present comparative data of morphometry and relative frequencies of sexes and both male colour morphs of T. semitaeniatus among three distinct populations from the State of Rio Grande do Norte, Brazil. Relative frequencies of male morphs differed substantially among populations. Male morphs are dimorphic in body size only within the population with equal relative morph frequencies, while the remaining populations have opposite morph-biased frequencies. Our results suggest that populations are under distinct selection pressures, which should be explored in future behavioural studies addressing intra and intersexual interactions between male morphs.

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