Efeitos da seleção sexual sobre o pareamento dependente de tamanho: padrões gerais, variações espaço-temporais e mecanismos subjacentes

Abstract

Size-assortative mating (SAM) is one of the patterns more studied in behavioral ecology, because it affects size variation of populations and can promote sympatric speciation. Some mechanisms were proposed to explain why this pattern is common in animals and in which scenarios it may occur. Mate choice has been the most studied mechanism. This hypothesis proposes that SAM should occur when: (1) large individuals have advantages in intrasexual competition; (2) one or both sexes prefer large partners; and (3) there is variation in the mate quality related to body size. This hypothesis has clarified several cases in which SAM occurred. However, in some cases, SAM did not occur even when predictions of mate choice hypothesis were corroborated, probably, because factors related to mating competition may influence mate choice changing its effects on SAM, such as the intensity of intrasexual competition and mate availability. Excessive costs of intrasexual competition and the difficulty of finding a partner can weak mate choice, leading to random mating. Variations in mating competition and mate availability can be estimated using population parameters, such as sex ratio and population density. Furthermore, mating competition hypothesis may explain and predict spatio-temporal variation. In this thesis, I investigate effects of mating competition on SAM, using two arthropod species, as experimental models, and a meta-analytic approach. Thus, I describe the first cases of SAM in ants and stink bugs and evaluate general patterns and spatio-temporal variation of SAM in animals. I found empirical support to mating competition hypothesis, inaugurating a new line of research with prolific studies about effects of sexual selection on assortative mating.