Intrasexual competition in females of a socially polygynous lizard Psammophilus dorsalis

Abstract

Competition between individuals of the same sex, intrasexual competition, has received much attention in males, mainly because such competition, which is primarily for mates (i.e. sexual selection), often selects for exaggerated, conspicuous ornaments and displays. In contrast, social interactions among females, particularly in common mating systems such as socially polygynous systems, have received limited attention. This is because sexual selection theory predicts lower variance in mating success in females than in males, and empirical work shows that females do not commonly display striking ornaments and conspicuous traits. However, recent reviews suggest that intrasexual competition in females can be widespread. Furthermore, while such competition is primarily for mates in males, females may compete not only for mates, but more commonly for resources related to enhancing offspring production and survival, including food, nesting sites, water, safety, etc. Reviews also indicate that intrasexual competition in females can have ecological and evolutionary consequences; and highlight the importance of studying intrasexual competition in females. In my thesis, I have focused on studying social interactions and intrasexual competition in females of a socially polygynous mating system. My study system, the Peninsular Rock Agama (Psammophilus dorsalis), is a sexually dimorphic lizard, in which, like most other polygynous systems, the brightly coloured and bigger males have received much attention, while our knowledge about the relatively duller and smaller females is limited. The nature of inter- and intra-sexual interactions can be broadly predicted by studying the space use of individuals and can be the first step towards understanding social interactions of a system. In my first chapter, I infer the interactions between and within sexes by studying their space use patterns, including variation in home range size, shifts in home ranges and intrasexual and intersexual overlaps in home range...