Cognitive processes play an important role in human mate choice. However, far less is known about this topic in non-human animals. In this thesis, I take a comparative approach to sexually... Show moreCognitive processes play an important role in human mate choice. However, far less is known about this topic in non-human animals. In this thesis, I take a comparative approach to sexually selective cognition by studying humans (Homo sapiens) and Bornean orang-utans (Pongo pygmaeus). I start by reviewing the literature on sexually selective cognition. Hereafter, I show that visual, but not auditory or olfactory attractiveness, plays a major role in initial human mate choice. Furthermore, I show that attractiveness has a profound influence on visual attention in humans, and that attentional biases towards attractive conspecifics may be associated with mate choice. I explore the same topic in Bornean orang-utans by presenting them with stimuli of fully developed males or males experiencing arrested development. The results of these studies suggest that orang-utans preferentially attend to fully developed males, but only in the eye-tracking task and not in touchscreen tasks. The last chapter explores vocalisations, and suggests that orang-utan mate preferences might reflect in female vocal behaviour. Altogether, the results of this thesis suggest that humans and orang-utans show cognitive biases towards mate-relevant traits. However, better understanding of the link between such biases and actual mate choice remains of pivotal importance. Show less
The acoustic courtship display of a male and a female great tit show all the characteristics of a passionate dance. This thesis examines the impact of anthropogenic noise on the acoustic... Show moreThe acoustic courtship display of a male and a female great tit show all the characteristics of a passionate dance. This thesis examines the impact of anthropogenic noise on the acoustic communication between males and females and the relationship with reproduction. Show less
Mate choice by female cichlid fish from Lake Victoria plays an important role in speciation and the maintenance of species. Females are expected to select against males that are intermediate in... Show moreMate choice by female cichlid fish from Lake Victoria plays an important role in speciation and the maintenance of species. Females are expected to select against males that are intermediate in their phenotype during the process of speciation driven by sexual selection. To test this, we hybridized two species of cichlids that differ in male nuptial coloration. Male hybrids were intermediate in nuptial coloration compared to the parental species. Hybrids had a comparable fitness to the parental species and did not suffer from inviability, sterility, skewed sex ratios, reduced survival or reduced growth rates. Females preferred males of their own species over males of the other species. This implies that female mate preference can drive speciation. Females of one species were able to distinguish between males of their own species and hybrid males; females of the other species however, were not able to see this difference. When there is hybridization in nature, for instance when coloration becomes invisible by an increase in turbidity of the water, there would be asymmetrical selection against hybrids. An understanding of these processes is crucial in speciation research and for the maintenance of biodiversity. Show less
