The role of the model in mate-choice copying in female zebra finches

Factors that affect non-independent mate choice

Mate choice is generally regarded as an independent event, but a growing body of evidence indicates that it can be influenced by social information provided by conspecifics. This is known as non-independent mate choice. Individuals use information gathered by observing interactions between conspecifics to copy or not copy the mate choice of these conspecifics. In this review, we examine the factors that affect non-independent mate choice and mate choice copying and how it is influenced by social and environmental information that is available to the subject or focal individual. Specifically, we discuss how non-independent mate choice and whether individuals copy the choices of conspecifics can be influenced by factors such as habitat and differences in ecology, mating system and parental care. We focus on the social information provided to the focal animal, the model and the audience. Nearly all studies of non-independent mate choice and mate copying have focused on individuals in species that use visual cues as the source of social information. Nevertheless, we highlight studies that indicate that individuals in some species may use chemical cues and signals as sources of social information that may affect non-independent mate choice and mate copying.

The effect of sexual selection on phenotypic diversification among human populations: A simulation study

Despite the generally low level of inter-population genetic differentiation in humans as compared with great apes, it has long been acknowledged that there is a considerable amount of geographic variations in human phenotypes, for example, skin pigmentation, cranial morphology, and soft-tissue facial morphology, to name but a few. Indeed, recent studies have suggested that the extent of inter-population diversity in some human phenotypes is greater than expected from random drift alone. Such an excess of phenotypic diversity is often attributed to adaptation to local environment. However, this account is valid only if populations differ in some ecological aspects that elicit differential selection acting on a given phenotypic feature. Another long-standing hypothesis is the sexual selection hypothesis, which claims that phenotypic diversity arises and/or is maintained owing to variations in preference for mating partners. In this paper, we explore the plausibility of the sexual selection hypothesis by means of computer simulations, in which the inter-population diversity of a quantitative trait is evaluated against the expectation from random drift, using the Q_ST-F_ST comparison. As possible driving factors of sexual selection, we consider two types of mate-choice preference: preference for the population average and preference for a culturally-transmitted arbitrary trend. Our simulations suggest that sexual selection can, under certain circumstances, maintain and/or generate a detectable amount of inter-population phenotypic diversity, even when populations are ecologically identical and loosely connected to each other by mutual migration. Since mating decisions in humans are considerably affected by social learning, human mate-choice preference may be more readily diversified between populations than in other animals. We suggest, therefore, that some of the observed human phenotypic variations may be better understood as a product of cultural, rather than ecological, diversification.

Test of the Deception Hypothesis in Atlantic Mollies Poecilia mexicana-Does the Audience Copy a Pretended Mate Choice of Others?

Animals often use public information for mate-choice decisions by observing conspecifics as they choose their mates and then copying this witnessed decision. When the copier, however, is detected by the choosing individual, the latter often alters its behavior and spends more time with the previously non-preferred mate. This behavioral change is called the audience effect. The deception hypothesis states that the choosing individual changes its behavior to distract the audience from the preferred mate. The deception hypothesis, however, only applies if the audience indeed copies the pretended mate choice of the observed individual. So far, this necessary prerequisite has never been tested. We investigated in Atlantic molly males and females whether, first, focal fish show an audience effect, i.e., alter their mate choices in the presence of an audience fish, and second, whether audience fish copy the mate choice of the focal fish they had just witnessed. We found evidence that male and female Atlantic mollies copy the pretended mate choice of same-sex focal fish. Therefore, a necessary requirement of the deception hypothesis is fulfilled. Our results show that public information use in the context of mate choice can be costly.