RESUMEN

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.

RESUMEN

Female preference for local cultural traits has been proposed as a barrier to breeding among animal populations. As such, several studies have found correlations between male bird song dialects and population genetics over relatively large distances. To investigate whether female choice for local dialects could act as a barrier to breeding between nearby and contiguous populations, we tested whether variation in male song dialects explains genetic structure among eight populations of rufous-collared sparrows (Zonotrichia capensis) in Ecuador. Our study sites lay along a transect, and adjacent study sites were separated by approximately 25 km, an order of magnitude less than previously examined for this and most other species. This transect crossed an Andean ridge and through the Quijos River Valley, both of which may be barriers to gene flow. Using a variance partitioning approach, we show that song dialect is important in explaining population genetics, independent of the geographic variables: distance, the river valley and the Andean Ridge. This result is consistent with the hypothesis that song acts as a barrier to breeding among populations in close proximity. In addition, songs of contiguous populations differed by the same degree or more than between two populations previously shown to exhibit female preference for local dialect, suggesting that birds from these populations would also breed preferentially with locals. As expected, all geographic variables (distance, the river valley and the Andean Ridge) also predicted population genetic structure. Our results have important implications for the understanding whether, and at what spatial scale, culture can affect population divergence.

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RESUMEN

Idiosyncratic variation within the normal range of androgens levels in women account for significant variations in personality and behavior. We studied if testosterone introduces significant biases in women's perception of fluctuating symmetry of male faces suitability for a long-term relationship. Participants were 145 female college students asked to rate in a two-choice forced paradigm the attractiveness, suitability as a long-term partner, and economic success, fatherliness and fidelity of an asymmetric and a symmetric male face. Since our sample consists of random women interested in participating, whether for personal reasons or because they were paid to participate, we controlled for menstrual phase. All participants provided salivary samples to determine testosterone (T), estradiol (E2) and progesterone (P4) levels. When the P4/E2 was low and T low-to-normal, the symmetric face was rated as more attractive, and a desirable long-term partner, but these preferences changed to the opposite when P4/E2 was high. In high T women, neither face was rated as more attractive, independently from the P4/E2 ratio, but the asymmetric face was preferred as a long-term partner when conception risk was high, changing to prefer the symmetric face as the P4/E2 increased. The overall perception of male faces was that the symmetric face was more economical successful but a poor parent and highly unfaithful compared to the asymmetric face. A significant interaction between T and P4/E2 for ratings success of the asymmetric face suggests that high levels of feminine T might be related to inter-sexual competition when conception risk is high.

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