Public information influences sperm transfer to females in sailfin molly males

No evidence for mate copying in Danio rerio

The zebrafish Danio rerio is an important model organism, but little is known about its mating preferences and how these are influenced by personality traits like boldness. In this study, we tested two strains of zebrafish and addressed whether females used social information to build a mating preference, a behavior called mate copying, and whether this social learning was affected by boldness. Thus, we provided positive social information for small males to test whether female zebrafish changed their mate preference after observing a pair of a small and a large male with a demonstrator female next to the small one. After that, we tested the observer female in a test maze to evaluate boldness. We found no significant evidence for mate copying as females did not change their preference for the small male after witnessing the large male alone and the small male interacting with another female and chose consistently larger males in a control without opportunity to copy. Whether the female was defined as shy or bold had no effect on mate copying. We conclude that mate copying is probably inexistent or only relatively weak in this species.

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.

Natural and sexual selection drive multivariate phenotypic divergence along climatic gradients in an invasive fish

Invasive species that rapidly spread throughout novel distribution ranges are prime models to investigate climate-driven phenotypic diversification on a contemporary scale. Previous studies on adaptive diversification along latitudinal gradients in fish have mainly considered body size and reported either increased or decreased body size towards higher latitudes (i.e. Bergmann's rule). Our study is the first to investigate phenotypic divergence in multiple traits, including sexually selected traits (size and shape of the male copulatory organ, the gonopodium) of invasive Gambusia affinis in China. We studied body size, life history traits and morphological variation across populations spanning 17 degrees of latitude and 16 degrees of longitude. Even though we found phenotypic variation along climatic gradients to be strongest in naturally selected traits, some sexually selected traits also showed systematic gradual divergence. For example, males from southern populations possessed wider gonopodia with increased armament. Generally, males and females diverged in response to different components of climatic gradients (latitudinal or longitudinal variation) and in different trait suites. We discuss that not only temperature regimes, but also indirect effects of increased resource and mate competition (as a function of different extrinsic overwinter mortality rates) alter the selective landscape along climatic gradients.

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.

Male mate choice in livebearing fishes: an overview

Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena: female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.

The virtual lover: variable and easily guided 3D fish animations as an innovative tool in mate-choice experiments with sailfin mollies-II. Validation

The use of computer animation in behavioral research is a state-of-the-art method for designing and presenting animated animals to live test animals. The major advantages of computer animations are: (1) the creation of animated animal stimuli with high variability of morphology and even behavior; (2) animated stimuli provide highly standardized, controlled and repeatable testing procedures; and (3) they allow a reduction in the number of live test animals regarding the 3Rs principle. But the use of animated animals should be attended by a thorough validation for each test species to verify that behavior measured with live animals toward virtual animals can also be expected with natural stimuli. Here we present results on the validation of a custom-made simulation for animated 3D sailfin mollies Poecilia latipinna and show that responses of live test females were as strong to an animated fish as to a video or a live male fish. Movement of an animated stimulus was important but female response was stronger toward a swimming 3D fish stimulus than to a "swimming" box. Moreover, male test fish were able to discriminate between animated male and female stimuli; hence, rendering the animated 3D fish a useful tool in mate-choice experiments with sailfin mollies.

A Role of DLPFC in the Learning Process of Human Mate Copying

In the current study, we conducted a behavioral experiment to test the mate coping effect and a functional magnetic resonance imaging (fMRI) experiment to test the neural basis involved in the social learning process of mate copying. In the behavioral experiment, participants were asked to rate the attractiveness of isolated opposite-sex (potential mates) facial photographs, then shown the targets associating with a neutral-faced model with textual cues indicating the models’ attitude (interested vs. not-interested) toward the potential mates, and then asked to re-evaluate the potential mates’ attractiveness. Using a similar procedure as the behavioral experiment, participants were scanned while observing the compound images in the fMRI experiment. The mate copying effect was confirmed in the behavioral experiment –greater increase in attractiveness ratings was observed for opposite-sex photographs in the interested than in the not-interested condition. The fMRI results showed that the dorsolateral prefrontal gyrus (DLPFC) was significantly active in the comparison of interested > not-interested condition, suggesting that a cognitive integration and selection function may be involved when participants process information from conditions related to mate copying.

Sex-Specific Audience Effect in the Context of Mate Choice in Zebra Finches

Animals observing conspecifics during mate choice can gain additional information about potential mates. However, the presence of an observer, if detected by the observed individuals, can influence the nature of the behavior of the observed individuals, called audience effect. In zebra finches (Taeniopygia guttata castanotis), domesticated males show an audience effect during mate choice. However, whether male and female descendants of the wild form show an audience effect during mate choice is unknown. Therefore, we conducted an experiment where male and female focal birds could choose between two distinctive phenotypes of the opposite sex, an artificially adorned stimulus bird with a red feather on the forehead and an unadorned stimulus bird, two times consecutively, once without an audience and once with an audience bird (same sex as test bird). Males showed an audience effect when an audience male was present and spent more time with adorned and less time with unadorned females compared to when there was no audience present. The change in time spent with the respective stimulus females was positively correlated with the time that the audience male spent in front of its cage close to the focal male. Females showed no change in mate choice when an audience female was present, but their motivation to associate with both stimulus males decreased. In a control for mate-choice consistency there was no audience in either test. Here, both focal females and focal males chose consistently without a change in choosing motivation. Our results showed that there is an audience effect on mate choice in zebra finches and that the response to a same-sex audience was sex-specific.