The effect of visual obstructions on the sexual behaviour of guppies: the importance of privacy

No geographical differences in male mate choice in a widespread fish, Limia perugiae

Behavior, like most other traits, can have a spatial component, and variability of behavior at the population level is predicted. In this article, we explore male mate choice at this level. Male mate choice, while maybe not as common as female choice, is expected to evolve when males respond to significant variation in female quality and, for example, prefer females with higher fecundity. In fishes, higher fecundity is associated with larger body size, an easily measured trait. In this study, we investigated the presence of male mate choice for larger females in a widespread species of livebearing fish, Limia perugiae, while comparing preferences between populations. We hypothesized that environmental variation, for example, in the form of salinity, might result in population differences. Using dichotomous choice tests, we analyzed behavioral data for 80 individuals from 7 distinct populations from Hispaniola. We found that L. perugiae males significantly preferred large females, but there was no significant statistical variation between populations.

The Case for Animal Privacy in the Design of Technologically Supported Environments

Privacy is an essential consideration when designing interactive systems for humans. However, at a time when interactive technologies are increasingly targeted at non-human animals and deployed within multispecies contexts, the question arises as to whether we should extend privacy considerations to other animals. To address this question, we revisited early scholarly work on privacy, which examines privacy dynamics in non-human animals (henceforth “animals”). Then, we analysed animal behaviour literature describing privacy-related behaviours in different species. We found that animals use a variety of separation and information management mechanisms, whose function is to secure their own and their assets' safety, as well as negotiate social interactions. In light of our findings, we question tacit assumptions and ordinary practises that involve human technology and that affect animal privacy. Finally, we draw implications for the design of interactive systems informed by animals' privacy requirements and, more broadly, for the development of privacy-aware multispecies interaction design.

Kin Recognition in Guppies Uses Self-Referencing Based on Olfactory Cues

AbstractKin recognition plays an important role in social behavior and evolution, but the proximate mechanisms by which individuals recognize kin remain poorly understood. In many species, individuals form a "kin template" that they compare with conspecifics' phenotypes to assess phenotypic similarity-and, by association, relatedness. Individuals may form a kin template through self-inspection (i.e., self-referencing) and/or by observing their rearing associates (i.e., family referencing). However, despite much interest, few empirical studies have successfully disentangled self-referencing and family referencing. Here, we employ a novel set of breeding crosses using the Trinidadian guppy (Poecilia reticulata) to disentangle referencing systems by manipulating exposure to kin from conception onward. We show that guppies discriminate among their full and maternal half siblings, which can be explained only by self-referencing. Additional behavioral experiments revealed no evidence that guppies incorporate the phenotypes of their broodmates or mother into the kin template. Finally, by manipulating the format of our behavioral tests, we show that olfactory communication is both necessary and sufficient for kin discrimination. These results provide robust evidence that individuals recognize kin by comparing the olfactory phenotypes of conspecifics with their own. This study resolves key questions about the proximate mechanisms underpinning kin recognition, with implications for the ontogeny and evolution of social behavior.

Mating Preference for Novel Phenotypes Can Be Explained by General Neophilia in Female Guppies

AbstractUnderstanding how genetic variation is maintained in ecologically important traits is a fundamental question in evolutionary biology. Male Trinidadian guppies (Poecilia reticulata) exhibit extreme genetic diversity in color patterns within populations, which is believed to be promoted by a female mating preference for rare or novel patterns. However, the origins of this preference remain unclear. Here, we test the hypothesis that mating preference for novel phenotypes is a by-product of general neophilia that evolved in response to selection in nonmating contexts. We measured among-female variation in preference for eight different, novel stimuli that spanned four ecological contexts: mate choice, exploration, foraging, and social (but nonsexual) interactions. Females exhibited preference for novelty in six out of eight tests. Individual variation in preference for novelty was positively correlated among all eight types of stimuli. Furthermore, factor analysis revealed a single axis of general neophilia that accounts for 61% of individual variation in preference for novel color patterns. The single-factor structure of neophilia suggests that interest in novelty is governed primarily by shared processes that transcend context. Because neophilia likely has a sizable heritable component, our results provide evidence that mating preference for novel phenotypes may be a nonadaptive by-product of natural selection on neophilia.

Consistent female preference for rare and unfamiliar male color patterns in wild guppy populations

How genetic variation is maintained in ecologically important traits is a central question in evolutionary biology. Male Trinidadian guppies, Poecilia reticulata, exhibit high genetic diversity in color patterns within populations, and field and laboratory studies implicate negative frequency-dependent selection in maintaining this variation. However, behavioral and ecological processes that mediate this selection in natural populations are poorly understood. We evaluated female mate preference in 11 natural guppy populations, including paired populations from high- and low-predation habitats, to determine if this behavior is responsible for negative frequency-dependent selection and to evaluate its prevalence in nature. Females directed significantly more attention to males with rare and unfamiliar color patterns than to males with common patterns. Female attention also increased with the area of male orange coloration, but this preference was independent of the preference for rare and unfamiliar patterns. We also found an overall effect of predation regime; females from high-predation populations directed more attention toward males than those from low-predation populations. Again, however, the habitat-linked preference was statistically independent from the preference for rare and unfamiliar patterns. Because previous research indicates that female attention to males predicts male mating success, we conclude that the prevalence of female preference for males with rare and unfamiliar color patterns across many natural populations supports the hypothesis that female preference is an important process underlying the maintenance of high genetic variation in guppy color patterns.

Sexual selection on the multicomponent display of black morph male Girardinus metallicus (Pisces: Poeciliidae)

Sexually selected displays often include suites of integrated traits. Black morph males of the poeciliid fish Girardinus metallicus perform courtship and aggressive displays that exhibit their conspicuous yellow and black coloration. Body size, gonopodium size and ventral black area are correlated with intermale aggression, which is key for access to mates. A previous study showed that females may prefer dominant males prior to watching them fight; however, that result was obtained in trials that allowed for male-male interactions across partitions, and to date no study has uncovered the traits important in female choice. We performed a more comprehensive investigation of the multicomponent sexual display including measures of male yellow hue, saturation and brightness. We examined the behavior of size-matched males paired to maximize the difference in yellow saturation, and measured female choice exclusive of male-male interactions and chemical cues. We found no female preference for any traits in the multicomponent sexual display. Males with brighter and more saturated yellow coloration were more likely to be dominant, and dominant males courted and attempted copulations more. Our results suggest that yellow coloration is sexually selected; however, the courtship display requires further investigation because we did not identify targets of female preference, and we discuss possible explanations for this finding.

Sexual selection on male body size, genital length and heterozygosity: Consistency across habitats and social settings

Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ratio of receptive males to females). How the OSR affects selection for specific male traits is poorly understood. It is also unclear how sexual selection is affected by interactions between the OSR and environmental factors, such as habitat complexity, that alter key male-female interactions such as mate encounter rates. Here, we experimentally manipulated the OSR and habitat complexity and quantified sexual selection on male mosquitofish (Gambusia holbrooki) by directly measuring male reproductive success (i.e. paternity). We show that despite a more equitable sharing of paternity (i.e. higher levels of multiple paternity) under a male-biased OSR, selection on focal male traits was unaffected by the OSR or habitat complexity. Instead, sexual selection consistently, and significantly, favoured smaller bodied males, males with higher genome wide heterozygosity (based on >3,000 SNP markers) and males with a relatively long gonopodium (intromittent organ). Our results show that sexual selection on male body size, relative genital size and heterozygosity in this system is consistent across environments that vary in ecological parameters that are expected to influence mate encounter rates.

Sex odour preference in guppy (Poecilia wingei) males is influenced by the social environment

The social environment of animals, particularly in the early stages of life, can have great impact on species-specific and sex-specific behaviours. These changes can be irreversible and continue during the entire life. In the present study we asked the question whether the social environment of male Endler’s guppies,Poecilia wingei, housed in an all-male community could affect their preference response to female or male odour cues in a flow through Y-maze. After 30 days in an all-male group males were tested for their preference-avoidance responses to conspecific odours. The males were attracted to male-scented water but not to water scented by females. In simultaneous choice between male and female odours they demonstrated no significant preference. The males were attracted to male-scented water after they were kept for 48 h or 12 days with females. After the Y-maze tests the males’ were placed with two females and their courting behaviour were recorded. The males showed low frequencies of reproductive behaviours. In the all-male group the males had been courting each other. The results show that the social environment influence sexual odour preference and courting behaviour in guppy males.

Immunohistochemical and histochemical characteristics of the olfactory system of the guppy, Poecilia reticulata (Teleostei, Poecilidae)

Olfaction in fish has been studied using preferentially macrosmatic species as models. In the present research, the labelling patterns of different neuronal markers and lectins were analyzed in the olfactory neurons and in their bulbar axonal endings in the guppy Poecilia reticulata, belonging to the group of microsmatic fish. We observed that calretinin immunostaining was confined to a population of olfactory receptor cells localized in the upper layers of the sensory mucosa, probably microvillous neurons innervating the lateral glomerular layer. Immunoreactivity for S100 proteins was mainly evident in crypt cells, but also in other olfactory cells belonging to subtypes projecting in distinct regions of the bulbs. Protein gene product 9.5 (PGP 9.5) was not detected in the olfactory system of the guppy. Lectin binding revealed the presence of N-acetylglucosamine and alpha-N-acetylgalactosamine residues in the glycoconjugates of numerous olfactory neurons ubiquitously distributed in the mucosa. The low number of sugar types detected suggested a reduced glycosidic variability that could be an index of restricted odorant discrimination, in concordance with guppy visual-based behaviors. Finally, we counted few crypt cells which were immunoreactive for S100 and calretinin. Crypt cells were more abundant in guppy females. This difference is in accordance with guppy gender-specific responses to pheromones. Cells immunoreactive to calretinin showed no evidence of ventral projections in the bulbs. We assumed the hypothesis that their odorant sensitivity is not strictly limited to pheromones or sexual signals in general.

How not to be seen: does eutrophication influence three-spined stickleback Gasterosteus aculeatus sneaking behaviour?

Experiments done in aquaria under control and either turbid or densely vegetated conditions indicated that three-spined stickleback Gasterosteus aculeatus sneaking behaviour is affected by decreased underwater visibility. Success of sneaking behaviour decreased significantly under increased turbidity but not increased vegetation density. The total number of sneaking attempts, including unsuccessful ones, was not affected by either form of decreasing visibility.