How visual system configuration can play a role in individual recognition: a visual modeling study.

Many species rely on individual recognition (i.e., the use of individual signals to identify and remember a conspecific) to tune their social interactions. However, little is known about how the configuration of the sensory system may affect the perception of individual recognition signals over space. Utilizing a visual modeling approach, we quantified (1) the threshold distance between the receiver and the signaler at which individual recognition can no longer accurately occur, and (2) the regions of the head most likely to contain the individual recognition signals. We used chickens (Gallus gallus) as our study species, as they use visual individual recognition and additionally have a well-studied visual system. We took pictures of different individuals and followed a visual modeling approach considering color vision, visual acuity, and pattern processing of the receiver. We found that distance degrades the quality of information in potential individual recognition signals. We estimated that the neighbor distance at which a receiver may have difficulty recognizing a conspecific was between 0.25 and 0.30 m in chickens, which may be related to a decrease in available features of the potential signal. This signal perception threshold closely matches the recognition distance predicted by previous behavioral approaches. Additionally, we found that certain regions of the head (beak, cheek, comb, eye) may be good candidates for individual recognition signals. Overall, our findings support that recognition in chickens occurs at short distances due to constraints imposed by their visual system, which can affect the costs and benefits associated with social spacing in groups.

Neurogenomic insights into paternal care and its relation to territorial aggression.

Motherhood is characterized by dramatic changes in brain and behavior, but less is known about fatherhood. Here we report that male sticklebacks-a small fish in which fathers provide care-experience dramatic changes in neurogenomic state as they become fathers. Some genes are unique to different stages of paternal care, some genes are shared across stages, and some genes are added to the previously acquired neurogenomic state. Comparative genomic analysis suggests that some of these neurogenomic dynamics resemble changes associated with pregnancy and reproduction in mammalian mothers. Moreover, gene regulatory analysis identifies transcription factors that are regulated in opposite directions in response to a territorial challenge versus during paternal care. Altogether these results show that some of the molecular mechanisms of parental care might be deeply conserved and might not be sex-specific, and suggest that tradeoffs between opposing social behaviors are managed at the gene regulatory level.

Correction to 'Parenting behaviour is highly heritable in male stickleback'.

[This corrects the article DOI: 10.1098/rsos.171029.].

Parenting behaviour is highly heritable in male stickleback.

Parental care is critical for fitness, yet little is known about its genetic basis. Here, we estimate the heritability of parenting behaviour in a species famous for its diversity and its behavioural repertoire: three-spined stickleback (Gasterosteus aculeatus). Male three-spined stickleback are the sole providers of parental care that is necessary for offspring survival; therefore, this system offers the opportunity to study the inheritance of parental behaviour when selection is primarily acting on males. Fanning behaviour is a conspicuous parental behaviour that is readily quantified in this species. We show that the heritability of fanning behaviour is ≥0.9 and significantly different from zero within a freshwater population. Moreover, there was abundant genetic variation for fanning behaviour, indicating that it could readily evolve. These results suggest that parenting behaviour is tractable for further genetic dissection in this system.

The Effect of Familiarity with Demonstrators on Social Learning in Three-Spined Sticklebacks (Gasterosteus aculeatus).

Social learning is an important process in the spread of information, especially in changing environments where inherited behaviors may not remain relevant. In many species, the decision of whom to trust to have reliable information depends on the relationship between individuals. Many fish species, including three-spined sticklebacks, preferentially associate with familiar individuals. Previous studies in three-spined sticklebacks have provided mixed evidence about the effect of familiarity on social learning in this species. Therefore, this study further explores familiarity and social learning in sticklebacks, specifically from a demonstrator-focused perspective. We found that in a food patch discrimination task, individuals with unfamiliar demonstrators performed significantly better than those with familiar demonstrators. In a problem-solving task, we found that focal fish attended to the behavior of demonstrators, but we did not detect an effect of familiarity on performance, and indeed the proportion of individuals to solve the task after observing demonstrators was low. These results suggest that sticklebacks have a preference for unfamiliar demonstrators, but that the use of social information varies depending on context.

Do reproduction and parenting influence personality traits? Insights from threespine stickleback.

Although one of the hallmarks of personality traits is their consistency over time, we might expect personality traits to change during life history shifts. Becoming a parent is a major life history event, when individuals undergo dramatic behavioural and physiological changes. Here we employ a longitudinal experiment to ask whether personality changes in response to the experience of parenting in male threespine sticklebacks, Gasterosteus aculeatus. Life history theory predicts that males should be less risk averse after successfully parenting, and the neuroendocrinology of parenting suggests that parenting could reorganize the hormonal landscape and behaviour of fathers. We randomly assigned males to either an experimental group (reproduced and parented) or a control group (did not reproduce and parent), and repeatedly measured a personality trait ('boldness') and 11-ketotestosterone levels (11-kT, the major androgen in fishes) in individual males. In the control group, males became bolder over time. However, in the experimental group, boldness did not change. Furthermore, 11-kT changed dramatically in the experimental group, and changes in 11-kT in parents were associated with boldness after parenting ceased. Our study is one of the first to assess proximate and ultimate explanations for changes in personality as a function of reproduction and parenting.