Season of birth affects social behaviours and stress physiology differently in males and females of the wild cavy (Cavia aperea)

Kniel N. Season of birth affects social behaviours and stress physiology differently in males and females of the wild cavy (Cavia aperea). Bielefeld University; 2020.Behavioural, physiological, and life-history traits are often shaped by the environment. The pace-of-life syndrome (POLS) hypothesis suggests that environmental differences affect individuals consistently, i.e. shaping personality traits. Recently, the original POLS concept has been refined to incorporate predictable differences between sexes. Here, we test POLS predictions regarding aggressiveness, affiliative interactions and their relationship with fearlessness, boldness and blood cortisol concentrations in a precocial rodent. We induced differences in pace-of-life by dynamically changing photoperiod (simulating spring or autumn). We measured boldness, fearlessness, social behaviours and baseline cortisol concentrations in both sexes. In addition, females were tested in a group integration situation. We show that affiliative and aggressive interactions in a social encounter test represent consistent (i.e. personality) traits. In accordance with POLS predictions, social behaviours differed between animals born in different seasons, facing predictably different life histories under natural conditions, albeit in a sex-specific way. Autumn-born males were less aggressive while autumn-born females were more aggressive. While there was no seasonal difference in baseline or stress-induced cortisol concentrations during integration into groups of unfamiliar females, spring-born females lost more body mass, indicating higher levels of stress. The non-social personality traits predicted aggressive behaviour in social situations, again, in a sex-specific way. While bold males showed more interactions in general and more aggressive interactions, boldness did not affect reactions of females. Fearless males and females initiated more aggressive interactions. Taken together, these results indicate that social personality traits interact with non-social personality traits in a complex, sex-specific way, leading to sex-specific syndromes

Does individual personality predict male mating preference for female body size in the Trinidadian guppy?

Kniel N, Godin J‐GJ. Does individual personality predict male mating preference for female body size in the Trinidadian guppy? Ethology. 2020;126(11):1019-1030.Within populations, individual animals vary considerably in their behaviour, including mate choice and personality. There is mounting interest in the potential covariation between these two behaviours within individuals, such that personality would influence mate choice. We experimentally tested this proposition under controlled laboratory conditions using male Trinidadian guppies (Poecilia reticulata) as a model study system. We assayed repeatedly the mating preference of individual males for females based on their body size. Additionally, we assayed repeatedly two ecologically relevant personality traits in males, namely exploration of a novel environment and boldness under a simulated predation threat. Finally, we analysed whether male mating preference and personality traits were repeatable, and tested whether the personality of individual males was correlated (covaried) with their mating preference scores. Although all but one of the measures of exploration and boldness behaviour were repeatable over time, male mating preference scores were not repeatable. Measures of male exploration and boldness were not inter‐correlated among individuals, suggesting the absence of a behavioural syndrome between exploration and boldness. Unexpectedly, males did not exhibit on average a significant mating preference for larger females over smaller ones; they chose randomly between the paired stimulus females. Overall, we found no compelling evidence for a relationship between individual personality traits and mating preference in male guppies, suggesting that personality does not predict mate choice, at least in our study population and under our experimental conditions. We discuss potential factors, other than male personality and body length, that might maintain inter‐individual variation in male mating preferences in the guppy in the wild

Characterizing the (co)variance of personality traits in female Trinidadian guppies (Poecilia reticulata)

A fundamental question in behavioural and evolutionary ecology is to what degree individual phenotypic traits are variable over time and across ecological contexts and whether they are correlated with each other, as (co)variation in traits determines in part their responses to selection and rate of evolution. A first step to addressing this question is to characterize variation in behavioural traits within and among individuals and their covariation in particular ecological contexts. Here, we ascertained whether adult female guppies (Poecilia reticulata), descendants of wild guppies in Trinidad, are consistent or repeatable in their behaviour over time, such that they exhibit individual ‘personalities’ or behavioural types, and whether their personality traits are inter-correlated. Using a repeated-measures design, we twice assayed individual females for each of three ecologically important behavioural traits, Exploration (of a novel environment), Sociability (shoaling with conspecifics) and Boldness (risk taking), under standardized laboratory conditions. We characterized the among-individual (co)variance structure of each behavioural trait measure, and estimated their respective repeatability and the among-individual correlations between these traits using mixed-effects models. All three traits were found to be significantly repeatable and thus can be considered personality traits. None of the estimated correlations between all possible pairings of the three traits were significantly different from zero. Although adult female Trinidadian guppies from our study population exhibited repeatable personality traits, these traits were not inter-correlated (i.e. did not constitute a behavioural syndrome) and were thus independent of each other. Our findings have important implications for the maintenance of behavioural variation within populations and trait evolution

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

<div><p>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 (<i>Taeniopygia guttata castanotis</i>), 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.</p></div

Adornment.

<p>Pictures of an unadorned stimulus male (left) and an adorned stimulus male (right). Stimulus females were adorned in the same way.</p

Additional file 1: of Quality of public information matters in mate-choice copying in female zebra finches

Table of weights, male time spent and male song. The table contains the weight of birds used in the experiments, the time stimulus males spent close to the test females, and the number of times stimulus males sang within the two mate-choice tests. Given are the median, 1st quartile and 3rd quartile. adorned = adorned stimulus males, unadorned = unadorned stimulus males. (XLS 37 kb

Correlation.

<p>Correlation between the time the audience bird spent in the front of its cage close to the focal males (a) or focal females (b) and the change in time spent of focal birds with the respective stimulus birds expressed as a log-ratio difference.</p

Audience Experiments in males (a) and females (b).

<p>Box plot showing median, 1st and 3rd quartile, 95% confidence limits and open points as outliers for mate-choice scores of time spent with stimulus birds. 1st test = first mate-choice test (no audience), 2nd test = mate-choice test (audience). ns = not significant. * = p < 0.05.</p

Male (a) and female (b) control.

<p>Box plot showing median, 1st and 3rd quartile, 95% confidence limits and open points as outliers and stars as extremes for mate-choice scores of time spent with stimulus birds. 1st test = first mate-choice test (no audience), 2nd test = mate-choice test (no audience).</p