How do developmental and parental exposures to predation affect personality and immediate behavioural plasticity in the snail Physa acuta?

Individuals differ in personality and immediate behavioural plasticity. While developmental environment may explain this group diversity, the effect of parental environment is still unexplored—a surprising observation since parental environment influences mean behaviour. We tested whether developmental and parental environments impacted personality and immediate plasticity. We raised two generations of Physa acuta snails in the laboratory with or without developmental exposure to predator cues. Escape behaviour was repeatedly assessed on adult snails with or without predator cues in the immediate environment. On average, snails were slower to escape if they or their parents had been exposed to predator cues during development. Snails were also less plastic in response to immediate predation risk on average if they or their parents had been exposed to predator cues. Group diversity in personality was greater in predator-exposed snails than unexposed snails, while parental environment did not influence it. Group diversity in immediate plasticity was not significant. Our results suggest that only developmental environment plays a key role in the emergence of group diversity in personality, but that parental environment influences mean behavioural responses to the environmental change. Consequently, although different, both developmental and parental cues may have evolutionary implications on behavioural responses.     

How does variation in the environment and individual cognition explain the existence of consistent behavioral differences?

According to recent studies on animal personalities, the level of behavioral plasticity, which can be viewed as the slope of the behavioral reaction norm, varies among individuals, populations, and species. Still, it is conceptually unclear how the interaction between environmental variation and variation in animal cognition affect the evolution of behavioral plasticity and expression of animal personalities. Here, we (1) use literature to review how environmental variation and individual variation in cognition explain population and individual level expression of behavioral plasticity and (2) draw together empirically yet nontested, conceptual framework to clarify how these factors affect the evolution and expression of individually consistent behavior in nature. The framework is based on simple principles: first, information acquisition requires cognition that is inherently costly to build and maintain. Second, individual differences in animal cognition affect the differences in behavioral flexibility, i.e. the variance around the mean of the behavioral reaction norm, which defines plasticity. Third, along the lines of the evolution of cognition, we predict that environments with moderate variation favor behavioral flexibility. This occurs since in those environments costs of cognition are covered by being able to recognize and use information effectively. Similarly, nonflexible, stereotypic behaviors may be favored in environments that are either invariable or highly variable, since in those environments cognition does not give any benefits to cover the costs or cognition is not able to keep up with environmental change, respectively. If behavioral plasticity develops in response to increasing environmental variability, plasticity should dominate in environments that are moderately variable, and expression of animal personalities and behavioral syndromes may differ between environments. We give suggestions how to test our hypothesis and propose improvements to current behavioral testing protocols in the field of animal personality.     

Individual quality and personality: bolder males are less fecund in the hermit crab Pagurus bernhardus

One explanation for animal personality is that different behavioural types derive from different life-history strategies. Highly productive individuals, with high growth rates and high fecundity, are assumed to live life at a fast pace showing high levels of boldness and risk taking, compared with less productive individuals. Here, we investigate among-individual differences in mean boldness (the inverse of the latency to recover from a startling stimulus) and in the consistency of boldness, in male hermit crabs in relation to two aspects of life-history investment. We assessed aerobic scope by measuring the concentration of the respiratory pigment haemocyanin, and we assessed fecundity by measuring spermatophore size. First, we found that individuals investing in large spermatophores also had high concentrations of haemocyanin. Using doubly hierarchical-generalized linear models to analyse longitudinal data on startle responses, we show that hermit crabs vary both in their mean response durations and in the consistency of their behaviour. Individual consistency was unrelated to haemocyanin concentration or spermatophore size, but mean startle response duration increased with spermatophore size. Thus, counter to expectations, it was the most risk-averse individuals, rather than the boldest and most risk prone, that were the most productive. We suggest that similar patterns should be present in other species, if the most productive individuals avoid risky behaviour.     

Aerial dispersal plasticity under different wind velocities in a salt marsh wolf spider

Dispersal can be regarded as a process operating both betweenand within patches of suitable habitat. For uncontrolled dispersalprocesses, the risk of crossing the borders of the habitat patchand arriving in the unsuitable landscape matrix will increasewith decreasing patch area, in particular when the distancebetween isolated habitat patches is larger than the species'average dispersal capacity. Ballooning dispersal in spiderscan be considered as a passive dispersal process, in which disperseddistances depend on the prevalent wind velocity. We executeda reaction norm analysis to analyze how dispersal propensityof the salt marsh wolf spider Pardosa purbeckensis dependedon population characteristics (patch size) and the environment(wind velocity). Dispersal propensity was affected by the interactionbetween wind velocity and maternal patch size. Ballooning propensitiesdecreased with decreasing salt marsh size. Interestingly, genotypesfrom large salt marshes show higher ballooning propensitiesunder higher wind velocities, whereas those from small habitatpatches show their highest dispersal propensity under low windvelocities. Crossing reaction norms and subsequently stronggenotype x environment interaction variation was observed inall populations but tended to be lower in genotypes from largesalt marshes. It is likely that this pattern results from differencesin wind velocity–related costs of within-habitat dispersalin salt marshes of different sizes.     

Responses of pet cats to being held by an unfamiliar person,from weaning to three years of age

Abstract

We have determined the extent to which individual responses of domestic cats on being handled by an unfamiliar person are stable between 2 and 33 months of age. Twenty-nine household cats from nine litters were tested at 2, 4, 12, 24 and 33 months of age, by being held for 1 minute by a standard, unfamiliar person. Between 4 and 33 months of age, individual differences in the number of attempts made by the cat to escape, and in whether or not it showed signs of distress, were stable, with the partial exception of the test at 12 months. There was no consistency between tests in whether or not a particular cat purred. At 2 months of age, the number of escape attempts was highest in cats which had been handled the least in the second month of life, but this trend was reversed in the number of escape attempts made at 4 months. The lack of distress exhibited by all cats in the test at 2 months indicated that all had received at least adequate socialization to people, and that none were therefore comparable with the unsocialized cats used in several previous studies. We conclude that under normal domestic conditions, the behavior of a cat when handled by an unfamiliar person reflects a stable character trait, and that extensive handling during the socialization period may be subsequently associated with a reduction in inhibited behavior when interacting with an unfamiliar person.     

No personality without experience? A test on Rana dalmatina tadpoles

While the number of studies reporting the presence of individual behavioral consistency (animal personality, behavioral syndrome) has boomed in the recent years, there is still much controversy about the proximate and ultimate mechanisms resulting in the phenomenon. For instance, direct environmental effects during ontogeny (phenotypic plasticity) as the proximate mechanism behind the emergence of consistent individual differences in behavior are usually overlooked compared to environmental effects operating across generations (genetic adaptation). Here, we tested the effects of sociality and perceived predation risk during ontogeny on the strength of behavioral consistency in agile frog (Rana dalmatina) tadpoles in a factorial common garden experiment. Tadpoles reared alone and without predatory cues showed zero repeatability within (i.e., lack of personality) and zero correlation between (i.e., lack of syndrome) activity and risk‐taking. On the other hand, cues from predators alone induced both activity and risk‐taking personalities, while cues from predators and conspecifics together resulted in an activity – risk‐taking behavioral syndrome. Our results show that individual experience has an unequivocal role in the emergence of behavioral consistency. In this particular case, the development of behavioral consistency was most likely the result of genotype × environment interactions, or with other words, individual variation in behavioral plasticity.