Lifespan and age, but not residual reproductive value or condition, are related to behaviour in wild field crickets (original) (raw)
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2016
1. According to a recent hypothesis, personality traits should form integrative pace-of-life syn-dromes with life-history traits. Potential life-history traits that explain personality variation are immune defence and growth rate. 2. We studied whether boldness, measured as hiding behaviour, is repeatable during ontogeny in the field cricket, Gryllus integer, and if it relates to the efficiency of immune function (i.e. the capacity to encapsulate a nylon implant), growth rate, developmental time and size as an adult. 3. Hiding behaviour was rank-order repeatable, and in general, juveniles were bolder than adults. Individuals that were cautious at early juvenile stages had higher encapsulation responses late in life compared with bold individuals. Most clearly, fast-growing individuals matured early and invested little in immune defence compared with their slower-growing conspecifics, i.e. showed patterns of a ‘grow fast, die young ’ life-history strategy. 4. Our results may arise fr...
Despite recent progress in elucidating the genetic basis for behavioral variation, the effects of the developmental environment on the maintenance and generation of behavioral variation across multiple traits remain poorly resolved. We investigated how nutritional status during development affected behavioral variation and covariance between activity in an open field test and response to cues of predator presence in the house cricket (Acheta domesticus). We provided 98 juvenile crickets with either a high or low quality diet during development, throughout which we measured body mass, activity in a modified open-field, and response to predator excreta twice every week for 3 weeks. Diet quality affected growth rate but not average activity or response to cues of predator presence, nor the correlation between the 2. However, repeatability (τ) in response to cues of predator presence was reduced by 0.24 in individuals exposed to the high quality diet versus the low quality diet. Larger individuals also increased their response to predator cues when reared on a high quality diet, suggesting negative feedbacks between growth rate and antipredator behaviors. Our results also indicate that changes in the developmental environment are not sufficient to collapse behavioral syndromes, suggesting a genetic link between activity and predator cue response in house crickets, and that nutritional stress early in life can lead to more consistent behavioral responses when individuals faced predatory threats. Our results demonstrate that subtle differences in the quality of the environment experienced early in life can influence how individuals negotiate behavioral and life-history trade-offs later in life.
2009
One of the most familiar behavioural linkages is the aggressiveness-activity behavioural syndrome. In this study I used sexually mature field crickets (Gryllus integer) from a laboratory stock as model animals to explore experimentally the relationship between individual variation in exploration activity and intrasexual aggression as well as to estimate if behavioural traits are heritable. I measured individual willingness to exit from a shelter into an unfamiliar, potentially dangerous environment and afterwards the individual's fighting success and the resultant dominance rank of males in male-male competition. Further, I used full-sib-half-sib analysis and parent-offspring-regression to study the heritability of the examined behaviours. My study could not confirm the previous observations of a aggressiveness–activity behavioural syndrome in the G. integer. However, there is still relatively little theory and data to explain the causes of behavioural correlations. There is evi...
Behavioral Ecology and Sociobiology, 2010
Recently, there has been increasing interest in behavioral syndrome research across a range of taxa. Behavioral syndromes are suites of correlated behaviors that are expressed either within a given behavioral context (e.g., mating) or between different contexts (e.g., foraging and mating). Syndrome research holds profound implications for animal behavior as it promotes a holistic view in which seemingly autonomous behaviors may not evolve independently, but as a "suite" or "package." We tested whether laboratory-reared male and female European house crickets, Acheta domesticus, exhibited behavioral syndromes by quantifying individual differences in activity, exploration, mate attraction, aggressiveness, and antipredator behavior. To our knowledge, our study is the first to consider such a breadth of behavioral traits in one organism using the syndrome framework. We found positive correlations across mating, exploratory, and antipredatory contexts, but not aggression and general activity. These behavioral differences were not correlated with body size or condition, although age explained some of the variation in motivation to mate. We suggest that these across-context correlations represent a boldness syndrome as individual risk-taking and exploration was central to across-context mating and antipredation correlations in both sexes.
Behavioral Ecology and Sociobiology, 2013
It is generally thought that attractive male traits are positively correlated with dominance (aggressiveness). However, growing evidence suggests that this is not necessarily the case. We investigated whether calling song, a male mating display used by females to evaluate potential mates in a field cricket (Gryllus integer), is correlated with aggressiveness. In this species, females prefer males with longer durations of singing time. We measured singing time by measuring song over three continuous days using a custom-designed audio-monitor and assessed aggressiveness by pairing males in agonistic interactions. Our results showed that for males caught in the field, the percentage of time spent singing was negatively correlated with aggressiveness. However, in males that were raised in the laboratory, the percentage of time spent singing was not correlated with aggressiveness. Since calling duration is an attractive male trait in these crickets, our data show that the attractiveness of males can be either negatively related to aggressiveness (field) or unrelated to aggressiveness (lab). Neither of these results fit the traditional view that preferred male mating cues should be positively correlated with dominance (aggressiveness). These results also suggest that measurements of aggressiveness made in the lab do not necessarily correspond with aggressiveness in the field.
Evolutionary Ecology, 2010
We used multiple regression, path analysis and non-parametric selection surface visualisation to investigate natural and sexual selection and, in addition, cross-sectional female choice statistics to analyse female choice in a wild population of the field cricket Gryllus campestris L. in central Germany. Adults (167 males, 75 females) were individually marked and followed daily over the entire adult stage. Two morphological traits (pronotum width, body condition) and two behavioural traits (burrow occupation time, daily displacement) were measured for each male and used in selection analyses. Individuals mated multiply and male mating success was strongly right skewed with less than 6% of the population achieving 50% of the copulations. In males, analysis of natural selection in terms of lifespan revealed positive directional selection on burrow occupation time and stabilising selection on daily displacement. Analysis of sexual selection in term of mating success showed positive directional selection on pronotum width and lifespan. Path analysis confirmed the close association between natural and sexual selection and illustrated indirect effects of the behavioural variables on mating success via their effect on lifespan. Multiple regression analysis further indicated positive quadratic (disruptive) sexual selection on lifespan but the non-parametric cubic spline regression showed this to be an artefact of the quadratic approach. In fact, lifespan was under ''threshold selection'' i.e. it was not under selection below a threshold and under positive directional sexual selection above the threshold. A positive correlational selection gradient between lifespan and body condition revealed that a high body condition is advantageous among long-lived males. Female choice statistics showed that females chose large and heavy males in the beginning of the season only and that choosiness decreases with increasing distance to potential alternative mates. Our findings highlight the benefits of combining several analytical methods to uncover selection patterns and to avoid misinterpretations based on single methods.
CONDITION DEPENDENCE OF MALE LIFE SPAN AND CALLING EFFORT IN A FIELD CRICKET
Evolution, 2008
Sexually selected traits are thought to impose survival costs on showy males. Recent empirical work found a negative relationship between male display and survival in a field cricket species (Orthoptera, Gryllidae, Gryllinae) where there is no evidence of a mating bias toward older males. In most species, however, male survival and ornamentation are positively correlated, and older males often have a mating success advantage over younger males. These findings suggest that male quality and survival are positively correlated, but more tests of this hypothesis are needed. We measured the condition dependence of male survival and calling effort in another grylline, Gryllus pennsylvanicus, where older males have previously been shown to have greater mating success. We varied condition by manipulating diet, and measured male life span and calling effort to assess the relative condition dependence of these traits. High- and medium-condition males survived longer than low-condition males, and high-condition males called more than medium- and low-condition males. Differences in calling effort among the condition treatments were not apparent early in life, but emerged as males aged. We discuss possible explanations for the differences between our study and contrasting results such as the previous grylline work.