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The evolution of reproductive isolation following hybridization is a major obstacle that may limit the prevalence of hybrid speciation among specific groups of organisms. Here, we use a flea beetle system to offer a behavioral hypothesis for why there are so few examples of homoploid hybrid speciation among insects. Specifically, we examined cuticular hydrocarbon (CHC) mating signals and mate-choice decisions of Altica fragariae and A. viridicyanea to test whether the signals produced by hybrids cause prezygotic reproductive isolation. Although hybrids of A. fragariae and A. viridicyanea had unique CHC profiles as compared to the parental species, mate-choice trials indicated that these differences were insufficient to prevent gene flow between hybrids and parental species. We found that mate-choice decisions and CHC signals were not correlated. Considering the ubiquity of CHC signaling molecules in insects, we propose that decoupling of CHC signals and mate choice may be a general mechanism limiting hybrid speciation in insects. [ABSTRACT FROM AUTHOR]

Urban environments impose novel challenges on animals and, as a result, the behaviors of urban wildlife are changing. In particular, high exploratory tendencies and an ability to gather more information from the environment may facilitate adoption of novel ecological opportunities. As of yet, very few studies have examined if urbanization predicts the way in which animals explore novel environments, or the extent of among-individual variation within these habitats. Here, we assess exploration and its temporal plasticity in black-capped chickadees (Poecile atricapillus ; N = 169 individuals, 14 sites) caught along an urban gradient to examine individual differences in exploration and changes in exploration over time and assays under a reaction-norm framework. As predicted, urban birds were significantly faster explorers in a novel environment (contacted more features and moved more), however urbanization did not predict individual differences in the change in exploration over time. Exploration score was moderately repeatable; interestingly, urban chickadees were more repeatable in their initial exploration behaviors, but seemed less repeatable in how they explored over time between assays in comparison to forest birds. Our results support the importance of high exploratory tendencies for urban animals, and suggest, for the first time, that individuals from urban and non-urban habitats differ in the amount of among-individual variation in exploration, and thus urban individuals may benefit from diverging more from one another in their behavior. Future work should examine the extent to which this variation in exploration and plasticity of exploration behaviors represent differences in how individuals gather information from their environment. [ABSTRACT FROM AUTHOR]

Although many studies have investigated the occurrence of extra-pair paternity (EPP) and its adaptive significance in wild population of birds, we still know surprising little about the plasticity in mating behavior of females at the individual level and how it affects the patterns of paternity. To address this question, we focused on the direct fertility benefit hypothesis for the function of EPP and studied if female birds react in extra-pair mating behavior after reproductive failures using a wild population of the Japanese great tit, Parus minor, a socially monogamous passerine with a moderate frequency of EPP and a high-multiple brooding rate. We simulated hatching failure by replacing with artificial eggs during the egg laying period to investigate whether females subsequently altered their mating behavior and became more promiscuous to improve reproductive success in their following clutches. The proportion of extra-pair offspring per clutches of both experimental and control pairs increased in the second clutches (replacement and repeat), but compared with the control pairs, the increase in the experimental pairs was significantly greater. The present study suggests that individual females appear to be making decisions based on specific cues and flexibly altering mating behavior in adaptive ways. Also, our results are compatible with one of the long-debated hypotheses for the evolutionary maintenance of EPP which predicts that females gain direct fitness benefit through increased reproductive success from mating multiply. [ABSTRACT FROM AUTHOR]

Ineffective hunters in cooperative foraging groups may be shielded from natural selection by their more effective group mates, whereas those living solitarily would starve and thus be removed from the population. The problem may be exacerbated in large groups where it may be easier for individuals to withhold participation. Group foragers may thus be ineffective individual hunters or exhibit greater inter-individual variation in hunting abilities, in particular, when living in large groups. We test these hypotheses in spider species of the genus Anelosimus that differ in their level of sociality and, among social species, in colonies of different sizes. We found that individuals from the more social species, and those from larger groups, reacted more slowly to prey than those from solitary species or small groups. Individuals from these categories also had greater inter-individual variation in reaction times. Individuals from large social groups also had lower prey-capture success than those from small ones. These differences may have been driven by the size of the group from which the social individuals were taken, as those from small colonies behaved similarly to individuals of the 2 less social species. This finding suggests that hunting ability may develop as a phenotypically plastic trait. [ABSTRACT FROM AUTHOR]

Learning associations between food-related stimuli and nutrients allows foragers to collect resources efficiently. In turn, the nutrients that foragers consume can themselves affect learning performance, through innate preferences for pre-ingestive stimuli, as well as post-ingestive reinforcement. Bees are insect models of learning and memory, yet the vast majority of this research concerns nectar (carbohydrate) rather than pollen (protein/lipid) rewards, despite the fact that many bees collect both simultaneously. We asked how one component of pollen surface chemistry, a free fatty acid (oleic acid), affected bees' performance in a nectar-learning task. We found that ingestion of oleic acid enhanced visual learning, likely through positive post-ingestive reinforcement. This was supported by our finding that although bees did not prefer to consume the oleic acid solution, its ingestion both decreased motor activity and increased survival. These results are a step towards understanding how nutritionally complex floral rewards may affect cognitive processes that underlie pollination mutualisms. [ABSTRACT FROM AUTHOR]

Predation is one of the strongest selective forces in nature. Organisms characterized by a complex life cycle, undergoing an ontogenetic niche shift, can reduce predation risk on natal stages by metamorphosing earlier. Yet, this antipredatory response may incur numerous life-history–related costs. Interestingly, the consequence of larval predation risk on adult dispersal, a key trait dictating the persistence of spatially structured populations, is largely understudied. Here, we explored the effect of larval predation risk on the life-history and dispersal characteristics of female adults in the mosquito Culex pipiens. As predicted, mosquito larvae reared in the presence of a caged larvivorous-fish metamorphosed earlier, while also suffering from reduced survival. Despite this reduction in development time, the body size of emerging females was larger, implying that more resources were allocated to increase the growth rate, probably at the expense of reduced maintenance and storage. This shift in energy allocation translated into decreased pupa and adult survival. Remarkably, the respective dispersal distance of these larger bodied females was greater. We suggest that the increase in dispersal distance allows these females to cover larger areas, while searching for oviposition sites that are safer than their natal aquatic habitat. Exploring the effects of larval conditions on adult dispersal is central for understanding the distribution of organisms with a complex life cycle in spatially heterogeneous environments, and specifically for disease transmission by mosquitoes. [ABSTRACT FROM AUTHOR]