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Behavioral Ecology Advance Access





Published: Tue, 12 Sep 2017 00:00:00 GMT

Last Build Date: Tue, 12 Sep 2017 10:43:35 GMT

 



Change in sex pheromone expression by nutritional shift in male cockroaches

2017-09-12

Abstract
Environmental conditions during sexual maturation impact sexual signal expression, but little is known about how individual histories of changing environmental conditions affect the intensity of male sexual advertisement. We investigated the effects of shifting dietary nutrient composition (protein vs. carbohydrates) in male Nauphoeta cinerea cockroaches on consumption, final lipid reserves, and sex pheromone levels subsequent to completing sexual maturation on a specific diet, at high and low concentration of dietary nutrients. Consumption, lipid reserves, and sex pheromone levels were highly affected by dietary nutrient composition with higher values on carbohydrate-biased diet, and males had significantly higher and lower levels of consumption, lipid reserves, and sex pheromones when shifted to a carbohydrate-biased and a protein-biased diet, respectively, compared with males maintained on either initial diet throughout the experiment. Males shifted to a carbohydrate-biased diet at high nutrient concentration fully recouped their sex pheromone levels, attaining levels that were not significantly lower than those in males maintained on carbohydrate-biased diet at high nutrient concentration throughout the experiment. Our study shows that male sexual display in N. cinerea is plastic and highly affected by present as well as previous dietary conditions. Signaling of adaptive quality through male sex pheromones can therefore vary dynamically within the early adult life of a male in response to the nutritional composition of food that is available to ingest. This contrasts morphological sexual traits in arthropods that are affected during development and are fixed at adulthood.



Species divergence in offspring begging and parental provisioning is linked to nutritional dependency

2017-09-11

Abstract
In animal species in which parents provide food to their dependent young, offspring often display conspicuous begging signals. These solicitation behaviors are important components of parent–offspring communication, but it is currently unclear how they and the parental response covary with offspring dependency on parental food provisioning across species. Burying beetles (Nicrophorus) are well known for providing elaborate biparental care, including provisioning of begging larvae. By using a multispecies approach, we show that larval begging intensity, as well as the time parents spend provisioning, differ greatly between individuals of the 3 species: N. orbicollis, N. pustulatus, and N. vespilloides. Our results demonstrate that the most dependent offspring of N. orbicollis invest the most time in begging, whereas the most independent offspring of N. pustulatus invest the least amount of time in begging. Thus, we suggest that begging intensity differs due to intrinsic differences in nutritional need between the species rather than because of an arbitrary divergence in begging behavior. We further show that in all 3 species, females spend significantly more time provisioning than males, although there is considerable divergence between species in the extent to which females and males contribute to the provisioning of larvae. We discuss the potential selective factors leading to this diversification of offspring begging and parental provisioning in relation to the distinct variation in offspring dependence between the 3 species.



Social information use and social learning in non-grouping fishes

2017-09-11

Abstract
Although it is natural to expect that group-living animals will utilize social learning, the expectation for non-grouping species is less clear. Only a few studies have explored the relationship between sociality and social learning. Here we presented 4 non-grouping fish species, fifteenspine sticklebacks (Spinachia spinachia), bullhead sculpins (Cottus gobio), stone loach (Barbatula barbatula) and juvenile European flounders (Platichthys flesus) with social information provided by groups of a shoal-forming heterospecific, the threespine stickleback (Gasterosteus aculeatus). Using a binary choice procedure we allowed individual test subjects to select between simulated prey patches. Although the test subjects could not sample the patches directly they were able to use information generated by the heterospecific demonstrators to select the “richer” of the 2 patches. For comparison we also recorded social information use in 2 shoaling species, threespine, and ninespine sticklebacks (Pungitius pungitius). We saw evidence of social information use and social learning in all 6 species, with no differences seen between social and non-grouping species. We argue that social learning is not likely to be restricted to group-living species, since many solitary species too are regularly exposed to social stimuli from both conspecifics and heterospecifics, and can benefit from using social information. We suggest that researchers have much to learn about the sensory, perceptive, and cognitive mechanisms underlying social learning, and the extent to which these vary (if at all) between grouping and non-grouping species.



Is male rhesus macaque facial coloration under intrasexual selection?

2017-09-11

Abstract
Exaggerated male traits can evolve under intra- or intersexual selection, but it remains less clear how often both mechanisms act together on trait evolution. While the males of many anthropoid primate species exhibit colorful signals that appear to be badges of status under intrasexual selection, the red facial coloration of male rhesus macaques (Macaca mulatta) appears to have evolved primarily under intersexual selection and female mate choice. Nonetheless, experiments show that red color is salient to males, raising the question of whether the signal may also be under intrasexual selection. Here, we examine whether males express this signal more strongly in competitive contexts. Facial images were collected on all 15 adult males of a free-ranging social group during the peak of the mating season, and coloration was quantified using visual models. Results show that males more similar in facial redness were more likely to interact aggressively than more dissimilar ones, suggesting that color may be involved in the assessment of rivals. Furthermore, males exhibited darker coloration on days they were observed copulating, and dominance rank predicted facial redness only on copulating days, suggesting that coloration may also advertise motivation to defend a mate. Male rhesus macaque facial coloration may thus mediate agonistic interactions with rivals during competition over reproductive opportunities, such that it is under both inter- and intrasexual selection. However, color differences were small, raising perceptibility questions. It remains possible that color variation reflects differences in male condition, which in turn alter investment towards male–male competition and mating effort.



A case for considering individual variation in diel activity patterns

2017-09-11

Abstract
There is a growing recognition of the role of individual variation in patterns emerging at higher levels of biological organization. Despite the importance of the temporal configuration of ecological processes and patterns, intraspecific individual variation in diel activity patterns is almost never accounted for in behavioral studies at the population level. We used individual-based monitoring data from 98 GPS-collared brown bears in Scandinavia to estimate diel activity patterns before the fall hunting season. We extracted 7 activity measures related to timing and regularity of activity from individual activity profiles. We then used multivariate analysis to test for the existence of distinct activity tactics and their environmental determinants, followed by generalized linear regression to estimate the extent of within-individual repeatability of activity tactics. We detected 4 distinct activity tactics, with a high degree of individual fidelity to a given tactic. Demographic factors, availability of key foraging habitat, and human disturbance were important determinants of activity tactics. Younger individuals and those with higher bear and road densities within their home range were more nocturnal and more likely to rest during the day. Good foraging habitat and increasing age led to more diurnal activity patterns and nocturnal resting periods. We did not find evidence of diel activity tactics influencing survival during the subsequent hunting season. We conclude that individual variation in activity deserves greater attention than it currently receives, as it may help account for individual heterogeneity in fitness and could facilitate within-population niche partitioning that can have population- or community-level consequences.