Behavioral Ecology最新文献

When making decisions about resource use, social species must integrate not only environmental factors but also the influence of opportunities and costs associated with group living. Bigger groups are expected to move further and to need access to larger areas for adequate food acquisition, but the relationships with group size can vary seasonally and with reproductive stage. Shelters are often more consistent in availability than food, but their use relates to factors such as predator defense and parasite transmission that are themselves influenced by group size and seasonality. Here, we used long-term data to investigate resource use and associated movement in a wild population of dwarf mongooses (Helogale parvula). We found that bigger groups occupied larger home ranges, moved larger daily distances and covered more daily area than smaller ones, while environmental greenness (measured by normalized difference vegetation index [NDVI]) influenced daily movements in the breeding season but not the non-breeding season. Both assessed axes of seasonality also had pronounced effects on shelter use: mongoose groups used more unique sleeping burrows, and switched between burrows more often, in the breeding season, but also switched more when environmental greenness was higher. By investigating specific periods within the breeding season, we revealed the constraints that vulnerable, poorly mobile offspring impose on both group movements and burrow use, highlighting a potentially overlooked cost of reproduction. Our results show how both social and environmental factors can affect key resource-use decisions, demonstrating potential costs and benefits to group living within distinctly seasonal geographic areas.

Aposematic signals warn predators that prey should be avoided due to dangerous secondary defences. However, as warning signals do not always produce avoidance, warning colors may evolve as a trade-off balancing detectability against signal saliency. For Batesian mimics, which display salient signals but lack secondary defenses, the costs of predator encounters are greater, potentially increasing the benefit of crypsis. This raises the question of whether imperfect mimicry may reduce detectability while retaining mimetic efficacy. We tested this hypothesis with the poisonous frog Ameerega bilinguis and undefended Batesian mimic Allobates zaparo, using computational visual modeling and screen-based detection trials with human participants. We found that both species incorporate camouflage into their warning colors, but to different degrees depending on viewing angle and behavior. Contrary to expectation, we found differences in detectability between model and mimic that do not adhere to the hypothesized cryptic mimetic phenotype. To aerial observers, we found the mimic to be more detectable than the model. To terrestrial observers, likely owing to the model's bright ventral color, we found the model more detectable in viewing angles that highlight the ventral coloration, whereas the mimic was more detectable in viewing angles that highlight the dorsal coloration. Consequently, we suggest that in addition to being the result of perceptual or developmental constraints, imperfect mimicry may also evolve as an adaptive strategy which balances camouflage with different signaling functions. Our findings complement the emerging view that aposematic signals may evolve in response to a multitude of selection pressures beyond aversion alone.

Females of some species improve their reproductive success not only by being choosy and selecting males with certain traits, but also by sequentially mating with multiple males within one reproductive season. However, it is relatively unknown whether females also evaluate parental care during mate choice and, if they do, whether males actively communicate their care status to approaching females. We monitored a natural population of the glassfrog Hyalinobatrachium valerioi, a species with sequential polyandry and paternal care, to assess the role of parental care and advertisement calling on male mating success. Using field observations and acoustic analysis, we found that even in this species which has single-note calls, variations in call parameters allow for individual discrimination. Calling was strongly associated with mating success in H. valerioi males. Males with longer calls achieved the highest total mating success over the entire study period, indicating that females might have a preference for longer calls. Moreover, active calling and the presence of clutches were both linked to male mating success on a given night, although we cannot fully exclude that the link between presence of clutches and mating success is due to attractive call features alone. Call parameters differed between males when they were calling on top of their clutches, compared to sitting on the leaf directly, which might provide reliable cues about parental state to approaching females. These findings demonstrate the prominent role of acoustic communication and female choice in a species with male parental care and sequential polyandry.