Current Zoology最新文献

Wetlands are unique ecological environments capable of harboring high biodiversity. However, urbanization can degrade, eliminate, or transform these habitats. Although amphibians utilize habitats created by humans in urban landscapes, few studies have investigated the influence of the habitat quality on the life history of anurans. We assessed life history traits such as snout-vent length (SVL), body condition, and reproductive investment in the South American common toad Rhinella arenarum, to determine whether urbanization is harmful or beneficial to this species. We sampled wetlands with different levels of urbanization in Río Cuarto city, Córdoba, Argentina. We recorded males with lower SVL in medium urbanized wetlands and those with the highest SVL in both low and high urbanization categories, similar to what was found for body conditions with males with low body conditions inhabiting wetlands with a medium degree of urbanization. In females, lower SVL was recorded in medium urbanization and highest SVL in high and low urbanization. It is observed that females recorded in highly urbanized wetlands have a very low body condition. The reproductive investment parameters were not significantly different, but we observed an association between a greater number of eggs and clutch size with wetlands of low urbanization. These results show a variability of responses of R. arenarum to urbanization, which could be due to phenotypic plasticity in its life history parameters, allowing it to inhabit urban areas. Continuous monitoring of the species in these wetlands is needed to determine if these biological responses are temporary or persistent.

Powered flight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures. Many basic aspects of feather functionality are unknown, which hampers our understanding of wing function in birds. This study measured the dimensions of primary and secondary flight feathers of 19 species of parrots. The maximum force the feathers could withstand from below was also measured to mimic the pressures experienced during a downstroke. The analysis tested whether: (1) feather dimensions differed along the wing and among secondary and primary remiges; (2) the force that feathers could withstand varied among the remiges; and (3) there would be isometric relationships with body mass for feather characteristics. The results show that body mass significantly affected vane width, rachis thickness, maximum force, and ultimate bending moment, but the relationship for feather length only approached significance. Many of the proximal secondary feathers showed significantly lower values relative to the first primary, whereas for distal primaries the values were greater. There were isometric relationships for force measurements of primary and secondary feathers with body mass, but there was positive allometry for feather lengths and vane widths. The forces feathers can withstand vary along the wing may be a proxy for the aerodynamic properties of the feathers in situ. Broader taxonomic studies that explore these topics are required for other species representing a range of different orders. A better understanding of the functionality of feathers will improve our understanding of how avian flight works particularly considering the variety in flight style and wing shape in birds.

Many prey species rely on publicly available personal and social information regarding local predation threats to assess risks and make context-appropriate behavioral decisions. However, in sexually dimorphic species, males and females are expected to differ in the perceived costs and/or benefits associated with predator avoidance decisions. Recent studies suggest that male Trinidadian guppies (Poecilia reticulata) show reduced or absent responses to acute personal information cues, placing them at greater risk of predation relative to females. Our goal here was to test the hypothesis that adult (reproductively active) male guppies rely on social information to limit potential costs associated with their lack of response to risky personal cues. Adult male guppies were exposed to personal chemosensory cues (either conspecific alarm cues (AC), a novel odor, or a water control) in the presence of a shoal of three females inside a holding container that allowed the transmission of visual but not chemical cues. At the same time, we exposed females to either risk from AC or no risk, resulting in the display of a range of female behavior, from calm to alarmed, available as social information for males. Alarmed females caused male fright activity to increase and male interest in females to decrease, regardless of the personal cue treatment. These results indicate that male guppies rely more on female information regarding predation risk than their own personal information, probably to balance trade-offs between reproduction and predator avoidance.

Animals constantly need to evaluate available external and internal information to make appropriate decisions. Identifying, assessing, and acting on relevant cues in contexts such as mate choice, intra-sexual competition, and parental care is particularly important for optimizing individual reproductive success. Several factors can influence decision-making, such as external environmental cues and the animal's own internal state, yet, we have limited knowledge on how animals integrate available information. Here, we used an entire island population (57 males, 53 females, and 1,109 tadpoles) of the neotropical brilliant-thighed poison frog Allobates femoralis to investigate how 2 factors (olfactory cues and personality traits) influence the ability of males to find and use new resources for tadpole deposition. We experimentally manipulated the location of tadpole deposition sites and their associated olfactory cues, and repeatedly measured exploration and boldness in adult males. We further reconstructed tadpole deposition choices via inferred parent-offspring relationships of adult frogs and tadpoles deposited in our experimental pools using molecular parentage analysis. We found that the discovery and use of new rearing sites were heavily influenced by olfactory cues; however, we did not find an effect of the measured behavioral traits on resource discovery and use. We conclude that in highly dynamic environments such as tropical rainforests, reliable external cues likely take priority over personality traits, helping individuals to discover and make use of reproductive resources.