摘要: 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 R & iacute;o Cuarto city, C & oacute;rdoba, 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.

摘要: Animal coloration has a wide range of biological functions and may be subject to different, sometimes conflicting, selective pressures. In crustaceans, the evolution of coloration is relatively unstudied, despite the broad range of colors and color patterns, which includes variability at multiple levels. Freshwater crayfish are known to show color variability within species and populations, as well as intra-individual variability, but the function, if any, of crayfish coloration is largely unknown. Here, I report on an experiment to understand patterns of color variability in the crayfish Faxonius virilis and show that variation is strongly correlated to ontogenetic changes from a summer non-reproductive form to a fall reproductive form. Crayfish showed comparatively little inter- and intra-individual color variation in their non-reproductive form, but substantial variation at both levels in the reproductive form. Transition to the reproductive form was associated with the development of greener or bluer coloration localized to the chelae on a subset of individuals, but these changes showed no clear correlation with sex or body size. Future investigations should focus on determining whether differences in color between individuals in the mating season are associated with any physiological or behavioral differences, or with differential susceptibility to predation.

摘要: The increasing interest in the study of spontaneous (SY) and contagious yawning (CY) was so far focused on several taxa, especially primates. Here, we focused on SY and CY in horses, a suitable species due to their complex social dynamics that has been largely overlooked in research on these phenomena. By analyzing videos of 48 horses on pasture, we identified 2 yawning morphologies: Covered (YCT) and Uncovered Teeth (YUCT). Using EquiFACS, we quantitatively demonstrated that YCT and YUCT differ in terms of muscle recruitment. Moreover, we provide the first evidence for the presence of CY by comparing 2 different conditions: chewing-yawn-chewing versus chewing-chewing-chewing. Supporting the Social Modulation hypothesis, in our mares, CY was more prominent among subjects sharing good relationships. Moreover, subjects responded more rapidly to kin compared with non-kin and kin frequently grooming each other responded even more rapidly to each other yawns. The high familiar yawn sensitivity can provide selective advantages increasing behavioral synchronization and group cohesion. Graphical Abstract

摘要: Developmental instability (DI) is a phenomenon whereby organisms are unable to buffer developmental disturbances, resulting in asymmetric variation of paired traits. Previous research has demonstrated a negative relationship between DI, measured as forearm asymmetry, and survival in the bat Carollia perspicillata. This study aims to test the hypothesis that individuals with higher DI exhibit a lower immune response. We measured a delayed-type hypersensitivity to the antigen phytohemagglutinin (PHA) on 74 males and 65 females of C. perspicillata before and after the breeding season (BS). Linear models were used to predict the immunological response based on body mass (BM), forearm asymmetry, sex, BS, and testicle length. The best-fitting model accounted for 29% of the variation in immune response and included asymmetry, BM, sex, and BS as predictors. The immune response was negatively associated with asymmetry and testicle length in males but positively related to asymmetry in females. Both sexes showed a reduced immune response in the late BS. Additionally, the association between immune response and BM changed direction seasonally, with heavier individuals showing weaker responses early in the BS and stronger responses later. Individual variation in male immunity was predicted by individual attributes, whereas variation in immune response in females was mostly seasonal. Our results support the link between DI, survival, and immune response in short-tailed bats, and suggest that the immunological component measured by the PHA response may be under finer selection in males due to its stronger correlation with individual traits.

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摘要: 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.

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