摘要: The parent-offspring conflict in avian species encompasses resource allocation and a balance necessary for survival for both parties. Parental investment is modulated according to various factors, among which begging is important. Endogenous hormones, particularly corticosterone (CORT), play a role in modulating begging behavior. However, most studies on hormonal regulation of begging behavior induced elevated hormone levels in the offspring through feeding or injections, thus, limiting our knowledge of the evolution of the parent-offspring conflict under natural conditions. In this study, we aimed to identify the key signals that parents respond to during interactions with their nestlings in the wild, considering factors such as endogenous hormone CORT, nestling age, and brood size, which may affect nestling begging behavior. Begging performance was evaluated by measuring the begging frequency and score of the red-whiskered bulbul (Pycnonotus jocosus), along with assessing CORT levels in feathers. CORT levels were significantly correlated with both the begging frequency and score of nestlings, while variables such as body mass and tarsus length did not influence parental feeding frequency. Additionally, factors such as the number of nestlings (brood size), age, and begging frequency were predictors of parental feeding frequency. Our findings indicate that begging frequency, nestling age, and brood size are signals that help navigate the intricacies of the parent-offspring conflict and that parents may rely on these key signals from the range of begging cues exhibited by nestlings to adjust their feeding strategies.

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摘要: Rising global temperatures have a wide range of effects at organismal, population, and ecosystem levels. Increased winter temperatures are expected to alter the energetics of species that are dormant during this time. Hatchling painted turtles (Chrysemys picta) spend their first similar to 8 months in shallow nests on land, where they putatively rely on residual yolk reserves to fuel energetic demands during this period of inactivity before they emerge in the spring. We performed a laboratory experiment to characterize changes in residual yolk quantity in hatchling C. picta and experimentally tested the effect of temperature on residual yolk, hatchling size, and survival over the winter brumation period. We manipulated winter nest temperature by simulating two natural thermal regimes (low vs high treatments) and one regime that approximates warmer temperatures expected by 2100 (future treatment). Because high temperature increases metabolism, we predicted that the future temperature treatment would decrease the amount of residual yolk remaining by the end of winter and reduce hatchling mass and survival. Residual yolk over winter did not differ from that before winter, and the temperature had no effect on the quantity of residual yolk or hatchling survival by the following spring. However, hatchlings that experienced future temperatures lost more mass over winter than those from the other treatments. These results correspond with previous work indicating that residual yolk does not fuel the energetic needs of hatchlings during winter. The effect of future warming temperatures on body mass may have negative consequences during energetically demanding activities during spring emergence and dispersal.

摘要: Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness, especially in ectotherms, which rely heavily on environmental temperatures for thermoregulation. Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change. The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats. We evaluated the effects of geographical gradients (i.e. elevation and latitude) and local environmental temperatures on thermal requirements (i.e. preferred body temperature, active body temperature in the field, and critical thermal limits) of Sceloporus species using published and field-collected data and performing phylogenetic comparative analyses. To contrast macro- and micro-evolutional patterns, we also performed intra-specific analyses when sufficient reports existed for a species. We found that preferred body temperature increased with elevation, whereas body temperature in the field decreased with elevation and increased with local environmental temperatures. Critical thermal limits were not related to the geographic gradient or environmental temperatures. The apparent lack of relation of thermal requirements to geographic gradient may increase vulnerability to extinction due to climate change. However, local and temporal variations in thermal landscape determine thermoregulation opportunities and may not be well represented by geographic gradient and mean environmental temperatures. Results showed that Sceloporus lizards are excellent thermoregulators, have wide thermal tolerance ranges, and the preferred temperature was labile. Our results suggest that Sceloporus lizards can adjust to different thermal landscapes, highlighting opportunities for continuous survival in changing thermal environments.

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摘要: Male frogs emit stereotypical advertisement calls to attract mates and deter conspecific rivals. The evolution of these calls is thought to be linked to anatomical constraints and the acoustic characteristics of their surroundings. The acoustic adaptation hypothesis (AAH) posits that species evolve calls that maximize propagation distance and reduce signal degradation in the environment where they are emitted. We applied phylogenetic comparative analyses to study the association of body size, vegetation density, type of aquatic ecosystem, and calling site on the evolution of acoustic traits in Cophomantini, a large radiation of Neotropical treefrogs (Hylidae). We obtained and analyzed body size, acoustic, and habitat data from a total of 112 species (58% of Cophomantini), using the most inclusive available phylogeny. We found a significant negative correlation between peak frequency, body size, and calling site, but contrary to the predictions of the AAH, we did not find support for associations among call traits and environmental characteristics. Although spectral allometry is explained by an anatomical constraint, it could also be maintained by female choice. We recommend that future studies strive to incorporate factors such as female mate preferences, eavesdropping by predators or parasites, and genetic drift.

摘要: Plague, a lethal zoonotic disease, primarily circulates within rodent populations and their fleas. In Iran, the widely distributed jird, Meriones persicus, serves as the principal reservoir for plague, with a belief in the existence of five out of its six recognized subspecies within the country. However, these subspecies are classified into four mitochondrial cytochrome b sub-lineages (IA, IB, IIA, IIB). This discrepancy, combined with the presence of an unnamed sub-lineage in central Iran awaiting taxonomic clarification, has left intraspecific taxonomy unsettled and obscured the true alignment between mtDNA sub-lineages and nominal subspecies. In this study, we investigated the intraspecific variation in the cytb gene across populations sampled throughout Iran, focusing on underexplored regions between the Zagros and Alborz Mountains and central Iran. While our genetic data generally support reported subspecies validity in Iran, we raise questions about M. p. baptistae, emphasizing the need for further data from its type territory in Pakistan. Two main lineages of M. persicus (I and II) exhibit geographical isolation, with limited overlap in the central Zagros Mts., where three subspecies (M. p. ambrosius, M. p. rossicus, and M. p. persicus) coexist. Superimposing infected rodents' geographic coordinates onto updated sub-lineages' distribution revealed a potential association between sub-lineage IA (M. p. rossicus) and all enzootic plague cases from 1946 to 2023. M. persicus rossicus extends into the Caucasus (where plague infections are common), Eastern Turkey, and Iraq. Consequently, interpreting this finding in the context of plague surveillance in Iran and neighboring areas requires caution.

摘要: Ticks can transmit many pathogens, including arboviruses, to their vertebrate hosts. Arboviruses must overcome or evade defense mechanisms during their passage from the tick gut to the hemolymph, salivary glands, and the feeding site in the host skin. This review summarizes current knowledge of defense mechanisms in specific tick tissues and at the feeding site in the host skin. We discuss the possible roles of these defense mechanisms in viral infection and transmission. The responses of tick salivary proteins to arbovirus infection are also discussed. This review provides information that may help accelerate research on virus-tick interactions. We summarize the recent progress in understanding defense mechanisms in specific tissues or sites that are encountered by arboviruses and discuss their possible roles in virus infection or transmission. image