摘要: Maternal egg-caring behavior can often be observed in oviparous scincid lizards. The expression of such behavior is predictably affected by the trade-off between its resultant costs and benefits for mothers and/or offspring, which has been investigated in only a few scincid species. Here, post-ovipositional Plestiodon chinensis females were treated to care for their egg clutches without interference, under simulated predation pressure, or to be care-deprived. Potential maternal costs and offspring benefits associated with egg-caring behavior were then evaluated by measuring changes in maternal body condition, egg mortality, and hatchling performance. Egg-caring behavior caused post-ovipositional females to participate less in outside-nest activity, eat less food, and show relatively poorer body conditions at egg hatching. By contrast, compared with care-deprived females, egg-caring females gained mass slightly faster, and achieved a similar body condition within a few months of hatching. Eggs that were cared for by their mothers were more likely to hatch and produced larger, faster-running and better-growing hatchlings with higher survival than uncared-for eggs. Simulated exposure to a potential predator had no distinct impact on maternal egg-caring behavior expression and offspring performance. These results indicated that marked benefits of offspring viability but minor maternal energy costs might play a decisive role in the occurrence of maternal egg-caring behavior in P. chinensis.

摘要: The basal ganglia have been implicated in auditory-dependent vocal learning and plasticity in human and songbirds, but the underlying neural phenotype remains to be clarified. Here, using confocal imaging and three-dimensional electron microscopy, we investigated striatal structural plasticity in response to hearing loss in Area X, the avian vocal basal ganglia, in adult male zebra finch (Taeniopygia guttata). We observed a rapid elongation of dendritic spines, by approximately 13%, by day 3 after deafening, and a considerable increase in spine synapse density, by approximately 61%, by day 14 after deafening, compared with the controls with an intact cochlea. These findings reveal structural sensitivity of Area X to auditory deprivation and suggest that this striatal plasticity might contribute to deafening-induced changes to learned vocal behavior.

摘要: Vertebrate embryos require access to water; however, many species nest in terrestrial habitats that vary considerably in moisture content. Oviparous, non-avian reptiles have served as models to understand how environmental factors, like moisture availability, influence development because eggs are often exposed to prevailing environments in the absence of parental care. Though much research demonstrates the importance of water absorption by eggs, many ecological factors that influence moisture availability in natural nests have received little attention. For example, the type of substrate in which nests are constructed is understudied. We experimentally incubated eggs of the brown anole lizard (Anolis sagrei) in 2 naturally occurring nest substrates that were treated with varying amounts of water to determine how natural substrates influence development at different moisture concentrations. One substrate consisted of sand and crushed seashells and the other was mostly organic material (i.e. decayed plant material). Both are common nesting substrates at our field site. When controlling for water uptake by eggs, we found that egg survival and hatchling phenotypes were similar between substrates; however, embryos developed more quickly in the sand/shell substrate than the organic substrate, indicating substrate-specific effects on embryo physiology. These results demonstrate that different natural substrates can result in similar developmental outcomes if the water available to eggs is comparable; however, some aspects of development, like developmental rate, are affected by the type of substrate, independent of water availability. Further study is required to determine how natural substrates influence embryo physiology independent of water content.

摘要: Recent research has challenged the idea that cervid antlers are such costly traits, supporting the assertion early-life antler investment is an honest signal of adult phenotypic quality. However, inferences were made based on antler measurements while growing (velvet) and thus, studies on fully-formed clean antlers are needed to avoid possible bias caused by the inter-individual variation in antler growth phenology. We studied a semi-captive population of European roe deer inhabiting a sub-Mediterranean area (Valsemana research station) and living under optimal conditions (ad libitum food supply and veterinary care). Based on repeated measurements taken from 146 individuals, we assessed whether allocation to secondary sexual traits during early life affected body mass or antler development during adulthood. Furthermore, we evaluated which body measurements better predicted future male quality. Additionally, using 488 individuals, we described age-class-specific variation in male body measurements and assessed the decline in antler size between adult and senescent stages (i.e. magnitude of senescence). Results agree with the assertion that there is no negative effect of a high investment in antler during early life on adult antler size or body mass, but we suggest the use of clean antlers as a more robust and reliable measure. The variables that better predicted body mass during adulthood were yearling body mass and body size at 6 months. Antler score between 10 and 18 months resulted in the best indicator of adult antler size. Finally, we support the idea that the magnitude of senescence in antler size is smaller in environments with higher resource availability during winter.

摘要: Members of the Torpedinidae (torpedoes) and Hypnidae (coffin ray) use electric organ discharges (EOD) to stun or kill their prey before consumption. We investigated whether EOD could also negatively affect the helminth larvae infecting these preys through a surrogate model: we applied electric discharges to individuals of blue whiting, Micromesistius poutassou, that harbored live larvae of Anisakis. Larval mortality throughout a 6-h period was significantly higher in the treatment group, suggesting that EODs could significantly hamper helminth recruitment. We then tested whether torpedinids and hypnids (strong-EOD families) harbored species-poor helminth (cestode) assemblages compared with weak-EOD Torpediniformes (Narcidae and Narkidae) and other Batoidea. Based on comparisons on estimated species diversity and mean species richness of tapeworms at host individual level we found that (i) Torpediniformes had the lowest tapeworm diversity of all Batoidea orders; (ii) Torpedo spp. consistently had the lowest mean cestode richness at host individual level, and this could not be related to other host factors influencing cestode diversity in chondrichthyans, that is body size, trophic level or dietary breath. However, a preliminary comparison between strong-EOD and weak-EOD Torpediniformes did not detect clear differences of cestode richness. Thus, evidence supporting an unambiguous contribution of EODs to depauperate cestode assemblages requires further research.