摘要: The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis, Pilleri & Gihr, 1972; YFP) is an exclusively freshwater cetacean species inhabiting the Yangtze River and its connecting large lakes. As the primary line of defense in maintaining physiological equilibrium, the epidermis of the porpoise is expected to have undergone structural adaptations due to the shift from the marine to the freshwater environment. This study compared the microstructural and ultrastructural features of the epidermis of YFP and its marine counterpart, the East Asian finless porpoise (Neophocaena asiaeorientalis sunameri, Pilleri & Gihr, 1975; EAFP). Microscopic structural observations and statistical analyses of the epidermal thickness demonstrated no significant differences in the cell structure or distribution between the two porpoise species. However, the epidermis of the YFP contained more abundant stratum basale cells. The outermost lipid stratum corneum exhibited a thinner cell layer with wider neutral lipid droplets to resist the passive entry of water molecules in the hypotonic environment. In contrast, for the EAFP, a more uniformly arranged stratum basale in the epidermis led to denser keratin fibers and robust desmosomes within each epidermal layer at the ultrastructural level. This tight arrangement of cells can reduce transepidermal water loss (TEWL) in an environment with higher osmotic pressure. In conclusion, the 2 finless porpoise species appear to employ different epidermal mechanisms to adapt to their distinct osmotic environments. The YFP appears to possess a lipid waterproofing epidermal structure, while the EAFP possesses a thick and compact water-retaining epidermal structure to cope with potential water loss.

摘要: Locomotion is thermally sensitive in ectotherms and therefore it is typically expressed differently among thermally heterogenous environments. Locomotion is a complex function, and whereas physiological and behavioral traits that influence locomotor performance may respond to thermal variation throughout life, other contributing traits, like body shape, may have more restricted responses. How morphology affects locomotor performance under variable temperature conditions is unknown. Here, we investigated 3 genetically distinct strains of zebrafish, Danio rerio (AB, WIK, and Tu) with a shared multi-generational history at 28 degrees C. After rearing fish at 28 degrees C, we measured prolonged swimming speed (Ucrit) at each of 6 temperatures (between 16 degrees C and 34 degrees C). Speed was strongly positively correlated among temperatures, resulting in most among individual variation being temperature-independent (i.e., fish were relatively fast or slow across all temperatures). However, we also detected significant variation along 2 axes reflecting temperature-dependent variation. Although strains differed in mean swimming performance, within strain (among-individual) patterns of speed variation were markedly consistent. Body shape and size explained significant variation among individuals in both temperature-independent and temperature-dependent axes of swimming speed variation. Notably, morphological traits that were most strongly associated with temperature-independent performance variation (i.e., faster-slower) differed from those associated with temperature-dependent (i.e., hotter-colder) variation. Further, there were significant differences among strains in both the direction and strength of association for specific morphological traits. Our results suggest that thermally heterogenous environments could have complex effects on the evolution of traits that contribute to whole organism performance traits.

摘要: Infant-care behavior, a range of caring behaviors by parental or alloparental individuals towards infants unable to live independently, plays a significant role in the survival of infants and the continuation of the species in non-human primates. During a behavioral ecological study of Taihangshan macaques, we observed 2 cases of infant adoptions by unrelated adult females. In case 1, a multiparous female adopted a lost infant from a neighboring group, with the infant being snatched back by her biological mother 35 days after the adoption. This is the first report of cross-group adoption in Macaca. In case 2, a nulliparous adult female, who had been once adopted by her elder sister, adopted an orphan from her group for 36 days. We describe the details of adoptions in Taihangshan macaques and explore possible reasons for adoptions to contribute to understanding the evolution of infant-care behavior and altruistic behavior of adoption in primates.

摘要: Insects are suitable model organisms for functional morphology research, especially in the context of exaptation, when the same morphological trait represents an advantage in disparate niches. Phylogenetically distant groups of pygmy grasshoppers (Orthoptera: Tetrigidae) have various pronotal projections defining their general appearance and body shape. However, body shape has never been related to niche occupation in these insects, thus the aim of this study is to investigate the relationship between pronotum shape and macrohabitat adaptation in Scelimeninae, a group of Asian and Papuan tetrigids encompassing amphibious and corticolous (bark-dwelling) representatives. With the use of geometric morphometrics and phylogenetic comparative methods, two morphological and functional groups were distinguished, with the body shape exhibiting a significant phylogenetic signal. The first group consists of elongated amphibious taxa (Scelimenini tribe) with highly uniform pronotum morphology, likely due to a strong selection for streamlined body shape. Stouter corticolous taxa (Discotettigini tribe) exhibit more conspicuous body shape variability, possibly increasing camouflage efficiency in tree bark habitats. Ecological divergence associated with macrohabitat adaptation may thus have been the primary driver of speciation in this insect group, but the evolutionary constraints leading to this divergence are still to be identified.

摘要: Functional constraints between different types of antipredator behavior should be common, especially if they are on the opposite sides of the behavioral spectrum such as flight and post-capture immobility. We examined a potential compromise between post-capture immobility displays and sprint speed in dice snakes (Natrix tessellata), using a field-based approach. We sampled snakes (N = 238) from two populations: from a dense island population free of mammal predators, and from a less dense mainland population, preyed upon by both bird and mammal predators. We explored the effects of sexual maturity, temperature, body size, presence of palpable food in the gut, and injuries on the occurrence and duration of post-capture immobility as well as sprint speed. Our results confirm the existence of functional constraints between locomotor performance and post-capture immobility in dice snakes. Faster dice snakes start escaping promptly after release, while slower individuals utilize more passive antipredator behaviors such as death feigning. Local adaptations seem to have great influence on behavioral compromise, since the mammal-free island population exhibited a higher incidence of post-capture immobility and a significantly lower sprint speed, compared to the less dense mainland population. Additionally, immature individuals tended to avoid death feigning and their post-capture immobility lasted shorter compared to adult individuals. It remains to be seen how individuals adjust their behavior to accomodate locomotor constraints, and in which specific phases of the predator-prey interaction these adjustments occur.

摘要: The diversity of rodents in Asian deserts is high. Nevertheless, little is known about their use of daily torpor and hibernation, which are employed by many small mammals worldwide for energy and water conservation to permit survival under adverse environmental conditions. We quantified for the first time, using temperature transponders and data loggers, long-term torpor expression and patterns in sympatric desert hamsters Phodopus roborovskii, striped hamsters Cricetulus barabensis and 3-toed jerboas Dipus sagitta under controlled conditions. Animals were live-trapped in Inner Mongolia in August and held in captivity under short photoperiods and low ambient temperatures (T(a)s) for about 6 months. Both hamster species (similar to half of individuals) expressed spontaneous (food available) daily torpor. Daily torpor in desert hamsters was less frequent and shallower than that in striped hamsters, which also had longer torpor bouts during torpor at T-a 15.8 +/- 0.4 degrees C. Only one individual jerboa entered hibernation spontaneously at T-a 6.2 +/- 0.5 degrees C, but all hibernated after food deprivation. The 2 hamster species only slightly changed their body mass during the acclimation, whereas jerboas greatly increased their body mass by 27.9% during the first 2 months of acclimation probably as a preparation for the hibernating season. Our data show that short photoperiod and moderately low T-a induces spontaneous daily torpor in the 2 hamster species, suggesting that it is used regularly in the wild. Hibernation in Jerboas occurred at T-a 6.2 +/- 0.5 degrees C especially when food was withheld suggesting limited food availability is the proximate trigger of their hibernation.

摘要: Animals can differ in their individual movement behaviors during their daily displacements. Studies of animal movement patterns often disregard the need to understand individual variation in these patterns and the role of this variation in shaping population distributions of movements. To assess the link between individual movements and population distributions, we radio-tracked 13 Fowler's Toads (Anaxyrus fowleri) in Long Point, Ontario, Canada, after their breeding season. We recorded individual coordinates every 30 min, from the moment they emerged from their burrows around dusk until they burrowed in the morning, and obtained a total of 157 movements. We used the resulting series of step lengths and turning angles in a Hidden Markov Model to estimate movement type as directed or non-directed. We also assigned to each encounter one of 3 space-dependent movement states: foraging, in transit, or searching, and found that movement type and state switched within individuals irrespective of time during a single night. We find that switching between movement types varied throughout the night, leading to stochastic within-individual variation in movements, and the distribution of movement distances differed significantly among individuals. Movement states, however, were time-dependent, suggesting displacement routines were similar across individuals. Variation in movement behavior within individuals scales up to result in variation among individuals which, in turn, was found to shape the distribution of the sampled population. Our findings therefore underline the importance of a multi-scale approach in the study of movement.

摘要: Migratory connectivity describes the linkage between breeding and nonbreeding sites, having major ecological implications in birds: 1 season influence the success of an individual or a population in the following season. Most studies on migratory connectivity have used large-scale approaches, often considering regional populations, but fine-scale studies are also necessary to understand colony connectivity. The lesser kestrel Falco naumanni, an insectivorous migratory raptor which form colonies during the breeding period, was considered to have strong connectivity based on regional populations. However, no small-scale studies on migratory connectivity have been conducted. Therefore, we GPS (Global Positioning System)-tracked 40 adult lesser kestrels from 15 different Spanish breeding colonies, estimating the overlap index between home ranges and the distance between their centroids. It was found that lesser kestrels from the same breeding colony placed their nonbreeding areas at 347 +/- 281 km (mean +/- standard deviation) away from each other (range = 23-990), and their home ranges overlapped by 38.4 +/- 23.6%. No differences between intra-colony and inter-colony metrics were found, which suggests that lesser kestrels from the same breeding cluster do not overwinter together, but they spread out and mixed independently of the colony belonging throughout the nonbreeding range of the species. Ultimately, this study highlights the importance of performing connectivity studies using fine-scale approaches.

摘要: Spiders frequently suffer abnormal molting and subsequent death when sustained on a monotypic diet of fruit flies Drosophila melanogaster. The fruit flies lack arachidonic acid (AA), a nutrient that may be critical for successful molting of spiders. To test this hypothesis, we compared the survival rates of juvenile wolf spiders, Pardosa pseudoannulata, fed on three kinds of diets, midges (Tendipes sp.), fruit flies enriched in AA and fruit flies lacking in AA. In addition, we analyzed the fatty acid composition of spiders feeding on midges and fruit flies enriched in AA and their prey. Juvenile spiders fed on midges and AA-enriched fruit flies reached full maturity without molting issues, whereas nearly all spiders fed the flies lacking in AA did not survive. Among the 35 different fatty acids, only the AA levels in both prey and spiders correlated positively with spider survival. Our findings provide compelling evidence that AA is crucial for the survival and molting of P. pseudoannulata.

摘要: Bite force is an important performance indicator of individual fitness that is closely related to food acquisition, male competition, and mating selection. It is also affected by a variety of factors and different mechanisms. Therefore, it is relatively difficult to understand the evolutionary driving forces of changes in bite force. In this study, the driving factors affecting the bite force of wild-derived red junglefowl (Gallus gallus jabouillei) were investigated from the aspects of morphological indicators and physiological characteristics. Results showed that the bite force of wild-derived red junglefowl was directly related to sex, showing obvious sexual differences. However, there was no correlation between the plasma testosterone level and bite force. The bite force of males was significantly greater than that of females, and the body index (i.e., PC1 of five body measures, namely body mass, body length, wing length, tail length, and tarsus length), the grasp index (i.e., tomial length x bill width) of males were significantly greater than those of females. Sexual selection may have played a key role in the evolution of bite force in the red junglefowl. Future studies should examine other key factors affecting changes in bite force to verify the correlation between secondary sexual characteristics and bite force in red junglefowls.