摘要: In the current research, we investigated the impact of gradually increasing inbreeding on the life span and reproductive rate of yellow steppe lemmings, Eolagurus luteus, that reproduced in the Moscow Zoo. The focal captive colony existed from 2017 to 2021. The studied animals belonged to the second to tenth generations. The founders of the colony were 5 females and 5 males originating from 3 females and 4 males livetrapped in the Zaisan basin (Kazakhstan). The degree of their descendant relatedness progressively increased. The animals intended to be used for reproduction were distributed to pairs with unfamiliar partners. We constructed the pedigree of 177 individuals and calculated their inbreeding coefficients. This parameter varied from 0 to 0.29, and the maximum values were registered in the lemmings of the seventh to tenth generations. We measured the life span of 61 individuals and used information about the reproduction or its absence in 45 pairs. A substantial decline in individual life span and reproductive parameters in the breeding pairs, along with a progressive increase in the inbreeding coefficients, was registered. The number of delivered litters, born pups, and young lived up to the age of puberty significantly depended on the level of mother inbreeding. The noticeable traits of inbreeding depression in the colony appeared in 2019-2020 when the offspring inbreeding coefficients reached approximately 0.2. Therefore, we assume that if the E. luteus population originates from a relatively small number of noninbred and unfamiliar individuals, then successful reproduction without significant inbreeding depression will continue for several generations of offspring.

摘要: Biological invasions are a major driver of global biodiversity loss, impacting endemic species, ecosystems, and economies. Although the influence of life history traits on invasive success is well-established, the role of behavior in the invasive potential of animals is less studied. The common coqu & iacute; frog, Eleutherodactylus coqui, is a highly successful invader in Hawai'i. We build on previous research characterizing changes in physiology and morphology to explore behavioral variation across the invasive range of coqu & iacute; in Hawai'i. Coqu & iacute; have expanded both outward and upward from their initial introduction site, and-by comparing frogs from different densities and elevations-we specifically asked how the physiological challenges of high-elevation living interact with the competitive challenge of high-densities at population centers. To investigate whether differences in the field represent local adaptation or behavioral plasticity, we additionally evaluated behavior following acclimation to a shared laboratory environment. Although we identified only subtle behavioral variation among populations in the field, we found that individuals from all populations became less bold, active, and exploratory in the laboratory, converging on a similar behavioral phenotype. Alongside previous work, our results suggest that coqu & iacute; adjust their behavior to local environmental conditions across their invasive range and that behavioral flexibility may contribute to invasive success.

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: 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: 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: Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings, resulting in the decline of female reproductive output in insect species. It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males, such as mating multiply with different males and/or discriminating against previously mated males (MMs). Similarly, males may exhibit adaptive behaviors toward females varying in mating status. However, in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm, there are few studies on male mating potential and previous mating experience on their subsequent mate choice. In this study, we used a polyandrous crab spider, Ebrechtella tricuspidata, a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1) male mating experiences influence female reproductive fitness; 2) females respond differently to males varying in mating status; and 3) males respond differently to females varying in mating status. Our results showed that female fecundity was independent of male mating experiences, but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac. Counter to our predictions, females preferred to choose and mate with the larger males, regardless of their mating status. In contrast, male mating status influenced their mating preference toward females. Virgin males did not show any preference between virgin and mated females; however, MMs were more likely to prefer the virgin females over the mated ones. Overall, our results indicated that female choice depended primarily on male relative size rather than male mating status, whereas male choice depended on female mating status. Depending on the investigation of reproductive dynamics and mate choice in E. tricuspidata, the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying in mating status.

摘要: Shrimps of the genus Synalpheus (Caridea) are commonly found in subtropical and tropical marine habitats around the world. The present work aims to provide the first description of the reproductive system of this genus using histological, histochemical, and morphological perspectives to elucidate the gonochoric or hermaphrodite sexual system in this genus. Males have a slender and very translucent reproductive system that is challenging to observe. The entire cephalothorax was histologically sectioned to ensure that all regions of the reproductive system could be identified. This non-gambarelloides group shows a gonochoric condition. The caridean pattern of the reproductive system was observed where the male has a pair of testes and a pair of very thin vasa deferentia, ending at the opening of the gonopore. Spermatophore structure is absent, without any layers surrounding the spermatozoa that are aggregated in a sperm mass. In females, the reproductive system consists of a pair of ovaries that extend to the end of the pleon. The extension of the ovary has a particular pattern compared to other caridean shrimps. Here, we hypothesize that males invest energy on somatic morphological structures to protect the host and female, using the larger pistol-like cheliped, while females invest energy in reproduction since all the members of this group are typical pair-bond examples. The observed pattern of the reproductive male morphology could also be evidence of a possible synapomorphy for this genus within the infraorder.

摘要: Understanding the molecular relevance of metabolic rate (MR) is crucial for unveiling the mechanisms driving the evolution of animals. In this study, we investigated the association between mitochondrial DNA characteristics and both resting and maximal MRs in conjunction with life-history traits among 139 species of teleost fish. We gathered fish MR data from various sources and procured sequences of 13 mitochondrial protein-encoding genes. We calculated the absolute substitution rate for entire nucleotide sequences and 4-fold degenerate sites of each gene, along with encoding amino acid sequences. Using the phylogenetic comparative method, we then explored the associations between MR and mitochondrial DNA absolute substitution rate. Additionally, we screened MR-associated single nucleotide variants in mitochondrial DNA. The findings indicate no positive correlation between MRs and any substitution rate values of both combined sequences and individual mitochondrial protein-coding genes, refuting the MR hypothesis. Instead, both maximum body size and longevity correlated negatively with molecular substitution rates, suggesting their influences on both mutation and fixation within mitochondrial genes in fish. Results also revealed significant correlations between base variation at ATP6_169 and both resting MR and maximum MR, identifying the unique ATP6_169G in Scombridae fish, which results in an extremely low isoelectric point (pI) value of the ATP6 protein. Considering its functional significance, the ATP6_169G in Scombridae fish might link to their lifestyle characterized by fast locomotion and high metabolic demands alongside a slower molecular evolutionary rate.