Journal of Zoology最新文献

The freshwater snail Latia neritoides occurs in certain streams and lakes of New Zealand's North Island. It defends itself against predators with a unique mechanism – the release of sticky, glowing mucus. Two possible origins of this defence mucus had earlier been suggested: the foot and the pneumostome area. After examining the glandular system of the foot in a previous study, in the present study we examined the general morphology of L. neritoides, focusing on the mantle cavity. With the first complete 3D model of L. neritoides now available, it is possible to evaluate previous morphological studies and to give non-specialists a better understanding of the soft part anatomy of this fascinating gastropod. As a by-product of this, we also compared the capabilities of μ-CT and HREM on a methodological level. We characterized the two most common gland types in the mantel cavity (Lmcg1/Lmcg2) on the basis of their ultrastructure. They are present in large numbers and, therefore, regarded as likely candidates for being the producers of one or more components of the defence mucus. This notion was confirmed by histochemical analyses of Lmcg1 and Lmcg2 and other gland types in L. neritoides.

Juvenile situational experiences that animals are exposed to different environmental conditions have the potential to shape the developmental trajectory of individuals, influencing their personality traits, anxiety level, cognition, and memory. However, empirical evidence regarding these effects remains limited. In this study on male Brandt's voles (Lasiopodomys brandtii) undergoing weaning process, we examined the consequences of juvenile situational experiences on their behavioral development, involving daily exploration of newly introduced objects with a diverse array of materials, shapes, sizes, and colors. The results showed that (1) the situational experience improved spatial cognition and memory, as evidenced by significantly higher scores in both the recognition index during test period (RIB) and the discrimination index during test period (DI) compared to the control group; (2) no significant differences were observed in autonomic activity between the two groups, including total distance traveled, resting time, mean speed, maximum speed, and duration of slow and fast movements across the entire arena; (3) situational experience reduced anxiety levels, indicated by increased exploration of the center area, more transitions between zones, shorter latency to enter the center zone, prolonged resting time in the center area, and greater total time spent and distance moved in the center area; and (4) the situational experience group exhibited significantly higher individual personality scores compared to the control group. In conclusion, our results imply that juvenile situational experience exerts significant positive effects on spatial cognition and memory, anxious behavior, and personality development in L. brandtii. These insights offer novel perspectives on the long-term impacts of juvenile situational experiences on adulthood, with potential applications in addressing mental health and behavioral anomalies. Additionally, our study provides practical implications for animal management and environmental enrichment strategies.

Subterranean rodents of the genus Ctenomys typically occupy fragmented habitats, many currently altered by anthropogenic development. These changes affect functional connectivity among individuals, reducing gene flow levels. This study assessed the functional connectivity of two sympatric species of subterranean rodents, Ctenomys australis and Ctenomys talarum, examining the impact of landscape changes on their population genetic structure at a fine spatial scale. We conducted a spatially continuous sampling over 12 km of coastline in Southeastern Buenos Aires Province, Argentina, genotyping 91 and 106 individuals of C. australis and C. talarum, respectively, using 10–12 microsatellite loci. We applied various spatial layers characterizing both species' habitats to evaluate the landscape configuration's effect on individual gene flow. We employed Bayesian genetic clustering methods to infer population structure levels. Ctenomys talarum showed greater structure than C. australis. NDVI temporal variation was the main factor influencing C. australis' genetic structure, whereas suitable habitat, linked to the current landscape configuration, was the most significant factor in shaping C. talarum's genetic structure. Differences in dispersal capacity and habitat specificity appear to have influenced the population genetic structures of these species. The results indicated varying sensitivities to landscape changes; temporal landscape variations primarily impacted C. australis' genetic connectivity, whereas for C. talarum, the current landscape configuration was more influential.

Otherwise, apparently cryptic mammals often have conspicuous patches of colour on distal regions of their body, possibly for signalling. To investigate ideas about communication within sociosexual contexts, we used a comparative dataset for 2726 terrestrial mammals to match the coloration and patterning of distal body areas (head, chest, rump and tail) to activity cycle, group size, sexual size dimorphism, mating system and congener overlap at both Class and Order levels. Using phylogenetic controls, we uncovered repeated associations between white colour patches and nocturnality, conspicuous rump patches and sexual selection and multicoloured, complex patterning on distal regions of the body being associated with small group size. Overall, however, we found rather few associations between conspicuous coloration and behavioural, social and morphological variables, suggesting that visual signalling is not a key driver of communication in mammals, perhaps because the majority are nocturnal and solitary, and rely on olfactory signalling.

There is a burgeoning interest in studying consistent individual differences in animal behaviour. Most studies consider mainly males, but sexes are subject to distinct selection pressures that may drive differences in life history and therefore lead to differences in a variety of behaviours. Here, we used Oophaga pumilio, a poison frog with sex differences in life-history strategies (e.g., sex bias in space use and parental care), to explore whether sexes differ or share personality characteristics like behavioural consistency and behavioural syndromes. Based on the natural history of this species, we predicted sex differences in behavioural consistency in exploration but not in boldness, and a correlation between these behavioural traits. We found no sex differences in behavioural consistency in boldness and exploration, although, we observed a tendency of higher consistency in males than females in boldness. When pooling all individuals, we found a higher consistency in boldness than exploration, suggesting the presence of a bold personality in general. We observed a positive between-individual correlation of boldness and exploration in both sexes indicating the presence of a behavioural syndrome. Our data suggest that selective mechanisms shaping individual behaviour act equally on both sexes in this poison frog.

People have unique sets of direct sensory interactions with wild species, which change through their days, weeks, seasons, and lifetimes. Despite having important influences on their health and well-being and their attitudes towards nature, these personalized ecologies remain surprisingly little studied and are poorly understood. However, much can be inferred about personalized ecologies by considering them from first principles (largely macroecological), alongside insights from research into the design and effectiveness of biodiversity monitoring programmes, knowledge of how animals respond to people, and studies of human biology and demography. Here I first review how three major sets of drivers, opportunity, capability and motivation, shape people's personalized ecologies. Second, I then explore the implications of these mechanisms for how more passively and more actively practical improvements can be made in people's personalized ecologies. Particularly in light of the declines in the richness of these ecologies that are being experienced in much of the world (the so-called ‘extinction of experience’), and the significant consequences, marked improvement in many people's interactions and experiences with nature may be key to the future of biodiversity.

Female sperm storage organs in arthropods are used as taxonomic characters since it is assumed that they do not change after maturation. However, in the Golden Silk spider, Trichonephila clavipes, the shape and sclerotization of the spermathecae change with a mating event. Moreover, mating in T. clavipes consists of several hundred copulations, but the male transfers all sperm during the first insertion of each pedipalp. Given this puzzling mating behaviour, we hypothesize that multiple copulations serve purposes other than sperm transfer and uptake, such as further altering the morphology of the storage site and/or transferring substances other than sperm. We compared virgin female T. clavipes with females after two copulations, one for each spermatheca, and after ad-libitum mating. Each treatment consisted of two sub-treatments in which the state of the sperm storage organs was inspected after a short (1–3 days) or a long (11 days) time interval after the female's final moult. The size of the spermathecae increased twofold in all mating treatments compared to virgin females. The thickness of the spermathecal wall increased significantly with time in all treatments similarly. The spermathecal epithelium, which releases secretion into the lumen of the spermathecae, seems most active in virgin females during the time when mating would normally occur and turns less active after mating and with age. The spermathecae contain secretion produced by the female before mating; and after mating, sperm and another secretion transferred by the male. The numerous sperm-less matings in the ad-libitum treatment resulted in male secretion in the copulatory ducts of the female genitalia, likely impeding sperm transfer by subsequent males. Out study shows that female genitalia can change considerably after having reached maturity and suggests that sperm-less matings evolved in the context of sperm competition.

The order Chiroptera includes 55 species in Nepal, which have been recorded within a wide range of elevation between 64 and 4154 m above sea level. Assessing the potential distribution ranges in present climatic scenarios and forecasting changes in distribution ranges in future climate have been adopted to predict likely adverse impacts on biodiversity and natural ecosystems. However, very few studies have assessed the impact of climate change on bats globally and locally. We assessed the current potential distribution ranges of six representative species of bats occurring in Nepal using species distribution models (SDMs) and predicted their responses in future climatic scenarios. The occurrences of the representative species of bats were projected with six to eight environmental variables under the different climatic scenarios; present, and socioeconomic pathways 4.5 and 8.5 for the years of 2050 and 2070 deploying maximum entropy modeling. We used Arc GIS 10.7.1 to calculate the distribution range, area, and elevation for the bat species. Among 18 uncorrelated bioclimatic variables eight variables significantly contributed to the SDMs. Among the six species, two showed a wider range of current distribution. Under the future climatic scenarios, distribution ranges and latitudinal and elevation shifting were found to be species specific. Future distribution ranges for two species are predicted to be constricted, but no significant changes are predicted for the others. Major parts of the current and future distribution ranges of the bat species lie outside the current protected areas of the country. Landscape level and species-specific conservation policies are necessary for bat conservation, and future surveys of bats should be targeted in western Nepal.

Recent advancements in stress physiology, driven by the relevance of the stress response in animal welfare and conservation, have focused on alternative techniques beyond blood sampling for measuring glucocorticoids (GC). While blood samples have been traditionally used, practical and ethical concerns have spurred exploration into minimally invasive media like saliva, feces, milk, hair, and feathers. This review addresses the dearth of research on reptile endocrinology, offering insights into measuring GC or their metabolites in reptiles through various biological tissues. It underscores the importance of considering temporal dynamics in stress response evaluation and advocates for further exploration of alternative tools to enhance our understanding of reptilian stress responses.

Age-related telomere length (TL) variation is relatively well-described for mammals, birds and other model organisms. Nevertheless, it remains largely unknown in ectotherms, especially turtles and tortoises, which are extremely long-lived species with slow or negligible senescence. In this study, we described TL dynamics in wild spur-thighed tortoises (Testudo graeca), one of the chelonian species with the lowest aging rates. By combining cross-sectional (single) and longitudinal (capture–recapture) samplings, we assessed the relationship between TL and individual characteristics (sex, age, individual growth rate, body condition index, presence of shell anomalies). We did not find any association between TL and sex, individual growth rate, or body condition. However, the relationship with age remains uncertain, likely due to the complex dynamics of TL over time. Interestingly, shorter telomeres correlated significantly with shell anomalies, which are usually assumed as a fitness proxy for reptiles. Overall, our results suggest TL as a potential indicator for ontogenetic studies on tortoises, while its utility as a marker of biological age appears limited.