Journal of Zoology最新文献

Endemic rodents constitute 19% of Australian terrestrial mammal species and this proportion is higher in arid zones and the north. We report substantial genetic diversity and population structure in the common rock-rat Zyzomys argurus, a saxicoline murid whose range extends across northern Australia and into the continent's interior. Samples of 686 individuals from 68 locations, encompassing the western half of the species' range, provide one of the most geographically and numerically extensive genetic studies of an Australian rodent. The Great Sandy Desert, a prominent feature over the last 0.5 my bp acts as a significant barrier to gene flow. Continental islands, formed during the past 10 000 years following the end of the most recent Pleistocene glacial maximum, have populations with lower heterozygosity and marked differentiation from each other and the adjacent mainland. On the mainland, despite considerable differentiation between locations, there is only weak evidence for isolation by distance and where it occurs it is associated with drainage basins. In the Pilbara, analyses of genetic structure within localized sub-locations, just a few kilometres apart, indicate considerable variation between them (F_ST) and inbreeding within (F_IS). We interpret this in the context of cyclonic and other extreme rainfall events that occur episodically, leading to boom-bust population cycles. Populations decline into refugia of isolated rock patches during extended periods of poor resources with consequent low genetic diversity (H_e) and large differentiation from others. Populations that irrupt after major episodic rainfall increases resource states, have a more extensive distribution with greater heterozygosity because of gene flow between previously isolated refugia and less differentiation between the locations. These observations have conservation significance for threatened congeneric species and other Australian arid rodents by demonstrating, in this common exemplar, the reduced evolutionary potential imposed by both transient isolation due to climatic variation and longer term disruptions by geographic barriers.

Investigations on resource use by predators are important for understanding the mechanisms of biological coexistence. Although time, habitat, and diet are considered the three major dimensions for niche partitioning, studies that comprehensively investigate these dimensions in predator guilds are limited. Snakes are one of the predators whose populations have been reported to be declining worldwide. While diet has been considered as a fundamental variable that allows snakes to coexist, the importance of spatiotemporal resources has also been noted especially in temperate regions. To clarify the coexistence mechanisms of terrestrial snakes, we assessed the niche partitioning patterns of snakes on Sado Island, a Japanese island rich in snake species, from the perspectives of spatiotemporal and dietary resources. Specifically, we investigated the daily and seasonal occurrences as temporal niches, landscape-level distribution as a spatial niche, and stomach content as a dietary niche. We found that niche partitioning in all three major resources occurred among snake species on the island. Daily occurrence was partitioned into three groups: completely diurnal, nocturnal, and active during both periods. Seasonal occurrence was partitioned into three groups: widely active from spring to autumn, mainly active in summer, and mainly active in autumn. Distribution was partitioned into two groups: mainly distributed in lowlands and distributed even in mountainous areas. Food habits were partitioned into three groups: rodents, frogs, and earthworms as main prey, respectively. Our results provide empirical evidence that snakes can coexist through multidimensional niche partitioning, and that spatiotemporal resources are also an important force in terrestrial snake coexistence. Furthermore, we suggest that snakes on the island coexist through subtle differences along the three major niche axes, and that conservation of a variety of niches, rather than a single niche, will increase the species diversity of local snakes.

When hermit crabs recognize the risk of predation, they generally hide inside their shells or flee from the area, and little is known about their escape behaviors after being captured by a predator. We discovered that the hermit crab Pagurus filholi abandons its shell and attempts to flee when captured by the predatory crab Charybdis japonica, and we examined the effectiveness of this behavior in laboratory experiments. We fed captive C. japonica with P. filholi occupying gastropod shells. When the C. japonica could not break the shell even a little, it gave up and the P. filholi neither abandoned its shell nor was eaten. However, when the predator succeeded in partially breaking the shell, the hermit crab often abandoned the shell, and when it did so, it often survived. Once the predator had completely broken the shell open (implying that the shell has been broken to the extent that it no longer has any structural integrity), all hermit crabs that remained back in the shell (22/22) were consumed, and those that abandoned the shell were also often consumed (3/5). Therefore, hermit crabs do not need to abandon their shells if a predator is unable to break the shell even slightly, but if a predator begins to break the shell, they have a better chance of survival if they abandon their shells at an early stage.

The aggregation of conspecifics in the invasive shrimp Palaemon macrodactylus could be driven by either patchy environmental conditions or conspecific attraction. This study aimed to determine whether the observed grouped distribution in natural conditions results from gregarious behavior and the type of cue used by shrimp to locate conspecifics. Four experiments were conducted during the non-reproductive season in which a focal shrimp was given the choice between a zone with cues of conspecifics or an empty zone. The cues permitted in each experiment encompassed visual and chemical cues, exclusively visual cues, exclusively chemical cues and a control devoid of any visual or chemical cues. The results indicated that focal shrimps exhibited a preference for conspecific zones when exposed to chemical cues alone or in combination with visual cues. However, visual cues alone were insufficient to induce grouping with their peers. The value of this trait is discussed along with other behavioral characteristics of the species as a possible explanation for its success as an invader.

Marine iguanas occasionally face severe food shortages because of algal dieback during El Niño events. Research on their adaptations to these periods has highlighted their unique ability to shrink in body length, which reduces their energetic needs. Additional mechanisms, like sustaining lower body temperatures and metabolic rates, could potentially also lower energy consumption, but have never been examined. We measured 665 iguanas over an 11-year period including three El Niño events, and examined how heart rates (a proxy for metabolic rates) and body temperatures change with sea-surface temperature oscillations (Oceanic Niño Index, ONI). Heart rate (adjusting for body size, temperature, season, and study site) was negatively correlated with ONI and lower during El Niño, whereas the adjusted body temperature did not correlate with ONI or differ between El Niño and other periods. We therefore hypothesize that marine iguanas can depress their metabolic rates in response to the harsh conditions, an adaptation that is complementary to shrinking and may further enhance their survival through periods of limited food. Direct metabolic measurements are needed to test this hypothesis.

Barriers faced by underrepresented groups in academia have increasingly formed the basis of serious discussion, consideration, and policies, recently (in the UK) under the mantle of equality, diversity, and inclusivity (EDI). While such recognition has not solved the challenges encountered by, for instance, women and ethnic minorities, it has at least ensured that consideration of such issues is becoming a normal part of policy and practice. One underrepresented group in academia is low socioeconomic status (working class) backgrounds, a characteristic that intersects widely with other more commonly considered EDI groups. However, socioeconomic status is not a legally protected characteristic in the UK, which has resulted in it receiving less attention in terms of consideration of the barriers it imposes and possible mitigations needed. Moreover, unlike often more salient EDI characteristics such as gender and ethnicity, outward-facing cues of socioeconomic status are less visible at a glance, although they are often detectable in more subtle or indirect ways. Coupled with the attempts many working-class academics make to ‘mask’ cues of their background, this creates a situation whereby low socioeconomic status is a ‘hidden’ barrier that commonly remains unrecognised and unaddressed throughout much of academia. Here, we provide an overview of the challenges faced by working-class academic scientists based partly on the literature, which is currently limited, and partly from the experiences of our diverse working-class authorship team. In doing so, we hope to bring greater awareness of working-class backgrounds to the table in EDI discussions, and we provide suggestions for future research on and mitigation of the challenges faced by academic scientists from low socioeconomic status backgrounds.

The history of Homo sapiens is studded with many events promoting relationships with wild animals changing their evolutionary path or impacting their adaptation. Artificial selection is recognized as the product of planned actions aimed to annex useful species into the anthropic niche. However, the effect of humans on animal evolutionary trajectories is diversified and cannot be assigned to a single driver. We characterized the genomes of feral pigs managed by different traditional husbandry practices to infer about the combining effect of artificial and natural selection. Whole genome characterization showed a clear distinctiveness of Sardinian wild boars (Sus scrofa) from free-range pig and domestic pig (Sus domesticus) populations, while Eurasian wild boars and hybrids are closely related, also in agreement with allelic frequency. In the Southern Italy system, we found 7 SNPs putatively under selection, associated with genomic regions including genes mainly involved in body weight control and feeding behavior, muscle growth and development, and adipocyte proliferation. Considering Sardinian wild boar and free-range pigs, over 3000 SNPs were found putatively under selection, and the genomic regions in which these SNPs fall include genes linked mainly to litter size and number of teats. The screening of genomic variability was useful to characterize feral pigs and wild boars from Southern Italy and Sardinia and the relationships between them, highlighting the effect of a peculiar artificial selection that modulates its weightiness due to the concomitant natural selection. In particular, the traditional Sardinian pig husbandry seems to act pushing down gene flow towards wild boar while favoring adaptations to life in the wild, creating a unique genetic pattern in free-range pigs, different both from the domestic and the wild genetic makeup. Our contribution opens up a discussion on the current European policy for the management of free-range pigs, the effective conservation actions for diversity in Suidae forms and their consequent impacts on biodiversity.

Large carnivores such as leopards (Panthera pardus) experience continuing threats from habitat loss and fragmentation, depletion of prey populations, and retaliatory killing following conflicts with humans. We aimed to identify factors affecting leopard occupancy and temporal overlap between leopards and tigers (P. tigris), their major prey, and human activities in the Parsa-Koshi Complex (PKC), Nepal. We deployed 154 cameras for 21 days each along wildlife trails throughout PKC during December 2022–March 2023. We found low leopard occupancy (0.17 ± 0.04) in PKC, with greater occupancy rates within protected areas, particularly in Parsa National Park and its buffer zone. Human (63.10 ± 23) and livestock (36.46 ± 102) detections were higher across the PKC. Leopard occupancy was positively associated with the presence of tigers and prey. Temporal overlap was moderately high between leopards and tigers, as well as between leopards and their prey. Our research suggests that coexistence between leopards and tigers is likely largely facilitated by higher prey availability, which may reduce competition. Further, we demonstrate that maintaining forest cohesion can improve habitat for leopards. Intensifying use of agricultural areas could reduce forest fragmentation and increase leopard habitat overall, in turn reducing leopard depredation of livestock and improving leopard-human co-existence and conservation.

Nature-based tourism in protected areas can benefit millions of people, generating significant economic income. However, tourism can also have negative impacts on the environment and wildlife. The emergence of the COVID-19 pandemic led to the closure of cities and towns, bringing substantial disruption to various human activities and providing an opportunity to assess the impact of reduced tourism activity from the general level. In this study, we assessed the association between tourism and guanaco (Lama guanicoe) activity patterns in Ischigualasto Provincial Park across two contrasting periods: pre-pandemic and pandemic during the COVID-19 outbreak. The different roads in the area were used as a proxy of tourism activity, and comparisons of activity patterns of guanaco between the roads were made, taking into account both periods. Based on camera-trapping data, we analyzed the daily activity patterns of the species, as well as whether there was a change in activity toward night hours. We found that guanacos changed their activity patterns in response to human tourism activities and increased their nocturnal activity in places with high tourist activity in pre-pandemic periods; however, we found no such effects during the pandemic when tourist pressure was low. These results are vital for the area's management aimed at conserving the species since, currently, after the pandemic, tourism activities have been resumed, and the number of visitors to Ischigualasto Provincial Park has grown exponentially.

Scent marking at latrines is used by a variety of mammals for communicating an individual's reproductive status, social rank, or territory. Both brown hyenas (Parahyaena brunnea) and spotted hyenas (Crocuta crocuta) make use of latrines. Previous research showed that the presence of the more dominant spotted hyena negatively affects the presence of brown hyena. As both species rarely occur in the same area, little is known about the temporal patterns of using shared latrine sites. Central Tuli, Botswana, is home to one of the highest densities of both spotted and brown hyena in southern Africa. We conducted a camera trap study and monthly scat counts for monitoring the visitation and defecation rates of brown and spotted hyenas at shared latrines to examine the temporal patterns of latrine use. Our results showed seasonal differences in latrine use, with lower visitation and defecation rates for both species during the wet season. We found high temporal overlap in latrine use for the two species. However, the time interval between consecutive spotted – brown hyena visits was larger than for consecutive brown hyena–spotted hyena and consecutive conspecific visits during the dry season, suggesting that brown hyena seem to show fine-scale temporal avoidance of spotted hyenas at shared latrine sites. The presence of spotted hyenas, or other large carnivores, could possibly inhibit intraspecific communication for brown hyena at shared latrine sites.