ABSTRACT Variability in a trait can increase species' ability to adapt to changing environmental conditions, which may reduce extinction risks under global environmental change. The African wild dog, Lycaon pictus , is an endangered species which exhibits geographical variation in coat colour, occupies a range of habitats, and also shows behavioural, demographic and phenological responses to weather conditions. We used a machine learning algorithm to estimate the relative proportions of black, tan, and white fur from 490 unique georeferenced photographs from across the species' current range. We found that wild dog coats had higher proportions of tan and white, and lower proportions of black, in hotter and drier areas. Wild dog coats also had higher proportions of white in wooded habitats, including mopane Colophospermum mopane woodland. We speculate that wild dogs' dappled coats provide camouflage in woodland, and that paler (tan or white) fur may provide a selective advantage in hotter and drier regions, through more efficient thermoregulation. Our findings indicate likely adaptive variation in a trait which could inform conservation decisions.
ABSTRACT Behavioural plasticity is considered highly relevant for biological invasions. As daily behavioural rhythmicity is plastic in response to environmental factors, we suggest that it may also be worth considering in the context of invasion success. We explored, under laboratory conditions, the potential role of plasticity in the recent invasion of the Atlantic blue crab ( Callinectes sapidus , Rathbun, 1896) in the Mediterranean Sea, by studying its behavioural rhythmicity in the presence of the native Mediterranean green crab ( Carcinus aestuarii, Nardo, 1847). Daily activity recordings under standardised photoperiod conditions (12‐h light:12‐h dark) revealed that both species exhibit daily behavioural rhythmicity with a nocturnal activity pattern. Notably, when in the presence of an individual from the other species, the Atlantic blue crab rapidly shifted to a pronounced diurnal activity pattern. The Mediterranean green crab's behavioural rhythm was also affected by the presence of the Atlantic blue crab, though to a much lesser extent. This suggests greater plasticity and contextual modulation in the daily behavioural rhythm of the Atlantic blue crab in response to the presence of other species, at least in the studied populations. Furthermore, across all conditions, the invasive species in our system was consistently more active than the native species. Plasticity in behavioural rhythms may differ between invasive and native species, and future studies should investigate whether and how these differences influence their interactions.
ABSTRACT Understanding how sociality shapes genetic structure remains largely unexplored across many social mole‐rat species. Some African mole‐rats are cooperative breeders with complex social systems, where dispersal costs and ecological constraints influence colony‐relatedness and population connectivity. We compared two semi‐arid dwelling subspecies of Hottentot mole‐rats ( Cryptomys hottentotus ), the highveld mole‐rat ( C. h. pretoriae ) and the Mahali mole‐rat ( C. h. mahali ), to uncover differences and similarities in their genetic and demographic patterns. Mahali mole‐rats have by far a greater distributional range occupying habitats with different levels of aridity and may occur in arid habitats. Conversely, highveld mole‐rats have a more restricted distribution and are often found in semi‐arid habitats. We combined microsatellite‐based genetic analyses with mark–recapture demographic monitoring to assess intra‐colony relatedness, inbreeding, dispersal distances and colony dynamics. Both subspecies exhibited high intra‐colony relatedness and limited gene flow across colonies, consistent with cooperative breeding theory. However, highveld mole‐rats showed significant isolation by distance (IBD), and higher colony attrition with increasing group size. In contrast, Mahali mole‐rats maintained more effective dispersal, and higher post‐dispersal reproductive success likely because of an increased population density. Notably, highveld mole‐rats dispersed longer distances, but these movements were largely ineffective likely due to a low population density that reinforced philopatry. Our findings reveal that differences pertaining to population ecology may shape genetic structure and social dynamics with little effects on the overall genetic structure.
Ecological niche and geographic range concepts are essentially interrelated with the latter being conditioned by species' fundamental ecological tolerances, their intrinsic ability to disperse across landscapes, and the various possible interactions between organisms. Despite local fluctuations in range margin areas, geographic ranges are expected to be relatively stable on a broad scale. Range expansion examples therefore provide good opportunities to understand the importance of dispersal in defining species distributions, and to determine whether fundamental niches are conserved or whether species undergo adaptive evolutionary changes during their expansion. In this study, we investigated the spreading tendencies of the specialist spider, Zodarion rubidum Simon, 1914, comparing different phenotypic traits between three localities from southern, central and northern Europe. We conducted four experiments using field-collected and laboratory-reared specimens. We focused on population-specific locomotory traits, temperature preference and inter-molt interval at two temperatures, and venom specificity to investigate the species' dispersal abilities and fundamental thermal and dietary niches. We found no indication of spatial sorting, i.e., no highly dispersive phenotypes in the northern population. Moreover, we found no clear indication of changes in the species thermal biology or in venom specificity over space. Specifically, Z. rubidum showed similar temperature preferences between localities, a slower development under warm temperatures in central and northern European populations (possibly reflecting an adaptive shift toward colder temperatures), and a consistent ability to paralyze phylogenetically distant ant species. Overall, we conclude that Z. rubidum spreading might have been human-mediated and that it does not show major changes in its fundamental niche across space. Les concepts de niche & eacute;cologique et d'aire de r & eacute;partition g & eacute;ographique sont par essence li & eacute;s, ce dernier & eacute;tant conditionn & eacute; par les tol & eacute;rances & eacute;cologiques fondamentales des esp & egrave;ces, leurs capacit & eacute;s intrins & egrave;ques & agrave; disperser & agrave; travers les paysages, et les diverses interactions possibles entre organismes. En d & eacute;pit de fluctuations locales dans les zones de limites d'aires de r & eacute;partition, les aires de r & eacute;partition g & eacute;ographiques sont suppos & eacute;es & ecirc;tre relativement stables & agrave; grande & eacute;chelle. Les exemples d'expansion d'aire de r & eacute;partition repr & eacute;sentent donc des opportunit & eacute;s int & eacute;ressantes pour comprendre l'importance de la dispersion dans la distribution des esp & egrave;ces, et pour d & eacute;terminer si les niches fondamentales sont conserv & eacute;es ou si les esp & egrave;ces connaissent des changements & eacute;volutifs adaptatifs durant leur expansion. Dans cette & eacute;tude, nous avons & eacute;tudi & eacute; les tendances d'expansion d'aire de r & eacute;partition d'une araign & eacute;e sp & eacute;cialiste, Zodarion rubidum Simon, 1914, en comparant diff & eacute;rents traits ph & eacute;notypiques entre trois localit & eacute;s du Sud, du Centre et du Nord de l'Europe. Nous avons conduit quatre exp & eacute;riences en utilisant des sp & eacute;cimens collect & eacute;s sur le terrain et d'autres & eacute;lev & eacute;s en laboratoire. & Agrave; une & eacute;chelle populationnelle, nous nous sommes concentr & eacute;s sur des traits de locomotion, de pr & eacute;f & eacute;rence de temp & eacute;rature et d'intervalle de temps entre deux mues & agrave; deux temp & eacute;ratures, et de sp & eacute;cificit & eacute; du venin, afin d'& eacute;tudier les capacit & eacute;s de dispersion de l'esp & egrave;ce ainsi que ses niches fondamentales thermiques et alimentaires. Nous n'avons trouv & eacute; aucune indication de tri spatial (& laquo; spatial sorting & raquo;), c'est-& agrave;-dire aucun ph & eacute;notype & agrave; forte capacit & eacute; de dispersion dans la population du Nord. De plus, nous n'avons trouv & eacute; aucune indication claire de changements dans la biologie thermique de l'esp & egrave;ce & agrave; travers l'espace ou dans la sp & eacute;cificit & eacute; de son venin. En particulier, Z. rubidum a montr & eacute; des temp & eacute;ratures pr & eacute;f & eacute;rentielles similaires entre les localit & eacute;s, un d & eacute;veloppement plus lent sous conditions de temp & eacute;ratures & eacute;lev & eacute;es chez les populations du Centre et du Nord de l'Europe (refl & eacute;tant possiblement un changement adaptatif vers des temp & eacute;ratures plus froides), et une capacit & eacute; constante & agrave; paralyser des esp & egrave;ces de fourmis phylog & eacute;n & eacute;tiquement & eacute;loign & eacute;es. Dans l'ensemble, nous concluons que la propagation de Z. rubidum pourrait avoir & eacute;t & eacute; facilit & eacute;e par les activit & eacute;s humaines et que l'esp & egrave;ce ne montre pas de changements majeurs dans sa niche fondamentale & agrave; travers l'espace.
In carnivore guilds, apex predators and mesocarnivores may interact through mechanisms ranging from antagonism to facilitation. The recent recolonization of the gray wolf Canis lupus in the Alps offers a valuable opportunity to investigate how wolf kill sites influence mesocarnivore behavior. We analyzed interactions between wolves and red foxes Vulpes vulpes at red deer Cervus elaphus carcasses in the Stelvio National Park (Italian Alps). Using camera traps deployed at 26 wolf-killed carcasses between November 2022 and December 2024, we assessed whether foxes exploited wolf kills and exhibited temporal avoidance of wolves, controlling for carcass characteristics and environmental factors. Fox presence-absence was modeled at an hourly resolution using generalized linear mixed models. Four variables were derived from camera-trap data to assess wolf influence on fox presence: wolf presence in the same hour, wolf presence in the preceding hour, time elapsed since the last wolf visit, and total wolf visit duration per hour. Foxes were detected at all monitored carcasses, whereas wolves were recorded at 20 of the 26 sites, with most activity occurring at night. Fox presence was most strongly associated with initial carcass consumption and, to a lesser extent, by human activity and habitat features. Our results provide limited evidence that fine-scale wolf activity influenced fox scavenging at wolf-killed carcasses, with no detectable temporal avoidance or attraction. Carcass profitability explained fox occurrence more strongly than any of the measured wolf variables, suggesting that foxes may respond primarily to carcass profitability rather than to fine-scale predation risk. Carcass sites represent high-value food resources, highlighting the ecological role of wolf kill provisioning in Alpine ecosystems.
