Biology subjects

Macdonald, D. W.

Publications and source records attributed to Macdonald, D. W..

4 recordsLinked to original sources

bioRxiv2025

Are all waterholes equal from a lion's view? Exploring the role of prey abundance and catchability in waterhole visitation patterns in a savannah ecosystem

Prey abundance and catchability shape the spatial ecology of predators. Predators can select habitats where prey are more abundant to maximize encounter rate with prey or habitats where prey are more catchable to maximize prey capture. These hypotheses are commonly referred to as prey-abundance and prey-catchability hypotheses. Although these hypotheses are often tested at the landscape scale, little is known about how between-patch variations in prey abundance and catchability determine the space use of predators. In many savannah ecosystems, large herbivores aggregate around waterholes, which become hotspots of prey and their selection by predators is classically interpreted as supporting the prey-abundance hypothesis. Here, we investigated whether between-waterhole variations in prey abundance and catchability influence the frequency and duration of lion visits to waterholes, testing the prey-abundance and prey-catchability hypotheses at the resource-patch scale. We combined datasets on (1) lion movements recorded from GPS collars deployed on 20 adult males and 16 adult females between 2002 and 2015, (2) prey abundance evaluated from long-term, regular monitoring of waterholes and (3) prey catchability evaluated from remote-sensing satellite imagery of vegetation cover around waterholes in Hwange National Park (Zimbabwe). Lions did not use all waterholes in their territory equally: there was a high variability in the frequency and duration of visits. Surprisingly, between-waterhole variations in prey abundance and catchability only slightly explained these variations in frequency - and even less in duration - of lion visits to waterholes. Yet, the frequency of lion visits to waterholes decreased with the number of waterholes within their territory, and male lions more frequently visited the waterholes surrounded by more open habitats. We discuss the limits of our work, but also the ecological mechanisms that may explain these findings. First, lions and their prey are involved in a shell-game that leads them to adopt unpredictable movement strategies. Second, lions have only access to a limited number of waterholes amongst which to distribute their hunting effort. Lastly, lions visit waterholes not only to hunt but also to interact with social mates and competitors. This work challenges the implicit assumption that all waterholes are the same from a lions view and calls for further studies investigating the drivers of the variability in lion visits at the resource-patch scale.

ecology↗

bioRxiv2024

Pre-implantation genome-wide methylation enables environmental adaptation in a social meso-carnivore

Many wild populations are increasingly stressed by rapid climatic change. While behavioural plasticity can enable limited tactical adaptive responses, standing genetic variation limits the species capacity to respond to climate change velocity. Epigenetic modification may provide a more rapid and plastic adaptive mechanism, but has been little studied in wild-living animals. Here we investigated CpG methylation during the pre-natal and early-life development of 95 European badger cubs between 2003 and 2011). During 10-months of delayed pre-implantation variability in precipitation between previous years February and April was the top determinant of methylation patterns among neonates, followed by mean temperature and temperature variability. Among the 4,641 significant weather-associated CpG sites, most occurred in the 47S rDNA region. Methylation of 47S rDNA was also associated with early-life weight, implying a mechanism that relays environmental stress to phenotypic stress. We also detected evidence for predictive adaptive response. Among the 1,641 CpG sites associated with early-life weight, pathways were associated with early-life growth, immune regulation, and to the development of aggression for competitive access to weather-limited food resources were over-represented. We conclude that a species epigenetics can have an important role in adaptive plasticity to environmental changes with important implications for biodiversity conservation and management.

genomics↗

bioRxiv2021

Patterns of Mustelid gammaherpesvirus 1 (MusGHV-1) genital reactivation linked to stressors in adult European badgers (Meles meles)

Herpesvirus infections are common and mostly asymptomatic in vertebrates, but can result in impaired reproduction. It is therefore important to understand infection patterns and associated risk factors, particularly the effects of different stressors. Here we use Mustelid gammaherpesvirus 1 (MusGHV-1) infection in European badgers (Meles meles) as a host-pathogen wildlife model to study the effects of a variety of demographic, social, physiological and environmental stressors on viral reactivation in the genital tract. We collected 251 genital swabs from 151 free-ranging individuals across 3 trapping seasons (spring, summer and autumn). We screened for MusGHV-1 using PCR and explored possible links between genital MusGHV-1 reactivation and stressors, and their interactions, using logistic regression. In adults, reactivation was more likely in males, especially those in poorer body condition during summer. In females, reactivation was more likely when living in social groups comprising a higher percentage of cubs, but counter to our predictions, recent lactation appeared not influential. In relation to age, reactivation was more common in individuals over 8 years old than among prime age adults, and among juveniles (<2 years old), especially females and individuals in better body condition, likely due to early puberty. Environmentally, reactivation was more prevalent in summer when food abundance is typically low. Our results evidence age effects on MusGHV-1 reactivation; in juveniles MusGHV-1 shedding in the genital tract is likely related to primary infection, while in adults, genital MusGHV-1 reactivation from latency was associated with aging, social and/ or environmental stress. ImportanceThe immuno-suppressive effects of elevated stress levels facilitate disease development, and can ultimately cause host extinction at the population level, especially where diseases are transmitted sexually. The impacts of stress on host-pathogen dynamics through disease, however, are still poorly understood outside the laboratory or captive environments. Our study provides rare evidence from a free-ranging wild mammal population that the infection dynamics of a common and sexually transmittable gammaherpesvirus are linked to demographic, social, physiological and environmental stress. We propose that the effects of stressors on STIs and viral reactivation are an important factor to be taken into account in conservation efforts when working with vulnerable wildlife populations.

microbiology↗

bioRxiv2018

Heterochrony of puberty in the European Badger (Meles meles) can be explained by growth rate and group-size: Evidence for two endocrinological phenotypes

Puberty is a key stage in mammalian ontogeny, involving endocrinological, physiological and behavioural changes, moderated by intrinsic and extrinsic factors. Thus, not all individuals within one population achieve sexual maturity simultaneously. Here, using the European badger (Meles meles) as a model, we describe male testosterone and female oestrone profiles (using Enzyme-immunoassays) from first capture (3 months, post-weaning) until 28 months (attaining sexual maturity and final body size), along with metrics of somatic growth, scent gland development and maturation of external reproductive organs as well as intra-specific competition. In both sexes, endocrinological puberty commenced at ca. 11 months. Thereafter, cub hormone levels followed adult seasonal hormone patterns but at lower levels, with the majority of cubs reaching sexual maturity during their second mating season (22-28 months). Interestingly, there was evidence for two endocrinological phenotypes among male cubs (less evident in females), with early developers reaching sexual maturity at 11 months (first mating season) and late developers reaching sexual maturity at 22-26 months (second mating season). Early developers also attained a greater proportion of their ultimate adult size by 11 months, exhibiting faster growth rates than late developers (despite having similar adult size). Male cubs born into larger social groups tended to follow the late developer phenotype. Our results support the hypothesis that a minimum body size is required to reach sexual maturity, which may be achieved at different ages, even within a single population, where early maturity can confer individual fitness advantages and enhance population growth rate.

zoology↗