Biology subjects

Buesching, C. D.

Publications and source records attributed to Buesching, C. D..

6 recordsLinked to original sources

bioRxiv2024

Food for thought: Rosy-faced lovebirds (Agapornis roseicollis) are capable of associative symbol learning and inference-based quantity discrimination

Cognitive capacity for quantity discrimination is highly adaptive in various ecological contexts and subject to convergent evolution across diverse animal species, yet the underlying mechanism involved is not fully understood. Discrimination accuracy generally increases with the ratio between two quantities; however, this ability is expected to differ across ratio ranges. To test this we presented a novel symbol system to 28 rosy-faced lovebirds (Agapornis roseicollis), associating additive tally marks with symbols representing a one-to-one correspondence with different food quantities. Trained lovebirds could spontaneously infer the relative food quantities represented by other symbols. Lovebirds proved capable of (1) associating symbols (i.e., object-file symbolism); with (2) "more-less" quantity inference, by deducing food quantities based on their knowledge of this symbol-quantity association; and (3) enhancing their performance in relation to disparity ratio (conforming to Webers law) and absolute difference. Furthermore (4), the influence of food ratio and absolute difference varied with different ratio ranges. Within a small ratio range ([≤] 3) discrimination performance improved with increments of ratio or absolute difference, whereas within a higher ratio range (> 3), the effect of these factors diminished. We conclude that rosy-faced lovebirds are capable of advanced numeracy and quantity discrimination, similar to larger parrot species.

animal behavior and cognition↗

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↗

bioRxiv2024

Investigating the use of odour and colour foraging cues by rosy-faced lovebirds (Agapornis roseicollis) using deep-learning based behavioural analysis

Olfaction and vision can play important roles in optimizing foraging decisions of birds, enabling them to maximize their net rate of energy intake while searching for, handling, and consuming food. Parrots have been used extensively in avian cognition research, and some species use olfactory cues to find food. Here we pioneered machine learning analysis and pose-estimation with convolutional neural networks (CNNs) to elucidate the relative importance of visual and olfactory cues for informing foraging decisions in the rosy-faced lovebird (Agapornis roseicollis) as a non-typical model species. In a binary choice experiment, we used markerless body pose tracking to analyse bird response behaviours. Rosy-faced lovebirds quickly learnt to discriminate the feeder provisioned with food by forming an association with visual (red/green papers) but not olfactory (banana/almond odour) cues. When visual cues indicated the provisioned and empty feeders, feeder choice was more successful, choice latency shorter, and interest in the empty feeder significantly lower. This demonstrates that visual cues alone are sufficient to inform lovebird foraging decisions without needing to use olfactory cues, suggesting that selection has not driven olfactory-based foraging in lovebird evolution.

animal behavior and cognition↗

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↗

bioRxiv2020

Negative density-dependent parasitism in a group-living carnivore

Animals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit immunologically and hygienically from cooperation, and individuals may alter their socio-spatial behaviour in response to infection, both of which could counteract density-related increases in exposure. Consequently, the costs and benefits of sociality for disease are often uncertain. Here, we use a long-term study of a wild European badger population (Meles meles) to investigate how within-population variation in host density determines infection with multiple parasites. Four out of five parasite taxa exhibited consistent spatial hotspots of infection, which peaked among badgers living in areas of low local population density. Combined movement, survival, spatial, and social network analyses revealed that parasite avoidance was the likely cause of this negative density dependence, with possible roles for localised mortality, encounter-dilution effects, and micronutrient-enhanced immunity. These findings demonstrate that animals can organise their societies in space to minimise parasite infection, with important implications for badger behavioural ecology and for the control of badger-associated diseases.

ecology↗

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↗