Biology subjects

Thorley, J.

Publications and source records attributed to Thorley, J..

8 recordsLinked to original sources

bioRxiv2026

Decomposing alarm-calling behaviour to investigate context-dependent threat discrimination and response escalation in a social mongoose

Prey can adjust their behaviour to perceived predation risk, which may induce non-consumptive fitness effects. However, quantifying perceived risk in field studies remains challenging as anti-predator behaviours often integrate multiple processes such as encounter probability and detection capacity. Partitioning prey responses into sub-processes may therefore provide novel insights on predation risk perception. To this end, we decomposed meerkat alarm-calling behaviour into threat discrimination, and response escalation. Using 23 years of data from a wild population in the Kalahari, we evaluated the context-dependence of both components in relation to landscape features, and group composition. We defined threat discrimination as the probability to emit an alarm call at predators (eagles) relative to non-predators (vultures) and response escalation as the strength and intensity of the ensuing collective reaction. We found that discrimination varied with habitat and vegetation productivity. Furthermore, larger groups and the presence of pups increased meerkat threat discrimination, but only during the dry season. Response escalation varied with habitat and group size, but pup presence only increased reaction strength. The contrasting context-dependence among the two alarm-calling components support decomposing compound behaviours rather than quantifying perceived risk from a single behaviour. Thus, we recommend future studies to use this approach, when possible, to improve inference on prey perception and responses to risk.

animal behavior and cognition↗

bioRxiv2025

The bind of the burrow: space use is dominated by selection for burrow habitat over foraging habitat in an arid-adapted carnivore

Our understanding of habitat selection in wild vertebrates has been heavily influenced by observations of preferred foraging areas. However, foraging is only one of many ways animals interact with their environment, and preferences for habitat features that support resting, breeding, and safety, along with trade-offs between these needs, remain underexplored. These trade-offs are likely to be particularly acute in complex environments where these needs are met in different locations. Using a long-term dataset of movements and life history, we examine how preferences for foraging areas and burrow sites shape space use in Kalahari meerkats (Suricata suricatta). Meerkats cannot dig new sleeping and breeding burrows and must use those abandoned by other species, potentially generating trade-offs in daily space use if overnight refuges are far from optimal foraging areas. We find that space use is strongly anchored by burrow location, with burrows in calcareous pans and dry riverbed ("white sand") habitat being preferred year-round and showing lower burrow switching rates. However, white sand areas were not preferred for foraging, and yielded lower weight gains, particularly during the dry season. As a result, meerkats faced a trade-off between optimal burrow locations and productive foraging grounds, as indicated by faster, longer, and more energetically costly travel when moving through or waking up in white sands. Our results suggest that changes in the distribution or abundance of key burrow-constructing species in desert environments may have cascading effects on the many secondary burrow-using species that depend on them for survival and reproduction. More broadly, our results highlight that limited refuge availability across the landscape can impose strong ecological constraints on animals and may restrict behavioural plasticity under environmental change, particularly if productive foraging areas shift.

ecology↗

bioRxiv2025

Linking differences in personality to demography in the wandering albatross

Population dynamics are shaped by individual differences. With a good understanding of the relationships between individual differences and vital rates, population models can be improved to yield more realistic and detailed demographic projections. Personality, i.e., consistent individual differences in behaviour, is expected to shape individual differences in performance. Yet, an empirical quantification of its impact on population dynamics is currently lacking. Here, we developed and analysed a three-dimensional hyperstate population model that accounts for three sources of individual differences simultaneously in its structure: age, breeding state and boldness as a measure of personality. We parameterized our model using empirical demographic and boldness data on the wandering albatross (Diomedea exulans) population from the Crozet archipelago. We conducted sensitivity analyses to quantify the relative importance of boldness. We then simulated scenarios of increased strength of relationship between boldness and three vital rates (survival, breeding probability and breeding success) to explore conditions under which shifts in boldness distribution could be observed in the future. We showed that the sensitivity of population growth rate to changes in vital rates followed the normal distribution of boldness within the population. Indeed, population growth rate was much less sensitive to changes in the vital rates of extreme shy or bold individuals, compared to that of individuals of intermediate boldness. Overall, sensitivity of population growth rate was greater for survival than reproductive rates across all three dimensions. Our simulations showed that increasing the strength of the relationship between boldness and survival would yield the greatest shift in boldness distribution over time compared to breeding probability and breeding success. However, shifts in boldness distribution appeared constrained by the low heritability (< 0.2) value and the large variance in boldness in this population. Our study provides an important contribution to our understanding of the role of personality in shaping the population dynamics of wild species. In the face of global change, our approach offers a promising avenue to predict the potential for behavioral adaptation. More generally, our approach may help to unravel the complex interplay between individual variations in any (or many) traits and population dynamics.

ecology↗

bioRxiv2021

Fitness of breeders in social Damaraland mole-rats is independent of group size

Damaraland mole-rats (Fukomys damarensis) are usually viewed as a eusocial or obligate cooperative breeder in which successful reproduction is dependent on help from closely related group members. However, because longitudinal studies of mole-rats in their natural environment are uncommon, the extent to which successful reproduction by breeders relies on assistance from other group members is unclear, and for non-breeders, the immediate and delayed fitness consequences of staying and helping are poorly understood. Using data from a 7-year field study of marked individuals, we investigate whether increasing group size confers reproductive and survival benefits to breeders and non-breeders, and explore the different routes through which individuals acquire breeding positions. We show that solitary natal dispersal was the most common route to breeding for both sexes and that the inheritance of dominant breeding positions was uncommon in both sexes. After dispersing, females typically settled alone in new burrow systems where they enjoyed high survival rates and remained in good body condition - often for several years - before being joined by males. In contrast to most obligately cooperative species, pairs of potential breeders reproduced successfully without helpers and experimentally formed pairs had the same reproductive success as larger established groups. Though larger breeding groups recruited slightly more pups on average, our data suggest that neither survival nor reproduction depend on the presence of non-breeding helpers, indicating that Damaraland mole-rats are not obligate cooperative breeders. We suggest that extended philopatry and group living in Damaraland mole-rats have evolved because of the high costs and constraints of dispersal rather than because of strong indirect benefits accrued through cooperative behaviour and that similarities between their breeding systems and those of obligatorily eusocial insects have been over-emphasized. Significance StatementThe social mole-rats are often considered eusocial mammals in which successful reproduction depends on assistance from non-breeding helpers. In this study we show that in wild Damaraland mole-rats, the presence of non-breeders is associated with both costs and benefits and that nascent breeding pairs show high reproductive success despite the lack of non-breeding helpers. These findings indicate that Damaraland mole-rats are not obligate cooperative breeders and suggest that similarities between their breeding systems and those of obligatorily eusocial insects have been over-emphasized.

ecology↗

bioRxiv2020

Morphological and genomic shifts in mole-rat 'queens' increase fecundity but reduce skeletal integrity

In some mammals and many social insects, highly cooperative societies are characterized by reproductive division of labor, in which breeders and nonbreeders become behaviorally and morphologically distinct. While differences in behavior and growth between breeders and nonbreeders have been extensively described, little is known of their molecular underpinnings. Here, we investigate the consequences of breeding for skeletal morphology and gene regulation in highly cooperative Damaraland mole-rats. By experimentally assigning breeding queen status versus nonbreeder status to age-matched littermates, we confirm that queens experience vertebral growth that likely confers advantages to fecundity. However, they also up-regulate bone resorption pathways and show reductions in femoral mass, which predicts increased vulnerability to fracture. Together, our results show that, as in eusocial insects, reproductive division of labor in mole-rats leads to gene regulatory rewiring and extensive morphological plasticity. However, in mole-rats, concentrated reproduction is also accompanied by costs to bone strength.

evolutionary biology↗

bioRxiv2020

Bowled over or over bowled? Age-related changes in the performance of bowlers in Test match cricket

Data from elite professional sports players provide a valuable source of information on human performance and ageing. Functional declines in performance have been investigated across a wide range of sporting disciplines that vary in their need for physical strength, endurance, cognitive ability and motor skills, but rarely have researchers considered other sources of heterogeneity that can exist among individuals. Using information on all male bowlers to have played Test match cricket since the early 1970s, I separated age-dependent variation in bowling performance at the population-level into within-individual and between-individual (cohort) changes. I found no evidence for senescence in bowling performance as measured via economy rate or wicket-taking ability, irrespective of the style of the bowler (fast or slow). Instead, analyses detected strong between-individual contributions to bowling performance as higher quality bowlers were able to compete at the elite level for longer, and were therefore over-represented in older age classes. Bowlers also experienced a deterioration in the last year of their Test careers. These results highlight that the very best Test match bowlers have been able to maintain and often improve their skill level well into their thirties, but how they accomplish this alongside the physical demands of Test cricket remains unresolved. Further multivariate models also identified a negative relationship among slow bowlers between their economy rate and their wicket-taking ability, suggesting that in general, the most economical slow bowlers in the modern era of Test match cricket have also taken wickets at the fastest rate. The same is not true for fast bowlers, which is perhaps partly because bowling at high speed compromises accuracy and thus increases scoring opportunities for batsman.

ecology↗

bioRxiv2020

High MHC gene copy number maintains diversity despite homozygosity in a Critically Endangered single-island endemic bird, but no evidence of MHC-based mate choice

AO_SCPLOWBSTRACTC_SCPLOWSmall population sizes can, over time, put species at risk due to the loss of genetic variation and the deleterious effects of inbreeding. Losing diversity in the major histocompatibility complex (MHC) could be particularly harmful, given its key role in the immune system. Here, we assess MHC class I (MHC-I) diversity and its effects on mate choice and survival in the Critically Endangered Raso lark Alauda razae, a species restricted to the 7 km2 islet of Raso (Cape Verde) since ~1460, whose population size has dropped as low as 20 pairs. Exhaustively genotyping 122 individuals, we find no effect of MHC-I genotype/diversity on mate choice or survival. However, we demonstrate that MHC-I diversity has been maintained through extreme bottlenecks by retention of a high number of gene copies (at least 14), aided by co-segregation of multiple haplotypes comprising 2-8 linked MHC-I loci. Within-locus homozygosity is high, contributing to comparably low population-wide diversity. Conversely, each individual had comparably many alleles, 6-16 (average 11), and the large and divergent haplotypes occur at high frequency in the population, resulting in high within-individual MHC-I diversity. This functional immune gene diversity will be of critical importance for this highly threatened species adaptive potential.

evolutionary biology↗

bioRxiv2019

Do cooperatively breeding mammals live longer? A re-appraisal

Recent comparative studies have suggested that cooperative breeding is associated with increases in maximum lifespan among mammals, replicating a pattern also seen in birds and insects. In this study, I re-examine the case for increased lifespan in mammalian cooperative breeders by analysing a large dataset of maximum longevity records. Unlike one previous study, I found no consistent, strong evidence that cooperative breeders have longer lifespans than other mammals, after having controlled for variation in body mass, mode of life and data quality. The only exception to this general trend was displayed by the African mole-rats (the Bathyergid family): all members of this family are relatively long-lived, but the social, cooperatively breeding species appear to be much longer-lived than the solitary species, the latter having not been known to live beyond 11 years in captivity. However, solitary mole-rat species have rarely been kept in captivity or followed longitudinally in the wild, and so it seems likely that their maximum lifespan has been grossly underestimated when compared to the highly researched social species. As few other subterranean species have received much attention in a captive or wild setting, I also suggest that current data also makes it impossible to rule out a causal role of subterranean living on lifespan extension in mammals, and that any future studies wanting to test for such an association should wait until more high quality longevity data is available from a wider range of permanently subterranean species.

evolutionary biology↗