Biology subjects

Davidson, G. L.

Publications and source records attributed to Davidson, G. L..

3 recordsLinked to original sources

bioRxiv2020

Inhibitory control, personality, and manipulated ecological conditions influence foraging plasticity in the great tit

O_LIOrganisms are consistently under selection to respond effectively to a diversity of, sometimes rapid, changes in their environment. Behavioural plasticity can allow individuals to do so instantaneously, but why individuals vary in this respect is poorly understood. Although personality and cognitive traits are often hypothesised to influence plasticity, the effects reported are highly inconsistent, which we hypothesise is because ecological context is usually not considered. C_LIO_LIHere we explore the roles of individual cognitive and personality variation - assayed using standard tasks for inhibitory control, a measure of self-control, and reactive-proactive personality axis (RPPA), respectively - in driving foraging plasticity, and asked how these effects varied across two experimentally manipulated ecological contexts: food value and predation risk. C_LIO_LIAfter great tits (Parus major) had initially been trained to retrieve high value food hidden in sand, they were then simultaneously offered the hidden food and an alternative food choice on the surface, that was either high or low value. Their choices were further examined under high and low perceived predation risk treatments. Individuals choices were classified in terms of whether they continued to forage on the hidden but familiar food source, or instead switched to the new visible food source. We defined the latter option as the plastic response. C_LIO_LIOur assays captured consistent differences among individuals in foraging behaviour. Both inhibitory control and exploration influenced whether birds switched from the familiar but hidden food source to the new alternative visible food on the surface. These effects depended on the relative value of the food items available and on the perceived level of predation risk, but also on the time scale over which the response was measured. C_LIO_LIOur results demonstrate how an executive cognitive function and one specific personality axis can simultaneously influence plasticity in a key functional behaviour. That their effects on foraging were primarily observed as interactions with food value or predation risk treatments also suggest that the population level consequences of behavioural mechanisms, such as these, may only be revealed across key ecological conditions or gradients. C_LI

animal behavior and cognition↗

bioRxiv2020

A time-lagged association between the gut microbiome, nestling growth and nestling survival in wild great tits

O_LINatal body mass is a key predictor of viability and fitness in many animals. While variation in body mass and therefore juvenile viability may be explained by genetic and environmental factors, emerging evidence points to the gut microbiota as an important factor influencing host health. The gut microbiota is known to change during development, but it remains unclear whether the microbiome predicts fitness, and if it does, at which developmental stage it affects fitness traits. C_LIO_LIWe collected data on two traits associated with fitness in wild nestling great tits (Parus major): weight and survival to fledging. We characterised the gut microbiome using 16S rRNA sequencing from nestling faeces and investigated temporal associations between the gut microbiome and fitness traits across development at day 8 (D8) and day 15 (D15) post-hatching. We also explored whether particular microbial taxa were indicator species that reflected whether nestlings survived or not. C_LIO_LIThere was no link between mass and microbial diversity on D8 or D15. However, we detected a time-lagged relationship where weight at D15 was negatively associated with the microbial diversity at D8, controlling for weight at D8, therefore reflecting relative weight gain over the intervening period. C_LIO_LIIndicator species analysis revealed that specificity values were high and fidelity values were low, suggesting that indicator taxa were primarily detected within either the survived or not survived groups, but not always detected in birds that either survived or died. Therefore these indicator taxa may be sufficient, but not necessary for determining either survival or mortality, perhaps owing to functional overlap in microbiota. C_LIO_LIWe highlight that measuring microbiome-fitness relationships at just one time point may be misleading, especially early in life. Instead, microbial-host fitness effects may be best investigated longitudinally to detect critical development windows for key microbiota and host traits associated with neonatal weight. Our findings should inform future hypothesis testing to pinpoint which features of the gut microbial community impact on host fitness, and when during development this occurs. Such confirmatory research will shed light on population level processes and could have the potential to support conservation. C_LI

ecology↗

bioRxiv2020

No evidence for cross-contextual consistency in spatial learning and behavioural flexibility in a passerine

Although the evolution of cognitive differences among species has long been of interest in ecology, whether natural selection acts on cognitive processes within populations has only begun to receive similar attention. One of the key challenges is to understand how consistently cognitive traits within any one domain are expressed over time and across different contexts, as this has direct implications for the way in which selection might act on this variation. Animal studies typically measure a cognitive domain using only one task in one context, and assume that this captures the likely expression of that domain in different contexts. This deficit is not surprising because, from an ecologists perspective, cognitive tasks are notoriously laborious to employ, and for design reasons most tasks can only be deployed in a specific context. Thus our knowledge of whether individual differences in cognitive abilities are consistent across contexts is limited. Using a wild population of great tits (Parus major) we characterised consistency of two cognitive abilities, each in two different contexts: 1) spatial learning at two different spatial scales, and 2) behavioural flexibility as both performance in a detour reaching task and reversal learning in a spatial task. We found no evidence of a correlation between the two spatial learning speeds, or between the two measures of behavioural flexibility. This suggests that cognitive performance is highly plastic and sensitive to differences across tasks, or that variants of these well-known tasks may tap into different combinations of both cognitive and non-cognitive mechanisms, or that they simply do not adequately measure each putative cognitive domain. Our results highlight the challenges of developing standardised cognitive assays to explain natural behaviour and to understand the selective consequences of that variation.

animal behavior and cognition↗