Biology subjects

Crane, J. M. S.

Publications and source records attributed to Crane, J. M. S..

4 recordsLinked to original sources

bioRxiv2022

Individual variation in the avian gut microbiota: the influence of host state and environmental heterogeneity

The gut microbiome has important consequences for fitness, yet the complex, interactive nature of ecological factors that influence the gut microbiome has scarcely been investigated in natural populations. We sampled the gut microbiota of wild great tits (Parus major) at different life stages and across multiple conifer and mixed woodland fragments, allowing us to evaluate multiple factors that relate to within-individual gut microbiota acquisition, including habitat type, nest position and life history traits. The gut microbiota varied with both environment and life-history in ways that were largely dependent on age. Notably, it was the nestling, as opposed to the adult gut microbiota that was most sensitive to ecological variation, pointing to a high degree of developmental plasticity. Individual nestling differences in gut microbiota were consistently different (repeatable) from one to two weeks of life, driven entirely by the effect of sharing the same nest. Our findings point to important early developmental windows in which the gut microbiota are most sensitive to environmental variation and suggest reproductive timing, and hence parental quality or food availability, interact with the microbiome.

ecology↗

bioRxiv2021

No reproductive benefits of dear enemy recognition in a territorial songbird

Territorial animals often respond less aggressively to neighbours than strangers. This dear enemy effect is hypothesized to be adaptive by reducing unnecessary aggressive interactions with non-threatening individuals. A key prediction of this hypothesis, that individual fitness will be affected by variation in the speed and the extent to which individuals reduce their aggression towards neighbours relative to strangers, has never been tested. We used a series of song playbacks to measure the change in response of male great tits to a simulated establishment of a neighbour on an adjacent territory during early stages of breeding, as an assay of individuals tendencies to form dear enemy relationships. Males reduced their approach to the speaker and sang fewer songs on later playback repetitions. However, only some males exhibited dear enemy behaviour by responding more strongly to a subsequent stranger playback, and when the playback procedure was repeated on a subset of males, there was some indication for consistent differences among individuals in the expression of dear enemy behaviour. We monitored nests and analysed offspring paternity to determine male reproductive success. Individuals that exhibited dear enemy behaviour towards the simulated neighbour did not suffer any costs associated with loss of paternity, but there was also no evidence of reproductive benefits, and no net effect on reproductive fitness. The general ability to discriminate between neighbours and strangers is likely adaptive, but benefits are probably difficult to detect because of the indirect link between individual variation in dear enemy behaviour and reproductive fitness, and because of the complex range of mechanisms affecting relations with territorial neighbours.

animal behavior and cognition↗

bioRxiv2020

Low hatching success in the critically endangered kakapo (Strigops habroptilus) is driven by early embryo mortality not infertility

In many endangered species, reproductive failure is a major barrier to recovery. The critically endangered k[a]k[a]p[o] (Strigops habroptilus) exemplifies this challenge: 61% of their eggs fail to hatch, and of these 73% show no sign of development. Undeveloped eggs have previously been attributed to male infertility, but recent studies of non-threatened bird species suggest fertilisation failure is rare in the wild. The underlying causes of fertilisation failure and embryo death differ, so distinguishing between them is essential for effective conservation management. Here we show that the majority (72%, n=124) of undeveloped k[a]k[a]p[o] eggs are fertilised, and combine this with conservation programme data on natural copulations, artificial inseminations, and paternity of developed eggs, to generate the most precise estimate to date of fertility in a wild population. We also demonstrate, for the first time in a wild bird, that artificial insemination results in greater numbers of sperm reaching the egg.

zoology↗

bioRxiv2019

Diet-induced changes to host gut microbiota are linked to foraging innovation in a wild bird.

The microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.

ecology↗