Sudyka, J. | bioRxiv Science

bioRxiv2021

Alterations to the Gut Microbiota of a Wild Juvenile Passerine in an Urban Mosaic

Urbanisation is a major anthropogenic perturbation that progressively alters multiple environmental parameters, thereby presenting novel evolutionary challenges to wild populations. Symbiotic microorganisms residing in the gastrointestinal tracts (gut) of vertebrates have well-established mutual connections with the physiology of their hosts and respond quickly to environmental alterations. However, the impacts of anthropogenic changes and urbanisation on gut microbiota remain poorly understood, especially in early development. To address this knowledge gap, we investigated the gut microbiota in juvenile great tits (Parus major) in an urban mosaic. First, we compared the microbiota of nestlings reared in artificial nest boxes or natural cavities. Next, we analysed microbiota variations employing two distinct urbanisation frameworks, (i) the classical urban/rural dichotomy and (ii) gradual changes in the amount of impervious surface area (ISA) in the urban space and identified the environmental variables that predicted the changes in the microbial communities. Alpha diversity was influenced by cavity type and by the amount of impervious surface surrounding the breeding location. Alpha diversity was also positively correlated with the tree cover density. Beta diversity differed between urban and rural sites, and these alterations covaried with sound pollution, the distance to the city centre and the distance to the closest road. Overall, the microbial communities reflect and are possibly influenced by the heterogeneous environmental modifications that are typical of the urban space. Strikingly, the choice of framework used to define the urban space can influence the outcomes of studies investigating animal-microbe symbiosis. Our results open new perspectives from which the potential function of microbial symbionts in the adaptation of their hosts to anthropogenic stress can be investigated.

ecology↗

bioRxiv2020

Exercise training in a color-polymorphic lizard reveals differential effects of mating tactics and color morphs on telomere, body condition and growth dynamics

Alternative reproductive tactics (ARTs) are correlated suites of sexually selected traits that are likely to impose differential physiological costs on different individuals. While some level of activity might be beneficial, animals living in the wild are often working at the margins of their resources and performance limits. Individuals using ARTs may have divergent capacities for activity, and when pushed beyond their capacity, they may experience condition loss, oxidative stress, and molecular damage that must be repaired with limited resources. We used the Australian painted dragon lizard that exhibits color-polymorphims with corresponding alternative reproductive tactics (ARTs) as a model to experimentally test the effect of exercise on body condition, growth, reactive oxygen species (ROS), and telomere dynamics--a potential marker of stress and aging and a correlate of longevity. For most males, ROS tended to be lower with greater exercise; however, males with yellow throat patches--or bibs-- had higher ROS than non-bibbed males. At the highest level of exercise, bibbed males exhibited telomere loss, while non-bibbed males gained telomere length; the opposite pattern was observed in the no-exercise controls. Growth was positively related to food intake but negatively correlated with telomere length at the end of the experiment. Body condition was not related to food intake but was positively correlated with increases in telomere length. These results, along with our previous work, suggest that aggressive bibbed males suffer physiological costs that may reduce longevity.

evolutionary biology↗