Biology subjects

Chaston, J. M.

Publications and source records attributed to Chaston, J. M..

4 recordsLinked to original sources

bioRxiv2025

The microbiota elicits compensatory adaptation in a seasonally-adapting animal host

Seasonal adaptation in Drosophila melanogaster is a model for understanding the evolutionary responses of organisms to cyclical environmental changes, including roles played by associated microorganisms ( microbiota). Here we examined how the microbiota influences D. melanogaster seasonal adaptation by rearing flies in outdoor mesocosms, fed diets inoculated with different bacterial strains that have distinct influences on the flies life history. The bacterial treatments influenced fly population dynamics and microbiota composition over a summer-to-fall season. The developmental phenotype of the treated flies initially differed but converged over time in flies reared with a complete microbial community. Conversely, rearing the flies free of their colonizing microorganisms revealed that the bacterial treatments led to evolution of distinct developmental phenotypes. The development time of flies from the different treatments consistently adapted to compensate for the direct influence of the bacteria on host development; e.g., flies evolved faster development times if they were inoculated with microbes that slowed development. This compensatory trend was apparent in flies reared in a second location and season, and is consistent with a previous report of wild-sampled flies whose development phenotype segregated with their microbiota composition. Together, these results reveal that microbiota-dependent selection consistently elicits compensatory adaptation in seasonally-evolving flies, which we conclude is a mechanism whereby horizontally-acquired, low-fidelity microbial partners can shape the evolution of their animal hosts. ImportanceUnderstanding how organisms adapt to seasonal change can model evolutionary responses in a broader changing world. Drosophila melanogaster is a powerful model for studying these dynamics, especially when considering the influence of transient yet impactful colonizing microorganisms. This study reveals that microbial partners can drive consistent, compensatory adaptation in host development across seasons and locations. By demonstrating that flies evolve faster development times in response to microbes that slow a model hosts period of growth and development, this work highlights one way that the microbiota can influence adaptation in their animal hosts. These findings also provide evidence that low-fidelity, horizontally-acquired microbes can exert selective pressures strong enough to shape host life history traits. These insights underscore the microbiotas role as an ecological and evolutionary force.

microbiology↗

bioRxiv2025

The Microbiotas Response to Host Adaptive Evolution

Over the past two decades, experimental evolution has significantly advanced our understanding of evolutionary patterns and mechanisms of genomic change. One critically underexplored dimension is the role of microbiota in host adaptive evolution. In this research we investigate the microbiota from forty laboratory-selected Drosophila melanogaster populations exhibiting four distinct aging trajectories, ranging from extremely-short lifespans to -long lifespans. Using metagenomic sequencing and colony forming unit (CFU) counts in both conventional and gnotobiotic conditions, we uncover substantial microbiota differentiation among these populations. The most striking pattern is the consistent loss of Wolbachia in populations selected for rapid aging, in contrast to its near complete dominance in long-lived populations. This suggests a positive association between relative abundance of Wolbachia and lifespan, alongside a negative correlation between Wolbachia and Acetic Acid Bacteria (AAB) titres. These findings position the microbiota, and particularly Wolbachia, as a potentially integral component in host life history evolution, with implications for understanding the microbial contributions to aging and adaptation. SignificanceFruit flies bred for short lifespans consistently lose the bacterial symbiote Wolbachia, while the microbiota of long-lived flies are almost entirely dominated by it. There is a stable, recurring link between this microbe and lifespan, and traits associated with lifespan. This persistent pattern suggests that microbiota, Wolbachia in particular, may play a direct role in shaping the evolution of lifespan.

microbiology↗

bioRxiv2024

Environment and diet shape the geography-specific Drosophila melanogaster microbiota composition

Geographic and environmental variation in the animal microbiota can be directly linked to the evolution and wild fitness of their hosts but often appears to be disordered. Here, we sought to better understand patterns that underlie wild variation in the microbiota composition of Drosophila melanogaster. First, environmental temperature predicted geographic variation in fly microbial communities better than latitude did. The microbiota also differed between wild flies and their diets, supporting previous conclusions that the fly microbiota is not merely a reflection of diet. Flies feeding on different diets varied significantly in their microbiota composition, and flies sampled from individual apples were exceptionally depauperate for the Lactic Acid Bacteria (LAB), a major bacterial group in wild and laboratory flies. However, flies bore significantly more LAB when sampled from other fruits or compost piles. Follow-up analyses revealed that LAB abundance in the flies uniquely responds to fruit decomposition, whereas other microbiota members better indicate temporal seasonal progression. Finally, we show that diet-dependent variation in the fly microbiota is associated with phenotypic differentiation of fly lines collected in a single orchard. These last findings link covariation between the flies dietary history, microbiota composition, and genetic variation across relatively small (single-orchard) landscapes, reinforcing the critical role that environment-dependent variation in microbiota composition can play in local adaptation and genomic differentiation of a model animal host. SIGNIFICANCE STATEMENTThe microbial communities of animals influence their hosts evolution and wild fitness, but it is hard to predict and explain how the microbiota varies in wild animals. Here, we describe that the microbiota composition of wild Drosophila melanogaster can be ordered by temperature, humidity, geographic distance, diet decomposition, and diet type. We show how these determinants of microbiota variation can help explain lactic acid bacteria (LAB) abundance in the flies, including the rarity of LAB in some previous studies. Finally, we show that wild fly phenotypes segregate with the flies diet and microbiota composition, illuminating links between the microbiota and host evolution. Together, these findings help explain how variation in microbiota compositions can shape an animals life history.

microbiology↗

bioRxiv2021

Increased microbial diversity and decreased prevalence of common pathogens in the gut microbiomes of wild turkeys compared to domestic turkeys

Turkeys (Meleagris gallopavo) provide a globally important source of protein and constitute the second most important source of poultry meat in the world. Bacterial diseases are common in commercial poultry production causing significant production losses for farmers. Due to the increasingly recognized problems associated with large-scale/indiscriminant antibiotic use in agricultural settings, poultry producers need alternative methods to control common bacterial pathogens. In this study we compared the cecal microbiota of wild and domestic turkeys, hypothesizing that environmental pressures faced by wild birds may select for a disease-resistant microbial community. Sequence analysis of 16S rRNA genes amplified from cecal samples indicate that free-roaming wild turkeys carry a rich and variable microbiota compared to domestic turkeys raised on large-scale poultry farms. Wild turkeys also had very low levels of Staphylococcus, Salmonella and E. coli when compared to domestic turkeys. E. coli strains isolated from wild or domestic turkey cecal samples also belong to distinct phylogenetic backgrounds and differ in their propensity to carry virulence genes. E. coli strains isolated from factory-raised turkeys were far more likely to carry genes for capsule (kpsII, kpsIII) or siderophore (iroN, fyuA) synthesis than those isolated from wild turkeys. These results suggest that the microbiota of wild turkeys may provide colonization resistance against common poultry pathogens. ImportanceDue to the increasingly recognized problems associated with antibiotic use in agricultural settings, poultry producers need alternative methods to control common bacterial pathogens. In this study we compare the microbiota of wild and domestic turkeys. Results suggest that free ranging wild turkeys carry a distinct microbiome when compared to farm raised turkeys. The microbiome of wild birds contains very low levels of poultry pathogens compared to farm raised birds. The microbiomes of wild turkeys may be used to guide development of new ways to control disease in large scale poultry production.

microbiology↗