Biology subjects

Ruokolainen, L.

Publications and source records attributed to Ruokolainen, L..

3 recordsLinked to original sources

bioRxiv2021

Within-species trait diversity reorganizes consumer competitive hierarchy and prey community structure in an experimental microbial ecosystem

A popular idea in ecology is that trait variation among individuals from the same species may promote the coexistence of competing species. However, theoretical and empirical tests of this idea have yielded inconsistent findings. We manipulated intraspecific trait diversity in a ciliate competing with a nematode for bacterial prey in experimental microcosms. We found that intraspecific trait variation inverted the original competitive hierarchy to favor the consumer with variable traits, ultimately resulting in competitive exclusion. This competitive outcome was driven by foraging traits (size, speed, and directionality) that increased the ciliates fitness ratio and niche overlap with the nematode. The interplay between consumer trait variation and competition resulted in non-additive cascading effects - mediated through prey defense traits - on prey community assembly. Our results suggest that predicting consumer competitive population dynamics and the assembly of prey communities will require understanding the complexities of trait variation within consumer species.

ecology↗

bioRxiv2020

Ten-year projection of white-nose syndrome disease dynamics at the southern leading-edge of infection in North America

Predicting the emergence and spread of infectious diseases is critical for effective conservation of biodiversity. White-nose syndrome (WNS), an emerging infectious disease of bats, has resulted in high mortality in eastern North America. Because the fungal causative agent Pseudogymnoascus destructans is constrained by temperature and humidity, spread dynamics may vary greatly by geography. Environmental conditions in the southern part of the continent, where disease dynamics are typically studied, making it difficult to predict how the disease will manifest. Herein, we modeled the spread of WNS in Texas based on available cave densities and average dispersal distances of species occupying these sites, and projected these results out to 10 years. We parameterized a predictive model of WNS epidemiology and its effects on hibernatory bat populations with observed environmental data from bat hibernation sites in Texas. Our model suggests that bat populations in northern Texas will be more affected by WNS mortality than southern Texas. As such, we recommend prioritizing the preservation of large overwintering colonies of bats in north Texas through management actions. Our model further illustrates that infectious disease spread and infectious disease severity can become uncoupled over a gradient of environmental variation. Finally, our results highlight the importance of understanding host, pathogen and environmental conditions in various settings to elucidate what may happen across a breadth of environments.

ecology↗

bioRxiv2020

Industrialization is associated with elevated rates of horizontal gene transfer in the human microbiome

Horizontal Gene Transfer, the process by which bacteria acquire new genes and functions from non-parental sources, is common in the human microbiome 1,2. If the timescale of HGT is rapid compared to the timescale of human colonization, then it could have the effect of personalizing bacterial genomes by providing incoming strains with the genes necessary to adapt to the diet or lifestyle of a new host. The extent to which HGT occurs on the timescale of human colonization, however, remains unclear. Here, we analyzed 6,188 newly isolated and sequenced gut bacteria from 34 individuals in 9 human populations, and show that HGT is more common among bacteria isolated from the same human host, indicating that the timescale of transfer is short compared to the timescale of human colonization. Comparing across 9 human populations reveals that high rates of transfer may be a recent development in human history linked to industrialization and urbanization. In addition, we find that the genes involved in transfer reflect the lifestyle of the human hosts, with elevated transfer of carbohydrate metabolism genes in hunter gatherer populations, and transfer of antibiotic resistance genes among pastoralists who live in close contact with livestock. These results suggest that host-associated bacterial genomes are not static within individuals, but continuously acquire new functionality based on host diet and lifestyle.

microbiology↗