Biology subjects

Zufall, R.

Publications and source records attributed to Zufall, R..

7 recordsLinked to original sources

bioRxiv2025

Temperature stress disrupts reciprocal adaptation in a microbial predator-prey system

Antagonist interactions, such as predator-prey interactions, are widespread in nature and drive both ecological and evolutionary outcomes. Coevolutionary outcomes of antagonistic interactions have been shown to be influenced by environmental conditions, yet the role of abiotic stress in modifying these outcomes remains insufficiently understood. Here we explored how the addition of temperature stress altered evolutionary trajectories of traits of both species in the Pseudomonas fluorescens - Tetrahymena pyriformis (bacteria-ciliate) predator prey system. We found that temperature stress impeded the evolution of traits important for antagonistic interactions in both species. Prey defense levels as well as predators ability to eat prey were limited under temperature stress. We also found that the addition of temperature stress altered growth rate evolution in evolving populations of both species. Taken together, our results show that temperature stress not only alters the evolutionary trajectories of both predator and prey traits but also hinders their coevolution. These findings suggest that environmental stressors may weaken reciprocal coevolution which could have important consequences for the stability and persistence of ecological communities.

evolutionary biology↗

bioRxiv2025

Rapid Adaptation to Road Salts in a Freshwater Microbial Eukaryote

Humans are changing habitat for wildlife in myriad ways and for populations to persist, they must adapt to this change. In parts of the world that experience snow and ice, road salts are often used to make driving safer in the winter. Runoff from these roads increases the salinity in nearby bodies of water, which has been shown to have detrimental physiological and ecological effects in freshwater ecosystems; however, the evolutionary consequences of salinization remain unclear. Tetrahymena are microbial eukaryotes that live in freshwater habitats and serve as an important link in the microbial food loop. In this study, we test how T. thermophila can evolve in response to increasing concentrations of road salts in their environment. Using experimental evolution, we found that T. thermophila adapt quickly to survive and grow better in increasing salinity. However, populations adapted to the highest salt concentrations experience fitness tradeoffs in salt-free environments. These results demonstrate the rapidity with which microbial populations can respond to anthropogenic changes to their environment, yet highlight the potential costs associated with this adaptation.

evolutionary biology↗

bioRxiv2024

Rapid adaptive evolution of microbial thermal performance curves

Microbial respiration is a key biotic driver of climate change. Warming boosts microbial population growth, which increases biomass and respiration. This feedback might be disrupted by adaptation in thermal performance curves (TPCs) -whose shape describes how temperature drives growth. In this study, we uncover substantial genetic variation (G) in microbial intrinsic population growth rates (r), demonstrate a causal link between G variation in r and G variation in TPC shape, and show how this variation constrains r-TPC shape evolution along specific evolutionary paths across temperatures. We also uncover Gene-by-Environment (G x E) variation in r, which results in specific signatures in TPC shape and predictable temperature-dependent rapid TPC evolution but also lower G, which could reduce future evolutionary potential. Overall, we show how temperature-dependent evolution in a linchpin of global ecosystem function--microbial TPC shape--is determined by a combination of heritable and non-heritable variation in intrinsic growth rates.

ecology↗

bioRxiv2022

Comparing evolvability and pleiotropy across environments

The environment can play an important role in determining evolutionary outcomes (Reboud and Bell 1997; Stanton et al. 2000; Gresham et al. 2008; Cooper and Lenski 2010; Becks and Agrawal 2012; Bailey et al. 2015). Populations may increase in fitness more after evolution in one environment than in another (Hegreness et al. 2008). This may be because the distance between the ancestral genotype and the top of the locally accessible fitness peak may be greater in one environment or the other. Additionally, the rate at which mutations occur and populations move up the peaks could differ. For this reason, comparing evolvability across environments presents an interesting problem. Here, we show an environment impacts evolvability in two ways, directly by impacting the rate of adaptative evolution, and indirectly by limiting the range of fitness outcomes that are possible. We show that correlated responses are often highly idiosyncratic, due to variation in the range of possible fitness outcomes in the environment and differences in pleiotropic effects across environments but can also be predicted from the ancestral growth rate regardless of the environment in which populations evolve. Interestingly, we also show a negative correlation between increase in an environment X following evolution in environment Y and the increase in environment Y following evolution in environment X. These results highlight the necessity to measure fitness in both environments when comparing the evolvability or repeatability of evolution across environments.

evolutionary biology↗

bioRxiv2021

Sex, amitosis, and evolvability in the ciliate Tetrahymena thermophila

Understanding the mechanisms that generate genetic variation, and thus contribute to the process of adaptation, is a major goal of evolutionary biology. Mutation and genetic exchange have been well studied as mechanisms to generate genetic variation. However, there are additional processes that may also generate substantial genetic variation in some populations and the extent to which these variation generating mechanisms are themselves shaped by natural selection is still an open question. Tetrahymena thermophila is a ciliate with an unusual mechanism of nuclear division, called amitosis, which can generate genetic variation among the asexual descendants of a newly produced sexual progeny. We hypothesize that amitosis thus increases the evolvability of newly produced sexual progeny relative to species that undergo mitosis. To test this hypothesis, we used experimental evolution and simulations to compare the rate of adaptation in T. thermophila populations founded by a single sexual progeny to parental populations that had not had sex in many generations. The populations founded by a sexual progeny adapted more quickly than parental populations in both laboratory populations and simulated populations. This suggests that the additional genetic variation generated by amitosis of a heterozygote can increase the rate of adaptation following sex and may help explain the evolutionary success of the unusual genetic architecture of Tetrahymena and ciliates more generally.

evolutionary biology↗

bioRxiv2020

Temperature affects the repeatability of evolution in the microbial eukaryote Tetrahymena thermophila

Evolutionary biologists have long sought to understand what factors affect the repeatability of adaptive outcomes. To better understand the role of temperature in determining the repeatability of adaptive trajectories, we evolved populations of different genotypes of the ciliate Tetrahymena thermophila at low and high temperatures and followed changes in growth rate over 4,000 generations. As expected, growth rate increased with a decelerating rate for all populations; however, there were differences in the patterns of evolution at the two temperatures. The growth rates of the different genotypes converged as evolution proceeded at both temperatures, but this convergence was quicker at the higher temperature. Likewise, we found greater repeatability of evolution, in terms of change in growth rate, among replicates of the same genotype at the higher temperature. Finally, we found no evidence of trade-offs in fitness between temperatures, but did observe asymmetry in the correlated responses, whereby evolution in a high temperature increases growth rate at the lower temperature significantly more than the reverse. These results demonstrate the importance of temperature in determining the repeatability of evolutionary trajectories.

evolutionary biology↗

bioRxiv2017

accuMUlate: A mutation caller designed for mutation accumulation experiments

MotivationMutation accumulation (MA) is the most widely used method for directly studying the effects of mutation. Modern sequencing technologies have led to an increased interest in MA experiments. By sequencing whole genomes from MA lines, researchers can directly study the rate and molecular spectra of spontaneous mutations and use these results to understand how mutation contributes to biological processes. At present there is no software designed specifically for identifying mutations from MA lines. Studies that combine MA with whole genome sequencing use custom bioinformatic pipelines that implement heuristic rules to identify putative mutations.\n\nResultsHere we describe O_SCPLOWACCUC_SCPLOWMUO_SCPLOWLATEC_SCPLOW, a program that is designed to detect mutations from MA experiments. O_SCPLOWACCUC_SCPLOWMUO_SCPLOWLATEC_SCPLOW implements a probabilistic model that reflects the design of a typical MA experiments while being flexible enough to accommodate properties unique to any particular experiment. For each putative mutation identified from this model O_SCPLOWACCUC_SCPLOWMUO_SCPLOWLATEC_SCPLOW calculates a set of summary statistics that can be used to filter sites that may be false positives. A companion tool, O_SCPLOWDENOMINATEC_SCPLOW, can be used to apply filtering rules based on these statistics to simulated mutations and thus identify the number of callable sites per sample.\n\nAvailabilitySource code and releases available from https://github.com/dwinter/accuMUlate.

bioinformatics↗