Biology subjects

Kerns, E. V.

Publications and source records attributed to Kerns, E. V..

4 recordsLinked to original sources

bioRxiv2025

Heritable differences in metabolic stability underpin thermal tolerance of threespine stickleback (Gasterostues aculeatus) ecotypes

Understanding how organisms adapt to divergent thermal conditions can inform efforts to preserve biodiversity in a warming world. Change in aerobic scope (AS)-total energy available to perform tasks outside of homeostasis-is an ecologically relevant predictor of performance across a range of temperatures. Mathematical models suggest that the shape of AS-temperature curves should evolve depending on environmental heterogeneity, but few studies have tested whether this occurs at the intraspecific level. We examined AS-temperature associations across two ecotypes of threespine stickleback fish (Gasterosteus aculeatus), including both short- and long-term heat treatments. We predicted that fish from shallow, thermally dynamic lakes would display greater AS stability at high temperatures than residents of deep, thermally stable lakes. We also tested whether heat and AS are correlated with variation in a fibrotic immune response after exposure to the cestode Schistocephalus solidus. We found few heat-associated differences in condition or immunity, but fibrosis decreased AS. Additionally, limnetic AS declined with heat and this shift was correlated with mortality. In contrast, benthic ecotypes displayed remarkable stability in AS and survival across temperatures. Connecting intraspecific variation in AS with local thermal environments is a promising avenue for estimating, and potentially fostering, population resilience to warming climates.

evolutionary biology↗

bioRxiv2025

Egg hatching in the cestode Schistocephalus solidus shows no evidence of quorum sensing

Schistocephalus solidus is a parasitic cestode with a complex, multi-host life cycle. S. solidus reproduces in its terminal host either by exchanging gametes with similarly sized individuals or selfing. Fertilized eggs then pass through the feces of the host and hatch at the bottom of freshwater lakes. Previous work found that selfing greatly depresses egg hatching rates, presumably as a result of inbreeding depression. We predicted that S. solidus may have evolved quorum sensing (QS) during hatching as a mechanism to facilitate synchronized infection, thereby increasing the opportunity for outcrossing in its terminal host. We tested whether density-dependent hatch rates were present across three parasite populations, examining both outcrossed and selfed progeny. We predicted that if QS was present, it would be common across all populations, and that increasing egg density would result in higher hatching rates. We also expected that outcrossed eggs would hatch at higher rates than those produced via selfing. While we found different hatching rates between populations, there was no effect of egg density. Selfed eggs did hatch at significantly lower rates than outcrossed eggs, replicating previous findings. Although we failed to find density dependent hatching in our limited sample, we conclude by discussing the conditions in which QS may evolve in isolated S. solidus populations.

evolutionary biology↗

bioRxiv2025

Variable performance of widely used bisulfite sequencing methods and read mapping software for DNA methylation

DNA methylation (DNAm) is the most commonly studied marker in ecological epigenetics, yet the performance of library preparation strategies and bioinformatic tools are seldom assessed in genetically variable natural populations. We profiled DNAm in threespine stickleback (Gasterosteus aculeatus) liver tissue, using reduced representation bisulfite sequencing (RRBS) and whole genome bisulfite sequencing (WGBS) across technical and biological replicates. We additionally collated publicly available RRBS and WGBS data from taxonomically diverse organisms, and then compared how the most commonly used methylation software (Bismark) performed relative to alternative pipelines (BWA meth, BiSulfite Bolt, and Biscuit). Even after choosing parameters to maximize Bismarks mapping efficiency, it was still outperformed by all other methods. Surprisingly, newer tools overrepresented DNAm compared to older methods, highlighting the importance of testing methods on nonmodel organisms. There were also distinct differences in DNAm profiles produced across library preparation methods, with large impacts of population and read depth filters. Methylated sites unique to WGBS predominantly mapped to introns and intergenic regions, while sites unique to RRBS primarily overlapped with promoters and exons. Moreover, the prevalence of nucleotides with intermediate methylation (within individuals) was greatly reduced in RRBS. Together, this suggests that RRBS may be more useful for detecting functionally-relevant methylation differences. Based on these results, we provide methodological recommendations for improving the reliability and utility of DNAm profiles, particularly concerning the detection of functionally relevant DNAm differences in genetically diverse natural populations.

bioinformatics↗

bioRxiv2024

Destabilized host-parasite dynamics in newly founded populations

When species disperse into previously unoccupied habitats, new populations encounter unfamiliar species interactions such as altered parasite loads. Theory predicts that newly founded populations should exhibit destabilized eco-evolutionary fluctuations in infection rates and immune traits. However, to understand founder effects biologists typically rely on retrospective studies of range expansions, missing early-generation infection dynamics. To remedy this, we experimentally founded whole-lake populations of threespine stickleback. Infection rates were temporally stable in native source lakes. In contrast, newly founded populations exhibit destabilized host-parasite dynamics: high starting infection rates led to increases in a heritable immune trait (peritoneal fibrosis), suppressing infection rates. The resulting temporal auto-correlation between infection and immunity suggest that newly founded populations can exhibit rapid host-parasite eco-evolutionary dynamics.

evolutionary biology↗