Biology subjects

Jonsson, P. R.

Publications and source records attributed to Jonsson, P. R..

3 recordsLinked to original sources

bioRxiv2023

Local adaptation of a marine diatom is governed by genome-wide changes in diverse metabolic processes

Marine phytoplankton play essential roles in global primary production and biogeochemical cycles. Yet, the evolutionary genetic underpinnings of phytoplankton adaptation to complex marine and coastal environments, where many environmental variables fluctuate and interact, remain unclear. We combined population genomics data with experimental transcriptomics to investigate the genomic basis underlying a natural evolutionary experiment that has played out over the past 8,000 years in one of the worlds largest brackish water bodies: the colonization of the Baltic Sea by the marine diatom Skeletonema marinoi. To this end, we used a novel approach for protist population genomics, combining target capture of the entire nuclear genome with pooled sequencing, and showed that the method performs well on both cultures and single cells. Genotype-environment association analyses identified >3,000 genes with signals of selection in response to major environmental gradients in the Baltic Sea, which apart from salinity, include marked differences in temperature and nutrient availability. Locally adapted genes were related to diverse metabolic processes, including signal transduction, cell cycle, DNA methylation, and maintenance of homeostasis. The locally adapted genes showed significant overlap with salinity-responsive genes identified in a laboratory common garden experiment, suggesting the Baltic salinity gradient is a major factor driving local adaptation of S. marinoi. Altogether, our data show that local adaptation of phytoplankton to complex coastal environments, which are characterized by a multitude of environmental gradients, is driven by intricate changes in diverse metabolic pathways and functions.

microbiology↗

bioRxiv2020

Ecological success of sexual and asexual reproductive strategies invading an environmentally unstable habitat

Many aspects of sexual and asexual reproduction have been studied empirically and theoretically. The differences between sexual and asexual reproduction within a species often lead to a biased geographical distribution of individuals with different reproductive strategies. While sexuals are more abundant in the core habitat, asexuals are often found in marginal habitats along the edge of the species distribution. This pattern, called geographic parthenogenesis, has been observed in many species but the mechanisms reponsible for generating it are poorly known. We used a quantitative approach using a metapopulation model to explore the ecological processes that can lead to geographic parthenogenesis and the invasion of new habitats by different reproductive strategies. We analyzed the Allee effect on sexual populations and the population sensitivity to environmental stress during the invasion of a marginal, unstable habitat to demonstrate that a complex interaction between the Allee effect, sensitivity to environmental stress and the environmental conditions can determine the relative success of competing reproductive strategies during the initial invasion and longterm establishment in the marginal habitat. We discuss our results in the light of previous empirical and theoretical studies. Author SummaryIndividuals can reproduce with or without sex. Very often, closely related species are distributed in a such a way that the sexually reproducing species is most frequently found in the core habitat while the asexually reproducing species is found on the edge of the habitat range. This biased distribution of reproductive strategies across a habitat range is called geographic parthenogenesis and has been observed in several species. While many processes have been proposed to explain such a pattern, a quantitative approach of the ecological processes was absent. We investigated important differences between sexual and asexual reproduction and how these differences affect the success of sexuals and asexuals invading a marginal, unstable environment. We showed that the relative frequency of each reproductive strategy in the marginal habitat depends on how much sexuals rely on population density to reproduce and how much asexuals are affected by environmental stress relative to sexuals. Our study presents a quantitative ecological explanation for geographic parthenogenesis and provides the conditions under which different distribution patterns can emerge.

ecology↗

bioRxiv2019

Strong spatial genetic structure in a Baltic Sea herbivore due to recent range expansion, multiple bottlenecks and low connectivity

In the Baltic Sea, recent range expansions following the opening of the Danish straits have resulted in a low-diversity ecosystem, both among and within species. However, relatively little is known about population genetic patterns within the basin, except for in a few commercially caught species and some primary producers thought to be ecosystem engineers. Here, we investigate the population genetic structure of the ecologically important crustacean Idotea balthica throughout the Baltic Sea using an array of 33,774 genome-wide SNP markers derived from 2b-RAD sequencing. We also generate a biophysical connectivity matrix, with which we compare the genomic data. We find strong population structure on small scales across the Baltic Sea, and that genomic patterns in most cases closely match biophysical connectivity, suggesting that current patterns are important for dispersal of this species. We also find a strong signal of multiple bottlenecks during the initial range expansion, in the form of reduced heterozygosity along the historical expansion front. The lack of gene flow among sampling sites in the Baltic Sea environmental gradient potentiates local adaptation, while at the same time also increasing genetic drift in low-diversity areas.

evolutionary biology↗