Biology subjects

Wunder, J.

Publications and source records attributed to Wunder, J..

4 recordsLinked to original sources

bioRxiv2025

Adaptation to seasonal drought in Arabis alpina is linked to the demographic history and climatic changes since the last glacial maximum

Understanding how species adapt to new environments is a central goal in evolutionary biology, and a topical question in climate change research. Here, we sequenced the genomes of 426 individuals of the perennial, Arctic-alpine herb Arabis alpina to study demography and adaptation, with a focus on populations in Northern Spain, that experience warm and dry summers. Our inference supports a scenario in which A. alpina colonized Northern Spain in a range expansion event that started near the Alps around 216 thousand years ago (kya). During the last glacial episode (115 to 12 kya), this expansion proceeded Westward, and effective population sizes were large across Europe, likely due to a larger suitable habitat for A. alpina. These ancient demographic events gave rise to a highly diverged genetic lineage in Northern Spain. In the present interglacial (between 12 kya and present), populations became increasingly fragmented, and lost genetic diversity across Europe. Furthermore, we detected signatures of selection at genes associated with responses to abiotic stress, including drought stress, and regulation of growth, for instance at SC5D and NAC055, which reflects the climatic changes since the last glacial period. Notably, an ancient polymorphism at the gene FRL1 emerged as a candidate for conferring variation in flowering behavior, and for contributing to adaptation to drought. Our study suggests that the combination of ancestral variation in flowering behavior, and positive selection on new mutations involved in drought responses, underlies the evolution of a new trait syndrome, and adaptation to climate change.

evolutionary biology↗

bioRxiv2024

Synovial Sarcoma Chromatin Dynamics Reveal a Continuum in SS18:SSX Reprograming

Synovial sarcoma (SyS) is an aggressive soft-tissue malignancy characterized by a pathognomonic chromosomal translocation leading to the formation of the SS18::SSX fusion oncoprotein. SS18::SSX associates with mammalian BAF complexes suggesting deregulation of chromatin architecture as the oncogenic driver in this tumour type. To examine the epigenomic state of SyS we performed comprehensive multi-omics analysis on 52 primary pre-treatment human SyS tumours. Our analysis revealed a continuum of epigenomic states across the cohort at fusion target genes independent of rare somatic genetic lesions. We identify cell-of-origin signatures defined by enhancer states and reveal unexpected relationships between H2AK119Ub1 and active marks. The number of bivalent promoters, dually marked by the repressive H3K27me3 and activating H3K4me3 marks, has strong prognostic value and outperforms tumor grade in predicting patient outcome. Finally, we identify SyS defining epigenomic features including H3K4me3 expansion associated with striking promoter DNA hypomethylation in which SyS displays the lowest mean methylation level of any sarcoma subtype. We explore these distinctive features as potential vulnerabilities in SyS and identify H3K4me3 inhibition as a promising therapeutic strategy.

cancer biology↗

bioRxiv2019

Microclimate predicts frost-hardiness of alpine Arabidopsis thaliana populations better than altitude because the microclimate effect increases with altitude

O_LIIn mountain regions average temperatures decrease at higher altitudes. In addition, microenvironmental conditions can strongly affect microclimate and may counteract average effects of altitude. C_LIO_LIWe investigated winter frost hardiness of Arabidopsis thaliana accessions originating from 13 sites along altitudinal gradients in the Southern Alps during three winters on an experimental field station on the Swabian Jura and compared levels of frost damage with the observed number of frost days (<1{degrees}C) in eight collection sites. C_LIO_LIWe found that frost-hardiness increased with altitude in a log-linear fashion. This is consistent with adaptation to higher frequency of frost conditions, but also indicates a decreasing rate of change in frost hardiness with increasing altitude. Moreover, the number of frost days measured with temperature loggers at the original collection sites correlated much better with frost-hardiness than the altitude of collection sites, suggesting that populations were adapted to their local microclimate. Notably, the variance in frost days across sites increased exponentially with altitude. C_LIO_LITogether, our results suggest that strong microclimate heterogeneity of high alpine environments may preserve functional genetic diversity in small populations. This challenges the suitability of habitat predictions based on large scale climatic variables (or proxies, such as altitude) for topographically complex areas. C_LI

evolutionary biology↗

bioRxiv2017

Demography And Mating System Shape The Genome-Wide Impact Of Purifying Selection In Arabis alpina

Plant mating systems have profound effects on levels and structuring of genetic variation, and can affect the impact of natural selection. While theory predicts that intermediate outcrossing rates may allow plants to prevent accumulation of deleterious alleles, few studies have empirically tested this prediction using genomic data. Here, we study the effect of mating system on purifying selection by conducting population genomic analyses on whole-genome resequencing data from 38 European individuals of the arctic-alpine crucifer Arabis alpina. We find that outcrossing and mixed-mating populations maintain genetic diversity at similar levels, whereas highly self-fertilizing Scandinavian A. alpina show a strong reduction in genetic diversity, most likely as a result of a postglacial colonization bottleneck. We further find evidence for accumulation of genetic load in highly self-fertilizing populations, whereas the genome-wide impact of purifying selection does not differ greatly between mixed-mating and outcrossing populations. Our results demonstrate that intermediate levels of outcrossing may allow efficient selection against harmful alleles whereas demographic effects can be important for relaxed purifying selection in highly selfing populations. Thus, both mating system and demography shape the impact of purifying selection on genomic variation in A. alpina. These results are important for an improved understanding of the evolutionary consequences of mating system variation and the maintenance of mixed-mating strategies.\n\nSignificanceIntermediate outcrossing rates are theoretically predicted to maintain effective selection against harmful alleles, but few studies have empirically tested this prediction using genomic data. We used whole-genome resequencing data from alpine rock-cress to study how genetic variation and purifying selection vary with mating system. We find that populations with intermediate outcrossing rates have similar levels of genetic diversity as outcrossing populations, and that purifying selection against harmful alleles is efficient in mixed-mating populations. In contrast, self-fertilizing populations from Scandinavia have strongly reduced genetic diversity, and accumulate harmful mutations, likely as a result of demographic effects of postglacial colonization. Our results suggest that mixed-mating populations can avoid the negative evolutionary consequences of high self-fertilization rates.

evolutionary biology↗