ORCID Profile
0000-0002-7221-7482
Current Organisation
Universität Wien
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Publisher: Springer Science and Business Media LLC
Date: 18-05-2011
DOI: 10.1038/HDY.2011.35
Publisher: Wiley
Date: 12-05-2016
DOI: 10.1002/ECE3.2171
Publisher: Wiley
Date: 04-2010
Publisher: The Royal Society
Date: 13-07-2020
Abstract: Many recent studies have addressed the mechanisms operating during the early stages of speciation, but surprisingly few studies have tested theoretical predictions on the evolution of strong reproductive isolation (RI). To help address this gap, we first undertook a quantitative review of the hybrid zone literature for flowering plants in relation to reproductive barriers. Then, using Populus as an exemplary model group, we analysed genome-wide variation for phylogenetic tree topologies in both early- and late-stage speciation taxa to determine how these patterns may be related to the genomic architecture of RI. Our plant literature survey revealed variation in barrier complexity and an association between barrier number and introgressive gene flow. Focusing on Populus, our genome-wide analysis of tree topologies in speciating poplar taxa points to unusually complex genomic architectures of RI, consistent with earlier genome-wide association studies. These architectures appear to facilitate the ‘escape’ of introgressed genome segments from polygenic barriers even with strong RI, thus affecting their relationships with recombination rates. Placed within the context of the broader literature, our data illustrate how phylogenomic approaches hold great promise for addressing the evolution and temporary breakdown of RI during late stages of speciation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
Publisher: Wiley
Date: 09-10-2019
DOI: 10.1111/NPH.16180
Publisher: Wiley
Date: 12-2004
DOI: 10.1111/J.0014-3820.2004.TB01621.X
Abstract: Leaf ecophysiological traits related to carbon gain and resource use are expected to be under strong selection in desert annuals. We used comparative and phenotypic selection approaches to investigate the importance of leaf ecophysiological traits for Helianthus anomalus, a diploid annual sunflower species of hybrid origin that is endemic to active desert dunes. Comparisons were made within and among five genotypic classes: H. anomalus, its ancestral parent species (H. annuus and H. petiolaris), and two backcrossed populations of the parental species (designated BC2ann and BC2pet) representing putative ancestors of H. anomalus. Seedlings were transplanted into H. anomalus habitat at Little Sahara Dunes, Utah, and followed through a summer growing season for leaf ecophysiological traits, phenology, and fitness estimated as vegetative biomass. Helianthus anomalus had a unique combination of traits when compared to its ancestral parent species, suggesting that lower leaf nitrogen and greater leaf succulence might be adaptive. However, selection on leaf traits in H. anomalus favored larger leaf area and greater nitrogen, which was not consistent with the extreme traits of H. anomalus relative to its ancestral parents. Also contrary to expectation, current selection on the leaf traits in the backcross populations was not consistently similar to, or resulting in evolution toward, the current H. anomalus phenotype. Only the selection for greater leaf succulence in BC2ann and greater water-use efficiency in BC2pet would result in evolution toward the current H. anomalus phenotype. It was surprising that the action of phenotypic selection depended greatly on the genotypic class for these closely related sunflower hybrids grown in a common environment. We speculate that this may be due to either phenotypic correlations between measured and unmeasured but functionally related traits or due to the three genotypic classes experiencing the environment differently as a result of their differing morphology.
Publisher: University of Chicago Press
Date: 08-2004
DOI: 10.1086/422223
Publisher: Wiley
Date: 04-06-2023
DOI: 10.1111/MEC.17034
Abstract: Speciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide ersity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as progression through time by using a series of species pairs along a ergence gradient. Here, we resequenced 201 whole‐genomes from eight closely related Populus species, with pairs of species at different stages along the ergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within‐species (i.e. nucleotide ersity and recombination rate) and among‐species (i.e. relative and absolute ergence) summary statistics of ersity and ergence. We observe relatively conserved patterns of genomic ergence across species pairs. Independent of the stage across the ergence gradient, we find support for signatures of linked selection (i.e. the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a ergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of ersity and differentiation.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Christian Lexer.