Biology subjects

Dorken, M.

Publications and source records attributed to Dorken, M..

4 recordsLinked to original sources

bioRxiv2025

Time in sympatry correlates with the strength of reproductive isolation in hybridising Typha

In North America, hybridisation between Typha angustifolia and T. latifolia results in the highly impactful T. x glauca. In Europe, where its parental taxa are also sympatric, T. x glauca is scarce, suggesting stronger reproductive isolation on this continent. Using genomic data from the two species in North America and Europe, we reconstructed their demographic histories and characterised barrier loci between them. Demographic modelling suggests that the initial contact between the two species in Europe occurred [~]800,000 years ago, indicating sympatry in that region since the Middle Pleistocene. In North America, their contact likely happened within the last centuries and was potentially driven by the human-mediated dispersal of T. angustifolia. We identified 47 candidate barrier loci between species in Europe, 6 of which are associated with reproductive functions. No barrier loci were found in North America. Our results suggest that prolonged sympatry can promote the evolution of reproductive barriers, whereas prolonged allopatry can reduce the likelihood of their development. Future studies could help determine whether time in sympatry is a predictor of the strength of reproductive isolation between hybridising taxa. Preventing invasions by hybrid taxa will require limiting the human-mediated dispersal of Typha (and other allopatric species) lacking reproductive isolation.

genomics↗

bioRxiv2024

Allopatric speciation in cattails: Genomic landscapes of divergence across Typha spp. suggest balancing selection, introgressions, and the absence of adaptive divergence

Understanding how speciation unfolds is a central goal of evolutionary biology. Historically, global climatic fluctuations have triggered allopatric diversification. Using genome-wide data, we reconstructed the phylogenetic relationships and demographic histories of five Typha species, a plant genus foundational to freshwater ecosystems, with widespread, partially sympatric ranges and at least one widespread, regionally invasive hybrid zone (Typha x glauca). Molecular clock and demographic analyses indicate that the species in this study diverged in the absence of gene flow, during periods roughly contemporaneous with population bottlenecks and expansions in Typha--likely triggered by geoclimatic events--and that this divergence was followed by secondary contact in more recent times. Genomic scans showed no evidence of selection with gene flow driving species differentiation, suggesting a minor role for sympatric ecological speciation underlying divergence. These observations are consistent with expectations for drift-driven allopatric speciation. Allopatric speciation in T. latifolia and T. angustifolia, their low genetic differentiation, and the scarcity of ecological divergence in building their reproductive isolation could explain these species ability to hybridise.

evolutionary biology↗

bioRxiv2023

A simple method to genetically differentiate invasive F1 Typha hybrids (T. x glauca) and advanced-generation/backcrossed hybrids from parent species (T. latifolia and T. angustifolia) in eastern Canada and northeastern USA

A widespread Typha (cattail) hybrid zone in southeastern Canada and northeastern USA comprises T. latifolia, T. angustifolia, and their hybrid T. x glauca. In this region the hybrid is considered invasive because of its detrimental impacts on wetlands and biodiversity. Researchers and managers are increasingly interested in tracking and controlling the spread of the invasive hybrid, but this can be hampered by challenges in differentiating taxa: while the parent species and F1 hybrids can often be identified from morphological characteristics, advanced-generation and backcrossed hybrids can be common, and these have obscured morphological distinctions among taxa. Here we present five species-specific genetic markers that differentiate T. latifolia, T. angustifolia, F1 hybrids, and advanced-generation/backcrossed hybrids. Unlike the pre-existing species-specific microsatellite markers, these markers require only PCR or PCR followed by a restriction enzyme digest, and can be visualized on an agarose gel. As a result, they require less specialized equipment than existing species-specific markers, and should therefore be useful for a larger group of practitioners. Future use of these markers could include monitoring range expansions, assessing the outcomes of restoration programs, and avoiding the unnecessary elimination of native Typha.

molecular biology↗

bioRxiv2019

Limited phenological and pollinator-mediated isolation among selfing and outcrossing Arabidopsis lyrata populations

Transitions from outcrossing to selfing have been a frequent evolutionary shift in plants and clearly play a role in species divergence. However, many questions remain about the initial mechanistic basis of reproductive isolation during the evolution of selfing. For instance, how important are prezygotic pre-pollination mechanisms (e.g. changes in phenology and pollinator visitation) in maintaining reproductive isolation between newly arisen selfing populations and their outcrossing ancestors? To test whether changes in phenology and pollinator visitation isolate selfing populations of Arabidopsis lyrata from outcrossing populations, we conducted a common garden experiment with plants from selfing and outcrossing populations as well as their F1 hybrids. Specifically, we asked whether there was isolation between outcrossing and selfing plants and their F1 hybrids through differences in 1) the timing or intensity of flowering; and/or 2) pollinator visitation. We found that phenology largely overlapped between plants from outcrossing and selfing populations. There were also no differences in pollinator preference related to mating system. Additionally, pollinators preferred to visit flowers on the same plant rather than exploring nearby plants, creating a large opportunity for self-fertilization. Overall, this suggests that prezygotic pre-pollination mechanisms do not strongly reproductively isolate plants from selfing and outcrossing populations of Arabidopsis lyrata.

ecology↗