Genetic structure in hybrids and progenitors provides insight into processes underlying an invasive cattail (Typha x glauca) hybrid zone

Traditional models of hybrid zones have assumed relatively low hybrid fitness, and thus focussed more on interspecific gene flow than on hybrid dispersal. Therefore, when hybrids have high fitness and the potential for autonomous dispersal, we have limited understanding of whether hybrid dispersal or repeated local hybrid formation is more important for maintaining hybrid zones. The invasive hybrid cattail Typha × glauca occupies an extensive hybrid zone in northeastern North America where it is sympatric with its progenitors T. latifolia and T. angustifolia. We characterized genetic diversity and genetic structure of the three taxa across a broad spatial scale, and tested the hypothesis that the hybrid shows stronger evidence of gene flow than its progenitor species, particularly among disturbed sites (ditches) compared to established wetlands. Support for this hypothesis would suggest that dispersal, rather than repeated local formation, is more important in maintaining hybrid zones...传统的杂交带（hybrid zone）模型通常假定杂交个体的适合度相对较低，因此更多聚焦于种间基因流而非杂交后代的扩散。因此，当杂交个体具备高适合度且拥有自主扩散潜力时，我们对于究竟是杂交后代扩散还是反复的本地杂交形成更有助于维持杂交带这一问题，认知仍较为有限。入侵性杂交香蒲（Typha × glauca）在北美东北部占据了大面积的杂交带，与其亲本物种宽叶香蒲（T. latifolia）和窄叶香蒲（T. angustifolia）同域分布。我们在大空间尺度上对这三个类群的遗传多样性与遗传结构进行了表征，并检验了如下假说：相较于其亲本物种，该杂交种表现出更强的基因流信号，且相较于成熟湿地，这一差异在受干扰生境（沟渠）中尤为显著。若该假说得到支持，则表明扩散而非反复的本地杂交形成，在杂交带的维持中发挥着更为关键的作用……