A low-latitude species pump: Peripheral isolation, parapatric speciation and mating-system evolution converge in a marine radiation

Geologically recent radiation can shed light on speciation processes, but incomplete lineage sorting and introgressive gene flow render accurate evolutionary reconstruction and interpretation challenging. Independently evolving metapopulations of low-dispersal taxa may provide an additional level of phylogeographic information, given sufficiently broad sampling and genome-wide sequencing. Evolution in the marine brown algal genus Fucus in the south-eastern Atlantic was shaped by Quaternary climate-driven range shifts. Over this timescale, divergence and speciation occurred against a background of expansion-contraction cycles from multiple refugia, together with mating-system shifts from outcrossing (dioecy) to selfing hermaphroditism. We tested the hypothesis that peripheral isolation of range edge (dioecious) F. vesiculosus led to parapatric speciation and radiation of hermaphrodite lineages. Species tree methods using 876 single-copy nuclear genes and extensive geographic coverage pro...地质年代较近的物种辐射分化可为物种形成过程提供研究视角，但不完全谱系分选（incomplete lineage sorting）与渐渗基因流（introgressive gene flow）仍给精准的演化重建与解读带来挑战。若采样范围足够广泛且开展全基因组测序，低扩散类群的独立演化集合种群（metapopulations）可提供额外层级的系统地理学信息。东南大西洋海域的海洋褐藻属墨角藻（Fucus）的演化进程由第四纪气候驱动的分布范围变迁所塑造。在此时间尺度下，多重避难所驱动的扩张-收缩循环背景中发生了物种分化与形成，同时伴随交配系统从异交（雌雄异株，dioecy）向自交雌雄同体的转变。本研究检验了下述假说：分布边缘的雌雄异株F. vesiculosus的周边隔离引发了邻域物种形成与雌雄同体谱系的辐射分化。研究采用基于876个单拷贝核基因的物种树分析方法，并结合广泛的地理采样覆盖度，对……