Data from: Comparative analysis indicates historical persistence and contrasting contemporary structure in sympatric woody perennials of semi-arid southwest Western Australia

We used a comparative approach to assess congruence of phylogeographic and genetic structure and diversity, demographic signals, and ratios of pollen to seed dispersal, in the context of species specific life history traits, for two widespread sympatric perennial plant species. We sampled Grevillea paradoxa and Melaleuca nematophylla across the species’ ranges throughout the Transitional Rainfall Zone and extending slightly into the Arid Zone of Southwest Western Australia. Both species exhibited range-wide phylogeographic and contemporary genetic structure. Moderate haplotype diversity centred in populations on Banded Iron Formation (BIF) outcrops and within the Murchison River gorge supports a hypothesis of historical persistence and evolution in these mesic refugia. These features are likely to play important roles in evolutionary persistence with ongoing climate change. There was little evidence of particularly complex demographic histories for the region. More limited haplotype diversity, as well as more limited nuclear genetic diversity and connectivity in G. paradoxa was consistent with predictions from life history traits of shorter life span, lower fecundity, more limited seed dispersal and shorter plants, but inconsistent with a prediction of greater pollen dispersal by bird pollinators. Low pollen to seed dispersal ratios suggest seed dispersal plays a greater than expected role in maintaining connectivity in this semi-arid landscape. The study highlights a need for research that integrates aspects of seed ecology and seed and pollen dispersal as well as phylogeographic and genetic patterns in Gondwanan shrublands and other semi-arid landscapes globally.

本研究采用比较研究方法，针对两种广布同域多年生植物物种，结合物种特异性生活史性状，评估其系统地理（phylogeographic）结构与遗传多样性、种群动态信号以及花粉与种子扩散比率的一致性。我们在两个物种的全分布范围内开展采样，覆盖西澳大利亚西南部的过渡降雨带（Transitional Rainfall Zone），并略微延伸至该区域的干旱区（Arid Zone），采样对象为Grevillea paradoxa与Melaleuca nematophylla。两个物种均呈现出全分布范围的系统地理结构与当代遗传结构。以条带含铁建造（Banded Iron Formation, BIF）露头区域及默奇森河峡谷内种群为中心的中等单倍型多样性，支持了这些湿润避难所曾存在历史存续与演化的假说。这些特征在持续气候变化背景下，可能对物种的演化存续发挥重要作用。该区域的种群动态历史并无显著复杂的迹象。Grevillea paradoxa的单倍型多样性、核遗传多样性及遗传连通性均更为有限，这与其寿命较短、繁殖力较低、种子扩散范围有限以及植株更矮小的生活史性状预测相符，但与“鸟类传粉者可实现更大范围花粉扩散”的预测相悖。较低的花粉-种子扩散比率表明，在这片半干旱景观中，种子扩散在维持种群连通性方面的作用超出预期。本研究强调，有必要开展整合种子生态学、种子与花粉扩散机制，以及系统地理与遗传格局的相关研究，以推动全球冈瓦纳灌丛及其他半干旱景观的相关科研工作。