Skeels Alexander, Dinnage Russell, Medina Iliana, Cardillo Marcel
Division of Ecology and Evolution, Research School of Biology Australian National University Canberra ACT 0200 Australia.
Landscape Ecology, Institute of Terrestrial Ecosystems, Department of Environmental Systems Science ETH Zürich Zürich CH-8092 Switzerland.
Evol Lett. 2021 Apr 28;5(3):277-289. doi: 10.1002/evl3.225. eCollection 2021 Jun.
Processes driving the divergence of floral traits may be integral to the extraordinary richness of flowering plants and the assembly of diverse plant communities. Several models of pollinator-mediated floral evolution have been proposed; floral divergence may (i) be directly involved in driving speciation or may occur after speciation driven by (ii) drift or local adaptation in allopatry or (iii) negative interactions between species in sympatry. Here, we generate predictions for patterns of trait divergence and community assembly expected under these three models, and test these predictions in (Proteaceae), a diverse genus in the Southwest Australian biodiversity hotspot. We quantified functional richness for two key floral traits (pistil length and flower color), as well as phylogenetic distances between species, across ecological communities, and compared these to patterns generated from null models of community assembly. We also estimated the statistical relationship between rates of trait evolution and lineage diversification across the phylogeny. Patterns of community assembly suggest that flower color, but not floral phenology or morphology, or phylogenetic relatedness, is more divergent in communities than expected. Rates of lineage diversification and flower color evolution were negatively correlated across the phylogeny and rates of flower colour evolution were positively related to branching times. These results support a role for diversity-dependent species interactions driving floral divergence during the Hakea radiation, contributing to the development of the extraordinary species richness of southwest Australia.
推动花部性状分化的过程可能是开花植物异常丰富性和多样植物群落形成的重要组成部分。已经提出了几种传粉者介导的花部进化模型；花部分化可能（i）直接参与推动物种形成，或者可能在物种形成之后发生，这是由（ii）异域分布中的遗传漂变或局部适应，或（iii）同域分布中物种间的负相互作用所驱动的。在这里，我们针对这三种模型下预期的性状分化模式和群落组装生成预测，并在哈克木属（山龙眼科）中对这些预测进行检验，哈克木属是澳大利亚西南部生物多样性热点地区的一个多样化属。我们量化了两个关键花部性状（雌蕊长度和花色）的功能丰富度，以及跨生态群落的物种间系统发育距离，并将这些与群落组装的零模型所产生的模式进行比较。我们还估计了整个系统发育中性状进化速率与谱系多样化速率之间的统计关系。群落组装模式表明，群落中的花色比预期更具分化性，而花期物候、形态或系统发育相关性并非如此。在整个系统发育中，谱系多样化速率与花色进化速率呈负相关，花色进化速率与分支时间呈正相关。这些结果支持了在哈克木辐射过程中，依赖多样性的物种相互作用推动花部分化的作用，这有助于澳大利亚西南部非凡的物种丰富度的发展。
