Data from: Remarkable life history polymorphism may be evolving under divergent selection in the silverleaf sunflower

Substantial intraspecific variation in life history is rare and potentially a signal of incipient ecological speciation, if variation is driven by geographically heterogenous natural selection. We present the first report of extensive life history polymorphism in Helianthus argophyllus, the silverleaf sunflower, and examine evidence for its evolution by divergent selection. In 18 populations sampled from across the species range and grown in a common garden, most quantitative traits covaried such that individuals could be assigned to two distinct life history syndromes: tall and late flowering with small initial flowerheads, or short and early flowering with larger initial flowerheads. Helianthus argophyllus exhibits regional genetic structure, but this population structure does not closely correspond with patterns of phenotypic variation. The early-flowering syndrome is primarily observed in populations from coastal barrier islands, while populations from the nearby mainland coast, although geographically and genetically close, are primarily late flowering. Additionally, several traits are more differentiated among regions than expected based on neutral genetic divergence (QST > FST), including the first principal component score corresponding with life history syndrome. This discordance between patterns of phenotypic and genetic variation suggests that divergent selection is driving genetic differences in life history across the species range. If so, the silverleaf sunflower may be in early stages of ecological speciation.若种内生活史变异由地理异质的自然选择所驱动，则这类显著的种内生活史变异较为罕见，且可能是初期生态物种形成的潜在信号。本研究首次报道了银叶向日葵（Helianthus argophyllus）广泛存在的生活史多态性，并检验了其经歧化选择演化的相关证据。我们对采自该物种分布全境并在同质园种植的18个种群进行分析，发现多数数量性状呈现协同变异，据此可将个体划分为两种截然不同的生活史型：一类为高秆晚花，初始头状花序较小；另一类为矮秆早花，初始头状花序更大。银叶向日葵存在区域遗传结构，但该种群结构与表型变异模式并未呈现紧密对应关系。早花型主要分布于海岸障壁岛的种群中，而邻近大陆沿岸的种群尽管地理与遗传距离均较近，却主要呈现晚花表型。此外，相较于中性遗传分化的预期水平，多个性状在区域间的分化程度更高（QST > FST），其中包括与生活史型相对应的第一主成分得分。表型变异与遗传变异模式间的这种不一致性，表明歧化选择正在驱动该物种分布范围内生活史相关的遗传差异。若此情况属实，银叶向日葵可能正处于生态物种形成的早期阶段。