Data from: Behavioral adaptations imply a direct link between ecological specialization and reproductive isolation in a sympatrically diverging ground beetle

Adaptation to a previously unoccupied niche within a single population is one of the most contentious topics in evolutionary biology as it assumes the simultaneous evolution of ecologically selected and preference traits. Here, we demonstrate behavioral adaptation to contrasting hydrological regimes in a sympatric mosaic of Pogonus chalceus beetle populations, and argue that this adaptation may result in nonrandom gene flow. When exposed to experimental inundations, individuals from tidal marshes, which are naturally subjected to frequent but short floods, showed a higher propensity to remain submerged compared to individuals from seasonal marshes that are inundated for several months. This adaptive behavior is expected to decrease the probability that individuals will settle in the alternative habitat, resulting in spatial sorting and reproductive isolation of both ecotypes. Additionally, we show that this difference in behavior is induced by the environmental conditions experienced by the beetles during their nondispersive larval stages. Hence, accidental or forced ovipositioning in the alternative habitat may induce both an increased performance and preference to the natal habitat type. Such plastic traits could play an important role in the most incipient stages of divergence with gene flow.

单一种群内对先前未占据的生态位（niche）的适应，是进化生物学（evolutionary biology）领域最具争议的议题之一，因其假定生态选择性状与偏好性状需同步演化。本研究以同域镶嵌分布的亮黑扁步甲（Pogonus chalceus）种群为对象，揭示了其对两种迥异水文状况的行为适应，并提出该适应过程可能引发非随机基因流（gene flow）。在实验性淹水处理条件下，自然遭遇频繁但短暂洪水的潮汐盐沼种群个体，相较于会被持续淹水数月的季节性沼泽种群个体，展现出更高的滞水倾向。这种适应性行为预计会降低个体定居于异种生境的概率，进而导致两种生态型（ecotype）发生空间分选与生殖隔离。此外，本研究证实，该行为差异是由甲虫在非扩散幼虫阶段所经历的环境条件诱导产生的。因此，在异种生境中偶然或被迫产卵，可能会使后代对其原生生境类型表现出更高的适合度与偏好性。这类可塑性性状（plastic traits），在伴随基因流的物种分化初始阶段，可能发挥关键作用。