Data from: Seasonal polyphenism in wing coloration affects species recognition in rubyspot damselflies (Hetaerina spp.)

Understanding how phenotypic plasticityevolves and in turn affects thecourse of evolution is a major challenge in modern biology.By definition, biological species are reproductively isolated, but many animals fail to distinguish between conspecifics and closely related heterospecifics. In some cases, phenotypic plasticity may interfere with species recognition. Here, we document a seasonal polyphenism in the degree of dark wing pigmentation in smoky rubyspot damselflies (Hetaerina titia)—a shift so pronounced that it led early researchers to classify different forms of H. titia as separate species. We further show howthe seasonal color shift impacts species recognition with the sympatric congener H. occisa. Interspecific aggression (territorial fights) and reproductive interference (mating attempts) are much more frequent early in the year, when H. titiamore closely resemblesH. occisa, compared to later in the year when the dark-phase ofH. titiapredominates.Using wing color manipulations of tethered damselflies, we show that the seasonal changes in interspecific interactions are caused not only by the seasonal color shift but also by shifts in discriminatory behavior in both species. We also experimentally tested and rejected the hypothesis that learning underlies the behavioral shifts in H. occisa. An alternative hypothesis, which remains to be tested, is that the seasonal polyphenism in H. titia wing coloration has resulted in the evolution of a corresponding seasonal polyphenism in species recognition in H. occisa.This study illustrates one of the many possible ways that plasticity in species recognition cues may influence the evolutionof interspecific interactions.

解析表型可塑性（phenotypic plasticity）的演化规律及其对进化进程的影响，是现代生物学面临的核心挑战之一。根据定义，生物物种存在生殖隔离，但诸多动物无法准确区分同种个体与亲缘关系相近的异种个体。在部分情境中，表型可塑性可能会干扰物种识别过程。本研究针对烟红宝石蜻蛉（smoky rubyspot damselfly，*Hetaerina titia*）的翅部深色色素沉着程度，记录了一种季节多型（seasonal polyphenism）现象：该表型变化幅度极大，曾导致早期研究者将该物种的不同形态误划分为独立物种。本研究进一步阐明了这种季节性体色变化如何影响该物种与同域近缘种*H. occisa*的物种识别过程。相较于*H. titia*深色表型占主导的年末时段，在年初*H. titia*与*H. occisa*形态更为相似的时期，种间攻击（领地争斗）与生殖干扰（交配尝试）的发生频率显著更高。通过对拴缚固定的蜻蛉开展翅部颜色操控实验，本研究证实：种间互作的季节性变化不仅源于季节性体色变化，还与两个物种的识别行为转变相关。本研究还通过实验验证并否决了"学习是*H. occisa*行为转变的基础"这一假说。另有一项尚未验证的备选假说认为：*H. titia*翅色的季节多型现象，推动*H. occisa*演化出了与之对应的物种识别季节多型。本研究阐明了物种识别信号可塑性影响种间互作演化的多种潜在路径之一。