Piersanti Silvana, Salerno Gianandrea, Di Pietro Viviana, Giontella Leonardo, Rebora Manuela, Jones Albyn, Fincke Ola M
Dipartimento di Chimica, Biologia, e Biotecnologie University of Perugia Perugia Italy.
Dipartimento di Scienze Agrarie, Alimentari e Ambientali University of Perugia Perugia Italy.
Ecol Evol. 2021 Mar 17;11(9):4399-4412. doi: 10.1002/ece3.7335. eCollection 2021 May.
Search image formation, a proximal mechanism to maintain genetic polymorphisms by negative frequency-dependent selection, has rarely been tested under natural conditions. Females of many nonterritorial damselflies resemble either conspecific males or background vegetation. Mate-searching males are assumed to form search images of the majority female type, sexually harassing it at rates higher than expected from its frequency, thus selectively favoring the less common morph. We tested this and how morph coloration and behavior influenced male perception and intersexual encounters by following marked and noting their reactions to conspecifics. Contrary to search image formation and associative learning hypotheses, although males encountered the minority, male-like morph more often, sexual harassment and clutch size were similar for both morphs. Prior mating attempts or copula with morphs did not affect a male's subsequent reaction to them; males rarely attempted matings with immature females or males. Females mated early in the day, reducing the opportunity for males to learn their identity beforehand. Once encountered, the male-like morph was more readily noticed by males than the alternative morph, which once noticed was more likely to receive mating attempts. Flexible behavior gave morphs considerable control over their apparency to males, influencing intersexual encounters. Results suggested a more subtle proximal mechanism than male learning maintains these color polymorphisms and call for inferences of learning to be validated by behavior of wild receivers and their signalers.
搜索图像形成是一种通过负频率依赖选择来维持遗传多态性的近端机制，在自然条件下很少得到验证。许多非领地性豆娘的雌性与同种雄性或背景植被相似。寻找配偶的雄性被认为会形成多数雌性类型的搜索图像，对其进行性骚扰的频率高于其实际出现频率所预期的，从而选择性地青睐较不常见的形态。我们通过跟踪标记个体并记录它们对同种个体的反应，来测试这一点以及形态颜色和行为如何影响雄性的感知和两性间的相遇。与搜索图像形成和联想学习假说相反，尽管雄性更常遇到少数的、类似雄性的形态，但两种形态的性骚扰情况和产卵量相似。之前与不同形态的交配尝试或交配对雄性随后对它们的反应没有影响；雄性很少试图与未成熟的雌性或雄性交配。雌性在一天中较早的时候交配，减少了雄性事先了解其身份的机会。一旦相遇，雄性对类似雄性的形态比对另一种形态更容易注意到，而另一种形态一旦被注意到，就更有可能受到交配尝试。灵活的行为使不同形态对雄性的可见性有很大的控制权，从而影响两性间的相遇。结果表明，维持这些颜色多态性的近端机制比雄性学习更为微妙，这就要求通过野生接收者及其信号发送者的行为来验证学习的推断。
