Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy.
NBFC, National Biodiversity Future Center, Palermo, Italy.
PLoS One. 2024 Mar 26;19(3):e0298330. doi: 10.1371/journal.pone.0298330. eCollection 2024.
The bright colors of Alpine leaf beetles (Coleoptera, Chrysomelidae) are thought to act as aposematic signals against predation. Within the European Alps, at least six species display a basal color of either blue or green, likely configuring a classic case of müllerian mimicry. In this context, intra-population color polymorphism is paradoxical as the existence of numerous color morphs might hamper the establishment of a search image in visual predators. Assortative mating may be one of the main factors contributing to the maintenance of polymorphic populations. Due to the marked iridescence of these leaf beetles, the perceived color may change as the viewing or illumination angle changes. The present study, conducted over three years, involved intensive sampling of a population of Oreina gloriosa from the Italian Alps and applied colorimetry and a decision tree method to identify the color morphs in an objective manner. The tertiary sex ratio of the population was biased in favor of males, suggesting that viviparous females hide to give birth. Seven color morphs were identified, and their frequencies varied significantly over the course of the study. Three different analyses of mating (JMating, QInfomating, and Montecarlo simulations) recognized a general trend for random mating which coexists with some instances of positive and negative assortative mating. This could help explain the pre-eminence of one morph (which would be favored because of positive selection due to positive assortative mating) in parallel with the persistence of six other morphs (maintained due to negative assortative mating).
高山叶甲（鞘翅目，叶甲科）的鲜艳颜色被认为是一种对捕食的警戒信号。在欧洲阿尔卑斯山脉，至少有六种物种呈现出蓝色或绿色的底色，这可能构成了经典的缪勒拟态案例。在这种情况下，种群内的颜色多态性是矛盾的，因为大量的颜色形态可能会阻碍视觉捕食者建立搜索图像。 assortative mating 可能是维持多态种群的主要因素之一。由于这些叶甲具有明显的虹彩，因此当观察或照明角度发生变化时，感知到的颜色可能会发生变化。本研究历时三年，对来自意大利阿尔卑斯山的 Oreina gloriosa 种群进行了密集采样，并应用比色法和决策树方法客观地识别颜色形态。该种群的三级性别比例偏向雄性，表明胎生雌性会隐藏起来分娩。确定了 7 种颜色形态，它们的频率在研究过程中发生了显著变化。三种不同的交配分析（JMating、QInfomating 和 Montecarlo 模拟）识别出了随机交配的一般趋势，同时也存在一些正和负的 assortative mating 情况。这可以帮助解释一种形态的优势（由于正选择导致的正 assortative mating 而受到青睐）与其他六种形态的共存（由于负 assortative mating 而得以维持）。
