Division of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University Aoba, Sendai, Miyagi, 890-8578, Japan.
Ecol Evol. 2013 Jul;3(7):2038-46. doi: 10.1002/ece3.610. Epub 2013 May 31.
Resource partitioning within a species, trophic polymorphism is hypothesized to evolve by disruptive selection when intraspecific competition for certain resources is severe. However, in this study, we reported the secondary partitioning of oviposition resources without resource competition in the damselfly Ischnura senegalensis. In this species, females show color polymorphism that has been evolved as counteradaptation against sexual conflict. One of the female morphs is a blue-green (andromorph, male-like morph), whereas the other morph is brown (gynomorph). These female morphs showed alternative preferences for oviposition resources (plant tissues); andromorphs used fresh (greenish) plant tissues, whereas gynomorphs used decaying (brownish) plants tissues, suggesting that they chose oviposition resources on which they are more cryptic. In addition, the two-color morphs had different egg morphologies. Andromorphs have smaller and more elongated eggs, which seemed to adapt to hard substrates compared with those of gynomorphs. The resource partitioning in this species is achieved by morphological and behavioral differences between the color morphs that allow them to effectively exploit different resources. Resource partitioning in this system may be a by-product of phenotypic integration with body color that has been sexually selected, suggesting an overlooked mechanism of the evolution of resource partitioning. Finally, we discuss the evolutionary and ecological consequences of such resource partitioning.
物种内的资源分割，当种内对某些资源的竞争很激烈时，营养多态性被假设通过分裂选择进化而来。然而，在这项研究中，我们报道了在无内竞争的情况下，斑腹单脉色蟌（Ischnura senegalensis）产卵资源的次生性分割。在这个物种中，雌性表现出颜色多态性，这是对性冲突的反适应进化。其中一种雌性形态是蓝绿色（雌雄同体形态，雄性形态），而另一种形态是棕色（雌性形态）。这些雌性形态对产卵资源（植物组织）表现出替代偏好；雌雄同体形态使用新鲜（绿色）的植物组织，而雌性形态使用腐烂（棕色）的植物组织，这表明它们选择了更隐蔽的产卵资源。此外，两种颜色的形态具有不同的卵形态。雌雄同体形态的卵更小且更长，与雌性形态的卵相比，它们似乎更适应坚硬的基质。这种物种中的资源分割是通过颜色形态之间的形态和行为差异实现的，这使它们能够有效地利用不同的资源。该系统中的资源分割可能是与身体颜色相关的表型整合的副产品，这表明了资源分割进化的一个被忽视的机制。最后，我们讨论了这种资源分割的进化和生态后果。
