Species integrity enhanced by a predation cost to hybrids in the wild

Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of parental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post-zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of-concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural p...

若近缘物种间可发生杂交并产生与亲本物种适合度相当的可育后代，则物种完整性可能受到挑战，甚至遭到破坏。因此，新近分化或近缘物种的存续，有赖于合子前（pre-zygotic）和/或合子后（post-zygotic）生殖隔离的建立与有效性。包括捕食作用在内的生态选择，通常被认为会降低杂交后代的适合度，但目前仍缺乏杂交存在捕食代价的野外实证依据。本研究为野外环境中捕食杂交后代作为合子后基因流屏障提供了概念验证（proof-of-concept）。鲤科鱼类（Cyprinid fishes）通常可产生可育且存活的杂交后代，因此是探究杂交后代生态代价的理想实验生物。本研究于2005年对两种淡水鲤科鱼类——斜齿鳊（Rutilus rutilus，英文名roach）和普通欧鳊（Abramis brama，英文名bream）及其杂交后代进行了电子标记。将标记后的鱼类放归其原生湖泊，使其暴露于自然的[原文未完整呈现]。