Data from: A test of hybrid growth disadvantage in wild, free-ranging species pairs of threespine sticklebacks (Gasterosteus aculeatus) and its implications for ecological speciation

AbstractEcological speciation is the evolution of reproductive isolation as a direct or indirect consequence of divergent natural selection. Reduced performance of hybrids in nature is thought to be an important process by which natural selection can favour the evolution of assortative mating and drive speciation. Benthic and limnetic sympatric species of threespine stickleback (Gasterosteus aculeatus) are adapted to alternative trophic niches (bottom browsing versus open water planktivory, respectively) and reduced feeding performance of hybrids is thought to have contributed to the evolution of reproductive isolation. We tested this “hybrid-disadvantage hypothesis” by inferring growth rates from otoliths sampled from wild, free-ranging benthic, limnetic, and hybrid sticklebacks from two lakes. There were significant differences in growth rate between lakes, life-history stages, and among years (maximum P = 0.02), as well as interactions between most factors, but not between hybrid and parental species sticklebacks in most comparisons. Our results provide little evidence of a growth disadvantage in hybrid sticklebacks when free-ranging in nature. While trophic ecology per se may contribute less to ecological speciation than envisioned, it may act in concert with other aspects of stickleback biology, such as interactions with parasites, predators, competitors and/or sexual selection, to present strong multifarious selection against hybrids., Usage notesStickleback age and otolith growth dataThe file is an excel spreadsheet with different tabs holding data for stickleback fish, their estimated ages (from otolith growth ring counts) and the size of the otolith used to age the fish, from which otolith growth rates were calculated. Also shown are the id's of each fish and their estimated admixture/hybridity coefficients.dryadentry.xls

摘要
生态物种形成（ecological speciation）是指生殖隔离的演化作为趋异自然选择的直接或间接结果。学界普遍认为，自然界中杂交后代适合度降低，是自然选择促进选型交配演化并推动物种形成的重要过程。三棘刺鱼（Gasterosteus aculeatus）的底栖型与浮游型同域物种分别适应了不同的营养生态位：前者以底栖觅食为主，后者以开阔水域浮游生物为食，此前学界曾提出杂交个体摄食能力下降推动了生殖隔离的演化。我们通过对两个湖泊中野生自由活动的底栖型、浮游型及杂交三棘刺鱼的耳石（otolith）样本进行分析以推断生长速率，对这一“杂交劣势假说”进行了检验。
不同湖泊、生活史阶段以及不同年份间的生长速率均存在显著差异（最大P值=0.02），且多数因子间存在交互效应，但多数对比中杂交个体与亲本物种刺鱼的生长速率并无显著差异。本研究结果表明，在自然自由活动状态下，杂交三棘刺鱼并未表现出生长劣势。尽管营养生态本身对生态物种形成的贡献可能低于此前预期，但它可与刺鱼生物学的其他方面（如与寄生虫、捕食者、竞争者的相互作用，以及性选择）协同作用，形成针对杂交个体的多重强选择压力。

使用说明
刺鱼年龄与耳石生长数据
本文件为Excel电子表格，包含多个工作表，存储三棘刺鱼的相关数据：基于耳石生长环计数估算的年龄、用于年龄鉴定的耳石尺寸（据此可计算耳石生长速率）；同时还包含每条鱼的编号以及其估算的混血/杂交系数。
dryadentry.xls