Data from: The effects of age, sex, and habitat on body size and shape of the blackstripe topminnow, Fundulus notatus

Lake and stream habitats pose a variety of challenges to fishes due to differences in variables such as water velocity, habitat structure, prey community, and predator community. These differences can cause divergent selection on body size and/or shape. Here, we measured sex, age, length, and eight different morphological traits of the blackstripe topminnow, Fundulus notatus, from 19 lake and stream populations across four river drainages in central Illinois. Our goal was to determine whether size and shape differed consistently between lake and stream habitats across drainages. We also considered the effects of age and sex as they may affect size and morphology. We found large differences in body size of age 1 topminnows where stream fish were generally larger than lake fish. Body shape mainly varied as a function of sex. Adult male topminnows had larger morphological traits (with the exception of body width) than females, in particular longer dorsal and anal base lengths. Subtle effects of habitat were present. Stream fish had a longer dorsal fin base than lake fish. These phenotypic patterns may be the result of genetic and/or environmental variation. As these lakes are human-made, the observed differences, if genetic, would have had to occur relatively rapidly (within about 100 years).湖泊与溪流生境因水流速度、生境结构、猎物群落及捕食者群落等变量的差异，对鱼类构成多重生存挑战。这些差异可对鱼类的体型与/或形态产生趋异选择压力。本研究针对伊利诺伊州中部4个河流流域内19个湖泊与溪流种群的黑纹底鳉（Fundulus notatus），测定了其性别、年龄、体长以及8项形态学性状。本研究旨在明确不同流域内，湖泊与溪流生境中的鱼类在体型与形态上是否存在一致的差异。同时，本研究亦考量了年龄与性别对体型及形态的潜在影响。研究发现，1龄黑纹底鳉的体型存在显著差异：溪流种群的个体普遍大于湖泊种群。形态差异则主要受性别影响：成年雄性黑纹底鳉的各项形态性状（体宽除外）均大于雌性，尤其是背鳍基长与臀鳍基长更长。生境亦存在微弱的影响效应：溪流种群的背鳍基长显著长于湖泊种群。上述表型特征差异可能源于遗传变异与/或环境差异共同作用。由于研究涉及的湖泊均为人工修建，若上述体型与形态差异由遗传因素导致，则其演化速度必然较快（仅需约100年时间）。