Photographs of representative shallow-bodied (a) and deep-bodied (c) male Robust Redhorse and shallow-bodied (b) and deep-bodied (d) male Notchlip Redhorse captured from spawning aggregations on mid-channel gravel bars in the Savannah River, Georgia-South Carolina during 2004–2005 and the truss network and landmarks used to quantify the morphology of Robust Redhorse and Notchlip Redhorse superimposed on a male Robust Redhorse (e)

Photographs of representative shallow-bodied (a) and deep-bodied (c) male Robust Redhorse and shallow-bodied (b) and deep-bodied (d) male Notchlip Redhorse captured from spawning aggregations on mid-channel gravel bars in the Savannah River, Georgia-South Carolina during 2004–2005 and the truss network and landmarks used to quantify the morphology of Robust Redhorse and Notchlip Redhorse superimposed on a male Robust Redhorse (e)

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Article
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Maintaining intraspecific diversity is an important goal for fisheries conservation and recovery actions. While ecomorphological studies have demonstrated intraspecific diversity related to feeding or flow regime, there has been little assessment of such variation in regard to spawning habitat. We evaluated the relationship between individual morph...

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... Organisms inhabiting these types of altered habitats are exposed to different environmental conditions compared to those inhabiting native environments, which can lead to members of the same species eventually exhibiting different phenotypes, depending on the type of environmental conditions they are exposed to. Intraspecific morphological divergence in fishes has been recorded in response to anthropogenic disturbances such as impoundments (Haas et al. 2010;Franssen 2011;Franssen et al. 2013;Grabowski et al. 2018). Impoundment causes the interruption of the continuity of a river, affecting both the migration of fishes and the transport of sediments and nutrients. ...
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Dam constructions cause fundamental changes in the natural landscape, creating new ecological and evolutionary challenges for aquatic organisms. In some cases, such water impoundments have been related with morphological changes in organisms. Understanding how populations respond to rapid environmental changes imposed by dams is the first step to elucidate the consequences that disturbed habitats may have on species evolution. In this work, we analyzed shape and size variation in Bryconamericus iheringii Boulenger 1887 from the Chasqueiro stream basin, south of Brazil, which was recently dammed. We used linear measurements and geometric morphometrics to identify morphological differences among specimens from the reservoir (lentic habitat) compared to the habitat upstream and downstream of the dam (lotic habitats). We also tested for size- and shape-related sexual dimorphism to determine whether variations observed were the same for both sexes. We found that B. iheringii from the artificial reservoir were distinct in shape and size to those from their natural habitat in the stream. The size variation between environments was the same for both sexes, but the shape variation differed between males and females. Regarding the linear measurements, lotic populations were larger (greater body length, width, pectoral fin base length and caudal peduncle length), probably in response to increased swimming activity. Regarding body shape, we found that both sexes have a more fusiform body in lotic habitats than in the reservoir. In addition, females showed an altered mouth position that was distinct between these environments. This work indicates that the water reservoir seems to be an important factor influencing morphological variation in B. iheringii, a species with sexual shape dimorphism.
... Intraspecific morphological divergence in fishes has been recorded in response to anthropogenic disturbances, such as the impoundments Franssen 2011;Grabowski et al. 2018). Impoundment causes interruption of the river continuity, affecting migration of fishes and transport of sediments and nutrients. ...
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The study of the intraspecific differentiation among fish populations that inhabit different environments can contribute to the understanding about the species evolution, contributing with knowledge about the interactions between aquatic organisms and their environment, increasingly subject to anthropic alterations. Thus, the main purpose of this Thesis was to study the intraspecific adaptive process of fishes exposed to heterogeneous environments, both natural and anthropogenic. For analyzes in natural environments, approaches using geometric and linear morphometry and population genomics analyzes were performed to evaluate the intraspecific variation in Jenynsia lineata from different habitats. Morphometric analyzes revealed a pattern of habitat-dependent sexual dimorphism, besides the body shape and size being distinct in the marine population. In relation to the genomic analyzes, we observed population structuring with the formation of three clusters, and the marine population showing a greater distinction form the all others. In addition, it was evidenced that there are differences in genetic parameters between lotic and lentic specimens. We also identified SNPs under potential divergent selection between the environments studied herein, which seem to be in genes with development function, as well as osmoregulation, among others, corroborating the hypothesis that J. lineata is a species locally adapted to variable environmental conditions. To evaluate how the local adaptation process occurs in altered environments via human action, the differences in the body shape and size of the Bryconamericus iheringii exposed to natural and altered environments along the Chasqueiro stream basin, southern Brazil, were analyzed. It was evidenced that B. iheringii shows shape sexual dimorphism (SShD), with both sexes presenting the body more fusiform in lotic environment, with females showing differentitation in the position of the mouth between these environments. Previous work with B. iheringii revealed no differences between natural streams (without damming), which emphasizes the potential selective force of the environmental change caused by the construction of the dam. Finally, it is observed that our knowledge about local adaptation in fish from the Neotropical region is still incipient, especially in the region of study, and the results presented here contribute with initial data for knowledge about local adaptation in fish of the coastal region of Rio Grande do Sul and Uruguay.
Article
Many subclades within the large North American freshwater fish genus Etheostoma (Percidae) show brilliant male nuptial coloration during the spring spawning season. Traditionally, perceived differences in color were often used to diagnose closely related species. More recently, perceived differences in male nuptial color have prompted further investigation of potential biodiversity using genetic tools. However, cryptic diversity among Etheostoma darters renders male nuptial color as unreliable for detecting and describing diversity, which is foundational for research and conservation efforts of this group of stream fishes. Etheostoma raneyi (Yazoo Darter) is an imperiled, range-limited fish endemic to north-central Mississippi. Existing genetic evidence indicates cryptic diversity between disjunctly distributed E. raneyi from the Little Tallahatchie and Yocona river watersheds despite no obvious differences in male color between the two drainages. Analysis of morphological truss and geometric measurements and meristic and male color characters yielded quantitative differences in E. raneyi from the two drainages consistent with genetic evidence. Morphological divergence is best explained by differences in stream gradients between the two drainages. Etheostoma faulkneri , the Yoknapatawpha Darter, is described as a species under the unified species concept. The discovery of cryptic diversity within E. raneyi would likely not have occurred without genetic tools. Cryptic diversity among Etheostoma darters and other stream fishes is common, but an overreliance on traditional methods of species delimitation (e.g., identification of a readily observable physical character to diagnose a species) impedes a full accounting of the diversity in freshwater fishes in the southeastern United States.