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Ornamental traits are sexually selected traits that an organism uses to attract a mate or defend against a rival. Studies have shown that ornamental traits are more sensitive to environmental changes during development relative to naturally selected traits and tend to develop smaller in size or more asymmetrical in response to disturbance. Hyalella azteca is a freshwater benthic macroinvertebrate that has been used in numerous studies to establish water quality criteria in freshwater ecosystems. Male H. azteca use their antennae and gnathopods (claws) during precopulatory struggles. Hence, these traits are considered “armaments”. Thus, ornamental traits in H. azteca provide a unique opportunity to examine the response of these traits to common disturbances affecting aquatic ecosystems such as nutrient enrichment. The objectives of the current study were to 1) experimentally assess population level responses of H. azteca to nitrogen enrichment, 2) experimentally assess the ornamental trait response signature of H. azteca to nitrogen enrichment and 3) characterize the ornamental trait response signature of natural populations of H. azteca in mesotrophic, eutrophic and hypereutrophic basins.

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Proceedings of the South Dakota Academy of Science

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