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Conforming to the status flow: The influence of altered habitat on fish body‐shape characteristics
Author(s) -
Akin Daniel R.,
Geheber Aaron D.
Publication year - 2020
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/fwb.13585
Subject(s) - flow (mathematics) , flow conditions , minnow , habitat , tributary , streams , ecology , phenotypic plasticity , fish habitat , fish <actinopterygii> , biology , environmental science , geography , fishery , mechanics , computer network , physics , cartography , computer science
Anthropogenic stream impoundments often result in altered flow regimes and reservoir formations. Functional fish characteristics may change in response to altered flow conditions, and understanding the underlying mechanisms at work (e.g. natural selection and phenotypic plasticity) is of great importance in both evolutionary and conservation contexts. Cyprinella lutrensis is a widely distributed minnow native to stream systems in Missouri, U.S.A. Following impoundment of the Osage River, C. lutrensis currently occurs in the resultant Truman Reservoir and surrounding tributaries. To examine the impacts of this habitat alteration on functional fish characteristics, we hypothesised that C. lutrensis populations in altered systems with no‐flow would show an overall less streamlined body shape as compared to those in flowing systems, assuming body streamlining is beneficial for locomotion in flowing environments. We conducted field and laboratory studies to test effects of flow and no‐flow on C. lutrensis body shape. Geometric morphometric techniques were used to quantify body shape in field and laboratory individuals, and non‐structural lipid extractions were conducted to assess whether fat storage contributes to body shape under flow and no‐flow treatments. Morphological comparisons between C. lutrensis from Truman Reservoir and surrounding streams yielded significant differences in body shape, with greater body streamlining in stream populations. A laboratory experiment using artificial stream units revealed similar significant differences in body streamlining between flow and no‐flow treatments within a single generation. In addition, individuals under no‐flow treatment had significantly higher levels of non‐structural lipids compared to flow treatment individuals. Our results indicate that changes in flow regime can alter the evolutionary trajectories (i.e. related to morphology) of fish populations. We suggest that body shape alterations are likely to occur within and across generations in a cumulative manner, therefore, it is plausible that both natural selection and plastic response mechanisms play roles in defining minnow body shape following flow alteration.