Functional and morphological bases of intraspecific variation in the feeding ecomorphology of largemouth bass, Micropterus salmoides.

摘要

This analysis first compared the feeding ecology and gross ecomorphology of largemouth bass, Micropterus salmoides, between Michigan and Florida populations to determine if the ontogeny of food habits and oral jaw gape differed between temperate (Michigan) and subtropical (Florida) populations. Second, the mechanical advantage, protrusibility, and linkage architecture of the oral jaws were compared to determine if they differed between populations and if they correlated with the differences observed in the food habits and gape comparisons. These analyses allowed for estimations of the capabilities of bass from both locations and provided insight as to the potential niche they may fill in each respective environment. Their realized abilities were determined through a series of performance tests in the laboratory. M. salmoides from both locations were filmed with digital high-speed cinematography while feeding on varying prey in different environments to determine if the morphological differences observed led to differences in their prey-capture performance. Bass from both locations differed significantly in the types and quantities of prey consumed (plankton χ2 = 46.55; df = 3; p 0.01; insect χ2 = 94.05; df = 13; p 0.01; fish χ2 = 152.74; df = 13; p 0.01; crustacean χ 2 = 187.08; df = 13; p 0.01) and also in their oral jaw gape heights and widths (ANCOVA's: F = 103.37; df = 1, 424; p 0.001; F = 46.99; df = 1, 424; p 0.001). They also differed in jaw protrusibility (ANCOVA: F = 52.16, df = 1, 166; p 0.001), linkage architecture (t-test: t = 6.286; df = 168; p 0.001; ANCOVA: F = 56.32; df = 1, 167; p 0.001), and jaw opening lever mechanics (opening lever ratio t-test: t = 7.711; df = 299; p 0.001). Each of these ecomorphological differences had implications for their prey-capture performance with both populations differing in nearly all (13 of 15) kinematic features measured and compared (p 0.05). M. salmoides from both locations appear to modulate their feeding behaviors relative to prey type and location, oftentimes conversely to what the ecomorphological and biomechanical analyses predicted. Further analyses into the functional morphology and ability of a single species to adapt to its specific environment will yield empirical information that may enable us to better understand the link between design and function in vertebrates. (Abstract shortened by UMI.)