The movement of individuals is foundational to many ecological processes. For example, the movement of an organism from one place to another alters population density at both sites and has potential for affecting the genetic dynamics within the new population. Individual movement events may be in synchrony with overall trends in populations, e.g. spawning migrations, or may be atypical (asynchronous). This latter movement type can affect population and metapopulation dynamics, depending on its prevalence within a population. Nevertheless, given the complexity of interactions, the causative factors of movement are understood vaguely, much less for aquatic organisms. Drivers of movement are extrinsic (e.g. habitat quality, predation or habitat heterogeneity) and intrinsic (e.g. sex, size, or behavioral tendencies). Interactions among these drivers provide crucial insight into the patterns of movement observed within populations. Habitat is here shown to affect observed movement patterns of populations of southern leatherside chub (Lepidomeda aliciae). Streams with higher-quality habitat were inhabited by populations exhibiting lower overall movement compared to lower-quality streams. However, observations of individual long distance movement relative to the norm within the population suggest that movement may also be behaviorally based. In further tests, it is shown that, indeed, behavioral tendencies of individuals can be measured and are predictive of annual movement by individuals. Other drivers, habitat availability and quality, were also found to influence movement on a yearly basis. Movement patterns are also affected by the presence or absence of predators. A tropical livebearer (Brachyrhaphis rhabdophora) has a higher percentage of individuals classified as generally moving when predators are absent from the environment compared to predator sites. Predation environment also significantly affects individual body shape with predator sites possessing caudal peduncles with greater surface area, an adaptation likely promoting burst speed for greater escape abilities. Classification of individuals as generally moving or generally not moving was also significantly related to variation of body shape of these fish. However, biological significance is ambiguous given the absence of obvious morphology trends explained by this factor. It is critical to understand these drivers to better understand the dynamic interface between ecology and evolution.



College and Department

Life Sciences; Biology



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dispersal, restricted movement paradigm, Lepidomeda, Brachyrhaphis, morphometrics, habitat quality, behavioral syndromes

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Biology Commons