Seasonal changes in morphological structuring in a guild of benthic stream fishes.

The ecomorphological model which attempts to identify important variation in the total morphology of groups of animals has been used with some success in communities of fishes. The applicability of the model to subsets of the community, such as guilds of ecologically similar species, is uncertain, and the effects of the possible changes in correlations among morphological variables caused by demographic changes across seasons is unknown. An ecomorphological model is applied to a guild of benthic stream fishes from the Tombigbee River, Mississippi. The model is found to describe structuring in the guild based on aspects of the trophic morphology and the length of the body. Morphologically distinct groups of species are described by the model. The effect of indeterminate growth seems not to be of sufficient magnitude to change groupings across seasons. However, species associations within morphological groups change seasonally. I conclude that ecomorphological models may be properly applied to community subsets, but the interpretation of the model must consider the nature of the data set with respect of seasonality.