Relationship between habitat dynamics, food availability, and growth patterns of ephemerellid mayflies from western North America

I examined whether variation in timing and length of the growth period for 11 species of Ephemerellidae was a function of either microhabitat stability or food availability. My data indicate that the growth patterns of these related species may be broadly constrained by taxonomic affinities. However, the final 90% of growth for each species almost always occurred during periods of maximum stability of preferred habitats. In addition, length of the growth period apparently varied directly with durational stability of preferred habitats, although this relationship is not exceptionally strong. For some species, timing of growth may also be influenced by predictable seasonal variation in availability of food. In general, hypotheses based on single factors are inadequate to explain all observed patterns. Also, comparison of my results with other studies indicates that the relative importance of different selective factors probably varies with geographic location