Asymmetric competition in larval amphibian communities: conservation implications for the northern crawfish frog, Rana areolata circulosa.

Asymmetric competition in larval amphibians can influence population dynamics and community structure. This density-dependent regulatory mechanism may be of particular importance for rare or endangered species such as the northern crawfish frog, Rana areolata circulosa. Interspecific competition of R. areolata with two congenerics, R. blairi and R. sphenocephala, was examined in artificial ponds. Analysis of covariance (differential mortality covariate) indicated that interspecific competition increased larval period length and decreased metamorphic body mass of R. areolata. The number of metamorphs produced was lower for R. blairi ponds when reared with R. areolata at high density. Body mass at metamorphosis was larger for R. sphenocephala when reared with R. areolata, suggesting that R. areolata facilitates larval growth in R. sphenocephala. These results indicate that the larval performance of R. areolata was reduced in the presence of interspecific competitors. Although many conservation efforts emphasize the preservation of critical habitat or particular rare species, interactive effects of biotic components in the focal community may also be important demographic regulators.