The Herpetological Journal

pp.155-161

Authors: Jerry Lea , Mandy Dyson And Tim Halliday

Abstract: The Mallorcan midwife toad (Alytes muletensis) has a very extended breeding season, and the nature of competition between larvae in the torrent pools where it breeds is likely to change across time. Larvae commonly overwinter and grow to a very large size and new hatchlings will have to compete with these overwintered larvae under varying conditions of density. The effects of density and cohort structure (i.e. the presence/absence of large overwintered tadpoles) on the growth and development of hatchling A. muletensis larvae were investigated in the laboratory using a factorial design. Large competitors, high densities and lower temperatures were all shown to suppress tadpole growth and development. Larger competitors were superior, especially the very large overwintered tadpoles. Whilst large size is advantageous, avoiding competition with overwintered tadpoles or high densities of tadpoles is probably much more important in determining size at - and timing of - metamorphosis. Because A. muletensis is an endangered species, knowledge of life history constraints can guide management of wild populations. The results are discussed in terms of potential optimal times to breed in light of the changing competitive environment.

Keywords: amphibian, anuran, competition, density effects, tadpoles