Growth and metamorphosis of Bufo melanostictus tadpoles: effects of kinship and density

Abstract

Growth and metamorphosis of the toad Bufo melanostictus was studied by rearing tadpoles of different sibships in isolation or in groups of siblings and nonsiblings (mixed rearing) under crowded and uncrowded conditions. All tadpoles survived and metamorphosed successfully. Growth rate and duration of metamorphosis of tadpoles reared in isolation were similar among the six sibships regardless of genetic differences. Tadpoles reared in sibling groups metamorphosed in 25 days, whereas those reared with nonsiblings metamorphosed between days 30-35. The largest mean body mass at metamorphosis was for sib groups reared in lower densities. When reared with siblings, growth was uniform, resulting in the production of bigger toadlets and a narrow spectrum of size classes. Mixed rearing retarded growth rates, increased larval duration, and produced smaller individuals at metamorphosis, resulting in extreme variability in size classes, especially under crowded conditions. Our study shows that both kinship and density affect larval duration and size at metamorphosis in this species.