Kinship influences larval growth and metamorphic traits of Bufo Scaber in a context-dependent manner

Abstract

Studies on the effects of group composition (i.e., kin or mixed groups) on metamorphic traits (SVL, body mass, and duration of larval period) can provide insights into the evolution and maintenance of kin selection in anurans. Tadpoles of Bufo scaber from different sibships were reared at varying densities as sibling or mixed groups to determine the influence of kinship on metamorphic traits. Body mass, SVL, and larval period were similar among sibships reared in isolation. When 10 tadpoles were reared in 1- or 5-liter water, growth, larval period, and size at metamorphosis were comparable between sibling and mixed groups. In contrast, when the density of rearing was increased to 20 or 40 tadpoles per five liters, metamorph size was significantly lower in sibling groups than in mixed groups. Crowding negatively affected growth, body mass, and SVL in both kin and mixed groups. In mixed groups, metamorphosis was delayed, and metamorphs were larger than those reared as siblings at corresponding densities. Further, there was a large variation in body mass and larval period indicating, albeit indirectly, asymmetric competition among the mixed group individuals unlike in sibling groups. The present findings demonstrate that, in B. scaber, kinship plays a role in driving the metamorphic traits in a context-dependent manner. They also show that effects of kinship are expressed selectively under adverse ecological situations such as overcrowding.