Population structure and competition among kin in the chorus frog (Pseudacris triseriata)

In natural populations on Isle Royale, tadpoles of the chorus frog live in small pools on the shore of Lake Superior. Hatchling densities are high and sufficient to cause competitive impact on survivorship, growth, and development. The temporal and spatial pattern of egg laying indicates that tadpoles in many of the pools belong to single sibships. Average coefficients of relationship among tadpoles indicate that relationship among competing larvae averages approximately 0.35, and varies widely among larval subpopulations, from <0.1 to c0.5. Two growth experiments were carried to test whether growth trajectories and larval characteristics at metamorphosis are influenced by relationship among competing tadpoles. Kin effects occurred only in the experiment carried out in small pens at high initial densities: in this experiment, pure sib populations grew faster, and a higher proportion attained metamorphosis, but there were no kin effects on larval period or body size at metamorphosis. The chorus frog appears to have a population structure conducive to kin-group selection. High variance in the average coefficient of relationship among pools should favor kin recognition and kin-specific interference behavior. Growth experiments suggest that the tadpoles respond to the genetic relationship of competitors, with significant effects on the distribution of fitness at metamorphosis among members of the group. -from Author