Kin discrimination in tadpoles of Hylarana temporalis (Anura: Ranidae) and Sphaerotheca breviceps (Anura: Dicroglossidae) hydroperiod and social habits

Abstract

Kin discrimination ability was studied in tadpoles of Hylarana temporalis and Sphaerotheca breviceps, which live in two distinctly different habitats; the former shows social aggregation and the latter live scattered. Early in development, tadpoles of H. temporalis are found in small aggregations in the streams of Western Ghats but in later stages they are generally seen in isolated pools cut off from the main channel following drying up of the stream. Sphaerotheca breviceps breed during south-west monsoons in rain-filled puddles and its tadpoles are always found scattered. We hypothesized that the tadpoles living in aggregation exhibit kin discrimination while those not living in aggregation may not exhibit kin discrimination. Further, tadpoles that face desiccation threat may also not exhibit kin discrimination behavior. Tests were conducted on tadpoles of the above two species at two developmental stages (Gosner Stages 28-30 and 34-36) to reveal their association choice with sibs and non-sibs. Tadpoles of H. temporalis associated with both familiar (reared with sibs) and unfamiliar (reared in isolation) sibs in early but not in later stages of development. Tadpoles of S. breviceps showed no association preference with sibs (familiar or unfamiliar) in both early and later stages. The findings on H. temporalis suggest that kin discrimination between sib from non-sib may be beneficial during early stages of development that takes place in flowing streams and it may be less important in later stages of development taking place in pools of water bodies that face desiccation. Absence of kin recognition in S. breviceps is associated with their lack of natural aggregation and perennial desiccation threat of the ephemeral ponds. We suggest that kin discrimination behavior in tadpoles is related to their social habits and hydroperiod of their habitat.