MICRO-GEOGRAPHICAL GENETIC STRUCTURE OF INIA GEOFFRENSIS IN THE NAPO-CURARAY RIVER BASIN BY MEANS OF CHESSERS MODELS

Thirty-three pink river dolphins (Inia geoffrensis) were caught at eight sampling places (one beach and seven lagoons; transect length of 280 km) in the Napo and Curaray rivers at the Peruvian Amazon. Nine microsatellites were applied to analyze the genetic structure of this species at the micro-geographic level and diverse population genetics procedures were used to determine if Inia is a solitary or a social reproductive species. Chesser’s social model was used to determine asymptotic values of the F-statistics and showed that this species is a social reproductive one and the basic genetic lineages could be composed of: 1- seven reproductive females per lineage in each breeding period, 2the number of reproductive males per linage is not important, 3- a reproductive male with four females, on average, within each lineage, and thus there is polygyny in this dolphin species, and 4- a probability of 0.30 that females of a same lineage have chosen the same male for breeding. This is the first work carried out at a micro-geographic level for a river dolphin species, where the basic social reproductive parameters are revealed.