Seasonal Movements of Podocnemis sextuberculata (Testudines: Podocnemididae) in the Mamirauá Sustainable Development Reserve, Amazonas, Brazil

Short Communication Population genetics analysis of Podocnemis sextuberculata (Testudines, Podocnemidae): lack of population structure in the central Amazon Basin

“…According to Kimura and Maruyama (1971), when Nm assumes values greater than four between localities, the localities can be considered belonging to as a single panmictic population, whereas Nm less than one indicates that the localities are differentiated. The high Nm observed among the localities sampled would indicate that P. sextuberculata has a high migration or dispersion rate, and confirms what the ecological data had already suggested, that this species has a high capacity for dispersion (Fachín-Terán et al, 2006). According to Gibbons (1986), many chelonian species move great distances in response to seasonal changes, but the response to adverse conditions can vary within or among species.…”

“…The authors found a lack of population structure in tributaries of the same hydrographic basin, but genetic differences among basins. Ecological data have suggested that P. sextuberculata shows a high capacity for dispersion (Fachín-Terán et al, 2006), which may lead to a lack of population differentiation within the Amazon Basin, similar to that observed with P. expansa. In this study, we tested the null hypothesis of panmixia of the populations of this species among Amazon Basin locations that are separated by distances over 1000 km, using the mtDNA gene ND1.…”

“…The lack of genetic structure between great geographic distances and extensive gene flow between the localities studied corroborate observations in field work. Fachín-Terán et al (2006), utilizing the mark-recapture method, observed that the distances covered by individuals of P. sextuberculata varied greatly, and evidence of territoriality that was not found in the RDS Mamirauá. The authors suggest that the population of P. sextuberculata is open, as there is a very low recapture rate (3.6%), indicating the dispersion of a high number of marked individuals.…”

“…In the RDS Mamirauá, P. sextuberculata moves in response to water level, the opposite of P. unifilis, where some individuals remain in the reserve. Fachín-Terán et al (2006), observing P. sextuberculata in the RDS Mamirauá, demonstrated by means of radio-telemetry the migration from the feeding places to breeding areas on the Japurá and Solimões Rivers. One individual of P. sextuberculata marked in RDS Mamirauá was also found in the Middle Juruá River, about 300 km away from the RDS Mamirauá (Andrade P, personal communication).…”

“…Such results indicate that P. sextuberculata individuals make seasonal migrations. At the beginning of the dry period, to avoid unfavorable conditions, they leave the flooded forests and lakes and head towards the main river channels (Fachín-Terán et al, 2006).…”