AMAZON RIVER DOLPHIN: HIGH PHYLOPATRY DUE TO RESTRICTED DISPERSION AT LARGE AND SHORT DISTANCES - Biology, Evolution and Conservation of River Dolphins Within South America and Asia - page 101

Chapter 6
A MAZON R IVER D OLPHIN : H IGH P HYLOPATRY
D UE TO R ESTRICTED D ISPERSION AT
L ARGE AND S HORT D ISTANCES
Juliana A. Vianna 1,3 , Claudia Hollatz 1 , Miriam Marmontel 2 ,
Rodrigo A.F. Redondo 1 , and Fabrício R. Santos 1 *
1 Departamento de Biologia Geral, ICB, Universidade Federal de Minas Gerais,
ICB - UFMG, Belo Horizonte, MG, Brazil.
2 Instituto de Desenvolvimento Sustentável Mamirauá, R.
Augusto Correa No.1 Campus do Guamá, Belém, PA, Brazil.
3 Universidad Andrés Bello, Escuela Medicina Veterinária, Santiago, Chile.
The Amazon River Dolphin ( Inia geoffrensis ) is widely distributed along the Amazon
and Orinoco basins, covering an area of about 7 million km 2 . We have generated 519 base
pair (bp) sequences of the control region (HVSI) and 1,140 bp of the Cytochrome B (Cyt-b)
gene of mitochondrial DNA (mtDNA) for two populations from the Amazon basin in Brazil,
separated by only 45 km. Six HVSI haplotypes were identified and we could detect a
remarkable population structure despite of the short distance separating the localities.
Compared to HVSI data from other South American countries, the Brazilian haplotypes
occupy an intermediate position related to Colombian Amazon, Colombian Orinoco and
Bolivian haplotypes. The Cyt-b data also detected a remarkable separation between both
Brazilian locations, and the phylogenetic analysis indicated an association of Amazon and
Orinoco haplotypes, separated from the Bolivian ones. This phylogeographic study
emphasizes the outstanding population structure for the Amazon River Dolphin, considering
both macro and microgeographic levels. These results suggest a strong phylopatry for this
species due to gene flow restriction through long distances, as well as short distances by
different water ecology characteristics. The studied Brazilian populations occur in close
localities but are separated by the turbid fresh water environment of the Amazon River, a
likely ecological barrier segregating I. geoffrensis populations.
* Corresponding author. [e-mail]