POPULATION STRUCTURE AND PHYLOGEOGRAPHY OF TUCUXI DOLPHINS (SOTALIA FLUVIATILIS) - Biology, Evolution and Conservation of River Dolphins Within South America and Asia - page 286

genealogy reflecting connectivity among sampled regions and identified divergent
haplotypes found in the extremes of the species distribution. These results indicate the
need to maintain connectivity between populations along the Amazon River and its
tributaries as a main objective of management and conservation programs for Sotalia
fluviatilis.
Keywords : phylogeography, Sotalia fluviatilis , population structure, mitochondrial DNA
I NTRODUCTION
The coastal and riverine forms of the South American dolphin Sotalia have been recently
accepted as different species (Monteiro-Filho et al . , 2002; Cunha et al . , 2005; Caballero et al.,
2007). The riverine species, Sotalia fluviatilis , ranges throughout the Amazon River and most
of its tributaries (Da Silva & Best, 1994). Although Sotalia are also reported 250 km up-river
in the Orinoco, it is unclear if these animals are residents or transients from the coast (Boher
et al., 1995)
Sotalia fluviatilis is considered ―data deficient‖ by the International Union for the
Conservation of Nature and Natural Resources (IUCN) (Klinowska, 1991; Reeves et al . ,
2003) and is listed in the Appendix I of the Convention on International Trade in Endangered
Species of Wild Fauna and Flora (CITES). However, other researchers consider it endangered
and in need of protection (Barros & Teixeira, 1994). The main anthropogenic threat that
affects this species is gillnet entanglement in most of its Amazonian distribution (Da Silva &
Best, 1996; Trujillo et al., 2000). In many places along the Amazon River, tucuxi dolphins are
considered to have spiritual power while in other areas they are killed for shark bait and their
eyes and genital organs sold as magical charms (Siciliano, 1994). The destruction of their
habitat, oil and pesticide pollution (Trujillo et al., 2000; Monteiro-Neto et al., 2003; Yogui et
al . , 2003) and construction of dams for hydroelectric projects are also affecting the future of
this species (Da Silva & Best, 1996).
Here we provide the first description of the phylogeography of Sotalia fluviatilis in the
Amazonian region based on the analysis of two mitochondrial genes, control region (CR) and
cytochrome b (Cyt- b ).
M ETHODS
Sample Collection and DNA Extraction
A total of 26 samples of skin, bone or teeth were obtained from S. fluviatilis in eleven
locations grouped into three geographic regions throughout their range (Figure 1 and Table
1). Tissue samples were obtained from dead stranded animals or animals captured in fishing
nets. Bones and teeth were obtained from skeletal remains found in the field (n = 9) or from
museum specimens (n = 3). Skin samples were stored in 70% ethanol at -20ºC. Bone and
tooth samples were stored at room temperature in individual sealed bags. DNA extraction
from tissue samples followed the protocol of Sambrook et al . (1989) modified for small