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 107

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Pairwise diference Pairwise diference

Figure 3. Graphic mismatch distributions of pairwise differences for Mamirauá (continuous line) and
Tefé (broken line) populations, using the control region data.

Comparative Phylogeography

All polymorphic sites found on the 519 bp HVSI fragment from the Brazilian Amazon
sequences were also part of the 400 bp studied by Banguera-Hinestroza et al . (2002).
Comparing our data with 96 control region sequences (Table 2) from three different locations
(Banguera-Hinestroza et al., 2002), a total of 20 haplotypes were identified, six from Brazil ( n
= 21), six from Bolivia (n = 41), two from Colombian Amazon (n = 38) and five from
Orinoco (n = 17). The haplotypes show 50 polymorphic sites (36 informative, 14 singletons),
47 transitions and three transversions, and one position containing both a transition and a
transversion.
Among the four localities, Brazil displays the highest haplotype diversity and Colombian
Amazon the lowest one, but Bolivia presents the lowest nucleotide diversity while Colombian
Orinoco has the highest one (Table 2). Tajima's and Fu's tests revealed no significant results
for expansion in all populations (data not shown), although MJN analysis (Figure 2) shows a
star-like pattern for Brazil and Bolivia while a mismatch distribution displays a significant
unimodal shape only for the Bolivia population.
Inter-population comparisons (Table 3) reveal significant distances between all pairs of
populations. Indeed, using a more appropriate exact test of population differentiation
(Schneider et al., 2000), very significant statistical values (P < 0.001) were observed for all
comparisons, including between the two Brazilian subpopulations (data not shown).
AMOVA analysis (Table 4); considering the four main localities, reveals that 90.4% of
the variation occurs among populations, showing an extremely reduced gene flow among
localities. The low N mf values (Table 3) also reflect the relative isolation observed among Inia
populations.