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 108

Table 2. Population genetic parameters for the four studied populations.

Populations N HT S d S/d h π

Brazilian
Amazon

0.7810
+/- 0.0562

0.0053
+/- 0.0034

21 6 7 2.07 3.38

Colombia
Orinoco

0.6471
+/- 0.1185

0.0211
+/- 0.0115

17 5 27 11.48 2.35

Colombian
Amazon

0.1494
+/- 0.0739

0.0023
+/- 0.0018

38 2 6 0.91 6.59

Bolivian
Amazon

0.5561
+/- 0.0755

0.0016
+/- 0.0014

41 6* 5 0.64 7.81

0.8083
+/- 0.0259

0.0357
+/- 0.0178

117 20 50

Total

Table 3. Population pairwise distances (  ST (TN) -below diagonal) and estimated female
migrants ( N mf -above diagonal) per generation among the four Inia populations. All  ST
values are significant at P < 0.0001).

Brazilian
Amazon

Colombian
Orinoco

Bolivian
Amazon

Colombian
Amazon

Brazilian Amazon - 0.11026 0.02003 0.11730

Colombian
Orinoco

0.67167 - 0.03904 0.09024

Bolivian Amazon 0.95820 0.91464 - 0.01523

Colombian
Amazon

0.62408 0.76368 0.96856 -

Pairwise  ST comparisons (Table 3) suggest that a significant part of the interpopulation
diversity is due to the inclusion of the Bolivian population. Excluding the Bolivian population
from AMOVA (Table 4) causes more than a 20% reduction of the variance and  ST values,
although heterogeneity still remains high among the remnant localities ( ST ~0.7). However,
when the same test was performed for each population subtraction, we did not observe any
significant reduction in  ST (0.90-0.94).
To test the partition of the genetic variability in relation to the possible geographic
barriers proposed by Banguera-Hinestroza et al., (2002), a three level AMOVA was made
using three groups: Brazil+Colombian Amazon, Bolivia, and Colombian Orinoco (Table 4).
The AMOVA shows 82.3% of variation occurring among groups, a very high value compared
to other tested groupings.
The SAMOVA tests with five populations (including both Brazilian subpopulations)
indicate three and four population groupings (Table 4) as the ones maximizing the variation
among groups ( F CT ). Surprisingly, the four groups' structure is the one presenting the highest
F CT , and separates both Brazilian subpopulations leaving a cluster formed by the Colombian
Amazon and Brazilian Tefé. This result emphasizes the distinctiveness of all populations as
already shown by the pairwise F ST 's comparison (Table 3) and the exact test of
differentiation. SAMOVA also indicates that Bolivia presents the most divergent population,
separating from the others in structures formed by two groups (Table 4). Using the Barrier
software (Manni et al., 2004) based in the pairwise F ST 's distances between populations