CHANGES IN THE DEMOGRAPHIC TRENDS OF PINK RIVER DOLPHINS (INIA) AT THE MICROGEOGRAPHICAL LEVEL IN PERUVIAN AND BOLIVIAN RIVERS AND WITHIN THE UPPER AMAZON:MICROSATELLITES AND MTDNA ANALYSES AND INSIGHTS INTO INIA’S ORIGIN - Biology, Evolution and Conservation of River Dolphins Within South America and Asia - page 172

constitution of a population, or during its history, and can more powerfully detect when the
populations reach a demographic stability after a rapid population growth.
Table 2. The test of Zhivotovsky et al. (2000) (S k ) to detect demographic changes applied
to microsatellites. SD = Standard deviation. LCL = Lower Confidence Limit. UCL =
Upper Confidence Limit. t = Student´s t test. IC = Interval of confidence. * Statistically
significant value at P < 0.05.

Bolivia
(Mamore
River)

Napo-
Curaray
River

Upper
Amazon

Marañon
River

Statistics Ucayali River

0.9951
± 0.2647

2.6250
± 0.8256

2.2580
± 0.7985

3.4587
± 1.7184

2.1342
± 0.7786 Var ± SD

95% LCL 0.4053 0.7575 0.4518 -0.5041 0.3388

95% UCL 1.5849 4.4932 4.0643 7.4214 3.9297

_
K ± SD

19.2440
± 9.1901

35.5744
± 16.2864

23.6875
± 11.2147

60.2202
± 42.5884

29.5012
± 12.6116

95% LCL -1.2327 -1.2680 -1.6818 -37.9888 0.4187

95% UCL 39.7208 72.4169 49.0569 158.4292 58.5836

S k -2.2533 0.2077 0.3498 0.1753 -0.0001

t -5.274* 0.956 2.098* 0.703 0.0005

(-3.090
/-1.416)

(-0.218
/0.634)

(0.023
/0.676)

(-0.313
/0.664)

(-0.455
/0.455)

95% IC

(-3.351
/-1.155)

(-0.351
/0.766)

(-0.078
/0.778)

(-0.465
/0.815)

(-0.597
/0.596) 99% IC

The Garza & Williamson (2001)'s test agrees quite well with the results showed by the
Zhivotovsky et al. (2000)'s test. The Bolivian population showed certain evidence of a
bottleneck event, although not drastic. To carry out this test previously, I estimated the  (=
4N e ) statistic and the percentage of multiple step mutations, which were  = 2.227 + 1.846
and 13.18 % for the Bolivian case, respectively. The average observed M value was 0.7846.
A 10,000 simulation run with these parameters (values cited above) and sample size used
resulted in an average M of 0.8143 with 95 % of the individual M values for each marker
under the critical value of M c = 0.7094 (indicative of a demographic constant population).
Five markers showed an individual M below this critical value (Ev14, M = 0.6667; Ev76, M
= 0.60; Ev37, M = 0.7072; Ev94, M = 0.3333; MK5, M = 0.6667), and therefore this fraction
is statistically significant ( 2 = 4.77, 1 df, P < 0.05). In contrast, not a single Peruvian river or
upper Amazon set showed evidence of any bottleneck. For instance, the overall Amazon set
showed  = 5.364 + 5.812 and 3.25 % and an average M of 0.9157, whereas the 10,000
simulated M was 0.8964 with 95 % of the individual M values for each marker under the
critical value of M c = 0.8159 labeling it a demographic constant population. Only one marker
was below this critical value (EV96, M = 0.60), but this was an insignificant quantity ( 2 =
0.18, 1 df, P > 0.05). Henceforth, the overall Amazonian pink river dolphin showed a
historical constant demographic size, contrary to that determined for the Bolivian pink river
dolphin population. The  value of the upper Amazonian population was two times that of the