Biology Reference
In-Depth Information
Therefore, the main aims of this chapter to determine a possible social reproductive
genetic system and a possible existence of genetic structure at a microgeographical level for
Inia geoffrensis
are as follows:
1- To determine the levels of genetic diversity in the population of
Inia geoffrensis
in a
280 km section of the Napo-Curaray rivers and within each one of the eight lagoons sampled
in that transect. 2- To estimate possible existence, or not, of Hardy-Weinberg equilibrium
inside each one of the lagoons studied. 3- To establish how the microsatellite genetic variance
is divided into several sampling units (rivers, lagoons, individuals, genes) by means of an
analysis molecular of variance (AMOVA). 4- To utilize F-statistics (Chesser 1991a,b, 1993)
and analyze if a social reproductive system affects pink river dolphins in the Peruvian
Amazon.
M
ATERIAL AND
M
ETHODS
During October and December 2003, we traveled 550 km of the Napo River, in Peru,
from its mouth at Francisco de Orellana until Arica in the Curaray River (close to the
Ecuadorian frontier), which is one of the main tributaries of the Napo River. Within these 550
km, 33 pink river dolphins were caught in eight locations distributed within 280 km of this
transect. The points, where the dolphins were caught, were as follows: 1- A little beach on the
left band of the Napo river near Santa Marta (S 03º 05' 00.1‖; W 73º 10' 32‖) where two
exemplars were captured. 2- Cocha Zapote (S 02º 57' 04.9‖; W 73º 18' 44.6‖), a lagoon of
the Napo river, where two animals were caught. 3- Cocha Echevarría (S 2º 20' 58.4‖; W 74º
07' 16.6‖), a lagoon of the Curaray river, where one specimen was sampled. 4- Aucacocha (S
2º 18' 28.8‖; W 74º 12' 12.6‖), a lagoon in the Curaray River, where six individuals where
captured. 5- Tiphisca Santa María (S 2º 17' 25.3‖; W 74º 15' 38.3‖), a lagoon in the Curaray
river, where two (2) dolphins were caught. 6- Tiphisca Loro (S 2º 11' 55.6‖; W 74º 32'
11.8‖), a lagoon of the Curaray River, where eight exemplars were sampled. 7- Tiphisca
Avispa (S 1º 58' 07.1‖; W 74º 57' 31.8‖), a lagoon of the Curaray River, where five
individuals were captured. 8- Tiphisca Chambirá (S 1° 54' 26.5''; W 75° 00' 16.5''), a lagoon
of the Curaray river, where seven dolphins were caught. The geographic sample points are
shown in Figure 1.
The dolphins were captured using special fishing nets with lengths of 400 meters and
widths of 10 meters, taking special care to ensure the physical safety of each dolphin. Five
Indian fishermen and three biologists worked together to capture each animal (including the
author). One 10-meter long wooden boat powered by a 40 horse power engine was employed
to capture the animals. The individuals were brought on board and I personally took a small
biopsy from the caudal fin of each dolphin captured. After the biopsy, the wound was covered
with an antibiotic. Later, the animals were measured for different biometric characteristics
and safely released after 5-8 minutes of manipulation. The animals were marked to avoid any
recapture. The biopsies were stored in absolute alcohol until DNA extraction.
Each capture reflected a large fraction of all the animals that were present in the lagoons
at the moment of capture. A total of 48 animals were present when we arrived and 33 animals
were captured in the eight sampling points. Therefore, 69 % of the individuals present ―in
situ‖ were captured with the nets.
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