Molecular systematics and population genetics of marine vertebrates from Brazil

This thesis examines the implications of patterns of DNA sequence variation in a variety of marine vertebrate species of ecological and fisheries interest from Brazilian waters. -- The degree of genetic variation in the marine and riverine dolphin Sotalia fluviatilis from Brazilian waters was investigated. A unique genotype found only in Sotalia from the Amazon River suggests that the freshwater form may be genetically distinct from the marine form. The species is genetically diverse in the marine environment, but the occurrence of a common genotype in all six coastal locations along the marine coast examined suggests that there is sufficient gene flow in the marine region to prevent local differentiation. -- A previously unexamined mitochondrial locus. COI (cytochrome oxidase I), was used in combination with three other loci to re-investigate phylogenetic relationships of cetaceans. In this data set, the largest sequence yet applied to this problem, the controversial Milinkovitch Hypothesis that sperm whales are more closely related to baleen whales than to toothed whales was not supported. Instead, four different clades with different taxonomic rankings (Physeteridae. Ziphiidae. Delphinida. and Mysticeti) were identified, in agreement with the traditional separation of toothed and baleen whales as distinct clades. Results of the analysis are sensitive to locus combinations and method of phylogenetic reconstruction. -- The species of angel sharks (Squatina. Squatinidae) endemic to the continental shelf of Southern Brazil constitute a monophyletic group. The recently described species S. occulta was found to be more closely related to S. guggenheim than to S. argentina. This phylogeny helps to explain the evolution of reproductive structures (number of ovaries) and patterns of vertical distribution in the water column (from deep to shallow waters) of squatinid sharks. -- Red snapper (Lutjanus purpureus) shows high genetic diversity off the coast of northern Brazil. Two genotypic clades have been identified, one of which occurs northwest and the other southeast of the discharge of the Amazon River mouth. This is in agreement with recent morphological and reproductive studies which suggest that L. purpureus on the continental shelf of northern Brazil comprises two stock units occupying relatively segregated territories, defined by differences in salinity and temperature. -- In contrast, the low genetic diversity of yellowfin tuna (Thunnus albacares) from northeastern Brazilian waters agrees with the hypothesis that only a single stock of yellowfin tuna occurs in the southwest equatorial region of the Atlantic Ocean. The genetic homogeneity of T. albacares in this area suggests that there is sufficient gene flow in that area to prevent development of local stocks

Eugenol como anestésico no manejo de ariacó, Lutjanus synagris (LINNAEUS, 1758), cultivado

RESUMOO objetivo deste trabalho foi avaliar a eficácia do anestésico natural eugenol, em diferentes concentrações, durante o processo de anestesia do ariacó (Lutjanus synagris) cultivado. Foram utilizados 108 indivíduos, divididos em três classes de tamanho: alevinos (n = 36), juvenis (n = 36), e adultos (n = 36); com pesos médios respectivos de 3,58 ± 0,63 g; 20,24 ± 5,53 g e 263,51 ± 52,20 g, para cada uma destas classes. As concentrações testadas para as três classes de tamanho foram de 25; 50 e 75 mg L-1 sendo os tempos de anestesia e de recuperação registrados com cronômetro digital. Os resultados mostraram que quanto maior a concentração eugenol utilizada menor o tempo decorrido para atingir cada estágio de anestesia, para as três classes de tamanho. O tempo total de indução anestésica foi menor que três minutos, e a melhor concentração foi 50 mg L-1, para todas as classes de tamanhos testadas. O tempo de recuperação para esta concentração de anestésico foi de 120,7 ± 36,3 s, 78,95 ± 16,52 s, 103,33 ± 22,09 s, para as classes de alevinos, juvenis e adultos, respectivamente. A utilização eugenol para a anestesia de L. synagris foi considerada eficaz, dentro dos padrões preconizados e a concentração ideal não variou com a classe de tamanho

Fluorescent amplified fragment length polymorphism (fAFLP) analyses and genetic diversity in Litopenaeus vannamei (Penaeidae)

The Pacific white shrimp, Litopenaeus vannamei (Penaeidae), represents about 95% of all Brazilian shrimp production. The Brazilian L. vannamei foundation broodstock was made up of specimens collected from different American Pacific sites, but little information was collected on the genetic structure of the broodstock. We used the fluorescence amplified fragment length polymorphism (fAFLP) method to study the genetic diversity of L. vannamei broodstock lines 03CMF1 and 03CBF1 originally produced by breeder-shrimps imported mainly from Panama and Ecuador, although wild individuals from other localities may also have been used in producing these two lines. Our results showed a total of 93 polymorphic bands ranging from 50 to 500 bp, the mean Nei's genetic diversity calculated for the total sample was 13.4% and identity and genetic distance analyses indicated high genetic homogeneity within and between both the broodstock lineages studied which suggests that they had similar genetic structure. These results may represent an important tool for the appropriate management of L. vannamei broodstocks. Copyright by the Brazilian Society of Genetics