Haydée A. Cunha

Population Structure of the Endangered Franciscana Dolphin (Pontoporia blainvillei): Reassessing Management Units

Franciscanas are the most endangered dolphins in the Southwestern Atlantic. Due to their coastal and estuarine habits, franciscanas suffer from extensive fisheries bycatch, as well as from habitat loss and degradation. Four Franciscana Management Areas (FMA), proposed based on biology, demography, morphology and genetic data, were incorporated into management planning and in the delineation of research efforts. We re-evaluated that proposal through the analysis of control region sequences from franciscanas throughout their distribution range (N = 162), including novel sequences from the northern limit of the species and two other previously unsampled localities in Brazil. A deep evolutionary break was observed between franciscanas from the northern and southern portions of the species distribution, indicating that they must be managed as two Evolutionarily Significant Units (ESU). Furthermore, additional FMAs should be recognised to accommodate the genetic differentiation found in each ESU. These results have immediate consequences for the conservation and management of this endangered species.

Phylogenetic status and timescale for the diversification of Steno and Sotalia dolphins.

Molecular data have provided many insights into cetacean evolution but some unsettled issues still remain. We estimated the topology and timing of cetacean evolutionary relationships using Bayesian and maximum likelihood analyses of complete mitochondrial genomes. In order to clarify the phylogenetic placement of Sotalia and Steno within the Delphinidae, we sequenced three new delphinid mitogenomes. Our analyses support three delphinid clades: one joining Steno and Sotalia (supporting the revised subfamily Stenoninae); another placing Sousa within the Delphininae; and a third, the Globicephalinae, which includes Globicephala, Feresa, Pseudorca, Peponocephala and Grampus. We also conclude that Orcinus does not belong in the Globicephalinae, but Orcaella may be part of that subfamily. Divergence dates were estimated using the relaxed molecular clock calibrated with fossil data. We hypothesise that the timing of separation of the marine and Amazonian Sotalia species (2.3 Ma) coincided with the establishment of the modern Amazon River basin.

Molecular sexing of tucuxi dolphins (Sotalia guianensis and Sotalia fluviatilis) using samples from biopsy darting and decomposed carcasses

We tested the zinc-finger sex chromosome-linked genes Zfx/Zfy and the sex-determining region Y (Sry) genes for gender determination of biopsy samples from marine and riverine tucuxi dolphins (Sotalia guianensis and S. fluviatilis). We also evaluated the performance of these genes with decomposed carcasses, for which sexing cannot rely on the direct examination of the reproductive tract. Both systems proved reliable for sexing 46 fresh and decomposed samples, making them especially useful when biopsy darting is coupled with photo-identification studies.

Molecular and Morphological Differentiation of Common Dolphins (Delphinus sp.) in the Southwestern Atlantic: Testing the Two Species Hypothesis in Sympatry

The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigated the molecular taxonomy of common dolphins through analyses of cytochrome b sequences of 297 individuals from most of their distribution. We included 37 novel sequences from the Southwestern Atlantic Ocean, a region where the short-and long-beaked morphotypes occur in sympatry, but which had not been well sampled before. Skulls of individuals from the Southwestern Atlantic were measured to test the validity of the rostral index as a diagnostic character and confirmed the presence of the two morphotypes in our genetic sample. Our genetic results show that all common dolphins in the Atlantic Ocean belong to a single species, Delphinus delphis. According to genetic data, the species Delphinus capensis is invalid. Long-beaked common dolphins from the Northeastern Pacific Ocean may constitute a different species. Our conclusions prompt the need for revision of currently accepted common dolphin species and subspecies and of Delphinus delphis distribution.

More than meets the eye: kinship and social organization in giant otters (Pteronura brasiliensis)

Giant otters live in highly cooperative groups. Behavioral observations suggest that groups are composed of a dominant reproductive pair and their offspring of previous years. We combined genetic data and long-term ecological information to determine genetic relatedness within and between groups to verify that hypothesis. We genotyped 12 polymorphic loci of 50 otters from 13 groups and two transient individuals. The average relatedness within groups (r = 0.23) was high, but the degree of relatedness varied within the groups, including groups of unrelated individuals, contradicting the current social hypothesis of an exclusively parent-brood model. Negative correlations between kinship and distance between territories were higher in females, and on two occasions, dominant females were replaced by related subordinates of the same group. Solitary transients were males, suggesting a tendency of male-biased dispersal. These data, combined with long-term ecological and behavioral information, indicate that direct benefits, such as alloparental care, and acquisition, inheritance, and defense of high-quality territories may drive the evolution of group living of this endangered social carnivore.

Polymorphic microsatellite loci from the endangered Giant Otter (Pteronura brasiliensis)

We describe the first microsatellite loci isolated from the giant otter (Pteronura brasiliensis), an endangered mustelid endemic to South America. Fourteen di- and trinucleotide polymorphic loci were characterised in fourteen individuals from the Pantanal wetlands, Central Brazil. Number of alleles per locus ranged from 2 to 5, and average observed heterozygosity was 0.577. Two loci were in linkage disequilibrium, and one further locus deviated from Hardy–Weinberg equilibrium, probably due to the presence of null alleles. The transferability of these markers to two other mustelids (Lontra longicaudis and Eira barbara) and to the mephitid Conepatus semistriatus was also evaluated. These loci are useful to study the ecology and evolution of these species.

Polymorphic microsatellite loci for two Atlantic oyster species: Crassostrea rhizophorae and C. gasar

Abstract Using a CA/CAA enriched library screening procedure, we isolated and characterised a total of seventeen polymorphic microsatellite loci for two species of Crassostrea with recognised economic importance. Eleven microsatellite loci were developed for C. rhizophorae, a Western Atlantic species for which no microsatellites were previously known. Another six loci were developed for C. gasar, a species that occurs on both sides of the South Atlantic, adding to the ten loci previously described for the species. The levels of polymorphism were estimated using 24 C. rhizophorae from Southeast Brazil (São Paulo) and 23 C. gasar individuals from North Brazil (Maranhão). The number of alleles per polymorphic locus varied from 3 to 27, and the observed and expected heterozygosities ranged between 0.174 and 0.958 and between 0.237 and 0.972 in C. rhizophorae and C. gasar, respectively. No linkage disequilibrium was found between any locus pair, and four of them exhibited deviations from Hardy–Weinberg expectations. Of the 17 loci developed, 8 cross-amplified in C. gigas and 13 in C. virginica. These markers are useful for evolution and population genetics studies of Crassostrea species and may provide fundamental data for the future cultivation of native oysters in Western Atlantic.

Colour pattern and external morphology of the Fraser's dolphin ( Lagenodelphis hosei ) in the Southwestern Atlantic

Little is known about the biology of the Fraser’s dolphin (Lagenodelphis hosei), which is found in tropical and subtropical oceanic waters around the world. There is, depending on age and sex, great variation in intensity and development of the components of the colour pattern and external morphological characteristics of the species. The main characteristic of the colour pattern is the eye-toanus stripe, which has highly variable development. This is the first description of Fraser’s dolphin external appearance in the Southwestern Atlantic, based on 13 specimens stranded dead on the coast of Rio de Janeiro State (Brazil) around 22(30#S. Individuals analysed presented sexual dimorphism in shape of the dorsal fin, presence of a post-anal hump and deepening of the caudal peduncle, features most prominent in mature males of the species. Specimens analyzed revealed that the Fraser’s dolphin possesses the same colour pattern and external morphological features reported in other areas.