Contamination status by persistent organic pollutants of the Atlantic spotted dolphin (Stenella frontalis) at the metapopulation level

The Atlantic spotted dolphin (Stenella frontalis) is an endemic species of the tropical-temperate Atlantic Ocean with widespread distribution. Although this species has been the subject of a large number of studies throughout its range, it remains in the "data deficient" category of the International Union for Conservation of Nature (IUCN). Chemical pollution by persistent organic pollutants (POPs) has been listed as one of the major threats to this species, however, there is no information on a wide scale. Thus, the aim of the present study was to investigate the contamination status of spotted dolphins on the metapopulation level as well as determine spatial and temporal variations in POP concentrations and bio-accumulation. A total of 115 blubber samples collected from a large part of the Atlantic basin were analysed for PCBs, DDTs, PBDEs, chlordanes, HCB and mirex. Although PCBs and DDTs were the predominant compounds in all areas, inter-location differences in POP concentrations were observed. Dolphins found at São Paulo, southeastern coast of Brazil, had the highest PCB concentrations (median: 10.5 μg/g lw) and Canary Islands dolphins had the highest DDT concentrations (median: 5.13 μg/g lw). Differences in PCB patterns among locations were also observed. Dolphins from the Azores and São Paulo demonstrated a similar pattern, with relatively highly contributions of tetra- (6.8 and 5.2%, respectively) and penta-CBs (25.6 and 23.8%, respectively) and lower contributions of hepta-CBs (20.8 and 23.5%, respectively) in comparison to other areas. Moreover, the sex of the animals and the year in which sampling or capture occurred exerted an important influence on the majority of the POPs analysed. Comparisons with toxicity thresholds available in the literature reveal that the São Paulo and Canary Island dolphins are the most vulnerable populations and should be considered in future conservation and management programs for the Atlantic spotted dolphin.

Tempo and rates of diversification in the South American cichlid genus Apistogramma (Teleostei: Perciformes: Cichlidae)

Evaluating biodiversity and understanding the processes involved in diversification are noticeable conservation issues in fishes subject to large, sometimes illegal, ornamental trade purposes. Here, the diversity and evolutionary history of the Neotropical dwarf cichlid genus Apistogramma from several South American countries are investigated. Mitochondrial and nuclear markers are used to infer phylogenetic relationships between 31 genetically identified species. The monophyly of Apistogramma is suggested, and Apistogramma species are distributed into four clades, corresponding to three morphological lineages. Divergence times estimated with the Yule process and an uncorrelated lognormal clock dated the Apistogramma origin to the beginning of the Eocene (≈ 50 Myr) suggesting that diversification might be related to marine incursions. Our molecular dating also suggests that the Quaternary glacial cycles coincide with the phases leading to Apistogramma speciation. These past events did not influence diversification rates in the speciose genus Apistogramma, since diversification appeared low and constant through time. Further characterization of processes involved in recent Apistogramma diversity will be necessary.

Molecular identification of a cryptic species in the Amazonian predatory catfish genus Pseudoplatystoma (Bleeker, 1962) from Peru

Pseudoplatystoma species are highly prized South American Pimelodid migratory catfishes. Until recently, their taxonomy was not clearly established, with discrepancies between morphological and molecular analyses. Here, Pseudoplatystoma species from the Peruvian Amazon were characterized at the molecular level from a sample representing the observed range of their color pattern variations in the study area. Analyses were performed using seven microsatellite loci for 103 specimens and, for part of them (52), using sequences of two regions of their mitochondrial genome [Cytochrome Oxidase subunit I (COI) and Control Region (CR)]. Factorial correspondence analysis and assignment tests based on microsatellite polymorphism showed that the specimens originally identified as P. punctifer belonged to two different gene pools highly differentiated from P. tigrinum. Morphological examination identified two different morphotypes (with and without black stripes), suggesting the existence of two distinct taxa within P. punctifer. This result was corroborated by the ML tree based on CR sequences, where all individuals but four clustered in a similar way as in the FCA and Bayesian assignment tests. For these four individuals, mitochondrial introgression or retention of ancestral polymorphism was likely. In contrast, the ML tree based on COI sequences showed that reciprocal monophyly was not yet achieved for this marker for the two P. punctifer taxa. The existence of three sympatric species of Pseudoplatystoma in the Peruvian Amazon is discussed in relation to their molecular characteristics, color patterns and ecology. Evolutionary scenarios regarding their divergence are hypothesized.

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

In the northeast Atlantic Ocean, the archipelago of the Azores is frequented by female–offspring groups of sperm whales ( Physeter macrocephalus L., 1758), as well as large males. The Azores apparently constitute both a feeding ground and a reproduction site. Little is known about the population and group structure of sperm whales in the area. We analysed 151 sloughed skin and biopsy samples collected from 2002 to 2004. Molecular analyses involved genetic tagging using 11 microsatellite loci and molecular sexing. Our objectives were to determine the population genetic structure, compare relatedness within and between social groups, infer kinship, and estimate the age of males at dispersal. Results suggest that individuals visiting the archipelago of the Azores belong to a single population. High genetic diversity and absence of inbreeding suggest that the population is recovering from whaling. Individuals sampled in close association are highly related, as well as those observed in the same area on the same day, suggesting that secondary social groups (i.e., the union of primary social units) are largely but not exclusively composed of relatives. Probable mother–offspring and full-sibling pairs were identified. Age of males at dispersal was estimated at 16.6 years, which was well above previous estimates for this species.

Mitochondrial phylogeny of African wood mice, genus Hylomyscus (Rodentia, Muridae): implications for their taxonomy and biogeography

This paper investigates the usefulness of two mitochondrial genes (16S rRNA and cytochrome b) to solve taxonomical difficulties within the genus Hylomyscus and to infer its evolutionary history. Both genes proved to be suitable molecular markers for diagnosis of Hylomyscus species. Nevertheless the resolving powers of these two genes differ, and with both markers (either analyzed singly or in combination), some nodes remain unresolved. This is probably related to the fact that the species emerged during a rapid diversification event that occurred 2-6 Myr ago (4-5 Myr ago for most divergence events). Our molecular data support the recognition of an "aeta" group, while the "alleni" and "parvus" groups are not fully supported. Based on tree topology and genetic divergence, two taxa generally recognized as subspecies should be elevated at the species level (H. simus and H. cf kaimosae). H. stella populations exhibit ancient haplotype segregation that may represent currently unrecognized allopatric species. The existence of cryptic species within H. parvus is questioned. Finally, three potentially new species may occur in West Central Africa. The Congo and Oubangui Rivers, as well as the Volta and Niger Rivers and/or the Dahomey gap could have formed effective barriers to Hylomyscus species dispersal, favoring their speciation in allopatry. The pronounced shifts in African climate during the late Pliocene and Miocene, which resulted in major changes in the distribution and composition of the vegetation, could have promoted speciation within the genus (refuge theory). Future reports should focus on the geographic distribution of Hylomyscus species in order to get a better understanding of the evolutionary history of the genus.

Patterns of diversification in two African forest shrews: Sylvisorex johnstoni and Sylvisorex ollula (Soricidae, Insectivora) in relation to paleo-environmental changes

We analysed the phylogeographic patterns of two congeneric and syntopic species of forest shrews and compared them with biogeographical scenarios proposed for the Central African tropical forest. Our results, based on 82 partial 16s rRNA mitochondrial sequences, suggest that both species must have originated in the Plio-Pleistocene and that their haplotype distributions could reflect the effect of forest fragmentation and expansion associated with paleoclimatic fluctuations during the Pleistocene. However, it seems that the two species responded very differently to environmental changes. While Sylvisorex johnstoni populations exhibit ancient haplotype segregation that may even represent currently unrecognised allopatric species, Sylvisorex ollula haplotypes are much less differentiated and suggest that this taxon has undergone a recent range expansion. The observed differences between these taxa may be explained by their presumably different ecological requirements and colonisation abilities, which in turn may be the result of a significant difference in body size between the two species. In conclusion, our results suggest that it is necessary to incorporate several ecologically well-documented species in studies that attempt to infer evolutionary processes from phylogeographic patterns

Grouping patterns, reproduction, and dispersal in a population of sitatungas (Tragelaphus spekei gratus)

A population of sitatungas (Tragelaphus spekei gratus) living in a forest swamp clearing, Maya Nord, in the Republic of Congo was studied over 3½ years and its grouping patterns and population dynamics were analysed. The sitatungas in this clearing formed a stable group, which remained in residence. The group (16–36 individuals) functioned like a harem. As a result of intrasexual competition, all the males and some of the females born at Maya left the group before reaching sexual maturity. We hypothesize that this large grouping resulted from the development of a tendency for females to be gregarious for reasons related to food availability. This tendency, combined with an aseasonal pattern of reproduction, favours direct monopolization of females by one male. Social and mating strategies observed at Maya fit the model of "female-defence polygyny" (Emlen and Oring). Our results provide an argument in favour of relating food availability and grouping patterns, and underline the plasticity of social organization and mating strategies in sitatungas.

Phylogeny and evolution of African shrews (Mammalia: Soricidae) inferred from 16s rRNA sequences

Current phylogenetic hypotheses on the African Crocidurinae (Soricidae) are based upon morpho-anatomical, karyological, and allozyme studies. The present study attempts to resolve the interrelationships among African Crocidurinae and their relationships to Eurasian Crocidurinae and to the subfamily Soricinae, on the basis of partial mitochondrial 16s rRNA sequences (549 bp). This is the first molecular study to include all but one of the nine currently recognized African shrew genera. In agreement with current views, two major lineages emerge. The first lineage includes Myosorex and Congosorex and supports the existence of a myosoricine taxon. The second lineage includes the six remaining genera. The genus Sylvisorex appears to be polyphyletic, whereas species of the controversial genus Crocidura are monophyletic. The genus Suncus presumably originated in Africa. The monospecific genera Ruwenzorisorex and Scutisorex and the two representatives of Paracrocidura cluster with species of other genera. Grouping patterns of species from different continents suggest that there have been multiple exchanges between Africa and Eurasia. The time estimates of these exchanges, inferred from two independent fossil-based calibrations of a molecular clock, coincide with the time estimates for migration events in other mammalian taxa.