Edson Pereira Silva

Techniques and statistical data analysis in molecular population genetics

Following the development of PCR methods, molecular techniques have become widely used for detecting genetic variation in natural populations. Most nucleotide changes can be detected by these techniques. Many of these changes probably reflect silent substitutions that are likely to be selectively neutral, making them particularly suitable to population genetic studies. In this paper, we review the published literature on molecular population genetics, with respect to the genome assayed (nuclear, mitochondrial or chloroplast), the organisms studied, the molecular techniques used, and the biological problems addressed. Several molecular techniques are then compared using experimental results obtained from a population genetic study of the Mytilus complex in the North Atlantic and Mediterranean. Finally, the most appropriate theoretical tools to analyse molecular population genetic data are discussed.

Holocene molluscs from Rio de Janeiro state coast, Brazil

A list of marine species of bivalves and gastropods found in seventy archeological sites of the shellmound type from Rio de Janeiro state was produced, based on the archeological material deposited in the collections of Museu Nacional (Rio de Janeiro, RJ), Instituto de Arqueologia Brasileira (Belford Roxo, RJ) and Museu do Sambaqui da Tarioba (Rio das Ostras, RJ). A total of 124 taxa were identified, of which 65 bivalves and 59 gastropods. The data retrieved from the shellmounds indicate stability of the composition patterns of mollusc biodiversity on the Rio de Janeiro state coast, at least in the period between 8,000 and 2,000 years B.P. The listing presented may be useful as a reference inventory for research pertaining to biological invasions, biogeography, conservation and management.

Holocene crustaceans from the Tarioba shell mound, Rio das Ostras, Rio de Janeiro, Brazil

Crustacean remains from the Tarioba shell mound (Sambaqui da Tarioba) archaeological site were investigated in order to produce a reference inventory of this taxonomic group. Information on past crustacean diversity is important for establishing baselines on biodiversity, as well as recovering paleoenvironmental information and comprehension of evolutionary change patterns for the Brazilian coast. The archaeological site was excavated by delayering the soil by artificial 10 cm sections which revealed five archaeological stratigraphic layers. A sample of mollusk shells for each of these layers was used for dating based on the C 14 method. The results show an occupation period of 550 yr for the Tarioba shell mound, with dates ranging between 4,070 cal BP (beginning of occupation) and 3,520 cal BP (occupation ending) and record nine species of crustaceans from the shell mound. However, a reduction of biodiversity over time was found that was not statically significant. Therefore, it seems that patterns of composition, richness and distribution of crustaceans have been stable in the last 4,070 years BP.

Shell Mounds of the Southeast Coast of Brazil: Recovering Information on Past Malacological Biodiversity

Brazilian classical studies on archaeology have attempted to explain human settlement and cultural trajectories in different geographical regions. However, zoological remains found in archaeological sites can also provide important information on biological diversity. Shell mounds (or sambaquis, the Brazilian term for them derived from the Tupi language) are acknowledged as artificial constructions made under cultural aims. These deliberated accumulations enclose a sample of the fauna existing between at least 6500 years BP and the start of the Common Era. In this chapter studies dedicated to use archaeozoological remains as surrogates for Late Holocene malacological biodiversity of the Central-South Brazilian coast are reviewed. Important issues such as the establishment of baselines and the problem of bioinvasion are addressed. In pursuance, raw data from the reviewed publications are used to test the main assumption lying under all inferences done by them, namely that shell mounds can be used as samplers of the past mollusk fauna. In conclusion it is sustained that shell mounds can be useful proxies for Late Holocene biodiversity.

High Levels of Genetic and Morphological Variability in Invasive Limnoperna fortunei (Dunker, 1857) Populations in South America

ABSTRACT Five populations of the invasive species Limnoperna fortunei were studied using polymorphic molecular (nine allozyme loci) and morphological (11 traits) markers in order to understand the patterns of genetic and morphological variability, structure and dispersion dynamics of this species in South America. High levels of genetic variability were found in South American invasive populations, and significant deviations from the Hardy-Weinberg proportions clearly indicated that the invasion process is still under way, probably by means other than natural migration.

Biodiversidad de moluscos marinos del sSambaqui da tarioba, Rio das Ostras, Rio de Janeiro (Brasil)

Shellmounds are archaeological sites found in almost all coastal areas around the world that have been recognized as artificial constructions dating between 8.000 and 2.000 years B.P. The Sambaqui da Tarioba has a malacological inventory with a total of 47 species. This set of species was accumulated over long periods, therefore, constitute a sample of the past diversity of molluscs in this region. To assess the representativeness of the shellmounds as a sampler of the marine molluscs diversity, data from this archaeological site were compared with present day inventory of molluscs from Rio de Janeiro coast. To describe the malacological diversity, two indices were used: average taxonomic distinctness (AvTD), defined as the average taxonomic path length between any two randomly chosen species, traced through a phylogenetic classification of the full set of species involved and variation in taxonomic distinctness (VarTD), which reveals the evenness of the distribution of taxa across the hierarchical taxonomic tree. The results indicate that the set of species recorded for Sambaqui da Tarioba is able to recover the biodiversity of a random sample of 47 species from the total inventory of molluscs recorded for Rio de Janeiro. This means that the malacological taxonomic diversity recorded for the Sambaqui da Tarioba is representative of that which is currently present in the coast of Rio de Janeiro state. This demonstrates that the use of shellmounds as a proxy of Holocene biodiversity can be a promising approach.

Biodiversidad de peces de concheros de la bahía de ilha grande, Rio de Janeiro, Brasil

Ilha Grande Bay region comprises a large biological biodiversity distributed in different ecological compartments and also is surrounded by shellmounds dating between 8.000 and 2.000 years B.P. A check list of Fish fauna from 11 of these shellmounds was done and compared with nowadays fish inventory for the region. Most of the species recorded for the shellmounds belongs to the class Chondrichthyes (53.5%), which is represented in the check list by 9 families and 38 species, being Carcharhinus Blainville, 1816, the genus with the highest number of species. Regarding the Osteichthyes, 16 families and 33 species were recorded. Micropogonias furnieri (Desmarest, 1823) was recorded for all sites. Most of the fish identified has a wide distribution in the western Atlantic (35.2%), pelagic behavior (35.2%) and inhabits estuarine environments (36.6%). Almost all the records are composed of noble fish representing top chain carnivorous which can reach large sizes, especially the Chondrichthyes. Comparisons done with current ichthyofauna data for the area (Ministry of Environment Brazil) have shown high similarity between past and present pattern of biodiversity, although some discrepancies were found for comparisons sorting species by their ecological compartments. The results show that shellmounds are valuable repositories of information concerning species composition in the past and, therefore, to the study of evolution of biodiversity patterns over time. Data on this nature are important for conservation and management strategies.