Filogeografia e evolução molecular de lagostas sapateiras (Scyllarides spp.) da América do Sul

• Autor(a) principal: Rey, Ghennie Tatiana Rodríguez
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/16179
• topic: Estrutura genética; DNA mitocondrial; Microssatélites; NuMts; Heteroplasmia; Scyllaridae; Estrutura genética; DNA mitocondrial; Microssatélites; NuMts; Heteroplasmia; Scyllaridae; Lagosta; Filogeografia; Genética de populações; DNA Mitocondrial; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

In the last years, two slipper lobsters, Scyllarides brasiliensis e S. deceptor, have become important contributors to in the lobster fisheries landings in the south-west Atlantic. Management strategies for fisheries species require understanding their connectivity and population dynamics. Thus, the aim of the first chapter of this thesis was to estimate the genetic diversity and population structure of those two lobster species along over 2800 km of the South American coast. For that, we used mitochondrial (cytochrome c oxidase I: COI; and the control region: RC) and nuclear markers (13 microsatellites loci developed in this thesis). Both species presented high levels of genetic variability (S. deceptor: N = 200, mtDNA: h > 0,841, π > 0,005; microsatellites: He = 0,685; S. brasiliensis: N = 211, He = 0,554) homogeneously distributed across localities (S. deceptor: ΦST < -0,004, ΦCT < 0,016, overall FST = 0,001, overall Dest = 0,003, FCT < 0,002, P > 0,05, K = 1; S. brasiliensis: overall FST = 0,004, overall Dest = 0,001, FCT < 0,004, P > 0,05, K = 1). The lack of population genetic structure in both species could be explained on the basis of biological traits, such as high fecundity and high dispersal potential of planktonic larvae, which promote high levels of connectivity between geographically distant populations. Moreover, the mitochondrial data indicate that the demographic history of S. deceptor was marked by population and geographical expansions, likely related to the suitable environmental conditions of interglacial periods during the late and middle Pleistocene. Several studies have shown that the presence of nuclear mitochondrial sequences (NuMts) and heteroplasmy limit the correct identification and amplification of mitochondrial markers. In phylogenetic and population studies, the inadverted presence of sequences from diverse origins violates the principle of orthology and can result in wrong evolutionary inferences. Thus, the aim of the second chapter of this thesis was to identify and characterize the NuMts and heteroplasmic sequences of three mitochondrial regions (COI, CR and the gene of the large ribosomal subunit: 16S) in four species of the genus Scyllarides (S. aequinoctialis, S. brasiliensis, S. deceptor e S. delfosi). Cloning and sequencing of genomic DNA and of enriched mtDNA extracts revealed that the genomes of these species may exhibit both NuMts (diverging by 0.6 and 17.6 % from mtDNA) and heteroplasmy (diverging by less than 0.2% from mtDNA prevalent). The NuMts possibly emerged from multiple independent integration events to the nucleus along the evolutionary history of the genus Scyllarides. Depending on their degree of similarity with the mtDNA, the presence of NuMts in phylogenetic analyses at genus level can cause overestimation of the number of species and affect the branch lengths and phylogenetic inferences among species.