Marcadores moleculares na análise de espécies e composição populacional de peixes marinhos de recifes de corais da família Pomacanthidae (Perciformes).
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2004-11-12Autor
Affonso, Paulo Roberto Antunes de Mello
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The Brazilian coast extends over nearly 8,000km. Along the coastline, several marine
ecosystems can be found and determine a rich ichthyofauna, regarding both diversity
and number of species. The reef sites are characterized as the main reason for such
abundance. As a paradox, genetic studies aiming to characterize the several species and
populations from this environment are nearly absent in Brazil. Based on these
statements, the major goals of the present work were to analyze the population structure
and the relationship among marine fish species from a Perciform family, common at
coral reefs and important for aquarium trade Pomacanthidae. The selected species
were Centropyge aurantonotus, Holacanthus ciliaris, H. tricolor, Pomacanthus arcuatus
and P. paru, distributed over nearly all the Brazilian shore, besides another species
from the family Chaetodontidae, closely related to that focused in this work -
Chaetodon striatus. For that, molecular markers obtained from analyses of genomic
DNA by RAPD and microsatellites were adopted. The results based on RAPD profiles,
from a set of primers, indicate that species from both families show a high genetic
variability, with inter-specific and inter-populational differences. Specific marks were
found in all species, useful for the establishment of phylogenetic relationships and
taxonomical discrimination. The dendrogram generated allowed to distinguish each
species, revealing that those from a same genus are more closely related. Albeit the
values of gene flow and genetic identity were relatively high after inter-populational
comparisons, indications of structuring along the Brazilian Province were detected,
particularly if we consider φs t values. The most conspicuous species along the coast,
composing widely distributed populations, tended to exhibit greater genetic similarities
among samples. Animals from oceanic isolates were not quite differentiated from
inshore populations, but showed decreased variability. The isolation and
characterization of microsatellites in the species P. paru and H. ciliaris, according to
PIMA (PCR isolation of microsatellite arrays) methodology, allowed us to select several
microsatellite loci, useful for populational approaches. Primers flanking such regions
were designed and it was verified that one locus, called Pp02 was polymorphic and it is
present in Pomacanthus and Holacanthus representatives. The populational analyses of
the locus Pp02 in P. paru revealed significant values of Fst and genetic differentiation,
in agreement with population structure hypothesis. These data, described for the first
time, are useful for the conservation management of such exploited animals and for the
inferences of dispersal and populational composition of reef species from the Brazilian
Province.