masterThesis
Padrões temporais e grau de diversificação cariotípica em espécies atlânticas da família Acanthuridae (Perciformes)
Fecha
2015-03-26Registro en:
FERNANDES, Maria Aparecida. Padrões temporais e grau de diversificação cariotípica em espécies atlânticas da família Acanthuridae (Perciformes). 2015. 54f. Dissertação (Mestrado em Sistemática e Evolução) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2015.
Autor
Fernandes, Maria Aparecida
Resumen
The Acanthuridae family is a representative group from the marine fish that plays a key role
in ecological dynamics of coral reefs. Three species are common along coastal reefs of
Western Atlantic: Acanthurus coeruleus, Acanthurus bahianus and Acanthurus chirurgus. In
the present study, cytogenetic data are presented for these three species Acanthurus based on
classical cytogenetic methods and mapping of repetitive sequences such as ribosomal 18S and
5S rDNA and telomeric repeats to improve their karyotype evolutionary analyses. The
cytogenetic pattern of these species indicated sequential steps of chromosomal
rearrangements dating back 19 to 5 millions of years ago (M.a.) that accounted for their
interspecific differences. A. coeruleus (2n=48; 2sm+4st+42a), A. bahianus (2n=36;
12m+2sm+4st+18a) and A. chirurgus (2n=34; 12m+2sm+4st+16a) share an older set of three
chromosomal pairs that were originated through pericentric inversions. A set of six large
metacentric pairs formed by Robertsonian (Rb) translocations found in A. bahianus and A.
chirurgus and a putative in tandem fusion found in A. chirurgus are more recent events. The
lack of interstitial telomeric sequences (ITS) in spite of several centric fusions in A. bahianus
and A. chirurgus might be related to the long period of time after their occurrence (estimated
in 5 M.a.). Furthermore, the homeologies among the chromosome pairs bearing ribosomal
genes, in addition to other structural features, highlight large conserved chromosomal regions
in the three species. Our findings indicate that macrostructural changes occurred during the
cladogenesis of these species were not followed by conspicuous microstructural
rearrangements in the karyotypes.