masterThesis
Dinâmica evolutiva do DNAr em cromossomos de peixes da família Eleotridae e revisão citogenética da ordem gobiiformes (Osteichthyes, Teleostei)
Fecha
2019-02-27Registro en:
SILVA, Simião Alefe Soares da. Dinâmica evolutiva do DNAr em cromossomos de peixes da família Eleotridae e revisão citogenética da ordem gobiiformes (Osteichthyes, Teleostei). 2019. 69f. Dissertação (Mestrado em Sistemática e Evolução) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2019.
Autor
Silva, Simião Alefe Soares da
Resumen
The Order Gobiiformes, with more than 2200 species is one of the most diversified
groups among teleosts. This high diversity of species is accompanied by significant
karyotypic diversification, whose the biological causes are not completely
established. Among its groups there is the family Eleotridae, with 23 genera and 171
species, of which six inhabits rivers near the coast and estuarine regions in vast
areas of the Brazilian coast. In order to extend the cytogenetic data for Eletridae and
to review the patterns of karyotype diversification in Gobiiformes, the species
Dormitator maculatus, Eleotris pisonis, Erotelis smaragdus and Guavina guavina with
occurrence in the South Atlantic were analyzed and a broad review of cytogenetic,
biological and ecological aspects of the Order Gobiiformes were performed. The
cytogenetic analyses employed conventional techniques (Giemsa staining, silver
nitrate impregnation, C-banding), base-specific fluorochromes (MM/DAPI) staining,
and fluorescence in situ hybridization with probes of 18S rDNA, 5S rDNA and repeats
(CA)15. The species E. smaragdus and E. pisonis presented 2n=46 chromosomes
(NF=46). D. maculatus exhibited a structurally diverse karyotype with 36sm+4st+6a
(NF=86), while G. guavina had a numerically divergent karyotype with 2n=52,
NF=52). The nucleoli organizing regions in the four species are located in different
positions of a chromosome, showing its potential to be an efficient cytotaxonomic
marker among the species. In situ rDNA mapping indicated a greater variation in the
structural arrangements of the 18S and 5S genes, confirming the high evolutionary
dynamics of the karyotypes of these species. The cytogenetic data set for the Order
Gobiiformes confirms 2n=46 acrocentric chromosomes, as a symplesiomorphic
condition for the Order. The varied set of repetitive sequences in the Eleotrid
chromosomes, and in Gobiiformes in general, associated to biological biology, such
as benthic habits, benthic adhesive eggs can act as trigger for karyotype
diversification. The results contributed to a better knowledge on the karyotype
evolution in Eleotridae, indicating a variety of rearrangements (inversions, fusions
and fissions) and extending the cytogenetic data for Gobiiformes. The heterogeneous
structural patterns of the chromosomes of this Order, together with their biological
aspects that favor population structure promoting an elevate evolutionary dynamics
in their chromosomes, making this group one of the most illustrative models of
karyotype megaevolution in marine environments.