Bianca de Almeida Carvalho

KARYOTYPES OF NINETEEN MARSUPIAL SPECIES FROM BRAZIL

Abstract Karyotypes of 127 individuals, representing 19 species of 10 genera of Brazilian marsupials (Didelphidae) were determined, with karyotypes of Gracilinanus emiliae and G. microtarsus, Marmosops incanus, Thylamys velutinus, and Philander frenata being described for the 1st time. The specimens were collected from 24 localities, in an area between 4°N (Surumú, Roraima) and 31°S (Mostardas, Rio Grande do Sul), in Brazil. Only 3 diploid numbers were found, 2n = 14 in G. emiliae, G. microtarsus, G. agilis, Marmosa murina, Marmosops parvidens, M. incanus, Micoureus demerarae, and T. velutinus; 2n = 18 in Monodelphis dimidiata, M. brevicaudata, M. kunsi, and M. domestica; and 2n = 22 in Chironectes minimus, Lutreolina crassicaudata, Didelphis albiventris, D. aurita, D. marsupialis, Philander opossum, and P. frenata.

T2AG3)n telomeric sequence hybridization suggestive of centric fusion in karyotype marsupials evolution.

It has been suggested that the karyotype of the marsupials derived from a low diploid number (2n = 14) which originated, through fissions of biarmed chromosomes, the karyotypes with a higher 2n. The telomeric sequence (T2AG3)nwas in situhybridized to the chromosomes of Gracilinanus microtarsusand G. emiliae, Micoureus demeraraeand Marmosa murina, species with 2n = 14, in Monodelphissp., M. domestica, M. kunsiand M. brevicaudatawith 2n = 18, and in Lutreolina crassicaudata, Didelphis albiventris, Chironectes minimus, Philander opossumand P. frenata, all of them with 2n = 22. The probe hybridization occurred in the telomeric regions of both arms, short and long, of all chromosomes of the complement of all individuals of all species analysed. However, in some pairs of the karyotypes of Gracilinanus microtarsusand Micoureus demerarae(with 2n = 14), and in Monodelphissp., M. domestica, M. kunsiand M. brevicaudata(2n = 18) ectopic signs of hybridization were detected proximal to the centromeres, suggesting the retention of this telomeric sequence in the centromeric regions of some chromosomes of these species. Based on these results, it is proposed that the karyotype of marsupials evolved from a 2n = 22 to a 2n = 14, by means of chromosomal fusions.

Population data of 17 Y-STR loci from Rio Grande do Sul state (South Brazil)

A sample of 255 Brazilian males from Rio Grande do Sul (RS), the Brazilian southernmost state, was typed for 17 Y-STR loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, YGATA_H4.1 and DYS385ab). A total of 247 haplotypes were identified, of which 239 were unique and eight were found in two individuals each. The haplotype diversity (99.98%) and discrimination capacity (96.86%) were calculated. Pairwise haplotype distances showed that the RS population is not significantly different from Brazil, Rio de Janeiro, and Argentina, is different from São Paulo, Italy, and North Portugal, and is very distant from Spain, the Amazon region, Germany, and South Amerindians. When the RS data was separated in the seven geopolitical regions, some pairs of regions were significantly different; however no region was different from the whole Brazilian sample.