Chromosome Homologies of Anteaters in Argentina (Myrmecophaga tridactyla and Tamandua tetradactyla, Myrmecophagidae, Xenarthra)

JUAN P. LUACES

Congreso; 21st International Chromosome Conference; 2016

The Myrmecophagidae family is a clade of xenarthran mam- mals with 2 existent genera and 3 living species endemically dis- tributed in the Neotropics. The karyological relationships of the genera of this family are poorly understood. The karyotype and cytotypes of 39 individuals (20 males and 19 females) of Myr- mecophaga tridactyla (Mt, 2n = 60 and NF = 110) and 29 individu- als (17 males and 12 females) of Tamandua tetradactyla (Tt, 2n =54 and NF = 108) were studied throughout their geographical dis- tribution in Argentina. Peripheral blood lymphocytes were cul- tured to obtain mitotic metaphases and G-, C-, and NOR-banding along with telomeric FISH were carried out. Spermatocyte micro- spreads were used to analyze synaptonemal complexes (SC) from testicular biopsies (n = 2).The G-banding pattern and chromo- some size showed a full homology for most pairs, and this was confirmed by SC. Pairs 2, 6, and 7 of Tt were the result of the cen- tromeric fusion of pairs 9-20, 14-17, and 24-26 of Mt, respectively, and the FISH analysis in Tt revealed telomeric signals at the cen- tromeric regions in these chromosomes, supporting this hypoth- esis. The differences in the number of chromosome arms between Mt and Tt may be explained by pericentric inversion mechanisms. The analysis of SC confirmed equal size morphology of the sex chromosomes between species; both sex chromosomes were sub- metacentric with an X chromosome larger than the Y. These re- sults provide a scenario for karyotype evolution in which Tt may have evolved from an ancestral karyotype, actually represented by Mt, by 3 chromosome fusions and constitute a contribution to the intra- and interspecific phylogenetic relationships in Myrme- cophagidae and the superorder Xenarthra.