RESUMEN
Deer species of the genus Mazama show significant inter- and intraspecific chromosomal variation due to the occurrence of rearrangements and B chromosomes. Given that carriers of aneuploidies and structural rearrangements often show anomalous chromosome pairings, we here performed a synaptonemal complex analysis to study chromosome pairing behavior in a red brocket deer (Mazama americana) individual that is heterozygous for a Robertsonian translocation, is a B chromosome carrier, and has a multiple sex chromosome system (XY1Y2). The synaptonemal complex in spermatocytes showed normal chromosome pairings for all chromosomes, including the autosomal and sex trivalents. The electromicrographs showed homology among B chromosomes since they formed bivalents, but they also appeared as univalents, indicating their anomalous behavior and non-Mendelian segregation. Thus, synaptonemal complex analysis is a useful tool to evaluate the role of B chromosomes and rearrangements during meiosis on the intraspecific chromosomal variation that is observed in the majority of Mazama species.
Asunto(s)
Cromosomas/genética , Ciervos/genética , Meiosis/genética , Translocación Genética , Animales , Reordenamiento Génico , Heterocigoto , Masculino , Polimorfismo Genético , Espermatocitos/metabolismoRESUMEN
The red brocket deer Mazama americana is a neotropical species that exhibits extensive karyotype variation under an unvarying morphotype. In order to deduce red brocket deer genetic units for conservation, gene flow between populations, and genetic variation, we initiated a cytogenetic and molecular genetic study based on representative samples from throughout their Brazilian geographic range. These data represent the first cytotaxonomical and molecular systematics, and although sample sizes are limited, our results clearly suggest that red brocket deer populations are significantly differentiated with respect to karyotypes and the mitochondrial sequences analyzed. We clearly recognized 2 independent species, and we will be focusing further research in analyzing the meiotic dynamic to determine the existence of other evolutionarily significant units under the red brocket complex.
