Chromosomal variability and evolution in the tribe Phyllotini (Rodentia, Cricetidae, Sigmodontinae)

LANZONE C.; CARDOZO D.; SÁNCHEZ D.; MARTÍ D. A.; OJEDA R.A.

ACTA THERIOLOGICA

POLISH ACAD SCIENCES

Lugar: Bialowieza; Año: 2016 p. 1 - 10

0001-7051

Sigmodontinae is a groupof rodents with a rich and complex diversification in South America. Amongthem, the tribe Phyllotini comprises at least ten genera and exhibits high chromosomevariability. It was proposed that chromosome evolution in mammals is influencedby centromeric meiotic drive (CMD). This mechanism of chromosome transmission generatesa bimodal distribution of karyotypes, which are either mostly acrocentric ormostly biarmed. Here we reviewed and analyzed chromosome data from Phyllotinito contrast them with that predicted by the CMD model. Additionally, we analyzedthe chromosome data in a phylogenetic framework. When only one karyotype wasconsidered per polymorphic species, the distribution resembles the CMD model, although it is not completely bimodal. The position of most polymorphic species in thecenter of the distribution, and the presence of XY1Y2 chromosomes in a specieswith exclusively biarmed autosomes suggested that the CMD model is applicable to some particular species. Within a phylogenetic framework, some genera arecharacterized by high fundamental numbers (FN), such as Calomys, Phyllotis and Andalgalomys, and others by low FN (Loxodontomys, Auliscomys). This suggests that FN is a good marker for inferring someintra and intergeneric relationships. However, the chromosome data are notcoincident with the close molecular relationship obtained between Andalgalomys and Salinomys, because these species have respectively the maximum andminimum diploid number (2n) found in the tribe. There are 87 describedkaryotypes, but only one species has 2n=52, considered ancestral forsigmodontines, or 2n=70, proposed as ancestral for phyllotines. This suggests amajor chromosomal restructuring at the base of the phyllotine radiation.