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

CECILIA LANZONE; D. CARDOZO; M. SÁNCHEZ; D. A. MARTÍ; R. A. OJEDA

MAMMAL RESEARCH

SPRINGER

Año: 2016

2199-2401

Sigmodontinae is a group of rodents with a rich andcomplex diversification in South America. Among them, thetribe Phyllotini comprises at least ten genera and exhibits highchromosome variability. It was proposed that chromosomeevolution in mammals is influenced by centromeric meioticdrive (CMD). This mechanism of chromosome transmissiongenerates a bimodal distribution of karyotypes, which are eithermostly acrocentric or mostly biarmed. Here, we reviewedand analyzed chromosome data from Phyllotini to contrastthem with that predicted by the CMD model. Additionally,we analyzed the chromosome data in a phylogenetic framework.When only one karyotype was considered per polymorphicspecies, the distribution resembles the CMD model, althoughit is not completely bimodal. The position of mostpolymorphic species in the center of the distribution and thepresence of XY1Y2 chromosomes in a species with exclusivelybiarmed autosomes suggested that the CMD model is applicableto some particular species. Within a phylogeneticframework, some genera are characterized by highfundamental numbers (FNs), such as Calomys, Phyllotis,and Andalgalomys, and others by low FN (Loxodontomys,Auliscomys). This suggests that FN is a good marker for inferringsome intra- and intergeneric relationships. However,the chromosome data are not coincident with the close molecularrelationship obtained between Andalgalomys andSalinomys, because these species have respectively the maximumand minimum diploid number (2n) found in the tribe.There are 87 described karyotypes, but only one species has2n = 52, considered ancestral for sigmodontines, or 2n = 70,proposed as ancestral for phyllotines. This suggests a majorchromosomal restructuring at the base of the phyllotineradiation.