Chromosomal Evolution in the Phylogenetic Context: A Remarkable Karyotype Reorganization in Neotropical Parrot Myiopsitta monachus (Psittacidae)

Myiopsitta monachusis a small Neotropical parrot (Psittaciformes: Arini Tribe) from subtropical and temperate regions of South America. It has a diploid chromosome number 2n= 48, different from other members of the Arini Tribe that have usually 70 chromosomes. The species has the lowest 2nwithin the Arini Tribe. In this study, we combined comparative chromosome painting with probes generated from chromosomes ofGallus gallusandLeucopternis albicollis, and FISH with bacterial artificial chromosomes (BACs) selected from the genome library ofG. galluswith the aim to shed light on the dynamics of genome reorganization inM. monachusin the phylogenetic context. The homology maps showed a great number of fissions in macrochromosomes, and many fusions between microchromosomes and fragments of macrochromosomes. Our phylogenetic analysis by Maximum Parsimony agree with molecular data, placingM.monachusin a basal position within the Arini Tribe, together withAmazona aestiva(short tailed species). InM. monachusmany chromosome rearrangements were found to represent autopomorphic characters, indicating that after this species split as an independent branch, an intensive karyotype reorganization took place. In addition, our results show thatM.monachusprobes generated by flow cytometry provide novel cytogenetic tools for the detection of avian chromosome rearrangements, since this species presents breakpoints that have not been described in other species.