<p class="1Body">With colourful plumage, charismatic character and vocal learning abilities, parrots are one of the most striking and recognizable bird groups. Their attractiveness has drawn human attention for centuries, and members of the Psittaciformes order were, also, among the first avian species to be subject to cytogenetic studies which have contributed to understand their taxonomic and evolutionary relationships.</p><p class="1Body">We present here the karyological results collected by the study of thirteen parrot species new to karyology. These results are additionally supported by G banded preparations obtained in five species.</p><p class="1Body">The order Psittaciformes is an interesting example of a, typically, non migratory avian lineage with Gondwanaland origin, whose evolutionary radiation has been shaped by the Cenozoic geographic and climatic events that affected the land masses derived from the Gondwanaland continental split.</p><p class="1Body">We discuss the results of our studies, in conjunction with the previously compiled Psittaciformes cytogenetic data to delineate a picture of the chromosomal evolution of the order, concurrently with the biogeographic history of the lands in the southern Hemisphere.</p><p class="1Body">Considering the available data on parrot cytogenetics, a "standard parrot karyotype pattern" is proposed for evolutionary comparisons.</p><p class="1Body">Several biogeographic, and phylogenetically related "karyogram patterns" are also identified, and mechanisms of chromosome rearrangement that associate this patterns among them, and with the standard parrot karyotype pattern are proposed. These schemes on parrot chromosomal variation are discussed in relation to the general avian chromosome evolutionary theses proposed by cytogenetic and molecular genomic researchers.</p>
Comparative Evolution of GII.3 and GII.4 Norovirus over a 31-Year Period