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Phylogeny and the evolution of the Psittaciformes (parrots, parakeets) as derived from the sequences of selected sex-chromosomal DNA sequence elements.

Our studies of the evolution of the spindlin gene in birds has enabled us to generate a better understanding of the evolutionary relationships between the different members of the Psittaciformes (Parrots and parakeets). Such understanding is important in order to obtain a better understanding of avian evolution in general, but may also give important information about the interaction between avian hosts (i.c. Psittaciformes) and their parasites (i.c. viruses). The Psittaciformes are a unique avian family of which the nearest relatives among the other birds are unknown. Molecular procedures have been widely employed to find the interspecific relationships between animals, plants, bacteria etc.

Our research at Avian Biotech (4) has shown, that based on an analysis of the W- and Z-specific forms of a segment of the spindlin gene, the Psittaciformes can be divided in four groups. Three species in New Zealand, the kea (Nestor notabilis), the kaka (Nestor meridionalis) and the kakapo (Strigops habroptilus) form a sister group to all other Psittaciformes. The remaining three groups are formed by the Australian Cockatoos (Cacatuiformes), the neotropical parrots (amazones, macaws, conures), the Pesquets parrot (Psittrichas fulgidus) of New Guinea and the Vasa parrot (Coracopsis vasa) of Madagascar and the African species such as the African grey parrot (P. erithacus) and Poicephalus (Psittacini). Finally a fourth group is formed by a large number of species which occur in the Australo-Pacific region as well as South and Southeast Asia such as the lories (Lorinae) and the parakeets (Psittaculini and Platycercini). The lovebirds (Agapornidae) from Africa are also included in this group. The results support a Gondwanan origin of the Psittaciformes and the suggestion that palaeogeographic events were a major force in psittacine evolution and divergence.


1) De Kloet, S. R. 2001. Loss of the gene for the alpha subunit of ATP synthase (ATP5W1) from the W chromosome of the African grey parrot (Psittacus erithacus). J. Mol. Evol. 53:135-143.

2) De Kloet, S. R. 2001. Development of a CAPS (cleaved amplified polymorphic sequence) assay for sex identification of the emu (Dromaius novaehollandiae). Mol. Ecol. Notes 1:273-274.

3) De Kloet, S. R. 2002. Molecular sex identification of tinamous with PCR using primers derived from the spindlin gene. Mol. Ecol. Notes 2:465-466.

4) De Kloet, R. S., and S. R. de Kloet. 2003. Evolution of the spindlin gene in birds: independent cessation of the recombination of sex chromosomes at the spindlin gene in neognathous birds and tinamous,
a palaeognathous avian family. Genetica 119:333-342.

5) De Kloet, R. S. and de Kloet, S. R. 2005. The evolution of the
spindlin gene in birds: Sequence analysis of an intron of the
spindlin W and Z gene reveals four major divisions of the
Psittaciformes. Mol. Phyl. and Evol. 36: 706-721.

6) De Kloet, E., and S. R. de Kloet. 2004. Analysis of the beak and feather disease viral genome indicates the existence of several genotypes which have a complex psittacine host specificity. Arch. Virol. 149:2392-2412.

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