Psittacopasserae is a
taxon
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
of
birds consisting of the
Passeriformes
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
(passerines, a large group of perching birds) and
Psittaciformes (parrots). Per Ericson and colleagues, in analysing genomic DNA, revealed a lineage comprising passerines, psittacines and
Falconiformes
The order Falconiformes () is represented by the extant family Falconidae (falcons and caracaras) and a handful of enigmatic Paleogene species. Traditionally, the other bird of prey families Cathartidae (New World vultures and condors), Sagitt ...
.
The group was proposed following an alignment of nuclear intron sequences by Shannon Hackett et al. in 2008,
it was formally named in a 2011 ''
Nature Communications
''Nature Communications'' is a peer-reviewed, open access, scientific journal published by Nature Portfolio since 2010. It is a multidisciplinary journal and it covers the natural sciences, including physics, chemistry, earth sciences, medici ...
'' article by Alexander Suh and other authors working with
Jürgen Schmitz's group,
based on genetic analysis of the insertion of
retroposon
Retroposons are repetitive DNA fragments which are inserted into chromosomes after they had been reverse transcribed from any RNA molecule.
Difference between retroposons and retrotransposons
In contrast to retrotransposons, retroposons never ...
s into the genomes of key avian lineages over the course of evolution during the
Mesozoic Era.
Technical considerations
Analysis of retroposon insertions offers a higher degree of confidence because retroposon insertion is "virtually
homoplasy
Homoplasy, in biology and phylogenetics, is the term used to describe a feature that has been gained or lost independently in separate lineages over the course of evolution. This is different from homology, which is the term used to characterize ...
-free", as retroposons insert at random positions throughout the genome, whereas
point mutation
A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequence ...
s in DNA cycle between only four possible options. This makes it less likely that random coincidence or
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
creates illusory similarities between unrelated groups. However, the technique requires very extensive genomic data - in the 2011 paper, approximately 200,000 retroposon-containing loci were examined to identify 51 individual retroposition events which are present in some birds but not others.
Significance in the evolution of birdsong
Passerines are renowned as songbirds, and parrots share a capacity for
vocal learning Vocal learning is the ability to modify acoustic and syntactic sounds, acquire new sounds via imitation, and produce vocalizations. "Vocalizations" in this case refers only to sounds generated by the vocal organ (mammalian larynx or avian syrinx) as ...
. Thus it is possible that vocal learning, and the corresponding variety of song, was present in a psittacopasseran ancestor.
References
{{Taxonbar, from=Q5856078
Neognathae