Reconstruction of gross avian genome structure, organization and evolution suggests that the chicken lineage most closely resembles the dinosaur avian ancestor.
Abstract
BACKGROUND: The availability of multiple avian genome sequence assemblies greatly
improves our ability to define overall genome organization and reconstruct evolutionary
changes. In birds, this has previously been impeded by a near intractable karyotype
and relied almost exclusively on comparative molecular cytogenetics of only the largest
chromosomes. Here, novel whole genome sequence information from 21 avian genome sequences
(most newly assembled) made available on an interactive browser (Evolution Highway)
was analyzed. RESULTS: Focusing on the six best-assembled genomes allowed us to assemble
a putative karyotype of the dinosaur ancestor for each chromosome. Reconstructing
evolutionary events that led to each species' genome organization, we determined that
the fastest rate of change occurred in the zebra finch and budgerigar, consistent
with rapid speciation events in the Passeriformes and Psittaciformes. Intra- and interchromosomal
changes were explained most parsimoniously by a series of inversions and translocations
respectively, with breakpoint reuse being commonplace. Analyzing chicken and zebra
finch, we found little evidence to support the hypothesis of an association of evolutionary
breakpoint regions with recombination hotspots but some evidence to support the hypothesis
that microchromosomes largely represent conserved blocks of synteny in the majority
of the 21 species analyzed. All but one species showed the expected number of microchromosomal
rearrangements predicted by the haploid chromosome count. Ostrich, however, appeared
to retain an overall karyotype structure of 2n=80 despite undergoing a large number
(26) of hitherto un-described interchromosomal changes. CONCLUSIONS: Results suggest
that mechanisms exist to preserve a static overall avian karyotype/genomic structure,
including the microchromosomes, with widespread interchromosomal change occurring
rarely (e.g., in ostrich and budgerigar lineages). Of the species analyzed, the chicken
lineage appeared to have undergone the fewest changes compared to the dinosaur ancestor.
Type
Journal articleSubject
AnimalsChickens
Chromosome Painting
Dinosaurs
Evolution, Molecular
Gene Ontology
Genomics
In Situ Hybridization, Fluorescence
Karyotype
Passeriformes
Recombination, Genetic
Synteny
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https://hdl.handle.net/10161/9319Published Version (Please cite this version)
10.1186/1471-2164-15-1060Publication Info
Romanov, Michael N; Farré, Marta; Lithgow, Pamela E; Fowler, Katie E; Skinner, Benjamin
M; O'Connor, Rebecca; ... Griffin, Darren K (2014). Reconstruction of gross avian genome structure, organization and evolution suggests
that the chicken lineage most closely resembles the dinosaur avian ancestor. BMC Genomics, 15. pp. 1060. 10.1186/1471-2164-15-1060. Retrieved from https://hdl.handle.net/10161/9319.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Erich David Jarvis
Adjunct Professor in the Dept. of Neurobiology
Dr. Jarvis' laboratory studies the neurobiology of vocal communication. Emphasis is
placed on the molecular pathways involved in the perception and production of learned
vocalizations. They use an integrative approach that combines behavioral, anatomical,
electrophysiological and molecular biological techniques. The main animal model used
is songbirds, one of the few vertebrate groups that evolved the ability to learn vocalizations.
The generality of the discoveries is tested in other vocal

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