Abstract
Songbirds are important models for the study of social behaviour and communication. To complement the recent genome sequencing of the domesticated zebra finch, we sequenced the brain transcriptome of a closely related songbird species, the violet-eared waxbill (Uraeginthus granatina). Both the zebra finch and violet-eared waxbill are members of the family Estrildidae, but differ markedly in their social behaviour. Using Roche 454 RNA sequencing, we generated an assembly and annotation of 11 084 waxbill orthologues of 17 475 zebra finch genes (64%), with an average transcript length of 1555 bp. We also identified 5985 single nucleotide polymorphisms (SNPs) of potential utility for future population genomic studies. Comparing the two species, we found evidence for rapid protein evolution (ω) and low polymorphism of the avian Z sex chromosome, consistent with prior studies of more divergent avian species. An intriguing outlier was putative chromosome 4A, which showed a high density of SNPs and low evolutionary rate relative to other chromosomes. Genome-wide ω was identical in zebra finch and violet-eared waxbill lineages, suggesting a similar demographic history with efficient purifying natural selection. Further comparisons of these and other estrildid finches may provide insights into the evolutionary neurogenomics of social behaviour.
Highlights
To date, nearly 50 mammalian genomes have been completely sequenced
The total waxbill brain transcriptome dataset consisted of 2 031 466 reads, and 2 013 275 after filtering
The transcript set described here closely matches the transcript length profile for the full Ensembl transcript set for zebra finch
Summary
Nearly 50 mammalian genomes have been completely sequenced. These diverse genome sequences capture many of the major lineages in the mammalian tree of life, and frame the study of evolution on a broad scale. Detailed sampling of closely related species, provides a complementary perspective. Analyses of closely related primate species have begun to reveal the molecular [1,2] and regulatory [3] changes underlying species differences. Among insects the effort to sequence 12 Drosophila.
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