Evidence from a House Finch (Haemorhous mexicanus) Spleen Transcriptome for Adaptive Evolution and Biased Gene Conversion in Passerine Birds



Identifying genes influenced by natural selection can provid
e information about lineage-specific adaptations, and tran-
scriptomes generated by next-generation sequencing are a us
eful resource for identifying such genes. Here, we utilize a
spleen transcriptome for the house finch (
Haemorhous mexicanus
), an emerging model for sexual selection and disease
ecology, together with previously sequenced avian geno
mes (chicken, turkey, and zebra finch), to investigate
lineage-specific adaptations within birds. An analysis of 4,
398 orthologous genes revealed a significantly higher ratio
of nonsynonymous to synonymous substit
utions and significantly higher GC content in passerines than in galliforms, an
observation deviating from strictly neutral expectations b
ut consistent with an effect of biased gene conversion on the
evolutionary rate in passerines. These data also showed that ge
nes exhibiting signs of positive selection and fast evolution
in passerines have functional roles related to fat m
etabolism, neurodevelopment, and ion binding.

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Last updated on 05/24/2016