Haemorhous mexicanus Transcriptome or Gene expression
Identifying genes influenced by natural selection can provide information about lineage specific adaptations, and transcriptomes generated by next-generation sequencing are a useful 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 genomes (chicken, turkey, zebra finch), to investigate lineage-specific adaptations within birds. An analysis of 4398 orthologous genes revealed a significantly higher ratio of non-synonymous to synonymous substitutions and significantly higher GC content in passerines than in galliforms, an observation deviating from strictly neutral expectations but consistent with an effect of biased gene conversion on the evolutionary rate in passerines. The data also showed that genes exhibiting signs of positive selection and fast evolution in passerines have functional roles related to fat metabolism, neurodevelopment and ion binding.