Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2006
Publication Date: 6/1/2006
Citation: Backstrom, N., Brandstrom, M., Gustafsson, L., Qvarnstrom, A., Cheng, H.H., Ellegren, H. 2006. Genetic mapping in a natural population of collared flycatchers (Ficedula albicollis): conserved synteny but gene order rearrangements on the avian Z chromosome. Genetics. Paper no. 106.058917(1). Available: http://www.genetics.org/cgi/content/abstract/genetics. Interpretive Summary: The chicken genome sequence, the first for any avian species, was a tremendous scientific accomplishment. Not only does the sequence help chicken researchers but due to evolutionary conservation, the sequence can be used as a first estimate in other avian species. In this paper, we show that the chicken linkage map shows a high degree of conservation with the collared flycatcher, one of the most well-studied species for ecology. Because of this high conservation with the chicken genome, efforts to identify genes favorable for the flycatcher are greatly enhanced. Furthermore, the results have implications on the evolution of sex chromosomes and genetic recombination rates, two basis biological questions. In short, this study provides the first results on how the chicken genome sequence can be transferred to other species, thus, helping basic and applied studies in other avian species, which in turn may enhance poultry biology and production.
Technical Abstract: Data from completely sequenced genomes are likely to open the way for novel studies of the genetics of non-model organisms, in particular when it comes to the identification and analysis of genes responsible for traits that are under selection in natural populations. Here we use the draft sequence of the chicken genome as a starting point for linkage mapping in a wild bird species, the collared flycatcher, one of the most well studied avian species in ecological and evolutionary research. A pedigree of 365 flycatchers was established and genotyped for single nucleotide polymorphisms in 23 genes selected from (and spread over most of) the chicken Z chromosome. All genes were found to be located on the Z chromosome also in the collared flycatcher, confirming conserved synteny at the level of gene content across distantly related avian lineages. This high degree of conservation mimics the situation seen for the mammalian X chromosome and may thus be a general feature in sex chromosome evolution, irrespective of whether there is male or female heterogamety. Alternatively, such unprecedented chromosomal conservation may be characteristic to most chromosomes in avian genome evolution. However, several internal rearrangements were observed, meaning that the transfer of map information from chicken to non-model bird species cannot always assume conserved gene orders. Interestingly, the rate of recombination on the Z chromosome of collared flycatchers was only 50% of that chicken, challenging the widely held view that birds generally have high recombination rates.