The zebra finch ( Taeniopygia guttata) provides an ideal model avian system in which to explore the role of the MC1R in plumage colouration. Thus, although colour variations need not necessarily involve the MC1R, , this gene remains the candidate of choice for explaining the genetic basis of melanin based plumage variation in birds. It is hence no wonder that the MC1R has been described as providing a unique window on the genetics of evolution. The phenotypic effects of the MC1R, however, do not stop at colouration, but it has been proposed that this gene might also affect behavior, immune function, the nervous system and stress response. The MC1R has recently been established as a key gene causally explaining colour variation in many vertebrates, with single amino acid substitutions sometimes having dramatic phenotypic effects. High MC1R activity leads to increased synthesis of eumelanin, whereas low activity leads to increased synthesis of phaeomelanin. Over the last decade, one particular component of the melanin synthesis pathway has become the focus of attention, the melanocortin-1 receptor gene ( MC1R) which encodes a seven-pass transmembrane G protein coupled receptor. Variation in plumage pigmentation has been documented in over 300 taxonomically diverse bird species and is often causally linked to melanins, either the black to brown eumelanin or the yellow to reddish-brown phaeomelanin. They also contribute towards a growing body of evidence suggesting that care should be taken to quantify, and where necessary control for, population structure in association studies.Įxplaining the tremendous variation in plumage colouration in birds has been a prominent research focus across a wide range of fields including sexual selection, speciation, sexual dimorphism and the evolution of plumage polymorphism. Our results are consistent with a previous study that found no association between MC1R polymorphism and plumage coloration in leaf warblers. No significant associations were detected in the resulting offspring, suggesting that our original findings were a byproduct of genome-wide divergence. We therefore crossed wild type with white individuals and backcrossed the F1s with white birds. To provide a control, the birds were genotyped at eight microsatellites and subjected to Bayesian cluster analysis, revealing two distinct groups. Allelic counts differed significantly between the two plumage morphs at multiple segregating sites, but these were mostly synonymous. We explored the role of the MC1R in a model avian system by sequencing the coding region in 162 zebra finches comprising 79 wild type and 83 white individuals from five stocks. However, the potentially confounding influence of population structure has rarely been controlled for. Polymorphisms at the melanocortin-1 receptor ( MC1R) gene have been linked to coloration in many vertebrate species. Fisher's exact test P-values are given for tests of association between allele counts at each position and plumage coloration (wild type versus white). Details of 9 segregating sites in the coding region of the MC1R of 92 zebra finch backcrosses. Observed (Ho) and expected (He) microsatellite heterozygosities and P-values for deviation from HWE, summarised separately for each of seven different stock/plumage morph combinations. Note that sequence data are only available from eight of the nine wild type individuals from the Bohle private stock in Detmold, as one individual failed to generate sequence data of sufficient quality. Details of 28 segregating sites in the coding region of the MC1R of 161 F0 zebra finches. Raw genotype data for 162 F0 zebra finches genotyped at eight polymorphic microsatellite loci.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |