Monogenic traits associated with structural variants in chicken and horse
Allelic and phenotypic diversity of visually appealing traits
Contents
Introduction 11
Good material is of material importance 12
Genetic variation 15
Chicken combs 16
Melanic pigmentation 17
Equid pigmentation 18
Introduction of papers 20
Paper I 20
Paper II 21
Paper III 23
Discussion 25
The rooster's Rose-comb 25
The strikingly Grey steed 27
Analysis 27
Rate and mode of Greying 27
The disappearing Dun 29
The Dun phenotype 29
Primitive markings and the non-dun horse 30
Differences and similarities 32
Predomestic horse colour 32
Lessons learnt 34
Allelic evolution 34
Exploring variation 35
Materials 37
Phenotyping 38
Conversations with the public 40
Future and reflections 42
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Individuals of the same species may be on the opposite ends of a cline and thus exhibit a pronounced difference in appearance, but one can expect to find a multitude of intermediate forms between the two extremes. Only rarely are there pronounced differences between individuals of a species without intermediate forms being more abundant than the extremes. Perhaps the most commonly observed such difference between individuals of a single animal species is sexual dimorphism, where the sexes differ, for instance in size, colouration or physical morphology, and there is no intermediate form to be found, discounting rare developmental exceptions such as chimeras and intersexed …show more content…
Then, when molecular genetics first emerged, monogenic traits were again in vogue as their inheritance and phenotypic effects had often been well characterised, and their linkage to other monogenic loci had led to the elucidation of linkage groups that were facilitative of molecular analysis. Analogous traits had been discovered in different species, so that when a disruption of a gene was found to cause a phenotypic variant in one species, that particular gene could be examined in other species exhibiting similar phenotypes. This led to a great number of monogenic traits being explained on the molecular level, where the sequence of a gene was in some way altered, resulting in a protein product that was either subtly or radically different from the unaltered form. However, not all monogenic traits immediately offered up easily targeted genes for examination, and were thus not explained on the molecular level in those early