Talk:Supergene
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I don't think supergene should be merged with gene complex, or gene duplication etc. Supergenes have cis-effects due to multiple loci (which maybe within a gene, or within a single gene's regulatory region), and tight linkage. They are classically polymorphic, and different elements code for different things. The two classic supergenes are (1) the Primula heterostyly locus, which controls "pin" and "thrum" types, and (2) the locus controlling mimetic polymorphism in Papilio memnon butterflies. Gene complexes are simply complexes of genes, often created via gene duplication, and often where each gene has similar though slightly diverged functon. For example, the human MHC region is a complex of tightly linked genes all acting in the immune system which have no claim to be a supergene, even though they very likely have epistatic effects and are in strong disequilibrium due in part to selection.
Classically, supergenes evolve from less tightly linked genes coming together via rearrangement or reduced crossing over, due to selection for particular multilocus phenotypes. However, most people today disbelieve this, because you need some linkage disequilibrium to select for tighter linkage, and you can't get the linkage disequilibrium until you have some already via some other process. Most people following Turner (1984) argue that supergenes arose in situ due to selection for correlated and epistatic traits, which happened to have been possible to produce via the existene of loci closely linked to the original variant. Turner calls this a "sieve" explanation, and the Turner explanation might be called the Turner sieve hypothesis.
No supergene has yet been characterized to my knowledge, but work is proceeding in a number of species. In a year or so, I predict we will understand a lot more (written in Jan 2006).
[edit] supergene and haplotype
Neither page refers to the other, but it seems they might both be referring to the same concept. Are they? And if so, some kind of synergy is needed. Macdonald-ross 18:13, 15 August 2007 (UTC)
