Hi all,
I am trying to undersatnd the concept of linkage disequilibrium. As far as I can make out, the term refers to the fact of two genes at two different loci sticking together while being inherited i.e. they don't recombine much.
Isn't this the same as the standard concept of genetic linkage we learnt in high school genetics? Why a new term for it then?
I will be glad to receive any clarifications. Thanks.

Disclaimer: Well, I'm not working in genetics and I am sure there are plenty of people who can give you a more technically correct answer, but...I'll try to give you the gestalt.

You are right in that if Genes A and B are linked, they don't recombine freely. This occurs at a species level. An example: sweet peas: a gene determining flower color (P=purple, p=red) and a gene affecting the shape of pollen grains (L=long, l=round) are linked and not inherited independently. But, if I look at any given sweet pea, knowing the color alleles doesn't necessarily tell me what pollen-shape alleles it has.

Linkage disequilibrium occurs at a population level, and means that haplotypes don't occur at the frequencies I'd expect due to random assortment of alleles, so if I know which allele the organism has for gene 1, I can predict which allele it has for allele 2. However, suppose I plant a seed with PL on one chromosome and pl on the other, self it and breed up a whole strain of sweet peas. Now, I will have plants that are PL|PL, PL|pl, and pl|pl. Now, if I tell you that I have a red-flowered sweet pea from my particular strain, you know that it will have round pollen, right? Of course, gradually LD will decay, faster if they are less tightly linked.