Читать книгу Population Genetics - Matthew B. Hamilton - Страница 46

To simulate the combined action of recombination and natural selection on gametic disequilibrium, use the program Populus, which can be obtained by following the link on the text website.

In version 5.5 of Populus, use the Natural Selection menu to choose the Two‐Locus Selection simulation. Set pAB = pab = 0.5 and pAb = paB = 0.0 as a case where there is maximum gametic disequilibrium initially. Use fitness values of wAaBb = 1, all others = 0.5 and wAAbb = waaBB = 1, all others = 0.5 to generate strong natural selection via epistasis. Finally, try recombination values of r = 0.5 and 0.05. Focus your attention on the D vs. t plot. What do the two different fitness cases do to levels of gametic disequilibrium and how effective is recombination in opposing or accelerating this effect?

To see the details behind the recombination and natural selection model of gametic disequilibrium, a spreadsheet version of this model is available in Microsoft Excel format. The spreadsheet model will allow you to see all the calculations represented by formulas along with a graph of gametic disequilibrium over time. You can vary the recombination rate, initial gamete frequencies, and relative fitness values to see how they impact change in D and determine its eventual equilibrium.