BIOL2202 Lecture Notes - Lecture 21: Balancing Selection, Overdominance, Dynamic Equilibrium
Document Summary
Static equilibrium: the equilibrium remains the same throughout time. Dynamic equilibrium there are changes in allelic frequency, but the change will cancel each other out and hence, there will be no net change: this happens when population is in hwe, but evolutionary forces act in opposing ways. Balancing selection: selection when one genotype has overdominance which compensates for the loss of other alleles. Hence net change in the gene pool is 0. They are both different letters because the deviation is independent to both of them. 100% of aa will be preserved every year. Only a fraction of the other two genotypes will be preserved. Unstable equilibrium (cid:1868)= (cid:1872)(cid:1871)+(cid:1872) (cid:1869)= (cid:1871)(cid:1871)+(cid:1872: the equilibrium can change if influenced by anything, a change that occurs in the population will shift the equilibrium to a new value. Stable equilibrium: the system will always return to a specific equilibrium point no matter the change, balancing selection is an example of stable equilibrium.