Biology 1001A Study Guide - Comprehensive Final Exam Guide - Gene, Evolution, Dna

• School: Western University
• Department: Biology
• Course: Biology 1001A
• Professor: Beth Mac Dougall- Shackleton

Document Summary

Heterozygote advantage when heterozygotes have a selective advantage over ho(cid:373)ozygotes (it does(cid:374)"t (cid:373)atte(cid:396) if the (cid:396)elati(cid:448)e fit(cid:374)ess of ho(cid:373)ozygous do(cid:373)i(cid:374)a(cid:374)t o(cid:396) (cid:396)ecessi(cid:448)e is greater or if they are equal) Start w/ a population with a lot of aa - genotyped individuals, a few aa-genotyped individuals and then add some heterozygotes (aa). Aa does better than both aa and aa, and number of aa - genotyped individuals increases. This means (cid:862)a(cid:863) (cid:449)ill i(cid:374)c(cid:396)ease (cid:449)hile (cid:862)a(cid:863) dec(cid:396)eases. E(cid:448)e(cid:374)tually, all individuals are aa so the allele f(cid:396)e(cid:395)ue(cid:374)cies of (cid:862)a(cid:863) a(cid:374)d (cid:862)a(cid:863) will stabilize at 0. 5. *** (the more common allele - a - decreases in frequency while the rare allele - a- increases in frequency). Negative frequency dependent selection selects for rare alleles. Heterozygote advantage also increase the frequency of rare alleles. Heterozygote disadvantage when either, or both homozygote has a selective advantage over heterozygote. Start w/ a population of aa and aa and add a few heterozygotes (aa).