I.  Examples of evolution by genetic drift in nature

    A.  Dissolution of tristyly in Lythrum salicaria.

        1.  Natural history  (see tristyly)

        2.  Maintenance of tristyly by natural selection (see Handout)

        3.  Expected effects of genetic drift

        4.  Experimental procedure

        5.  Results

        6.  Conclusions

     B.  Genetic Drift of Blood group frequencies in Italian populations
 

III.  Interaction between natural selection and genetic drift

     A.   Computer simulations (demonstrated in class)

      B.  Quantitative results

     C.  Fate of weakly advantageous and disadvantageous alleles