BIOL 111 Lecture Notes - Daphne Major, Fish Fin, Exponential Growth

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Multiple

Document Summary

Mutations are the ultimate source of all genetic variation. Mutations change the genetic code which generates new alleles which may change amino aid sequences which may have phenotypic effects. Examples of mutations with phenotypic effects in drosophila: Most mutations decrease fitness (i. e. survival and reproductive success) and are considered deleterious. The average mutation reduces fitness by about 2% The few beneficial mutations are likely to be of small effect (hopeful monsters are rare) Stronger in smaller populations: allele frequencies in computer simulations. In the lab: 107 populations of fruit fly, each generation founded by eight males and eight females, two selectively neutral eye colour alleles, allele frequencies = 0. 5 in all populations in the generation zero. All organisms have the potential for exponential growth and yet most populations remain relatively stable in the number of individuals. Prediction: traits that improve survival should increase in frequency (or size) through time.