BIOL1020 Module 5 - Population Genetics

3 Pages
Unlock Document

Dr Paul Ebert

Population Genetics DNA and variation Single gene is passed on through time  part of revolutionary process DNA replicates in individuals – evolution happens in populations Selection pressure: a force that causes a particular organism to evolve in a certain direction  Favourable mutation may increase chances of survival Sources of genetic variation 1. Genetic mutation - nucleotide-pair substitution - Silent (synonymous): does not affect amino acid i.e. third position in codon - Missense: altering phenotype - Nonsense: protein no longer created 2. Genetic mutation – nucleotide-pair insertion or deletion - Frameshift causing immediate/extensive nonsense - Insertion of entirely new amino acid 3. Random mutations create allelic variation 4. Recombination and independent assortment in sexually reproducing organs Genetic variation affects individual’s fitness – can be deleterious, neutral or advantageous  Germline (meiosis) mutations matter  Somatic (mitosis) mutations matter to individual but are not heritable (i.e. cancer) Hardy-Weinberg principle (1908) Frequency of alleles and genotypes in a population will remain constant from generation to generation providing:  Only Mendelian segregation applies  Recombination of alleles is occurring Gene pool not evolving assumes:  No mutations  No gene flow  No selection  Random mating  Large population 2 2 Equilibrium = p + 2pq + q Genotype frequency = Allele frequency = Evolutionary processes Evolution: a change in the frequency of alleles over space and time in the gene pool of a reproducing population Allele frequencies change via: 1. New mutations 2. Random chance - Genetic drift – particularly important in small populations - Bottlenecking: portion of population eliminated; population reflects genetics of survivers - Founder effect: genetics reflect those of initial members 3. Non-random mating 4. Gene flow; transfer of alleles - Migration and reproduction Fundamentals of natural selection  Directional selection: change in environm
More Less

Related notes for BIOL1020

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.