Class Notes (836,580)
Canada (509,856)
Biology (2,931)
BIO3119 (10)
Lecture 4

BIO3119 Lecture 4: POPULATION GENETICS LECTURE 4 - POPULATIONS AND GENETIC VARIATION
Premium

5 Pages
75 Views
Unlock Document

Department
Biology
Course
BIO3119
Professor
Howard Rundle
Semester
Fall

Description
find more resources at oneclass.com Short Introduction to Genetic Variation Learning outcomes  By the end of this section you should: o Understand why genetic variation is important o Be comfortable with simple terminology (e.g. loci, gene, allele, mono and polymorphic, identify by state and descent) o Be familiar with two different ways of quantifying genetic variation (prop. of polymorphic loci and average heterozygosity) o Be able to calculate genotype frequencies from absolute numbers of different genotypes, and allele frequencies from genotype frequencies. Population genetics considers the processes that cause changes in allele and/or genotype frequencies in populations:  natural selection, genetic drift, Mutation, Recombination, gene flow/migration, inbreeding/assortative mating o Aside: what is a population?  consists of members of the same species  are usually geographically continuous  any individual can potentially mate with any other individual in the population  can be studied as a unit;  for example, you can study the size of a population, or the frequency of a particular allele in that population Genetic Variation  Most of the processes that cause changes in allele and/or genotype frequencies in populations require genetic variation to have any affect: o natural selection, genetic drift, recombination, gene flow/migration, Inbreeding/assortative mating.  Example: natural selection o Natural selection in the differential survival and/or reproductive success of individuals differing in phenotype, and is the only evolution process that produces adaptation. o Imagine a phenotypically homogeneous population.  Can natural selection occur in this population?  Natural selection works with DNA changes that are already present. Population Genetics  Seeks to understand the structure and dynamics of naturally occurring genetic variation both within and among populations/species Definitions:  Gene – a sequence of DNA that codes for a protein find more resources at oneclass.com find more resources at oneclass.com  Locus – location on a chromosome, may be coding or noncoding.  Allele – the alternative form(s) of DNA at a particular locus  Monomorphic locus – only one allele for this locus in the population  Polymorphic/segregating locus – a locus with multiple alleles in the population Two ways in which alleles at the same locus can differ: 1. By descent a. If alleles were inherited from a common ancestor in the recent past (i.e. they are copies of a single ancestral allele), they are termed autozygous b. If alleles were NOT inherited from a common ancestor in the recent past, they are termed allozygous ▯▯allo▯ ▯ea▯s ▯other▯▯ 2. By state a. Alleles with different DNA (protein) sequences differ in state. b. c. d. Genotype and allele frequencies  Let▯s call our two alleles 1 and A 2 o Three possible (combinations) genotypes exist, A A , 1 A1, 1nd2A A . 2 2  Of course, A 1 2nd A A 2r1 the same genotype.
More Less

Related notes for BIO3119

Log In


OR

Join OneClass

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

Sign up

Join to view


OR

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.


Submit