Class Notes (811,170)
Canada (494,539)
Biology (Sci) (2,418)
BIOL 111 (283)

Evolutionary Mechanisms

2 Pages
Unlock Document

McGill University
Biology (Sci)
BIOL 111
Irene Gregory- Eaves

27/09/11 Evolutionary Mechanisms: causes changes in genes/phenotype Mutations: - Source of all genetic variation - Change genetic code = new alleles, new variants to genes = change in amino acids expressed  change physiology, behavior, etc. - Most mutations reduce fitness (ability to survive) = deleterious - On average we have 1 new mutation – most will have no effect - Though on average each mutation will cause a ~2% reduced fitness - Beneficial mutations are likely to be of small effect 1) Genetic drift: random changes in allele frequency, unrelated to survivability of genes Eg. Meteor - Evolution due to genetic drift is completely random when it comes to neutral alleles - Stronger in smaller populations: random chance/mortality eventually will fix alleles as there is no broad gene distribution to start with - Allele drift to one pole or the other (one allele will eventually be irradiated) 2) Natural Selection: Darwin/Wallace: 1. All organisms have the potential for exponential growth, but most populations remain stable = high mortality in nature 2. Traits vary among individuals (differences will vary reproductive success) 3. Traits influence survival 4. Traits are heritable =Traits that improve survival should increase in frequency through time (if probability of death and hence chance at reproduction depends on heritable traits, then more sustainable will become more prevalent over time) Ex. Daphne Major drought: - survey birds
More Less

Related notes for BIOL 111

Log In


Don't have an account?

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.