Class Notes (807,726)
Canada (492,831)
Biology (2,348)
BIOLOGY 1M03 (663)
Ben Evans (167)
Lecture 7

BIOLOGY 1M03 Lecture 7: 7- Genetic Drift, Gene Flow, Mutation, Inbreeding

5 Pages
Unlock Document

McMaster University
Ben Evans

Bio 1M03 January 20, 2016 Genetic Drift, Gene Flow, Mutation, Inbreeding Genetic Drift - It a great concern to conservation biologists because the small populations found on nature reserves or in zoos are especially susceptible to it - Because genetic variation is lost rapidly in small populations, this potential reduces a species ability to respond to environment changes in the future - In a small population it causes the polymorphism to be lost and makes it harder to cope - Javan Rhinos o Originally widespread in southeast Asia o With 3 sub-species o Indian Javan rhino went extinct around 1925 o The Vietnamese Javan rhino had 12 individuals in 2006 but the last survivor was shot by a poacher in 2010 o Now only populations is in Ujung Kulon Np, probably around 40 individuals and extinction is very likely in our generation o The more variation is lost in every generation o Fewer levels on phenotypic variation o Less ability to cope with changes in the environment - Genetic drift can be caused by any event or process that involves sampling of alleles from one generation to another Founder Effect - A small subset of a population moves to a new place - Cultural Isolation or Endogamy: marriage within a small group - Examples in humans are often associated with atypical prevalence of disease o Amish community in Lancaster County Pennsylvania: Ellis-van Creveld syndrome (growth deformities) o Ashkenazi Jew: Tay-Sachs disease o Because these people tend to marry within themselves reducing variation and increasing some allele frequencies that may be disease causing. - Due in increased homozygosity - Human diaspora from Africa was associated with multiple founder effects - African ancestry are more diverse and heterozygous - There is more diversity in the source location than in the dispersion locations Bottleneck Effect - Reduction in population size - Reduction in variation - Two factors that influence the impact of bottleneck on genetic variation o Severity: how many individuals are present during the time o Duration: how long does it last o Both are negatively correlated with eachother - The longer and more severe the bottleneck the more variation and diversity are lost - Cheetahs o Cheetahs are so inbred that transplanted skin grafts do not provoke immune response o So little variation, only 7100 left in wild and only 77% are in protected areas. o Probably die to 2 bottlenecks ▪ One 10000 years ago: able to tell by looking at molecular variation ▪ Another today o Very genetically similar o Variation is very scarce - Primates also threatened by extinction o 60% threatened Gene Flow - Migration - The movement of alleles from one population to another - Occurs whenever individuals leave one populations, join another and breed - Tends to homogenize gene frequencies between the source and recipient populations - Reduces genetic differences - Population: is a group of individuals (usually from the same region) that has different allele frequ
More Less

Related notes for BIOLOGY 1M03

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.