Class Notes (834,976)
United States (324,008)
Biology (868)
BIO 311D (190)
Lecture 31

BIO 311D Lecture 31: Organization of Genetic Variation (Apr 12)

5 Pages
Unlock Document

BIO 311D
Levin Donald

BIO 311D, Dr. Donald Levin, Lecture #31, 12 April 2017 (All images are taken from Dr. Levin’s lecture slides, which are available on his website Organization of Genetic Variation  Review of last lecture o High frequency (0.2) of sickle cell anemia in parts of Africa o Heterozygote advantage over homozygotes 1. Smaller percentage infected 2. Lower parasite count in blood 3. Lower death rate  Frequency of alleles for thalassemia (actually the sum for alleles that lead to various forms) o Frequency greater than 0.2 (relatively high) in some areas because of heterozygote advantage in malarial environment o Balance in selection o Very low in Ireland  For G6PD enzyme deficiency o Greater frequency than 0.2 in Saudi Arabia and parts of Africa o Very low in Europe  Agents of evolutionary change o Mutation: ultimate source, rare for individual to mutate o Gene flow: potent change agent o Nonrandom mating: commonly inbreeding, decreases heterozygosity o Genetic drift: only in a very small population o Selection: produces adaptive evolutionary changes  Adaptation – trait that enhances survivorship and reproduction o i.e. pesticide resistant = adaptation to an environment with pesticide o Heterozygosity in itself is not an adaptation; must be a phenotype  Different skin tones around the world of indigenous populations o Due to geographical variation o Lighter skin tones in the north, darker in the south  For the northern hemisphere  Higher solar radiation = darker skin color o Skin color = adaptation because the body needs sunlight to produce vitamin D but too much UV radiation from sunlight can have negative effects o Light skin in higher latitudes: not as much sunlight available so the body needs to take in as much as possible to make vitamin D so it doesn’t bock light with as much melanin o Dark skin in lower latitudes: a lot of sunlight available so higher priority is to protect against UV radiation, so produces more melanin  Incidence of rickets (vitamin D deficiency) o Wealthy Moslems who stay indoors more have higher incidences than upper=class Hindus, who have higher incidences than other Hindus o “best” skin color depends on the environment  Body weight and temperature o Europe – cool temperature, taller people o Africa – tallest people live in the coolest environments
More Less

Related notes for BIO 311D

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.