Class Notes (838,183)
Canada (510,737)
Biology (2,437)
BIOLOGY 1M03 (677)
Ben Evans (167)
Lecture 4

BIOLOGY 1M03 Lecture 4: 4- Evolutionary by Natural Selection
Premium

4 Pages
90 Views
Unlock Document

Department
Biology
Course
BIOLOGY 1M03
Professor
Ben Evans
Semester
Winter

Description
Bio 1M03 January 13, 2016 Evolutionary by Natural Selection Genetic Homology - An identical or almost identical system is used by all known organisms to store the sequences of amino acids - Plasma membrane - Chimps and humans differ by only ~1.5% of shared nucleotides - If you incorporate insertions and deletions they differ by ~6% - Variation in gene regulation is what led to the differences between humans and chimps - Differences in splicing and regulation led to evolution and differences - Genes are usually named after the mutant genotype - Eyeless is a version in fruit flies and the same mutant/genotype is called Pax 6 in humans - Humans have compact eyes - Eyeless and Aniridua influence where eyes are located in fruit flies and humans respectively - Presumably both are derived from an ancestral gene with the same function’ even though the eyes of humans and fruit flies are so different - Ectopic expression is artificial expression in a place where it is not supposed to be expressed in - Functions of genes can be moved and still have the same effect - The amino acid sequences can be expressed in places where it should not normally - Not only amino acid similarity across organisms but also functional similarities Developmental homology - When you have similarities between species in situ (embryology) due to common ancestry - Humans, chicks and house calls all have gills while they are in the embryonic form but none of those animals require gills in order to survive - Indicating that they are derived from a common ancestor Branchial Cleft Cyst: congenital epithelial cyst that is derived from the branchial arches that are normally reabsorbed during embryonic development Structural Homology - Similar to developmental homology - Come from common ancestry - Toxins and allergins may similarly affect other species (or cell cultures) and allow us to identify problems before (or after) problems experientially arise in humans - We see that there are immune similarities between mice and humans so medicine is tested on mice to see how it affects the body - Medicines can be tested in other species because mechanisms of action are homologous - Biological function in humans can be inferred from homologous function in other species Evidence for Evolution - Fossils - Extinction - Transitional Forms - Vestigial Traits - Speciation and adaptation - Geographical, temporal and phylogenetic continuity/consistency - Genetic homology - Developmental homology - Structural homology How does Natural Selection Work? - Individuals in a population vary in their traits (variation) - Some of these trait differences are heritable, meaning they are passed on to offspring (heritable) - In each generation not all individuals reproduce the same amount and/or not all offspring survive (fitness effects and competition) - Alleles will increase in frequency and the alleles will increase over time - Unique adaptations are a consequence of changes in allele frequencies - Natural selection doesn’t change individuals but changes populations - Individual with certain heritable traits are more likely to survive and reproduce - Natural Selection is one of the processes that determines whether individuals with certain traits produce more offspring than do individuals without those traits - Evolution can also be thought as a change in allele frequencies in a population over time - Moth Example Resistance to Antibiotics and Alleles that Confer Drug Resistance - The bacterium Mycobaterium tuberculosis causes TB a disease that killed up to a third of all adults in big cities in the 19 century - Still kills more adults than any other viral or bacterial disease - Sanitation, nutrition and antibiotics (rifampin) greatly reduced deaths due to TB in the industrialized nations from 1950’s-1980’s - However, in the late 1980’s rates of TB started to surge due to the evolution of d
More Less

Related notes for BIOLOGY 1M03

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