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

4 Pages
Unlock Document

Ben Evans

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


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.