Week 2

Question 1

explain how the geographical distributions of mammals reflects their phylogenetic history

Answer 1

marsupials and monotremes are located east of the wallace line and mammals are primarily located west of it this is due to where the islands where before they shifted creating two separate evolutions

Question 2

What does evidence of evolution show

Answer 2

It shows that species have changed over time and that ancestors evolve into descendants

Question 3

Def:Homology

Answer 3

a similarity amound species in DNA sequences, gene content or other genetic attributes that is due to shared ancestor

Question 4

Def: Genetic Homology

Answer 4

a similarity among species in DNA sequences, gene content or other genetic attributes that is due to shared ancestry

Question 5

Def: Developmental Homology

Answer 5

a similarity among species in embryonic traits that is due to shared ancestry

Question 6

Examples of genetic homology

Answer 6

-an identical or almost identical system is used by all know organisms to store the sequence of amino acids in proteins in nucleotides
-plasma membrane
-transcription of DNA and translation of RNA
-use of ribozymes and ATP
-highly similar genetic code

Question 7

Examples of developmental homology

Answer 7

-gill pouch present during embryological development which becomes reabsorbed in mammals
-structural homology: arm structure in most mammals

Question 8

Why does homology matter

Answer 8

-toxins and allergens may similarly affect other species and allow early identification of problems
-medicines can be tested in other species
-biological function in humans can be inferred

Question 9

Explain the process of taking antibiotics for tuberculosis if the mutant strain is present

Answer 9

-kills wildtype strain
-feel better
-mutant proliferates resulting in another infection
-mutant unaffected by anti-biotic
-leads to death

Question 10

What antibiotic is used to treat tuberculosis

Answer 10

rifampin

Question 11

How does rifampin work

Answer 11

It works by interfering with bacterial RNA polymerase

Question 12

How is the tuberculosis mutant bacteria not affected by rifampin

Answer 12

mutation in rpoB gene which encodes for bacterial RNA polymerase, preventing rifampin from interfering with this protien

Question 13

Explain the correlation between the Bmp4 gene and beak size and how it was discovered

Answer 13

Increase in Bmp4 gene is though to correlate with an increase in beak size in finches
scientists used chickens to ectopically express Bmp4 and observed an increase in beak depth allowing scientists to predict that the same effects are seen in finches

Question 14

Myths of evolution

Answer 14

-Its goal directed
-produces a hierarchy of life
-animal behaviour is selfless
-natural selection results in most optimal phenotype

Question 15

Examples of fitness trade offs

Answer 15

-Pelvis size and brain size, parental care, peacock tails, sickle cell anemia, morning sickness

Question 16

Def:pleiotropic

Answer 16

influence more than one characteristic, limiting the ability of natural selection to optimize each one

Question 17

Genetic correlation

Answer 17

occurs when selection favoring alleles for one trait cause a correlated but suboptimal change in an allele for another trait

Question 18

Historical Constraints

Answer 18

Present variation biases future possibilities

Question 19

Formal Constraints

Answer 19

evolution needs to work within the laws of physics

Question 20

Temporal constraints

Answer 20

evolution occurs by mutation and it takes time for a series of useful mutations to occur

Question 21

What are four factors that tend to change allele frequencies

Answer 21

Natural selection
genetic drift
gene flow
mutation

Question 22

Def: genetic drift

Answer 22

allele frequencies change stochastically (by statistics not natural selection)

Question 23

Def: Gene flow

Answer 23

introduction of alleles for another population

Question 24

Def: Mutation

Answer 24

modifies allele frequencies by continually introducing new alleles, even deleterious ones

Question 25

Hardy-weinberg principle

Answer 25

serves as a model for generating predictions about genotype frequencies that are consistent with the null hypothesis of random association of alleles
-models allele frequencies in generations if the only thing affecting their genotype as the allele frequencies of the generation before them

Question 26

Assumptions under the Hardy-weinberg principle

Answer 26

no natural selection
no genetic drift
no gene flow
no mutation
no biased mating