CHAPTER 13

Question 1

Define the Theory of Evolution, list and describe evidence to support it (p. 248 - 251).

Answer 1

gradual change in the genetic makeup of a species over time

Evidence to support:
1. Fossil Records
- oldest organisms = prokaryotes ^3.5 BYA
2. Biogeography => geographic distribution of species
ex: Australia - has many marsupials but few placental mammals
Why: Due to plate tectonics
3. Comparative Anatomy
ex: forelimbs of diverse mammals
-> have homologous structures —> same skeletal elements
-> ALSO, vestigial structures => important to ancestors
ex: wings on flightless birds
4. Comparative Embryology
- All vertebrate embryos have a post-anal tail and gill slits
ex:
- gill slits –fish–> gills
- gill slits –human–> parts of ears + throat
5. Molecular Biology
-> The Genetic Code (bases) is universal for all life on earth => common ancestry
Note: The smaller the difference in DNA between 2 species => more closely related

Question 2

Define Natural Selection.

Answer 2

Main mechanism for evolution
1. individuals that are better adapted to their environment will survive longer -> producing more offspring
2. pass on successful traits (genes) to offspring

Question 3

who proposed natural selection and when.

Answer 3

Charles Darwin published “Origin of Species” in 1859
Also -> Alfred R. Wallace

Question 4

What 3 things are needed for natural selection to work?

Answer 4

1. Overproduction of offspring:
   => many more than the environment can support (food, space, etc) -> leads to a “struggle for existence”
2. Individual variation
3. Inheritance -> passing on genetic info

Question 5

Define a population, microevolution.

Answer 5

Population → same species living in the same place at the same time

smallest biological level that can evolve

Question 6

What are the sources of genetic variation?

Answer 6

1. MUTATION
   -> changest to DNA
   -> creates new allele (A, a, ǎ)
2. SEXUAL REPRODUCTION
   -> Mieosis:
3. Prophase I - crossing over
4. Metaphase I - Independent Assortment
5. Random Fertilization

Question 7

Define the Hardy-Weinberg formula and be able to define the components of the formula:
p + q = 1 and p2 + 2pq + q2 = 1

Answer 7

analyzing gene pools using math models, for models to be true => the population is stable, not evolving
p = frequency of the dominant allele (A)
q = frequency of the recessive allele (a)

Question 8

If given allele frequency p or q, calculate the frequencies of the 3 possible genotypes.

Question 9

What are the 5 evolutionary forces that can act on a population and put it out of Hardy-Weinberg
equilibrium? How does each force affect alleles/allele frequencies in the population?

Answer 9

1. GENETIC DRIFT - in a small population, loss of a rare allele, due to chance
   ex: volcano, flood, earthquake
2. MATE/SEXUAL REPRODUCTION - increase in frequency of genes involved in mate choice
   ex: peahen chooses peacock with best tailfeathers to mate with
3. MUTATION - creates new alleles (A, a, ǎ)
4. GENE FLOW - migration in or out of fertile individuals
   -> may bring in new alleles
   -> some may be lost
5. NATURAl SELECTION - Increase in advantageous alleles, decrease in unsuccessful traits