lecture 7

Question 1

evolution

Answer 1

pattern; descendant with modification. changes in allele frequencies of a population over time.

Question 2

natural selection

Answer 2

process; a mechanism that can explain evolution.

Question 3

In 1858

Answer 3

Darwin and Wallace independently come up with natural selection. but in 1859 Darwin publishes his book.

Question 4

The Origin of Species

Answer 4

described evolution as descent with modification meaning that change over time produced modern modified species from ancestral species.

Question 5

Pattern component of evolution by NS makes two claims…

Answer 5

1. species change through time

2. species are related by common ancestry

Question 6

Darwin combines 3 main ideas

Answer 6

1. superfecundity - more offspring produced than can survive
2. natural variation - Darwin saw a lot of this with the finches etc.
3. Heritability of traits - all breeders can show this (think dogs)

Question 7

Artificial Selection

Answer 7

• humans can manipulate traits in domesticated species to evolve readily (dogs) so why haven’t they evolved in nature?
• Darwin realized that a process like artificial selection does happen automatically in nature.

Question 8

Theory of evolution was revolutionary for several reasons

Answer 8

• overturned the idea that species are static and unchanging
• replaced typological thinking with population thinking
• was scientific; proposed a mechanism that could account for change through time
• made predictions that could be tested through observation and experimentation

Question 9

Change in species through time…

Answer 9

does not follow a linear, progressive pattern, but instead of based on variation among individuals in populations

Question 10

A population consists of…

Answer 10

…individuals of the same species that are living in the same area at the same time
- this view utilized population thinking rather than typological thinking (all individuals of a species are NOT identical)

Question 11

Variation among individuals in a population…

Answer 11

is the key to understanding the nature of species and drives evolution

Question 12

Natural selection

Answer 12

• changes the population frequency of variants each generation, but it doesn’t change the individuals
• NS acts on individuals because individuals experience differential success
• evolutionary change effects population however, not individuals.

Question 13

Darwin’s 4 postulates

Answer 13

1. among individuals of a species, there is variation in phenotypic traits
2. at least some of this variation is heritable
3. individuals vary in their ability to survive and reproduce (=fitness)
4. variation in some phenotypic trait is correlated with variation in fitness (=adaptive traits)

Question 14

Complications in estimating heritability

Answer 14

1. misidentified paternity
2. nest parasitism
3. shared environments
4. maternal effects

Question 15

Evolution is not goal-directed

Answer 15

• evolution simply favors individuals that happen to be better adapted to the environment at the time
• adaptions do not occur because organisms want or need them
• times change. adaptions today may be costly tomorrow or used for something else entirely.

Question 16

The essence of evolution by NS

Answer 16

• heritable variation leads to differential reproductive success.
• evolution is the OUTCOME of this process

Question 17

The modern synthesis (1930s)

Answer 17

• resolved 50+ years of controversy over the validity of evolution by NS
• combination of genetic, population genetics, paleontology
  1. individuals vary as a result of mutation creating new alleles, and segregation and independent assortment generates new combinations of alleles
  2. individuals pass their alleles on to offspring intact, not blended

Question 18

For any change in the characteristic of a population or species through time…

Answer 18

you should be able to explain how it could happen based on:

1. heritable variation in the trait
2. differential reproductive success, based on variation in the trait

Question 19

Antibiotic resistant bacteria is on the rise

Answer 19

• variation exists in the pop: both resistant and nonresistant stains were present prior to administration of the drug
• variation is heritable: the variation in the phenotypes of the two strains is due to variation in their genotypes.
• there is variation in reproductive success: antibiotic resistant bacteria were able to replicate. nonresistant strains could not.
• evolution occurred: over time, the antibiotic resistant bacteria increased in number compared to nonresistant strains.