lecture 4: evolution by natural selection

Question 1

What 4 patterns are explained by evolution by natural selection?

Answer 1

1. Species are diverse, but there is an unity.
2. Species are adapted to their environments.
3. Similar species are found relatively near to each other.
4. Species are not perfect.

Question 2

Who is behind the concept of evolution by natural selection?

Answer 2

Darwin and Wallace

Question 3

What are Darwin and Wallace’s two claims?

Answer 3

1. Evolution has occurred; species change through time.

2. Mechanism of evolution = natural selection

Question 4

What is special creation (2 elements) ?

Answer 4

1. Species were created independently by God.

2. Species were unchangeable and had been unchanged since the moment of their creation.

Question 5

(1) What is typological thinking? (Plato)

Answer 5

Types are created and immutable.

Question 6

(2) What is Aristotle’s scale of nature?

Answer 6

Types can be ranked higher/lower based on complexity.

Question 7

(3) What was Lamarck’s thinking (2 elements)?

Answer 7

Species change through time from low to high (scale of nature); INVIDUALS EVOLVE.

1. Individuals change in response to environment depending if of use/disuse of certain traits.
2. Pass on acquired characteristics to their offspring.

Question 8

(4) What was Darwin and Wallace’s thinking?

Answer 8

Species change through time and are related via a common ancestor (tree-thinking); POPULATIONS EVOLVE (variations within populations).

Question 9

What are the two components of Darwin’s Theory of Evolution?

Answer 9

1. Decent with Modification

2. Natural Selection

Question 10

What is “fitness”?

Answer 10

The ability to survive and reproduce offsprings who can survive and reproduce too.

Question 11

What is “adaptation”?

Answer 11

Any traits that increase fitness.

Question 12

What are Darwin’s 4 observations?

Answer 12

1. Competition among individuals in a population to survive and reproduce.
2. Variation in traits exists in population.
3. Certain traits give individuals a survival/reproductive advantage.
4. Many traits are heritable (can be passed on to offspring).

Question 13

What are Darwin’s 2 conclusions?

Answer 13

1. Individuals with advantageous trait are more likely to survive and reproduce.
2. Over time, more individuals in the population will have the advantageous trait.

Question 14

What is natural selection?

Answer 14

Individuals with certain traits produce more offspring that survive than do individuals without those traits. Selected traits increase in frequency in the population, from one generation to the next, causing evolution.

Question 15

Evolution by natural selection occurs when…

Answer 15

Heritable variation lead to differential success in survival and reproduction.

Question 16

What is selection pressure?

Answer 16

When nature puts pressure on the survival and reproduction of individuals in a population. Selection pressures vary from one environment to another OR in the same environment throughout time.

Question 17

Where can selection pressure come from?

Answer 17

1. Physical environment: climate, availability of ressources

2. Interactions with another species: competition, mutalism, predator/prey, parasite/host

Question 18

What is Decent with Modification (2 claims)?

Answer 18

1. Species change through time.

2. Species are related by common ancestry.

Question 19

What evidence support that “species change through time”? (2 elements)

Answer 19

1. Fossil record

2. Vestigial traits

Question 20

What does fossils show?

Answer 20

1. Traces of organisms that lived in the past; life is ancient
2. Proof for extinct species
3. Extinct species & extant species with similar traits share same geographic location
4. Transitional features (“missing link”) show evolution of species

Question 21

What are vestigial traits?

Answer 21

Trait that is incompletely developed with no/reduced function, but is similar to a more developed, functioning trait in closely related species
EX: tail & human’s coccyx

Question 22

What is a homology?

Answer 22

A similarity between species that evolved from a common ancestor.

Question 23

What is biogeography?

Answer 23

Study of geographical distribution of organisms today and over time. Reveals that similar species are linked by geography.

Question 24

What are the biogeographic relationships?

Answer 24

Similar species (extinct or extant) involved from a common ancestor inhabitates same area.

Question 25

What is an analogy?

Answer 25

Similarity not due to a common ancestor.

Question 26

What is convergent evolution?

Answer 26

Organisms with separate ancestors may show simlar adaptations due to similar selection pressures all around the world. It produces ANALOGIES.

Question 27

Why are adaptations limited (4 elements)?

Answer 27

1. Fitness trade-offs: cannot maximize one trait without negatively affecting another
2. Genetic constraints: gene pool in population is limited
3. Historical constraints: some adaptations are built from exaptations (ancient adaptation that does not serve same purpose anymore)
4. Environmental constraints: envrionments change and idea of “perfection” changes too