Chapter 7 - The Theory Of Evolution

Question 1

What was the 100 year experiment?

Answer 1

Since 1896, corn plants were selected based on whether they had high or low oil content. Initially, corn was ~4.7% oil content, but after 100 years/80 generations, one group had 19% oil and the other had

Question 2

Define evolution.

Answer 2

The process in which significant changes in the inheritable traits of a species/population occur over time

Question 3

5 areas of evidence for evolution

Answer 3

1. The Fossil Record
2. The Geographical Distribution
3. Homologous Structures
4. Similarities in Embryonic/Early Development
5. Biochemical Similarities

Question 4

What are vestigial features and an example

Answer 4

Homologous features that no longer hold any function (e.g, cave-dwelling fish have eyes but do not see

Question 5

What are analogous features and an example

Answer 5

Structures similar in function but not in origin of anatomical structure (e.g, butterfly wings/bird wings, fly eyes/human eyes, spider legs/dog legs)

Question 6

What is The Theory of Evolution?

Answer 6

The idea that species acquire traits as they interact with their environment and then pass these on to their offspring

Question 7

What were some problems of Lamark’s principles?

Answer 7

• many features do not change in response to use

- features that do change do not change on a DNA level, they are not passed down

Question 8

Who was the first to propose a mechanism for evolution?

Answer 8

Lamark

Question 9

Lamark’s principle of use & disuse

Answer 9

• structures that were used became larger and stronger

- structures not used became smaller and weaker

Question 10

Lamark’s principle of inheritance of acquired traits

Answer 10

• individuals could pass on traits to offspring that they had acquired during their lifetime

Question 11

Problems with Lamark’s principles

Answer 11

• many features do not change in response to use

- features that do change do NOT change at a DNA level and therefore cannot be passed on to the next generation

Question 12

Define gene flow, list an example and a benefit.

Answer 12

any movement of individuals from one population to another (AKA migration); e.g. pollen being blown; may be an important source of genetic variation

Question 13

The Hardy-Weinburg Principle states that…

Answer 13

the frequency of an allele in a population will remain constant over time, as long as:

• pop. is very large
• mating opportunities are equal
• no mutations
• no migration
• no natural selection

Question 14

Define genetic drift

Answer 14

changes to allele frequency as a result of chance; the smaller the # individuals, the greater the influence of genetic drift

Question 15

Genetic bottlenecks

Answer 15

a loss of genetic diversity following an extreme reduction in population size (usually results in genetic drift)

Question 16

Founder effect

Answer 16

genetic drift resulting from when a small # individuals establish a new population

Question 17

What is adaptive radiation?

Answer 17

when a single species evolves into a # of distinct but closely related species

Question 18

Difference between divergent evolution and convergent evolution and an example of each

Answer 18

divergent evolution: similar species begin to evolve to look extremely different from one another (large scale; e.g. deer mouse, flying squirrel, porcupine, beaver)
convergent evolution: distantly related species evolve to look similar (e.g. dolphins & sharks)

Question 19

Coevolution

Answer 19

one species evolves in response to the evolution of another species

Question 20

Darwin’s 5 key observations that led to his theory of evolution by natural selection

Answer 20

1) Individuals within a species vary
2) Some of this variability can be inherited
3) Every generation produces more offspring that can survive
4) Populations of species tend to remain stable in size
5) Result of natural selection is a pop. adapted to it

Question 21

Darwin’s inferences (3)

Answer 21

1) Members of the same species compete w/ each other for survival
2) Individuals w/ more favorable variations are more likely to survive (survival is not random)
3) As surviving individuals produce more offspring, favourable conditions become more common

Question 22

Convergent evolution

Answer 22

The evolution of similar traits in distantly related species

Question 23

Coevolution

Answer 23

One species evolves in response to the evolution of another species

Question 24

Divergent evolution

Answer 24

Similar species evolve to look very different (large scale)

Question 25

What makes a cladogram different from a phylogenetic tree?

Answer 25

Cladograms do not indicate the amount of time in between, and is based upon ancestry and synapomorphies, while phylogenetic trees are more based on physical similarities between species.

Question 26

Synapomorphy

Answer 26

A characteristic shared by two or more groups, first appearing in their most recent shared ancestor

Question 27

Adaptive radiation

Answer 27

single species evolves into a number of distinct but closely related species (e.g. Darwin’s finches)

Question 28

Genetic drift

Answer 28

changes to allele frequency as a result of chance (smaller population = greater influence of genetic drift)

Question 29

Genetic bottlenecks

Answer 29

an extreme reduction in population size results in a loss of genetic diversity, usually resulting in genetic drift

Question 30

Founder effect

Answer 30

genetic drift resulting from when a small # of individuals establish a new population

Question 31

Hardy-Weinburg principle

Answer 31

frequency of alleles will remain constant as long as:

• pop. is very large
• no migration/mutations/natural selection
• equal chance of reproductive success
• mating opportunities equal

Question 32

Gene flow

Answer 32

(AKA migration) any movement of individuals from one pop. to another; may result in increase of genetic variation

Question 33

Cladistics

Answer 33

Determining evolutionary relationships based on presence or absence of recently evolved traits

Question 34

Synapomorphy

Answer 34

A shared derived trait