Evolution

Question 1

Evolution

Answer 1

A genetic change within a population over time

1. Species accumulate difference
2. Descendants differ from their ancestors
3. New species arise from existing ones

Question 2

Robert Hooke (1635-1703)

Answer 2

• Concluded fossils are remains of plants and animals
• Studied mainly “petrified wood”
• Hypothesized that living organisms had somehow turned into rock

Question 3

Lamarck’s Explanation for

Evolution

Answer 3

• French scientist (1744-1829)
• Proposed that similar species descended from a common ancestor (fossil records)
• Hypothesized that acquired traits were passed on to offspring

Question 4

Acquired Trait

Answer 4

• Not determined by genes

* Arises during an organism’s lifetime as a result of the organism’s experience or behavior

Question 5

Thomas Malthus

Answer 5

• “much of human suffering – disease, famine, homelessness and war was the inescapable consequence of the human populations potential to grow much faster than the rate at which supplies of food and other resources could be produced
• Resources couldn’t keep up with the increase in population 🡪 kept the population number down

Question 6

Charles Lyell (Scottish Geologist)

Answer 6

• Book: Principles of Geology had a strong influence on Darwin
• Proposed: gradual forces gradually change Earth’s surface and these forces are still operating today
• Natural catastrophes are very important in evolution

Question 7

Darwin – a brief history

Answer 7

• Charles Darwin was born on February 12, 1809 in Shrewsbury, England.
• From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle
on a British science expedition around the world.
• He observed many things 🡪 basis for his ideas

Question 8

Darwin’s Observations

Answer 8

1. Overproduction of Offspring – species tend to produce excessive numbers of offspring
2. Heritable Variations – individuals of a population vary extensively in their characteristics and many are inherited
3. Limited Natural Resources – environmental resources are limited

Question 9

Alfred Wallace

Answer 9

• Had a theory IDENTICAL to Darwin

* Caused Darwin to publish his Origin of Species by means of natural selection

Question 10

Natural Selection

Answer 10

Natural selection: proposed by Darwin as the mechanism of evolution

1. individuals have specific inherited characteristics
2. they produce more surviving offspring
3. the population includes more individuals with these specific characteristics
4. the population evolves and is better adapted to its present environment

Question 11

Darwin’s Theories

Answer 11

1. Descent with Modification – newer forms appearing in fossil records are actually the modified descendants of older species
   - Organisms similar to each other come from a common ancestor while organisms that are more dissimilar share a remote ancestor
2. Modification by Natural Selection – states HOW evolution occurs
   - Organisms having traits that make them better suited for survival tend to leave more offspring than organisms with fewer beneficial traits

Question 12

Survival of the “Fittest”

Answer 12

Darwin’s theory for how long necks evolved in giraffes

Question 13

Evidence for Evolution

Answer 13

1. Homologous Structures
2. Analogous Structures
3. Vestigial Structures
4. Embryology
5. Genetics

Question 14

Homologous Structures

Answer 14

Similar structure; different function

Question 15

Analogous Structures

Answer 15

Similar function; different structure

Question 16

Vestigial Structures

Answer 16

Organ has lost its’ function over time

Question 17

Embryology

Answer 17

• The study of Embryos and their traits.

* Embryological Structure Similarities means a recent common ancestor.

Question 18

Genetics

Answer 18

Similarities in amino acid chains.

Question 19

Gene Pools

Answer 19

• Combined genetic information of all the members of a particular population.
• Relative Frequency of an allele - # of times the allele occurs in a gene pool compared to other alleles.

Question 20

Sources of Genetic Variation

Answer 20

• Mutations – any change in genetic sequence

* Gene Shuffling – crossing over, which occurs during cell division (meiosis)

Question 21

Allele

Answer 21

One or two more alternative forms of a gene that arise by mutation and are found on the same place in a chromosome.

Question 22

Traits

Answer 22

1. Single Gene Traits – traits controlled by one gene.

2. Polygenic Traits – traits controlled by two or more genes.

Question 23

Natural Selection: Single Gene Trait

Answer 23

Natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution

Question 24

Natural Selection: Polygenic Traits

Answer 24

Natural selection can affect the distributions of phenotypes in any of three ways:

1. Directional Selection
2. Stabilizing Selection
3. Disruptive Selection

Question 25

Adaptive Radiation (Divergent Evolution)

Answer 25

Single species or a small group of species have evolved into several different forms that live in different ways.

Question 26

Convergent Evolution

Answer 26

Unrelated organisms come to resemble one another

Question 27

Coevolution

Answer 27

Two species evolve in response to changes in each other over time

Question 28

Punctuated Equilibrium

Answer 28

Long, stable periods interrupted by brief periods of more rapid change

Question 29

Mechanisms of Evolution

Answer 29

1. Genetic Mutation 2. Gene Flow 3. Nonrandom Mating 4. Genetic Drift 5. Natural Selection

Question 30

1. Genetic Mutation

Answer 30

Polymorphism – two or more distinct phenotypes | Mutations – can be harmful or beneficial

Question 31

2. Gene Flow

Answer 31

Movement of alleles among populations by migration

Question 32

3. Nonrandom Mating

Answer 32

Individuals choose their mates | *Inbreeding – doesn’t change allele frequencies

Question 33

4. Genetic Drift

Answer 33

Changes in allele frequencies in a certain direction

Question 34

Bottleneck Effect

Answer 34

* Example of Genetic Drift * Severe reduction in population; reduces overall biodiversity * Ex: Cheetahs

Question 35

5. Natural Selection

Answer 35

Formation of a new species

Question 36

Speciation

Answer 36

* Origination of a new species. | * Species – group of organisms that breed with one another and produce fertile offspring.

Question 37

What factors are involved in the | formation of a new species?

Answer 37

Gene pools of two populations must becomes separated for them to become new species.

Question 38

Isolating Mechanisms

Answer 38

* As new species evolve, populations become reproductively isolated from each other. * When the members of two populations cannot interbreed and produce fertile offspring, reproductive isolation has occurred

Question 39

Behavioral Isolation

Answer 39

Behavioral isolation occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.

Question 40

Geographic Isolation

Answer 40

Geographic isolation occurs when two populations are separated by geographic barriers such as rivers or mountains.

Question 41

Temporal Isolation

Answer 41

Temporal isolation occurs when two or more species reproduce at different times.

Question 42

Speciation of Finches

Answer 42

``` Speciation in the Galápagos finches occurred by: • Founding of a new population • Geographic isolation • Changes in new population's gene pool • Reproductive isolation • Ecological competition ```

Question 43

1. Founders Arrive:

Answer 43

* A few finches—species A—travel from South America to one of the Galápagos Islands. * There, they survive and reproduce.

Question 44

2. Geographic Isolation

Answer 44

* Some birds from species A cross to a second island | * The two populations no longer share a gene pool

Question 45

3. Changes in the Gene Pool

Answer 45

* Seed sizes on the second island favor birds with large beaks * The population on the second island evolves into population B, with larger beaks

Question 46

Reproductive Isolation

Answer 46

* If population B birds cross back to the first island, they will not mate with birds from population A * Populations A and B are separate species * Organisms are unable to breed due to the isolating factors.