Answers Sec 14-2 Evolution By Natural Selection
p. 296
1. What did natural selection attempt to explain?
How "artificial selection" occurred in nature
2. Define artificial selection. (sec 14-1)
Only the individuals with the desired traits are allowed to reproduce
3. What did Darwin observe about wild animals & plants.
Much variation
4. Give 2 examples of the “struggle for existence”
Plant stem height, plant root depth to get light and water
5. Within a species, what did Darwin observe?
Individual differ from each other
6. Define Survival of the fittest.
Individuals well suited to their environment survive and reproduce
7. What is different between natural selection and artificial selection?
Natural selection operates over long periods of time and without human control or direction
8. What prevents members of a species from covering the Earth?
Less fit individuals do not survive
9. What colour were the trees during the early 19th century?
Light brown speckled with green
10. What colour were most of the peppered moths?
Mottled light brown
11. Where all the moths this colour?
No, some were dark
12. How did the environment change during the industrial revolution? Who was the cause of the change?
Soot from coal turned the trees dark, humans caused the change
13. What began to happen to the moth population?
White ones being eaten, black ones surviving
14. Describe the evolutionary hypothesis to explain this change.
As environment changed, the moths with the dark colour were camouflaged and not eaten as often
15. What do genes have to do with this?
Genes determine colour, the rare dark gene became the most common gene
16. Describe Kettlewell’s experiment
Same as peppered moths except he coloured the trees either light or dark
17. What was his conclusion?
The environment selects the type of organism that will be able to survive. Dark selects for dark, light selects for light
Answers
Ws 14-3 Genetics and Evolutionary Change
1. What was Darwin’s “handicap”? No knowledge about how traits where passed on (genetics)
2. Who’s work was invaluable in order to explain the mechanism of evolutionary change? Mendel
3. The 4 things that today can be explain in genetic terms are: fitness, adaptation, species, process of evolutionary change
4. What are genes? Carriers of inheritable characteristics, source of the random variation
5. What are genes the source of? Random variation upon which natural selection operates
6. What do mutations cause? Some variation
7. Another source of variation is caused by? Variation during meiosis: chromosomes are shuffled like a deck of playing cards
8. What was wrong with Lamark’s theory? He said organisms self direct genetic variation toward a goal (it wants to evolve)
9. What happens when variations occur? Natural selection begins on the new variation
10. In the evolutionary struggle for existence, what is more important, the individuals genes or the entire organism?
Entire organism
11. What does natural selection operate on? Phenotypic variation among individuals
12. Define phenotype. physical and behavioural characteristics produced by the interaction of genotype and environment
13. Give an example of phenotypic variation. Height of all students in class
14. What type of phenotypic variation does fg 14-11 show? Height phenotypic variation
15. Which phenotypes are there very few of in fg 14-11? tall and short
16. What causes phenotypic variation? Combination of genetic instructions and environmental influences, such as nutrition and exercise
17. The main cause of phenotypic variation is caused by? Differences in genotype
18. Define population. Members of the same species in an area that can breed with each other
19. Give an example of 2 populations of the same species. All the fish in a certain pond, fish in another pond belong to a different population
20. Define interbreed. Mate with other members of your species
21. What is a gene pool? A common set of genes within a population due to interbreeding
22. Define relative frequency. The number of times a certain allele occurs in a population (gene pool) compared to another similar allele for that
gene
23. What does sexual reproduction not change? Relative frequency of alleles in a population
24. Explain the similarity between sexual reproduction and shuffling a deck of cards. Each allele represents each type of card in a deck.
Shuffling the deck is like sexual reproduction, it mixes up the alleles (cards) but does not create new cards or alleles
The relative frequency of each card (allele) remains the same in the population (deck)
25. What is the modern definition of evolution? Change in the relative frequency of alleles in the gene pool of a population
26. Using the modern definition of evolution and fg 14-13, how do you know evolution is occurring? The relative frequency of an allele is
changing: dark is becoming more frequent
Document1 Page 1 of 3 Last printed 08/02/2016 6:32 PM
27.
28.
29.
30.
31.
32.
33.
34.
35.
What phenotype “evolving”? dark
What is the evolutionary fitness definition? The success an organism has in passing on its genes to the next generation
Define adaptation. Any genetically controlled characteristic of an organism that increases its fitness
Muscles acquired as a result of exercise are not passed on to the offspring. This is therefore not considered to be an….? evolutionary
adaptation and cannot contribute to evolutionary fitness
What could be considered to be an adaptation regarding muscles? Gene that allows individual to develop stronger muscles by doing less
work or by eating less food
What is the rule rather then the exception regarding a species? Variation within a population is the rule
Define species. A group of similar-looking (though not identical) organisms that breed with one another and produce fertile offspring
What can occur if a genetic change occurs in ONE individual within a population? Spread through the population as that individual and its
offspring mate with other individuals
What will occur if the genetic change increases fitness? The gene will eventually be found in many individuals in the population
Answers ws 14-4 The Development of New Species
p. 304
1. Define speciation. how new species evolve from old ones
2. Define niche.
The combination of an organism's "profession" and the place in which it lives
3. Why does 1 species drive the other one to extinction if 2 species occupy the same niche in the same location for a long period of time?
They will compete with each other for food and space, one will not survive because it will not be as efficient
4. Why is it an advantage for 2 species to occupy different niches? Not compete with each other as much
5. What do all species share? Common gene pool
6. Define reproductive isolation. The separation of populations so that they do not interbreed
7. What occurs when the gene pool of a population is reproductively isolated? Natural selection can work differently on each group,
adaptations that appear in one group are not passed to the other
8. List 3 examples of geographic reproductive isolation. Rivers, mountains, roads
9. How do you think how differences in courtship behaviour (fg 14-17), physical appearance (fg 14-15), or differences in fertile periods may
result in reproductive isolation? Each may not want to reproduce with the other organism because of these differences may only reproduce
with individuals that are similar to themselves
10. What does natural selection do to reproductively isolated populations? It increases the differences between the separated populations as
each becomes better adapted to each different environment
11. What happens to the gene pools of these populations? Their separate gene pools gradually become more dissimilar
12. List three ways the 2 populations are separated. Physical barriers, behavioural barriers, very different genes
13. What is the final step in becoming a separate species. Reproductive isolation becomes permanent: no longer different populations anymore
but a new species
14. Darwin’s Finches: An Example of Speciation: Where did Darwin’s 13 finches come from (fg 14-18)? South American mainland
15. If each species came from a common ancestor, what main factor allows them to co-exist? Each species exhibits body structures and
behaviours that enable it to live in a separate niche
16. What are the 3 “factors” that lead to the formation of a new species? Geographic & behavioural barriers and reproductive isolation
17. Darwin’s finches 5 steps of speciation: What are the founding fathers and mothers? The 1st few members of the species to arrive in the new
area
18. Step 2: How did the birds from island “A” become separated? Some birds flew from island A to island B (storm?)
19. What prevented the blending of their gene pools with island A?
ocean between them. They do not like to fly over water.
20. Changes in the Gene Pool: What was the natural selector causing the birds of island “A” to differ from island “B”
types of food on each island
21. Reproductive Isolation: Why do the gene pools of Island “A” not mix with island “B”?
Each member of each island is so different from each other that they do not want to mate with each other
22. Sharing the Same Island: What are the 3 possibilities when species “A” and “B” come together on island B? coexistence, extinction, or
further evolution
23. Give an example what must occur in order to: a) coexist if the 2 species occupy different niches
24. b) become extinct
if the 2 species are to similar they will compete for resources with each other until 1 goes extinct
25. c) undergo further evolution if 1 species has enough genetic variation, 1 of the species may continue to evolve
26.
Speciation and Adaptive Radiation: Define adaptive radiation and give an example.
One species gives rise to many species
27.
Another name for adaptive radiation is? Divergent evolution
28.
What do niches have to do with adaptive radiation? Each new species must have its own niche to occupy
29.
Give 2 examples of adaptive radiation. (fg 14-20, fg 14-21) 43 different species of Hawaiian honeycreepers evolve from 1, modern day birds,
mammals, and reptiles evolved from 1 type of reptile
30.
Give an example of a homologous structure from chapter 13. same structure (origin), different function
bird wing, dog arm
31.
Explain the relationship between adaptive radiation and homologous structures. During adaptive radiation, one main group (similar) of
organisms evolve a variety of characteristics that enable them to survive and fill new niches → new species
32.
How is adaptive radiation related to convergent evolution? Adaptive radiations (speciation) among different organism produce species that are
similar in appearance and behaviour.
33.
Define convergent evolution. Type of adaptive radiation that occurs amoung different starting organisms. They are similar in appearance and
function but different in structure and origin
34.
Define analogous structures. Structures that are similar in appearance and function, but they have different origins
35.
Give 3 examples of analogous structures. Wings of butterflies, birds, and bats: very different origins
Answers Ws 14-5 Evolutionary Theory Evolves
1.
Today, evolution and variation is now defined in terms of _____ genetics
2.
Is natural selection the only theory to explain genetic change? no
Document1 Page 2 of 3 Last printed 08/02/2016 6:32 PM
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
What plays an important role in evolutionary change? chance
What is an allele? A variation of a gene
Define genetic drift. An allele can become common in a population by chance: the random change in the frequency of a gene
Explain the “randomness” about the genetic drift example involving reproduction. An individual with a particular allele may
produce more offspring than other members not because it is better adapted but just by chance
Explain the “randomness” about the genetic drift example involving an environmental event such as the Mount St. Helen’s
eruption. The eruption wiped out many members in the area. If this area happened to have a certain allele in this population, the
allele would have been eliminated. This would leave other alleles from other areas to become the more common one
Why does genetic drift occur most efficiently in small populations? Chance events are less likely to effect all the alleles in a
very large population.
Some of the alleles would have survived in a large population because some of the
population was located off the volcanoe death zone
How does genetic drift imply that all characteristics of an organism does not need to contribute to its fitness? not all
characteristics may be "life or death" importance
chance events may allow certain traits to survive even though they do
not improve or hinder fitness
Give an example. 1 and 2 horn rhinoceros: number of horns probably does not affect fitness, 1 population evolved 1 horn
while the other population evolved 2 horns
1 hump vs 2 hump camels
Is it possible for the gene pool of a species to remain the same for long periods of time? yes
What conditions must exist for a species to remain the same for long periods of time? Environment remains unchanging, no new
similar species arrive into area
Give an example of such an organism.
Horseshoe crab
sharks
Define gradualism. Theory that evolutionary change occurs slowly and gradually
List 1 source for the evidence of gradualism fossil record
Explain equilibrium. Long periods of time where organisms do not change very much
What seems to occur occasionally in the fossil record? Rapid changes in organisms during a short time period
Define “short” time with regard to the geological time scale. 100 000 or millions of years
Explain how a small population can lead to rapid evolution. Population becomes isolated from the main part of the population
and because genetic changes can spread more quickly among fewer individuals
Explain how migration can lead to rapid evolution. Ex Galapagos finches: small group occupy and evolve to fill available many
niches
List a common cause for mass extinctions.
Changes in global climate
ex: meteor impact on earth
How does a mass extinction lead to the production of a large number of new species? Many new niches are made available to
other organisms that previously would not have been able to occupy them
Define punctuated equilibria. Tem to describe the pattern of long stable periods interrupted by brief periods of change.
Often seen after mass extinctions
Document1 Page 3 of 3 Last printed 08/02/2016 6:32 PM