Chapter 5

Question 1

Natural selection

Answer 1

the differential success ( in survival and reproduction) of individuals that arises from their interactions with their environments

Question 2

Fitness

Answer 2

Contributions an individual is able to make to future generations

Question 3

Adaptation

Answer 3

heritable behaviour, morphological, or physiological trait that has evolved over time by natural selection such that it maintains or increases the fitness of an organism under a given set of environmental factors.

Question 4

All living organisms must….

Answer 4

1. Assimilate and grow
2. reproduce
3. respond to the environment

Question 5

Steps of natural selection

Answer 5

1. individual variation
2. variation provides an advantage
3. variation is heritable

Question 6

Phenotypic plasticity

Answer 6

the ability of a gene to express itself differently in response to the environment. Animals have less because they have the ability to move, unlike plants

Question 7

Target of selection

Answer 7

phenotype that is directly acted upon by selective forces

Question 8

selective agent

Answer 8

environmental pressure that results in fitness differences among individuals

Question 9

Directional selection

Answer 9

extreme version of a trait is favoured

Question 10

Stabilizing selection

Answer 10

mean value of trait is favoured

Question 11

Disruptive selection

Answer 11

increases the frequency of both extremes of a trait

Question 12

Gene frequencies can change due to what four factors?

Answer 12

1. mutation
2. genetic drift
3. gene flow
4. non-random mating

Question 13

Mutation

Answer 13

source of genetic variation that natural selection acts upon. Can be beneficial, harmful, or neutral

Question 14

Genetic drift

Answer 14

random changes in allele frequencies usually due to small population size (founder effect and bottle-neck effect)

Question 15

Founder effect

Answer 15

a few individuals colonize an area (example of genetic drift)

Question 16

Bottle-Neck efect

Answer 16

a disturbance removes most of a population. Population then recovers from a few remaining individuals.

Question 17

Gene flow

Answer 17

Individuals move to a new are and successfully mate, introducing new genes

Question 18

Non-random mating

Answer 18

an individual chooses its mates based on phenotypic characteristics

Question 19

Cline

Answer 19

measurable, gradual change over a geographic region in the mean of a phenotypic trait associated with an environmental gradient

Question 20

Ecotype

Answer 20

a population adapted to its unique, local conditions

Question 21

Geographic isolates

Answer 21

Populations in which gene flow is prevented by geographic barriers such as rivers, or mountains

Question 22

Subspecies

Answer 22

populations that are distinguishable from each other by one or more traits

Question 23

Speciation

Answer 23

evolution of new species

Question 24

Adaptive Radiation

Answer 24

process by which one species gives rise to multiple species that exploit different features of the environment, such as food, resources, or habitat