Chapter 7 - Evolution and adaptation

Question 1

What are some observations that can be made in a population?

Answer 1

• More offsprings born than ones that actually survive
• Natural variation between individuals of a population
• Offpsrings are similar to their parents because they inherit alleles

Question 2

What did those observations conclude?

Answer 2

• Variation influences the ability to survive and reproduce viable offspring
• Survival phenotypes are passed down to the next generation

Question 3

What is the survival advantage?

Answer 3

It increases the individuals fitness as their alleles are passed down to the next generation

Question 4

What are some survival advantages

Answer 4

• gathering food
• avoid predators
• attracting a mate
• producing offspring

Question 5

What is natural selection?

Answer 5

The process of increasing the likelihood of survival and reproduction of individuals with specific phenotypes

It works through selective pressures (environmental factors) and different phenotypes

Question 6

What is natural selection’s effect on allele frequencies?

Answer 6

It increases allele frequencies for phenotypes with high survival advantage.

Question 7

What is the definition of species?

Answer 7

A group of genetically similar organisms that can interbreed to produce viable or fertile offsprings

Question 8

What are isolating mechanisms?

Answer 8

Factors that prevent individuals from interbreeding as they separate two or more gene pools.

Question 9

What is speciation?

Answer 9

It occurs when one population separates to form two new populations that are different enough to no longer produce viable offsprings

often the result of isolating mechanisms that prevent gene flow between populations

Question 10

What are the two main groups isolating mechanisms can be classified into?

Answer 10

Prezygotic barriers and postzygotic barriers

Question 11

What are prezygotic barriers?

Answer 11

• stops fertilisation
• prevents mating from happening in the first place

Question 12

What are some examples of prezygotic barriers?

Answer 12

• Temporal isolation
• Behavioural isolation
• Ecological isolation
• Mechanical incompatibility
• Gametic isolation

Question 13

What is temporal isolation?

Answer 13

different specific breeding times

Question 14

What is behavioural isolation?

Answer 14

different courtship patterns for species

Question 15

What is ecological isolation?

Answer 15

geographical barriers like oceans and mountains

Question 16

What is mechanical incompatibility?

Answer 16

different reproductive structures

Question 17

What is gametic isolation?

Answer 17

conditions of the female tact being fatal for the sperm

Question 18

What is postzygotic barriers?

Answer 18

• does not prevent fertilisation
• prevents the formation of viable offspring

Question 19

What are the 3 types of postzygotic barriers?

Answer 19

• reduced hybrid viability
• reduce hybrid fertility
• hybrid breakdown

Question 20

What is reduced hybrid viability?

Answer 20

hybrid offspring do not develop properly
- not born
- does not survive reproductive stage

Question 21

What is reduced hybrid fertility?

Answer 21

if offspring survives reproductive stage, but cannot produce functional gametes
- infertile and sterile (cannot produce healthy offspring0

Question 22

What is hybrid breakdown?

Answer 22

if first generation hybrid is fertile, then the second generation offspring does not develop properly

Question 23

What are the two forms of speciation?

Answer 23

• Allopatric speciation
• Sympatric speciation

Question 24

Which form of speciation is more common?

Answer 24

Allopatric

Question 25

What is allopatric speciation?

Answer 25

formation of new species because of genetic isolation caused by a geographical barrier

Question 26

What are the stages of allopatric speciation?

Answer 26

At least two populations of the same species exist.

The populations are separated by a geographic barrier.

Different mutations arise in the different populations, genetic drift causes different random changes in allele frequencies and differences in selective pressures drives natural selection in different directions.

The two populations become genetically different enough that members could not interbreed to produce viable offspring, even if the populations came into contact.

They are reproductively isolated and classified as two different species.

Question 27

What is sympatric speciation?

Answer 27

It occurs between populations that live in the same geographical area

Gene flow is still possible

Occurs when gene flow is reduced by factors like habitat differentiation, sexual selection or polyploidy.

Question 28

What is habitat differentiation?

Answer 28

Subpopulation uses slightly different resources or lives in a specific part of the habitat which is different to the parent population

Question 29

What is sexual selection?

Answer 29

Differences in mate preferences drive sympatric speciation

Question 30

What is polyploidy?

Answer 30

Occurs when an individual has more than two copies of every chromosome.

More common in plants than animals