Mechanisms Of Evolution

Question 1

Define stablishing Selection

Answer 1

Acts against individuals who deviate too far from the average, favours the average

Question 2

What is an example of Stabilizing selection?

Answer 2

A plant that is too short may not be able to compete with other plants for sunlight, whereas tall plants may be susceptible to wind damage. Combined, these two selection pressures select to maintain plants of a medium height.

Question 3

Define natural selection

Answer 3

Traits in different forms of life that better enable them to adapt to specific environmental pressures. For example, predators, changes in climates or competition for food or mates. Some traits will survive an reproduce in greater numbers thus ensuring the perpetuation of these favourable traits in succeeding generations.

Question 4

What are the 3 types of natural selection?

Answer 4

Stabilising selection

Distrusting selection

Directional selection

Question 5

What is Darwin’s theory

Answer 5

Natural selection- traits change over time

Question 6

Define evolution

Answer 6

The change of something over time

Question 7

Define speciation

Answer 7

The making of new species- a process in which two populations become reproductively isolated from eachother
Without isolating groups in a population, any new genes will be spread through the entire population
New genes allow for a survival advantage then the whole population would gradually change
By preventing the mixing of new genes, different species can develop from a common ancestor.

Speciation requires reproductive isolation

Question 8

Reproductive isolation

Answer 8

Occurs when two members of two populations - but from the same species- can not interbreed. At that point, they have different gene pools.

Question 9

What is geographic isolation

Answer 9

Physical barriers (rivers, oceans, mountains) preventing mixing of populations

Question 10

What is habitat isolation

Answer 10

Species found in the same region but prefer different habitats eg. lizards in swamps as opposed to forests

Question 11

What is temporal isolation

Answer 11

Species breed at different times of the year
Western shrunk = summer
Eastern shrunk = winter
(Overlap but seperate species)

Question 12

Behavioural isolation

Answer 12

Two populations capable of interbreeding, but have differences in courtship/mating rituals or other types of behaviour (different bird songs, mating colours or dances, etc.)

Question 13

What are the different types of speciation?

Answer 13

Divergent:
Gradual accumulation of many small genetic changes through differential natural selection with sub populations existing simultaneously
Phyletic:
Abrupt mutations in a few regulatory genes occur after the species has survived for a long time to produce entirely new species

Question 14

The pattern of evolution?

Answer 14

Gradualism:
Accumulation of small genetic differences over millions of years without reproductive isolation driven by natural selection

Punctuated Equilibrium:
Small number of genetic changes occur rapidly after years of morphological stability, possibly due to the mutations of a few important genes

Question 15

Sexual selection

Answer 15

Mode of natural selection where members of one biological sex choose mates of the other sex to make with
Compete with members of the same sex for members of the opposite sex

Question 16

Mutation?

Answer 16

Mutation is the permanent alteration of the nucleotide sequence of the genome of an organism, virus, DNA or other genetic elements

Question 17

Gene flow

Answer 17

The transfer of alleles or genes from one population to another

Question 18

Genetic drift?

Answer 18

Mechanism of evolution where allele frequencies of a population change over generations due to chance

Question 19

Convergent evolution

Answer 19

Organisms that aren’t closely related independently evolve similar traits
Due to adapting to similar environments or ecological niches

Question 20

Divergent evolution

Answer 20

Differences between groups of a population of organisms which can usually lead to the formation of new species
Usually a result of living in isolated environments

Question 21

Parallel evolution

Answer 21

Independent evolution of similar traits starting from a similar ancestral condition

Question 22

Co-evolution

Answer 22

Occurs when two or more species reciprocally affect each other’s evolution

Such as a bee and flower

Question 23

Viability

Answer 23

Ability to work sucessfully

Question 24

Directional selection

Answer 24

Extreme phenotype is favoured over others causing the allele frequency to shift in favour of phenotype

Question 25

Distruptive selection

Answer 25

Describes changes in population genetics in which extreme values for a trait are favoured
In this case the variance of the trait increases and the population is divided into two distinct groups

Question 26

Allopatric speciation

Answer 26

Geographic speciation

Question 27

Sympatric speciation

Answer 27

Process though new species evolve through a single ancestral species inhabiting from the same geographic region

Question 28

Mechanical isolation

Answer 28

Prezygotic reproductive barrier when different species are isolated by different genitalia

Question 29

Population bottleneck

Answer 29

Sharp reduction in size of a population due to environmental events such as fire or floods

Question 30

Analogous structure

Answer 30

Various structures having the same function but have evolved separately thus not sharing the same common ancestor