Variation and Evolution - Finished

Question 1

What is variation?

Answer 1

Difference between individualsof the same species

Question 2

What are the two types variation?

Answer 2

Continuous

Discontinuous

Question 3

What is the definition of continuous variation?

Answer 3

Anywhere on a sliding scale of measurement

Lots of seperate genes interacting) (genes intending with environment

Question 4

What is the definition of discontinuous variation?

Answer 4

Cannot be measured (categoric) or cannot be measured on a sliding scale (discrete)(single gene)

Question 5

Examples of heritable differences?

Answer 5

Eye colour, height

Question 6

Examples of non heritable differences?

Answer 6

Scars

Question 7

What ios interspecific competition?

Answer 7

Competition between members of different species
Lion vs. Leopard
Lion vs. Zebra

Question 8

What is intraspecific competition?

Answer 8

Competition between members of the same species
Lion vs. Lion
Most severe type of competition = every resource is the same

Question 9

What are selective agents?

Answer 9

resources that affect an individuals ability to survive

Question 10

What does the normal distribution of selection pressures look like?

Answer 10

few at the extremes of a feature (extremely tall/short) most organisms close to average

Question 11

What are selection pressures?

Answer 11

Lots of competition for resources

Question 12

What does a directional selection pressure look like on a graph?

Answer 12

(example = drop in temperature)
graph moves to the right. average getting further right as well.
Supports evolution = Population has changes over time / adapted to changes in the environment (selection pressures)

Question 13

What does a stabilising selection pressure look like on a graph?

Answer 13

Graph moves inwards, extreme populations get smaller.
Bad to be at the extremes/ good to be average
No support for evolution - no change in the population
Disadvantage - less genetic variation, less chance to respond to changes in the environment
Creates a smaller gene pool

Question 14

What is the definition of a gene pool?

Answer 14

All of the genes/represented alleles present in the population

Question 15

What does a disruptive selection pressure look like on a graph?

Answer 15

Graph begins to decrease at the average. Splits in 2
Bad to be average
Supports evolution = Changes the population, splits in two

Question 16

What is speciation?

Answer 16

The formation of a new species.

If one genotype/allele is lost hen the whole populations gene pool can be rapidly altered

Question 17

What are speciation mechanisms?

Answer 17

Isolation mechanisms

Ways of stopping gene flow between populations/maintaining reproductive isolation

Question 18

What is allopatric speciation?

Answer 18

Geographical isolation

Separation by Rivers/Mountains

Question 19

What is Sympatric speciation?

Answer 19

Non Geographical isolation
Separation of species due to:
Mechanical isolation (incompatible isolation)
Behavioural isolation (displays/courtship)

Question 20

Both allopatric speciation and sympatric speciation are pre zygotic what does that mean?

Answer 20

STOP fertilisation from happening

Question 21

What does Post Zygotic speciation mean?

Answer 21

Fertilisation is possible BUT further fertilization in future generations is not.
Lion + Tiger = Liger
Horse + Donkey = Mule

Question 22

What is the definition of Hybrid sterility?

Answer 22

2 different species interbred together

non homologous pairs from the parents mean offspring are sterile

Question 23

What is the definition of genetic drift?

Answer 23

Variations in allele frequency that occur as a result of random chance

Question 24

WHat is the founder principle?

Answer 24

A new population is established by individuals with gene pools unrepresentative of the other populations

Question 25

What was Darwin’s Theory of Evolution?

Answer 25

Organisms reproduce at a high rate (more than is needed to replace themselves) - This leads to overpopulation which is a problem with a finite food supply.
Some organisms due to variation will have a selective advantage over others (cope with finding food better). These are more likely to survive and reproduce which would pass on the suitable alleles.

Question 26

What does Darwins Theory of Evolution show?

Answer 26

Variation within a population