The Origin of species

Question 1

Mutation

Answer 1

• Genetic code changes
• More significant in gametes
• Spontaneous but increased chemicals or radiation
• Mammal mutated a gene to break down certain toxic chemicals (PON1)
• Mutations allowed the domestication of otherwise-toxic amydalin Almonds, when the toxin gene was turned off.

Question 2

Gene flow

Answer 2

• All the alleles in a population = Gene pool
• Movement of genes between population
• Flow influenced by dispersal, migration and geographic fragments
• Taiwan Stag bettle live in sub-population created by dispearal individuals

Question 3

Genetic Drift

Answer 3

• Chance Altercations in a population’s allele frquences
• Caused often by bottlenecks such as disease or predation
• 19th century, Northern Elephant seal hunted and reduced to 20-30. After conservation effects, population is now 1000 however, population variation is reduced
• Can be caused by founder effect. Few individuals start a new colony, genetic diseases from founders become common.

Question 4

Natural selection

Answer 4

• Driven by climate, predation or resistence
• Affect frequency of traits
• Lead to non-random alleles frequency chances
• Stablising, directional or disruptive

Question 5

Population Growth

Answer 5

• Initial rapid growth of low population
• Growth rate slows when maximum sized reached
• At high populations, traits favoured ablity to reproduce with less resources
• At low populations, traits favoured allowing rapid reproduction

Question 6

Allopatric Speciation

Answer 6

• Population forms a new species whilst geographically seperated from parent population
• More likely in isolated populations
• Some alleles may be lost due to “founder effects”

Question 7

Sympatric speciation

Answer 7

• Occurs in geographically overlapping areas
• Gene flow is reduced by chromosomal changes
• Mutations may isolate a subpopulation from parent population
• May be due to hybridisation

Question 8

Prezygotic barrier

Answer 8

• Impedes mating between species or fertilisation
• Caused by habitat isolation or different breeding behavours

Question 9

Prostzygotic barrier

Answer 9

• Prevents fertile offspring
• Caused by differences in DNA