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1. A level year 13 master > Natural selection and speciation > Flashcards

Natural selection and speciation Flashcards

1
Q

Genetic and environmental factors cause ….

A

Variation

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2
Q

What is the primary source of genetic variation?

A

Mutation

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3
Q

Define gene pool

A

All of the alleles of all of the genes of all the individuals within a particular population at a given time

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4
Q

What is intraspecific competition?

A

Competition between individuals of the same species

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5
Q

Give 3 reasons why differential survival and reproduction could occur.

A

Predation

Disease

Competition

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6
Q

An organism has a selecive advantage. What does this mean?

A

Better adapted for the conditions present.

More likely to survive and reproduce.

Pass on favourable alleles

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7
Q

How is genetic variation produced?

A

Crossing over

Independent segregation/random assortment

Random fusion of gametes

Mutation

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8
Q

Name 3 types of selection

A

Stabilising

Directional

Disruptive

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9
Q

Describe stabilising selection

A

Preserves the average phenotype

Selection against extreme phenotypes.

Occurs when environment is stable

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10
Q

Give an example of stabilising selection

A

Human birth weight

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11
Q

Give an example of directional selection

A

Antibiotic resistance in bacteria

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12
Q

Give a defition of speciation

A

Evolution of a new species from an existing one

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13
Q

Define a species

A

Group of similar organisms that breed producing fertile offspring

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14
Q

Give the 2 types of speciation

A

Allopatric and sympatric

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15
Q

Allopatric speciation occurs when …..

A

When 2 populations become geographically isolated

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16
Q

Give examples of how organisms might be geographical isolated

A

Physical barrier which prevents interbreeding e.g. oceans, rivers, mountains, deserts, landslide

17
Q

Define reproductive separation

A

when 2 populations can no longer interbreed and produce fertile offspring

18
Q

Example of allopatric speciation

A

Finches on the Galapagos Islands!

19
Q

Sympatric speciation occurs

A

Within a population of organisms living in the same area (doesn’t require geographical isolation)

20
Q

Sympatric speciation arises because ….

A

They have different breeding seasons
They may inhabit different habitats in the same area so never meet, Anatomical differences,

21
Q

Name the type of selection shown

A

stabilising

22
Q

Name the type of selection shown

A

directional

23
Q

Describe how allopatric speciation occurs

A

Two populations are geographically isolated

Creates separate gene pools with no interbreeding

Variation due to mutation

Different selection pressures

Differential reproductive success

Leeds to change in allele frequencies

Occurs over long period of time

Populations no longer able to interbreed to produce fertile offspring

24
Q

Name the type of selection shown

A

Disruptive

25
Q

What does evolution do to the frequency of alleles in a population?

A

Changes them - increase or decrease

26
Q

What happens to the frequency of the alleles that give organisms an advantage?

A

Increases

27
Q

What happens to those organisms that are better adapted to the selective pressures in the environment?

A

Survive, reproduce and pass on favourable alleles

28
Q

What happens to the phenotype during stabilising selection?

A

Preserves the middle of the range phenotypes

29
Q

Which phenotype is selected for during directional selection?

A

An extreme phenotype - these are more likely to survive and reproduce

30
Q

What phenotype is preferred in disruptive selection?

A

BOTH extremes (select against the middle phenotype)

31
Q

What is genetic drift?

A

Chance (not the environment) determines which organisms survive,
reproduce and pass on their alleles

32
Q

Genetic drift has a greater effect on which size population?

A

Smaller populations

33
Q

Describe Sympatric Speciation

A

Occurs in the same population

Mutations cause variation in alleles

Reproductive separation with no gene flow

Different alleles selected for

Change in allele frequency

Disruptive selection

Different species formed which cannot interbreed

1. A level year 13 master (19 decks)

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