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biology > Populations And Evolution > Flashcards

Populations And Evolution Flashcards

1
Q

Define allelic frequency

A

Frequency of an allele

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2
Q

Define gene pool

A

All alleles in a population

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3
Q

What conditions must be met in the Hardy weinberg principle

A 
No mutations
Large population
Isolated population
No selection pressure
Mating is random
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4
Q

How is phenotype arranged when variation is mainly due to genotype

A

Distinct groups

Bar chart

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5
Q

How is phenotype arranged when variation is mainly due to environment

A

Continuum

Normal Distribution

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6
Q

What are the causes of genetic variation

A

Meiosis
Mutation
Random fertilisation

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7
Q

Define selection pressure

A

Environmental factor limiting population

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8
Q

What factors drive natural selection

A 
Overproduction of offspring
Genetic variation
Phenotypic variation
Selection pressure
Intraspecific competition for resources
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9
Q

Describe how natural selection occurs

A

More offspring than is needed is produced.
Gene pool contains a variety of alleles
Mutations cause new alleles to arise
Organisms with advantageous alleles more likely to obtain resources, survive and reproduce
Advantageois alleles passed down generations due to selective advantage
Freq of new allele increases at expense of less advantageous ones.

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10
Q

Define evolution

A

Change in allele frequency

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11
Q

Why do population sizes remain constant despite over production of offspring

A

Intraspecific competition

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12
Q

Types of selection.

A

Disruptive, directional and Stabalising

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13
Q

When does directional selection occur

A

Chnage to environment that is constant and in one direction

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14
Q

What changes are made by directional selection

A

Change to phenotype same variation

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15
Q

Describe how antibiotic resistance occurs in bacteria

A

New allele produced via mutation coding for enzyme comp to antibiotic causing antibiotic breakdown so organism is resistant.

Upon exposure to antibiotics organisms with new allele are more likely to survive and reproduce (binary fission).

New allele passed on down generation’s via plasmids. Increase in allelic frequency

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16
Q

When does stabilising selection occur

A

When there is no chnage to the environment

17
Q

What effects does Stabalising selection have

A

Less variation

Same phenotype

18
Q

When does disruptive selection occur

A

When there is a fluctuation in an environment

19
Q

What occurs due to disruptive selection

A

Two extremes are favoured at the expense of the intermediate forms

New species

20
Q

What type of selection drives evolution

A

Disruptive

21
Q

Define speciation

A

Formation of new species

22
Q

Define genetic drift

A

Change to allele frequency due to chance events

23
Q

Give examples of events causing genetic drift

A

Lightning

Earthquake

24
Q

What two subcategories of genetic drift are there

A

Bottle neck

Founder effect

25
Q

What types of populations does genetic drift have the largest effect on and why

A

Small populations

Small number of individuals obtain large proportion of alleles

26
Q

Define the bottle neck effect

A

A sharp decrease in population size causing a random set of alleles to survive

27
Q

Define founder effect

A

Population decends from a small number of colonizing ancestors

Low genetic diversity

28
Q

Define allopatric speciation

A

Populations are geographically isolated

29
Q

Describe how speciation occurs

A

Population becomes reproductive isolated so no gene flow

Different selection pressures are present in each population due to different abiotic and biotic factors

Genetic variation in each pop due to mutations.

Genetic drift causes random changes to allele frequency

Different alleles are. Advantageous in each population

Different phenotype selected for

Advantageous alleles make organisms more likely to survive and reproduce

Frequency of advantageous allele increases at the expense of less advantageous alleles.

Gene pools diverge so much no longer able to produce fertile offspring

Adaptive radiation

30
Q

Define sympatric speciation

A

In same area but still reproductive isolated

31
Q

Types of isolation

A 
Geographical
Ecological
Temporal
Behaviuoral
Mechnaical
Gametic
Hybrid sterility
32
Q

Define ecological isolation.

A

Same areas but different habitats or niches

33
Q

Define temporal isolation

A

Breeding seasons don’t align

34
Q

Define behavioural isolation

A

Different courtship behaviours

35
Q

Define mechanincal isolation

A

Anatomical differences

36
Q

Define Gametic isolation

A

Genetic or biochemical incompatibility preventing gamete fertilisation

37
Q

Define hybrid sterility

A

Hybrids can’t produce viable offspring

biology (28 decks)

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