Speciation and artificial selection

What is speciation?
The formation of a new species through the process of evolution, the new species will no longer be able to interbreed with original species and produce fertile offspring
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What is allopatric speciation?
Most common form of speciation, some members of the population are separated from main group (e.g. physical barrier), no gene flow and genes mutate according to different selective pressures either side of barrier till they become a new species
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Give an example of allopatric speciation
Finches on the galapagos islands, separated by islands and sea they have all bred into different species, with beaks changing to adapt to food sources e.g. blunt broad beaks to crack nuts, thin long beaks to get nectar (adaptive radiation)
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What is sympatric speciation?
Speciation that occurs within populations that share the same habitat, more common in plants, it is when 2 organisms of different species interbreed and produce hybrid fertile offspring, offspring cant interbreed with members of parent species though
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Give an example of sympatric speciation
Bread wheat has been formed by 2 generations of sympatric speciation in plants
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What are reproductive barriers?
Barriers can form so prevent successful interbreeding, there are 2 types: prezygotic reproductive barriers (prevent fertilisation) & postzygotic reproductive barriers (reduces viability or reproductive potential of offspring)
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What are polymorphic populations?
Populations that display more than one distinct phenotype
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What is the 'wild type' allele?
The allele coding for the most common characteristic within a population, other forms of that allele are mutations
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What is artificial selection?
Selection of certain individuals for breeding who have desirable characteristics, in hope that their offspring will also have the desirable characteristics
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Offspring who carry the desired characteristics are then interbred for more offspring to have the characteristics, what type of breeding is this?
Interbreeding- the breeding of closely related individuals
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What can happen after generations of selective breeding?
Speciation (allopatric)
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What are a few problems with inbreeding?
It limits the gene pool & decreases genetic diversity, could be wiped out easily (e.g. certain strain of virus), reduces chances of evolution, recessive alleles for genetic disorders in species & interbred ones are more likely to inherit the disorder
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What are seed banks?
Places where samples of seeds are kept from both wild type to mutations
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What are gene banks?
Places where genetic materials are stored and usually frozen, e.g. sperm, eggs etc
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Why do we keep gene & seed banks?
So that we can use them to increase genetic diversity again, owing problems to inbreeding, reduces occurrence of homozygous recessives & disorders and increasing potential to adapt to environmental changes
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Card 2

Front

What is allopatric speciation?

Back

Most common form of speciation, some members of the population are separated from main group (e.g. physical barrier), no gene flow and genes mutate according to different selective pressures either side of barrier till they become a new species

Card 3

Front

Give an example of allopatric speciation

Back

Preview of the front of card 3

Card 4

Front

What is sympatric speciation?

Back

Preview of the front of card 4

Card 5

Front

Give an example of sympatric speciation

Back

Preview of the front of card 5
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