- Proteins make organisms different and determine variety of proteins.
- All members of same species have same genes.
- Alleles decide what genes code for, they make species and individuals different.
- More alleles = greater diversity = more likely to adapt to change.
Selective Breeding (artifical selection):
- Identify individuals with desired characteristics and use them as parents.
- Unwanted alleles bred out, leading to reduction in genetic diversity and high-yielding breeds.
- Reliable and cheap but interfering with nature.
- When is it disabling to the animal and is just inconvenience acceptable?
- Alleles may be of benefit in the future.
- In Cattle:
- AI increases pace of change.
- Bred for milk (high production & rapid delivery) and meat (high muscle:bone ratio).
- Mastitis (udder inflammation), lameness and infertility.
- Killed and taken from their mother very early.
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The Founder Effect and Genetic Bottlenecks.
- Few individuals from population colonise a new region.
- Carry small fraction of alleles so are not representative of larger population.
- Population develops and shows less diversity.
- Genetically distinct populations.
- May develop to separate species as can't adapt as well.
- Population has large drop in numbers.
- Few survivors have smaller variety of alleles i.e. less genetic diversity.
- Diversity stays restricted, few alleles therefore less likely to adapt.
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