Genetic Diversity.

• 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.

Founder Effect:

• 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.

Genetic Bottlenecks:

• 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.