3. Genetic Diversity Flashcards
Define genetic diversity.
The number of different alleles of genes in a species or population.
Large number of different alleles in population means a large variety of different characteristics and high genetic diversity.
What do alleles code for?
Different versions of characteristics.
eg blonde hair/brown hair.
What happens if a population has low genetic diversity?
May not be able to adapt to a change in the environment and the whole population could be wiped out by a single event -disease.
Name 2 ways genetic diversity can be increased in population?
Mutations in DNA forming new alleles.
Different alleles being introduced into population.
Mutations in DNA forming new alleles.
Can be advantageous but can lead to problems.
Different alleles being introduced to population.
When individuals from another population migrate into it and reproduce - gene flow.
Genetic diversity is an important factor to what?
Natural selection as some characteristics are more advantageous than others.
What is a genetic bottleneck?
An event that causes a big reduction in a population.
eg large number of organisms within population die before reproducing.
Reduces number of different alleles in gene pool and reduces genetic diversity
What do the survivors of the genetic bottleneck do?
Survive.
Reproduce.
And a large population is created from a few individuals.
EXAMPLE.
Why were nothern elephants seals hunted?
By humans in late 1800s.
Reducing their original population to around 50 seals.
EXAMPLE.
The 50 northern elephants seals that survived did what?
Produced a population of 170,000.
New population has little genetic diversity compared to southern elephants seals, which didn’t suffer from a reduction.
Define gene pool.
Complete range of alleles om population.
2 ways which decreases genetic diversity
Genetic bottle necks
Founder effect
Founder effect
When few organisms from a population start a new colony and there are only a small number of different alleles in initial gene pool.
Frequency of each allele in new colony may be different to frequency of the same allele in original population - genetic diseases
Name 2 ways that the founder effect occurs ?
Migration leading to geographical separation
New colony is separated from original population for religious purpose
