Genetic Diversity Flashcards
What is genetic diversity?
total number of different alleles in a population
what is a population?
a group of individuals that occupy the same place and can interbreed
what is allele frequency?
how often a particular allele occurs within a population
what is a gene pool?
total number of alleles of a particular population (at a specific time)
what is the advantage of genetic diversity?
the greater the diversity, the greater the number of different alleles that all species possess
- Therefore they are more likely to survive and adapt to environmental change
- they have a wider range of alleles - wider range of characteristivcs
- higher probability that an individual posesses desriable characteristic for new conditions
name five factors that increase genetic diversity
- random mutation
- genetic recombination
- independent assortment
- immigration
- outbreeding
name six factors that decrease genetic diversity
- inbreeding
- reduced gene pool
- small population
- selective breeding
- genetic bottleneck
- founder effect
what is selective breeding?
- humans artificially choosing desirable characteristics and using them as breeding stock
what is the consequence of selective breeding?
- reduced variety of alleles at desired number
- reduced genetic diversity
- unable to adapt to sudden environmental change
how does natural selection work?
- random mutation causes genetic variation
- mutation can either be harmful or beneficial
- individiual with advantageous characteristivs would survive an environmental selection pressure
- survive and reproduce
- pass on beneficial allele to offspring
- over many generations, the frequency of the advantageous allele increases and becomes more common
what are genetic bottlenecks?
- original population contains many different alleles
- sudden population reduction due to natural disaster for example
- only one group has allele which benefits their survival and only they live
- this group reproduces and a population is created of individuals with reduced genetic diversity, since there are fewer different alleles
what are the problems with bottlenecks?
- less variation - as alleles are lost from gene pool
- not representative of original population
- some alleles are overrepresented among population so some may be eliminated completely
give an example of a genetic bottleneck
- northern elephant seal
- over hunting in late 1800s reduced population
- surviving seals repopulated - new population has reduced genetic diversity
name a type of genetic bottleneck
founder effect
what is the founder effect?
- few individuals from a population form a new colony in a new habitat
- since there is a small number of individuals, there is a small number of different alleles in the gene pool
- allele frequency of the new colony is different to allele frequency of original population
- new colony more susceptible to genetic disorder due to lack of new alleles introduced into the population
