What is variation?
Differences in organisms
Where is variation?
In your genes (DNA)
How does variation come about?
Natural selection, mutations, genetic drift, gene flow, sexual recombination
selects certain alleles over others therefore changing genes (what is means to be "fit" changes)
random changes in individual's DNA results in changes to whole gene pool (affects gene pool, but in individuals)
slight changes in genes in a small population due to chance events (natural disasters, random, not selecting individuals) EX. Flooding, volcano, etc.
2 Examples of Genetic Drift
Founder and Bottleneck Effect
Leaves a group and 'founds' a new area, first ones there. Gene pool of group B may or may not be the same as it was in group A.
Natural disaster kills most of a population, those that survive may or may not have similar genetic make-up as previous population
independent assortment, crossing over and random fertilization is what makes you unique
What makes you unique?
Gene structure: independent assortment, crossing over, random fertilization
requires 50/50 gender, random mating and infinitely large. Ideal conditions, doesn't exist, used to compare and find differences in normal populations by using Darwinian theory.
all genes of all individuals in a population
(allele frequency) relative amount of dominant and recessive alleles in a population
change in a gene frequency over time (in a population)
Darwin's Theory of Natural Selection
environment is always changing, variety within species exists, competition exists