Selection and speciation Flashcards
Why do individuals in a population of a species show a wide range of variation in phenotype?
Mutation
Meiosis
Random fertilisation/fusion of gametes
Variation predominantly caused by a single gene is what?
Discontinuous
Variation predominantly caused by genetic factors produces what kind of data?
Categoric
Variation caused by more than one gene is what?
Continuous
What is natural selection?
Process by which organisms that are better adapted to their environment survive and reproduce in greater numbers, resulting in the increase of the frequency of advantageous alleles within the population
Describe the process of natural selection
Variation exists within a population
Better adapted individuals are more likely to survive and reproduce
More likely to pass on their alleles
Less well adapted fail to survive and reproduce
Less likely to pass on their alleles
Organisms are subject to selection pressures due to the environment they live in
What does selection pressure determine?
The spread of an allele within the gene pool
What is stabilising selection?
Favours the average phenotype and tends to eliminate extremes
Reduces variability and reduces opportunity for evolutionary change
What is directional selection?
Favours an extreme phenotype
What is disruptive selection?
Favours two extreme phenotypes
What is evolution by natural selection?
Change in the allelic frequencies within a population
What must two population undergo to become genetically distinct?
Reproductive isolation via a accumulation of mutations and different selection pressures
What is another term for genetic drift?
Bottleneck
What is another term for gene flow?
Founder effect
What does genetic drift mean?
Random increase or decrease in allelic frequency
