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Population Genetics and Evolution - Coggle Diagram

- - - - Factors that cause gene pool to change
        
        Accidents
        
        events in which organisms cannot adapt
        
        Ex. volcanic eruption
        
        Artificial selection
        
        process where humans purposely change the allele frequency of a gene pool
        
        Ex. selective breeding for crops
        
        Mutation
        
        all genes are subject to mutagenic factors and they occur continually
        
        Existing alleles decrease in frequency but new alleles increase in frequency
        
        Natural selection
        
        most significant factor to cause gene pool to change, survival of the fittest
        
        2 conditions must be met for natural selection to occur
        
        population must produce more offspring than can possibly grow and survive to maturity in that habitat
        
        progeny must differ from each other in their types of alleles
- - - - one species gradually becomes so changed that it must be considered a new species
      - requires millions of years for a species to evolve
        
        as the new beneficial allele arises it is spread among the populations and this is known as gene flow #
        
        gene flow occurs in many ways some examples are
        
        seed dispersal
        
        vegetative propagation
        
        Pollen transfer
    - - some populations of a species evolve into a new, second species, while the other populations either continue relatively unchanged as the original, parental species or evolve into a new, third species
      - if alleles that arise in some individuals but does not reach them all the two are reproductively isolated
        
        2 fundamental causes of this are
        
        abiological reproductive barriers
        
        any physical, nonliving feature that prevents two populations from exchanging genes
        
        biological reproductive barriers
        
        any biological phenomenon that prevents successful gene flow