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Chapter 17: Population Genetics and Evolution - Coggle Diagram
Chapter 17: Population Genetics and Evolution
Population Genetics
deals with the abundance of different alleles within a population and the manner in which the abundance of a particular allele increases, decreases, or remains the same with time.
Factors that Cause the Gene Pool to Change
Mutation
because of mutation, existing alleles decrease in frequency, and new alleles increase
whether or not mutation is significant depends in part of on the population's size
Artificial Selection
the process in which humans purposefully change the allele frequency of a gene pool
also used to produce ornamental plants that flower more abundantly or for a longer time
often carried out in conjunction with artificial mutation
Natural Selection
the most significant factor causing gene pool changes; usually described as survival of the fittest
two conditions must be met before natural selection can occur
does not include purpose, intention, planning, or voluntary decision
Rates of Evolution
Speciation
natural selection has caused a new species to evolve, a process called speciation
can occur in two fundamental ways:
Phyletic Speciation
Divergent Speciation
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
Adaptive Radiation
a special case of divergent evolution in which a species rapidly diverges into many new species over just a few million years
This movement of alleles physically through space, called gene flow, occurs in many ways, such as by pollen transfer, seed dispersal, and vegetative propagation
there are many species of seedless plants (lycopods, Equisetum, ferns) that have persisted for tens of millions of years without diverging into new species
Evolution and the Origin of Life
the most seriously considered hypothesis about the origin of life on Earth is that of chemosynthesis
prezygotic isolation mechanisms
neither pollination nor fertilization occurs
