Download Microevolution

SBI 3U
November 12th, 2012
 What
is microevolution?
 Mechanisms of microevolution: natural
selection, artificial selection, genetic drift
and gene flow
 Gene
pool: consists of
all the alleles in the
individuals that make
up a population
 Populations that do not
undergo change to
their gene pools are
not currently evolving:
Hardy-Weinberg
Equilibrium
The Hardy-Weinberg Equilibrium will hold
under 5 conditions:
1. There must be random mating
2. There is a large population
3. There is no movement in or out of the
population
4. There are no mutations
5. There is no natural selection
 Makes
it possible to recognize when gene
pools are changing
 A generation-to-generation change in the
frequencies of alleles within a population is
called microevolution
 Natural
Selection
 Artificial Selection
 Genetic Drift
 Gene Flow
 Environment
increases the frequency of
alleles that provide a reproductive
advantage to individuals and thus leads
to the evolution of adaptations
 Involves
the intentional breeding of
domestic plants and animals to produce
certain traits
 Change
in the gene pool of a population
due to chance
 The smaller the population, the more
impact genetic drift has
The Bottleneck Effect:
 Natural disasters may drastically reduce the size of
a population  smaller gene pool
 By chance, certain alleles may be represented more
frequently than others among the survivors
The Founder Effect:
 Genetic drift in a new colony is known as
the founder effect, because the change in
allele frequencies relates to the genetic
makeup of the founders of the colony
Involves the exchange of genes with another
population
 Occurs when fertile individuals or their gametes
migrate between populations
 Tends to reduce genetic differences between
populations
