Mechanisms for Speciation
Mechanisms for speciation
 Mutations
 Genetic drift
 Immigration or emigration
 Reproductive isolation
 Natural Selection
What are mutations?

How do mutations affect populations?
Some mutations have no affect on the genotype and phenotype of an
individual while others change a single amino acid or many amino acids
affecting protein production and genotypes and phenotypes. When
individuals of a population mate together these mutations are inherited and
passed along from parent to offspring.
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How can mutations cause the creation of new species?
What is genetic drift?

How does genetic drift affect populations?
When mutations in a small population change the genotypes in that population
the number of times an allele is seen may be different than those within a large
population.

How can genetic drift cause the creation of new species?
What is immigration?
What is emigration?

How does immigration or emigration affect populations?

How can immigration or emigration cause the creation of new species?
What is reproductive isolation?

How does reproductive isolation affect populations?
The population no longer breeds together, therefore creating a new gene pool.
This may happen when members of a population no longer recognize mating
behaviors, are separated by a physical barrier, or mate at different times of the
year than normal.

How can reproductive isolation cause the creation of new species?
What is natural selection?

How does natural selection affect populations?

How can natural selection cause the creation of new species?
Natural Selection’s affect on single gene and polygenic traits

Natural Selection acts on single gene traits by

Providing ________ distinct phenotypes in a population

Natural Selection acts on polygenic traits by

Providing ____________ phenotypes in a population
Favoring individuals in a population in three different ways

Natural Selection favoring average individuals in a population


Called _______________ _________________
________________________________________ in a population

Natural Selection favoring one extreme variation in a population


Called __________________________________
Can lead to the __________________________________ of a population

Natural Selection favoring both extreme variations in a population


Called _____________________________________
leads to the evolution of ________ new species