Speciation occurs through three main types: allopatric speciation, sympatric speciation, and adaptive radiation. Allopatric speciation involves reproductive isolation of populations separated by geographic barriers. Sympatric speciation can occur through balanced polymorphism, polyploidy, or hybridization without a geographic barrier. Adaptive radiation is the rapid evolution of many species from a single ancestor as it colonizes areas with diverse ecological niches. Evolution can occur through four patterns: divergent evolution of isolated populations, convergent evolution of unrelated species adapting to similar environments, parallel evolution of related lineages making similar changes, and coevolution of interacting species influencing each other's adaptations.

1. Speciation and Types of evolution

2. Speciation
 Species: a group of individuals capable of interbreeding
 Speciation: the formation of new species (3 main types)
 Allopatric Speciation
 Sympatric Speciation
 Adaptive Radiation

3. Allopatric Speciation
 Occurs when a population is divided by a geographic barrier
 Barriers: mountains, rivers, regions excluding vital resources
(water, food) areas covered with volcanic lava
 Interbreeding between populations not possible (reproductive isolation)
 Gene frequencies can diverge due to natural selection, mutation, and
genetic drift

4. Sympatric Speciation
Apple maggot flies
 The formation of new species without the
presence of a geographic barrier
 Occurs by one of 3 ways:
 Balanced Polymorphism
 Polyploidy
 Hybridization

5. Adaptive Radiation
 Relatively rapid evolution of many
species from a single ancestor.
 Ancestral species colonizes an area
where diverse geographic or
ecological conditions are available
for colonization.
 i.e. many available ecological
niches for a population to
spread into.
 Examples: Darwin’s Finches,
Australian Marsupials

6. Patterns of Evolution
 Evolution can take place
along the lines of the
following patterns:
 Divergent Evolution
 Convergent Evolution
 Parallel Evolution
 Coevolution
Divergent Evolution
 Describes two or more species that originate
from a common ancestor.
 This may happen as a result of allopatric or
sympatric speciation or by adaptive radiation
Convergent Evolution
 Describes two unrelated species that share
similar traits.
 Similar traits arise because each species has
independently adapted to a similar niche
 These traits are called: Analogous Traits

7. Parallel Evolution
 It is two related species or two related
lineages that have made similar
evolutionary changes after their
divergence from a common ancestor
 Example:
 Species from two groups of
mammals, the marsupial mammals
and the placental mammals, have
independently evolved similar
adaptations when ancestors
encountered comparable
environments
Coevolution
 It is the evolution of one species in
response to new adaptations that appear
in another species
 An example: evolutionary arms race
between predators and prey…or
 Plants and plant eating insects
 Pollinators and flowering plants
 Pathogens and animal immune
systems