Speciation is the process of formation of new species

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