1. V. The Process of Speciation
Speciation – formation of a new
species.
Species – a group of organisms
that can breed with one
another & produce fertile
offspring.
*Members of a species can lose
the ability to interbreed due to
isolation.
Isolation – anything preventing
two groups within a species
from interbreeding.

2. A. Isolating Mechanisms
*As new species evolve, populations
become reproductively isolated from
each other.
Reproductive isolation – loss of two
groups’ ability to interbreed &
produce fertile offspring.
-Reproductive isolation can
develop through :
1. Behavioral isolation – when
two populations are capable
of interbreeding but have differences in courtship rituals/other reproductive strategies that involve
behavior, ex :
Eastern & Western meadowlarks.

3. Geographic Isolation
2. Geographic isolation – when two populations are separated by geographic barriers such as rivers, mountains, or bodies of water, ex : Abert squirrel & Kaibab squirrel.

4. Temporal Isolation
3. Temporal isolation – when two or more species reproduce at different times, ex : rainforest orchids.

5. Processes of Change *Species can also go through
the following processes of
change :
1. Divergent Evolution
2. Convergent Evolution
3. Coevolution
1. Divergent evolution – when isolated populations of a species evolve independently.
-Happens because of
geographic barriers or when a
small group leaves an original
population to colonize a new
area. Ex : Brown vs. Polar bears.

6. Convergent Evolution
2. Convergent evolution – when natural selection produces analogous (similar) adaptations
in response to similar environments, ex : Serval cat (Africa)
& Maned wolf (SA) - long ears/legs &
the same prey.

7. Coevolution
3. Coevolution – when two or more populations that closely interact over an extended period of time evolve together, ex : flowers & bees.

8. B. Adaptive Radiation Adaptive radiation – evolution of many diverse
species from 1 common ancestor, ex : Darwin’s
finches- spread.