Topic:
Speciation
Name: ____________________________
Date:_________________________
Objective: SWBAT understand how speciation occurs.
Questions/Main Ideas:
What is species?
Species= a group of organisms that breed with one another and produce
fertile offspring (all individuals come from same gene pool).
Speciation= the process that leads to the formation of new species.
What is speciation?
What are the three
methods of
reproductive
isolation?
How does speciation
occur?
What are patterns of
evolution?
Reproductive isolation= keeping populations separated, so they are unable
to breed, eventually creating separate gene pools.
1. Behavioral Isolation= when two populations have different courtship
rituals or other types of behaviors.
- Ex) Frogs are attracted to only certain calls or birds have specific
mating dances
2. Geographic Isolation= when two populations are separated by
geographic barriers such as rivers, mountains or bodies of water.
- Ex) Abert and Kaibab
squirrels of the Grand
Canyon
3. Temporal Isolation= when
two populations reproduce
at different times.
- Ex) Frogs having different
mating times throughout
the spring and summer
- Founders Effect= when the
pioneer species starts the first generation
Ex) First birds that fly to the Galapagos from South America
- Geographic isolation leads to changes in the gene pool because
different birds are better adapted for different islands.
- They will not be able to interbreed with one another – even if they
fly to other islands. At this point in time the birds are different
species.
- Competition for food and inhabiting different niches will further
speciation.
Patterns of Evolution
1. Mass extinction= sudden death of organisms within a species,
which opens up a lot of niches for other organisms to move into.
Ex) Dinosaurs
2. Adaptive radiation= when a single species evolves into several
different species over time.
Ex) Darwin’s finches
3. Convergent Evolution= when unrelated organisms resemble one
another because of the environment that they live in.
Ex) Dolphins and sharks
4. Coevolution= when two species evolve in response to changes in
each other over time (so they evolve together).
Ex) Bees and flowers
5. Gradualism= organisms are always changing at a slow and constant
pace.
6. Punctuated Equilibrium= long periods of stabilization followed by
short periods of rapid evolution (proposed by scientist Stephen
Gould)
Summary: