Transcript IB Speciation ppt

Speciation
Species

An organism that can mate with
another and produce fertile
offspring
Speciation

Isolating Mechanisms


Different gene pools
2 species cannot interbreed to produce
fertile offspring  Reproductively
Isolated
Behavioral Isolation

Differences in
courtship rituals or
other types of
behavior

Songs of birds
Geographic Isolation

2 populations
separated by
geographic
barriers (rivers,
mountains, bodies
of water)

Abert Squirrel vs.
Kaibab Squirrel
Temporal Isolation

Species reproduce
at different times
Speciation
Northern
population
Early fox
population
Spreads
northward
and
southward
and
separates
Arctic Fox
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Southern
population
Gray Fox
Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.
Adapted to heat
through lightweight
fur and long ears,
legs, and nose, which
give off more heat.
Speciation

Two species arise from one

Requires Reproductive isolation






Allopatric




Geographic: Physically separated
Temporal: Mate at different times
Behavioral: Bird calls / mating rituals
Anatomical: Picture a mouse and an elephant hooking up
Genetic Inviability: Mules
Speciation that occurs when 2 or more
populations of a species are geographically
isolated from one another
The allele frequencies in these populations
change
Members become so different that that can no no
longer interbreed
Sympatric

Populations evolve with overlapping ranges
COEVOLUTION: Interaction
Biodiversity

Species so tightly connected, that
the evolutionary history of one
affects the other and vice versa.
Adaptive Radiation

Single species or
small group of
species evolves
into several
different forms


Darwin’s Finches
Reptiles &
Dinosaurs
How Long does Evolution take?

Gradualism


Slow changes over time
Punctuated Equilibrium

Long, stable periods followed by short
periods of quick changes
Gradualism