Transcript Evolution of New Species

Evolution of New Species
Changes in populations may lead
to the formation of new species.
What is a biological species?
• A group of interbreeding organisms that
produce viable fertile offspring.
• Examples: all humans!
Eastern box turtles
Natural Selection may lead to
speciation
• There are types of selection:
• Directional
• Stabilizing
• Disruptive
Stabilizing Selection
• Selection against two
extremes
Example – average
weight of human
babies at birth
Direcional Selection
• Natural Selection
Causes the species to
Change in a certain
Direction
Example – bird beaks
Disruptive Selection
• Selection in two
•
directions away from
a mean.
Two groups of
organisms exist with
very different features
to exploit different
resources.
Speciation
• Evolution of new species occurs when
some barrier keeps organisms from
interbreeding.
How do new species arise?
• Once a population of organisms no longer
interbreeds successfully with another
population – two species have evolved
from one.
• How does this separation occur?
• Sometimes natural selection will divide
species.
• How might directional selection lead to a
new species?
(Hand out the paper.)
Geographic Isolation
• Physical barrier
•
divides a population
and they no longer
interbreed
Darwin’s Galapagos
finches are an
excellent example.
Reproductive Isolation
• Formerly
interbreeding
organisms in
the same
location no
longer mate and
produce fertile
offspring
Adaptive Radiation=Divergent
evolution
• New species arise when
•
resources are limited and
certain groups of
organisms live in
different niches and as a
result no longer
interbreed.
One common ancestor
leads to many different
species
Convergent evolution
• Unrelated species in
•
similar environments
share similar
pressures and thus
develop similar traits.
Example: wings for
flying
animals=analogous,
not homologous
Adaptive Radiation=Divergent
evolution
• New species arise when
•
resources are limited and
certain groups of
organisms live in
different niches and as a
result no longer
interbreed.
One common ancestor
leads to many different
species
21. Adaptive radiation=divergent
evolution or convergent evolution
• The “tree of life”
shows common
ancestry of all living
organisms
22. Geographic or reproductive
isolation?
• Female birds prefer
“showy” mates
therefor e
• Female birds prefer
“showy” mates
therefore female birds
will mate with only
the male of their
species
Quiz Time!!!!
• Number 1-20 on a piece of scrap paper.
• In each slide an example will be shown.
• Determine the type of selection or
isolation indicated in the slide.
Hey buddy, why
don’t you hitch a
ride. May be we
can hook up?!
We are
different
species!
1. Geogrpahic or
reproductive
isolation
2. Adaptive radiation = divergent
evolution or convergent evolution?
3. Reproductive or geographic
Isolation?
These fish live in the same pond, but
do not interbreed.
4. Geographic or reproductive
• Two species live in different habitats
5. Reproductive or
geographic
• Species that breed during different times
of the year, different seasons or different
years are not able to mate.
6. Divergent or convergent evolution
In plants and animals, flower structure or body
parts forbid mating
7. reproductive or geographic isolation?
• Anatomically incompatible = parts do not
fit!
OH No!!!!!!
8. Geographic
or reproductive
isolatio?
9. Divergent or
convergent
evolution
Originally there was one species of mouse
existed – now a mountain range exists,
they no longer interbreed.
10. geographical or reproductive?
11. divergent or convergent?
12. Convergent or divergent
13. analogous or homologous?
14. Geographical or reproductive
isolation?
• Signals get crossed – incorrect mating
dance in birds or insects.
15.. Convergent or divergent?
16. Analagous or homolgous?
17. Divergent or convergent
evolution?
18. analogous or homologous?
Originally there was one species of shrimp
existed – now that the isthmus of Panama
exists, they no longer interbreed.
19. geographical or reproductive?
20. divergent or convergent?