Transcript 2. Evolution and Adaptation - Hicksville Public Schools / Homepage

AIM: Explain how a species adapts to its
niche and describe convergent
evolution and coevolution.
DN: Can two species share the same
exact niche? Why or why not?
HW: Article Summary #1
EVOLUTION AND
ADAPTATION
EVOLUTION
A gradual change in a population
of organisms over time
Evolution occurs when genetic variation
allows certain individuals to better
survive in their environment. Over
time, these changes (adaptations) will
be passed from generation to
generation.
Adaptation
A genetically controlled change in an
organism that helps it to survive and
reproduce under a changing environment
• A change in the environment will affect the
niches of the organisms that live in that
environment
• A species may successfully occupy a
niche, but if that niche disappears, the
species may become extinct.
• Changes in the environment affect the
evolution of populations
ADAPTATIONS
EVOLVING IN A NICHE
• 5 species of warblers live in the forests of
the northeastern United States
• All 5 species feed on the insects in spruce
trees
• Although they may seem to compete with
each other, each species feeds in a
different part of the tree
• Their niches overlap slightly, but are
different enough to allow all 5 species to
coexist
5 species of Warblers
Specialized Species
• An organism with a small niche
• Vulnerable to extinction (any small
change in the environment can affect
it)
Example: Koala Bear
• Eats only leaves of
eucalyptus trees
Generalized species
• An organism with a big niche
• Has several food choices making it
more likely to survive a change in the
environment
Example: Cockroaches and Mice
• Can easily change their behaviors to
fit new environmental conditions
CONVERGENT EVOLUTION
The independent development of similar
adaptations in two species with similar
niches
• If niches in two ecosystems are similar,
the organisms that evolve there may also
look similar
The Dolphin (mammal) and the
ichthyosaur (extinct reptile) are
examples of convergent evolution
Coevolution
Two species adapt (through evolution) to
improve their own survival and rely on one
another for survival.
(they need each other to survive)
Example: Acacia trees and stinging ants
• The tree provides a nesting site for ants
• The ants protect the trees from animals
and other insects
ONE CANNOT SURVIVE WITHOUT THE
OTHER!!!!
Acacia Tree and Stinging Ants
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What is evolution?
What is a specialized species? Give an example.
What is a generalized species? Give an example.
Why are generalized species more adaptable to
changes in the environment.
Explain convergent evolution and give one example.
Why does convergent evolution happen?.
What is coevolution? Provide an example of
coevolution.
Why do species such as the warblers evolve to avoid
competition with other species?
What would happen to the ant colony living on an
acacia tree if that tree was chopped down? What
does your answer imply about the effect of destroying
an organism’s habitat?
Review Questions
1. Why do species such as the warblers evolve
to avoid competition with other species?
2. Explain convergent evolution and give one
example. Why does convergent evolution
happen?
3. What would happen to the ant colony living
on an acacia tree if that tree was chopped
down? What does your answer imply about
the effect of destroying an organism’s
habitat?