Transcript EvolutionaryTheory04

Evolutionary Theory Island Biology
What Biological Processes Make the Organisms
on Islands So Unique?
Dispersal
1. Define dispersal:
•
The process of scattering or spreading from a
certain area.
2. Give examples of how plants disperse their seeds.
•
Birds
chance
•
Wind
chance
•
Float
chance
•
Shoots out of fruit
natural
•
Spring open and scatter
natural
3. Analysis: How is dispersal important to evolution on
islands? How life arrives.
Evolution and Natural Selection
4. Define:
 Evolution •
Charles Darwin
The process of modern organisms descending from
ancient organisms; change over time.
 Natural Selection •
The process in nature that results in the most fit
(best adapted) organisms producing offspring. 3
steps: variation --> selection --> reproduction.
•
The mechanism that drives evolution.
 Adaptation •
The process that enables organisms and species to
become better suited to their environments.
Evolution and Natural Selection
4. Define:
 Survival of the Fittest •
Individuals with characteristics best
suited to their environment survive.
 Fitness -
•
The combination of physical traits
and behaviors that help an
organism survive and reproduce in
its environment. Measured by the
number of successful offspring.
Evolution and Natural Selection
5. What three assumptions of Lamarck’s were incorrect
about evolution?
•
A Desire to Change
•
Use and Disuse
•
Passing on Acquired Traits
Evolutionary Theory Evolves
6. What is genetic drift? Give 2 examples.
•
Genetic change in a population, occurring in the
absence of natural selection, due to random, chance
events.
•
Examples of events leading to genetic drift:
-
mutation
-
chance dispersal
-
extreme weather conditions etc.
Evolutionary Theory Evolves
6. Gradualism •
The theory that evolutionary change
occurs slowly and gradually (by
natural selection).
7. Punctuated Equilibrium -
•
Rapid evolution after long periods of
equilibrium.
•
May occur when a small population
of a species becomes isolated from
the main part of the population or due
to other random (stochastic) factors.
Speciation
9. Define:
 Niche •
Darwin’s Finches
The combination of an organism’s habitat and it’s
role in that habitat. (address + profession)
 Speciation •
The process of new species evolving from preexisting ones.
10. Why can no two species occupy the same niche?
•
Competition arises for food and space. The most
efficient species will survive and reproduce.
Speciation
11. What is reproductive isolation?
•
Definition: Separation of populations so that they do
not interbreed to produce fertile offspring.
•
One of the most common ways in which new species
form is when populations are separated.
 What can cause reproductive isolation to occur?
•
Geographic barriers
•
Differences in courtship behavior
•
Differences in fertility periods
 Analysis: What is unique to the evolutionary process on
islands and why? Islands are ISOLATED (distant) and small.