Download Natural Selection - noraddin

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Population genetics wikipedia, lookup

Introduction to evolution wikipedia, lookup

Theistic evolution wikipedia, lookup

Saltation (biology) wikipedia, lookup

Hologenome theory of evolution wikipedia, lookup

Natural selection wikipedia, lookup

Inclusive fitness wikipedia, lookup

Speciation wikipedia, lookup

Evidence of common descent wikipedia, lookup

Punctuated equilibrium wikipedia, lookup

Sexual selection wikipedia, lookup

Mate choice wikipedia, lookup

Ecology wikipedia, lookup

The Descent of Man, and Selection in Relation to Sex wikipedia, lookup

Transitional fossil wikipedia, lookup

The ideas that shaped Darwin…
Hutton, Lyell, Lamarck and Malthus
Evidence of a Changing Earth
Scientists Hutton and Lyell
studied the organisms
found in fossils.
The older the fossil, the
deeper it was buried
Changes in the
appearance of the
organisms could be seen
between layers.
Lamarck’s Evolution Hypothesis
In 1809, Lamarck
proposed that an animal’s
behavior could change the
traits passed down to their
He thought, the more you
use it, the more it grows.
He did not know about
how genes were passed
Malthus’ Population Growth
Population growth is
limited by the
resources available,
such as food and living
Once the food or the
space starts to run out,
then the growth rate
will have to slow and
then stop.
Darwin’s Work
Inherited Variation
Slight mutations in the
genetic code happen
Before Darwin, scientists
did not think this was
Darwin claimed that
differences matter and
can change the direction
of a species
Artificial Selection
Nature provides genetic
Humans often select for
traits that they find most
Example: We like larger,
sweeter tomatoes, so we
will selectively breed
plants for those traits.
Struggle for Existence
Species have to
compete for the
best food, living
space and mates
This drives the
selection process
Survival of the Fittest
Organisms with the best adaptations for the
environment will survive.
These adaptations are passed down through
the genes from parents to babies.
The others will die off.
Darwin called this,
“Natural Selection.”
Evidence for Evolution
The Fossil Record
There are many marine
life fossils
They saw many species
with shells
The shells got
increasingly complex,
suggesting evolution
took place over time
Homologous Body Structures
Same bones, but
different uses
Mammal Examples:
 Human Arm
 Horse Leg w/Hoof
 Whale Flipper
 Bat Wing
Similarities in Embryos
Types of Selection
Directional Selection
Individuals at one end of the curve are better
fitted for the situation, so all shift.
Stabilizing Selection
Individuals in the middle of the curve are best
fitted for the situation, so ends drop off.
Disruptive Selection
Individuals at either extreme are better fitted
for the situation than an average individual.
Genetic Drift
Certain traits many become more common in a
population by chance, rather than by a type of
purposeful selection.
Hardy-Weinberg Principle
There are 5 was to have a population at
equilibrium (where there is no change)
Random Mating
Large Population
No Movement into or
out of the population
No Mutations
No Natural Selection
The Process of Speciation
Reproductive Isolation
Only individuals of the same species can mate
Behavioral Isolation
Individuals could breed, but their styles of
behavior or courtship make them not attracted
to one another.
Geographic Isolation
Individuals could mate, but they are
separated by distance
Temporal Isolation
Individuals could
mate, but they
naturally mate at
different time
Process for the Evolution of Darwin’s Finches
How Speciation Occurred…
Founders Arrive: A few finches flew to one of the
islands from South America and mated
Separation of Populations: Some of these
finches flew to a neighboring island
Changes in Gene Pool: Adapting to new island
Reproductive Isolation: Now the finches on the
different islands are too different to mate!
Ecological Competition: need food & nests
Continued Evolution: natural selection continues
Patterns of Macro-Evolution
Species that cannot adapt to their environment
will die out.
Adaptive Radiation
Many species evolve from a single species
Convergent Evolution
Some species look
However, they are not
closely related
Similar environmental
factors cause the
species to evolve in
similar ways.
The process when two species evolve in
response to changes in each other over time
Example: Flowers change to keep attracting
the bees needed to pollinate them.