Download Darwin`s Theory of EVOLUTION by Natural Selection

Darwin’s Theory of EVOLUTION by
Natural Selection
Evolution
Evolution: The long, slow process of
change in a species over time
What is Natural Selection?
1. “Survival of the Fittest“: organisms that are better
suited for their environment survive and reproduce
more successfully
2. Reproduction leads to the formation of the same
type of organism
What is Natural Selection?
3. Organisms produce more offspring than will
survive
– The more produced, the better chance more will
survive
4. Selection occurs without human (artificial
influence)
What does it mean to be the
fittest?
1. Fitness: Ability of an individual to survive and
reproduce
a. sharp quills on a porcupine
2. Fitness is a result of adaptations
Adaptations
1. Adaptations: Successful adaptations enable
organisms to be better suited for their environment
– Adaptations increase fitness
– Adaptations are due to RANDOM MUTATIONS!!
CAN’T BE ACQUIRED!!
Adaptations
2. Can be structural,
physiological, or
behavioral
– giraffes’ neck (structural)
– human calluses
(physiological)
– hunting at night
(behavioral)
Other Adaptations
Plants:
1. waxy coating, spines, root systems,
leaf size, ability to store water
Other Adaptations
Animals:
2. burrowing, nocturnal, water tight
skin, adaptive camouflage
What Does Natural Selection
Lead to?
1. Biodiversity is a result of many adaptations of
species that lead to speciation (creation of a new
species)
2. Biodiversity: Is the sum total of all the different
organisms in the biosphere
– over 1.5 million and counting
Biodiversity
3. Natural variety exists in any population of
organisms
What does Natural Selection
Create?
1. Struggle for Existence: members of
each species compete regularly to
obtain food, living space, and other
necessities for life