Transcript 18 Adaptions and Natural Selection

Charles Darwin & Natural Selection
4 Principles of Natural Selection
1) Variation
individuals in a population differ from one another
2) Heritability
variations are the result of inherited genetics
3) Overproduction
populations produce more offspring than can survive
4) Reproductive Advantage
some variations allow that organisms to produce
more offspring than others (more “fit”)
FITNESS
• measures the ability an organism to
survive and reproduce in their
(their niche)
environment
NICHE
• the role an organism plays or
sustains in a habitat
ex: habitat
where they fit into
the food chain,
predator/prey relationship
NATURAL SELECTION
• Organisms that are more fit for
their niche (have the most beneficial
variations) are more likely to
survive and reproduce creating
offspring that have increased
fitness for their niche and improved
variations and are more likely to
survive and reproduce and, and,
and, and….
KISS Method…
organisms with good traits survive
(more fit for their niche)
organisms with bad traits die off
(less fit for their niche)
…strong shall survive….
ADAPTATION
structural, behavioral or
physiological features that
helps an organism better
survive
ADAPTATION
STRUCTURAL
ADAPTATION
PHYSIOLOGICAL
BEHAVIORAL
ADAPTATION
• Coloration increases the chance of
survival for an animal.
APOSEMATIC COLORATION:
coloration that advertises toxicity,
poison, bad taste
(warning coloration)
MIMICRY:
harmless species looks
like a dangerous species
Viceroy
Butterfly
Monarch
Butterfly
Non-poisonous king
snakes mimic poisonous
coral snakes.
CRYPTIC COLORATION:
coloration that blends in
with their natural habitat
(camouflage)
Katydids
Stick Bug
Living stones are
examples of plant
cryptic coloration
• Stripes of zebras provide a unique form
of camouflage
STRUCTURAL ADAPTATIONS
• Heat Pits:
• The ability to sense
the heat of other
creatures.
• 6th sense of animals
Jacobson’s Organ
Compound Eye
Thousands of tiny lenses
Acute detection of motion
Senses light & dark finitely
Poor resolution and depth perception
Reproductive Adaptations
“Large Rack” syndrome
Alpha Males
beak structure = beak function
Feet fit their niche
BEHAVIORAL ADAPTATIONS
• r-type
reproduction:
• produce many
offspring = high
mortality
• Insect, rabbit, fish
r-type reproduction
Spider’s hatching
K-type strategist
•
•
•
•
few offspring
low mortality
highly developed young
young are nurtured
Behavioral Adaptations
• Group Hunting
Meerkats
PHYSIOLOGICAL ADAPTATIONS
•
• Hibernation
A fascinating aspect is that Inuit Sled Dogs switch from
resting to heavy work without an obvious training period. In
contrast, human athletes would have to train for weeks
when aiming to reach a similar level of performance as Inuit
Sled Dogs during winter
A camel's blood remains hydrated, even though the body
fluids are lost, until this 25% limit is reached
They can withstand at least 20-25% weight loss due to
sweating (most mammals can only withstand about 3-4%
dehydration before cardiac failure results from the
thickened blood