Download Intro to Evolution PPT - Get a Clue with Mrs. Perdue

The diagram below represents a plant cell.
Which process takes place in structure A?
A
B
C
D
cellular respiration
heterotrophic nutrition
digestion of fats
protein synthesis
A population of long-necked giraffes shares a
habitat with a second population of organisms
that eat the leaves of low-growing vegetation.
A scientist speculates that if the second
population leaves the area, the giraffe
population could exhibit shorter necks over
time. Which mechanism could result in the
giraffe population exhibiting shorter necks?
A The long-necked giraffes would breed with a short-necked
species.
B Giraffes with a genetic mutation for short necks would
survive and reproduce.
C The presence of food on shorter plants would lead to a
relaxation of giraffe necks.
D Giraffes would learn to bend their necks while feeding,
causing a shortening of neck muscles.
 changes in living organisms over time
 explains how modern organisms have
descended from ancient organisms
Why do we accept this as a
Scientific Theory?
 Many different species alive today
 All life shares common characteristics
 The Earth is very old
 Life is very old
 Life has changed over time
 The changes have been little changes over long
periods of time
Evolution
But how does this work?
Evolution shows how organisms can be similar
and
how organisms can be different
 Father of Evolution
 Proposed a way how evolution
works
 How did creatures change
over time?
 by natural selection
 Collected a lot of evidence to
support his ideas
 1809-1882
 British naturalist
 Invited to travel around the world
 1831-1836 (5 year journey!!)
 records many observations of nature and took notes
& drew pictures in hundreds of notebooks
 Stopped in Galapagos Islands
 500 miles off coast of Ecuador
Many of Darwin’s observations made
him wonder… Why?
Darwin asked:
Why were these creatures found only
on the Galapagos Islands?
Darwin found:
Evidence that creatures have
changed over time
present day Armadillos
Darwin asked:
ancient Armadillo
Why should extinct
armadillos & modern
armadillos be found on
same continent?
Darwin found:
Different shells on tortoises on different islands
Darwin asked:
Is there a relationship
between the environment
& what an animal
looks like?
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small
insectivorous
tree finch
Large
insectivorous
tree finch
Small
ground
finch
Cactus
eater
Insect eaters
Seed eaters
Vegetarian
tree finch
variation
Bud eater
Medium
ground
finch
Large
ground
finch
natural selection for best
survival & reproduction
 Darwin’s conclusions:
1. Variations in beaks
 differences in beaks in the original flock
 adaptations to foods available on islands
2. Natural selection for most fit
 over many generations, the beak adaptations allowed
survivors to create the population diversity
3. Offspring inherit successful traits
 Best adaptations allow offspring to out-compete others and
survive to reproduce
4. This creates new species over time
 LaMarck
 evolution by acquired traits
 Organisms change their
adaptations through use
 Give those new adaptations to
their offspring
 example
 in reaching higher leaves giraffes
stretch their necks & give the
acquired longer neck to offspring
 not accepted as valid
 Darwin
 giraffes that already have
long necks survive better
 leave more offspring who
inherit their long necks
 variation
 selection & survival
 reproduction &
inheritance of more fit
traits
Competition
 for food, mates, nesting sites, escape predators
Fitness = having the right adaptations to out-compete
others
Survival of the Fittest = organisms with the “best”
traits/adaptations survive to reproduce
not the
…the
fittest!
strongest…
bravest…
fastest…
biggest…
Adaptations
the traits that help an organism fit
the environment better to
survive & reproduce
Darwin concluded:
Each species has descended, with changes, from other
species over time.
Darwin called this…
Descent With Modifications
or
(change in population over time)