Download Change over Time

Change over Time
Adaptation
 a characteristic that helps an
organism survive in its
environment
 Two types of adaptations

Structural – physical feature


Ex. Long neck, gills, striped fur
Behavioral – action of organism

Ex. Hibernation, hunting at night
Great Blue Heron
Adaptations
The Great Blue heron has adapted in
many ways.
1. They have mastered the art of
hunting by standing still in shallow
water waiting for their prey, then
stabbing it with their extremely
sharp beak.
2. In addition, they adapted to avoid
predators by building their large
nests of sticks in trees so they
cannot be reached easily by most
predators.
3. Lastly, it adapted to its
environment by getting a grey-blue
camouflage and a streaked white
neck to blend in with its
surroundings.
Amur Tiger
Characteristics
that improves an
individual’s
ability to survive
and reproduce
in a particular
environment.
Species
A group of organisms that can
mate with one another to
produce fertile offspring
Scientists believe that as Earth
changes species also change
or
Species die out
or
New species appear

Scientists observe that
species change over time
Evolution
 The process in which
populations gradually change
over time
Evolution happens by Natural
Selection
 the process of sorting
individuals based on their ability
to survive and reproduce within
their ecosystem.
THE PRINCIPLES OF NATURAL SELECTION
THE
PRINCIPLES
OFoffspring
NATURAL
1.
Organisms
produce more
that canSELECTION
survive.
1. Organisms produce more offspring that can survive.
2. Differences, or variations, occur among individuals of a
species.
2. Differences,
or variations, occur among individuals of a
species.
3. Some variations are passed to offspring. (Every individual
itsvariations
own combination
of traits
so it is similar
but not
3. has
Some
are passed
to offspring.
(Every to,
individual
identical
to,combination
its parents.) of traits so it is similar to, but not
has its own
to, its parents.)
4. identical
Some variations
are helpful. Individuals with helpful
variations
surviveare
and
reproduce
better than
those without
4. Some
variations
helpful.
Individuals
with helpful
these
variations.
variations
survive and reproduce better than those without
variations.
5. these
Over time,
the offspring of individuals with helpful
variations make up more of a population and eventually
may become a separate species.
What might happen to an
albino lemur in its natural
environment?
Examples of Natural Selection in Action –
Changes in Populations
Adaptation to Hunting
People hunt elephants for
their tusks. As a result, fewer
of the elephants that have
tusks survive to reproduce,
and more of the tuskless
elephants survive.
Insecticide Resistance
A few insects in a population
may be naturally resistant to a
chemical insecticide. These
insects pass their resistance
trait to their offspring, and an
insect population gradually
becomes resistant to the
insecticide.
Competition for Mates Many
species have so much competition
for mates that interesting
adaptations result. For example, the
females of many bird species prefer
to mate with males that have
colorful feathers.
Darwin’s Finches Darwin noticed that the finches of the Galápagos
Islands were a little different from the finches in Ecuador. And the
finches on each island differed from the finches on the other
islands.
Natural Selection in Action - The Process of Speciation
Separation Speciation often
begins when a part of a
population becomes separated
from the rest.
Adaptation Populations
constantly undergo natural
selection. After two groups have
separated, natural selection may
act on each group in different
ways.
Division Over many generations,
two separated groups of a
population may become very
different until the point when they
can no longer mate with one
another. At this point, the two
groups are no longer the same
species.
Evidence of changes
Fossils
The remains or imprints of once-living
organisms found in layers of rock
 Fossil record
Timeline of when certain organisms existed
Made by studying fossils embedded in rock
Evidence #1:
 Fossils in newer rock layers more similar to
organisms today
 Older fossils less similar to today’s
organisms



Part of fossil record is missing
Fossils are rare – few organisms will become
fossils

..
Evidence #2:
Many organisms have common
characteristics (bone structure,
development in womb)
This indicates organisms have
common ancestors

Evidence: Case Study =
Whale
Evidence in fossils links whales to
mammals that lived on land
To
 Organisms that partly lived on water
and partly on land
To
 An organism that lived in water
To
 Modern day whales


Scientists think that the ancient ancestor of
whales was probably a mammal that lived on
land and that could run on four legs. The
organisms shown form a sequence between
ancient four-legged mammals and modern
whales. Several pieces of evidence indicate
that these species are related by ancestry
Evidence in skeletal structure
of today’s whale
Whales have hip bones!!
(whales do not walk)

When comparing organisms:
Evidence found :
In skeletal structures
 Structures and order of bones are
similar in organisms
Evidence #3: When comparing DNA
 DNA in living organisms are similar
 More closely related organisms have
a greater amount of DNA in common
(chickens and dinosaurs)
