Transcript Adaptations Over Time

Changes /Adaptations Over
Time
Species
• A group of
organisms that
share traits
(characteristics)
that may be
similar.
• They also have to be
able to reproduce
Evolution
• Change in inherited characteristics of a
species over time.
Basic Concepts of Natural
Selection
• Individual living things are different from
each other. This is called variation.
• Variation is important because without it,
populations cannot evolve over time.
• Living things produce more offspring than
can survive, and many that survive do not
reproduce.
• Living things compete for limited
resources, such as food and shelter.
Theories
• Scientific theory: well-tested
concept or explanation not proven
– Jean Baptiste de Lamarck
– Charles Darwin
Lamarck
Lamarck's Theory of Evolution:
Darwin was not the first person
to propose a theory of
evolution.
In the early 1800s, a wellknown French naturalist named
Jean-Baptiste Lamarck also
developed a theory of
evolution.
•He introduced the idea that the environment
caused changes in animals and these changes
were inherited by the animals' offspring.
•changes in an organism during its lifetime could
be passed on to its offspring.
•if an organism that used certain organs more
than others, then the organ used the most would
evolve.
• For example, Lamarck thought that
giraffes could stretch their necks to feed
on the leaves of tall trees. These giraffes
would have offspring with long necks.
• He called this the hypothesis of use and
disuse.
• This idea is often called "the inheritance of
acquired characteristics," or "soft
inheritance," and it is now known to be
incorrect.
• Changes in an organism cannot be
passed onto its offspring unless they are
controlled by genes.
Charles Darwin
H.M.S. Beagle
Darwin
• Darwin observed that species of
finches on islands off the coast of
South America looked similar to a
mainland species of finches
• He hypothesized that plants and
animals on the islands originally came
from South America
http://www.pbs.org/wgbh/nova/evolution/explore-galapagos.html
• Darwin reasoned that members of a
population best able to survive and
reproduce will pass their traits to the
next generation; over time
• Resulting in a different (separate)
species
• Darwin say similarities but could not
explain WHY they existed.
Darwin
• His hypothesis became known as a
theory of evolution by natural
selection- organisms with traits
suited for the environment will more
likely survive and reproduce
http://www.pbs.org/wgbh/nova/evolution/darwin-never-knew.html
http://videos.howstuffworks.com/science/evolution-of-life-videosplaylist.htm#video-29147
• Fossils- the preserved
remains of an organism that
had died long ago.
• Darwin saw the fossil bones
of organisms that had died
and was puzzled by some
of them, such as the fossil
bones that resembled living
sloths. These were much
larger than those that were
still living. He wandered
what had happened to the
giant creatures of the past.
Fossils
• Fossil records show extinct
organisms
• Showed similarities to living
organisms
• Hypothesized current organism
descended from the fossilized
organism
http://videos.howstuffworks.com/discovery-health/4911-100-greatest-discoveries-evolution-video.htm
Adaptations
• A trait that helps an organism survive and
reproduce.
– Ex finches beaks-help in obtaining food
– Coloring
Natural Selection
• Factors that affect the process:
– Overproduction
– Variation
– Competition
– Selection
– Environmental Change
– Genes and Natural Selection
Variation
• An inherited trait that makes an individual
different from other members of its species; an
adaptation is a variation that makes an
organism better suited to its environment.
• 1. Environmental factors can cause changes in
source of genes.
• 2. Geographic isolation can make two
populations so different they become different
species.
•
http://www.pbs.org/wnet/nature/lessons/the-birds-and-the-beaks/video-segments-extraordinarybirds/1481/
Variety
Speed of Evolution
• Two models that explain the speed of
evolution
– Gradualism
– Punctuated equilibrium
Speed of evolution
• Gradualism
– Slow, ongoing
process
– Change may
take place
through a slow
but continuous
process
• Punctuated
equilibrium
– Gene mutation
can result in a
new species in a
short period of
time