Download Species Variation Over Time

Species Variation Over Time
QUESTION?????
HOW HAVE TELEPHONES CHANGED OVER
TIME?
What is Evolution?
• Evolution in biology, refers to the
process through which species change
over time.
• The change results from a change in
genetic material of an organism and is
passed on from one generation to the
next.
Jean Baptiste de Lamarck
• Lamarck was the 1st scientist to
propose a model of how life evolves.
• Through the use of fossils, he became
convinced that an organism can
acquire a new trait during its lifetime and pass
it on to its offspring.
• Ex: Giraffes long necks
Lamarck’s Giraffes
Charles Darwin
• Lamarck was unable to come up
with evidence to support his idea.
• Charles Darwin spent 5 years
traveling across the coast of
South America, studying
rock formations and fossils.
Darwin’s Travels
Charles Darwin
Darwin visited the Galapagos Islands, a chain of
volcanic islands 600 miles off the coast of South
America.
He found that plants and animals on the islands
differed from those on the mainland as well as those on
other islands.
Darwin’s Tortoises
He noticed tortoises with short necks lived in
damp areas with abundant plants while those
with long necks lived in dryer areas with cacti.
Darwin’s Finches
Darwin’s Finches
• Darwin is most noted for his observations of a
bird called a finch.
• Darwin noticed that among the different
islands, there was a variety of beak shapes
and sizes.
Darwin’s Finches
• Some finches had heavy short beaks for
pecking trees or seeds, while others had small
think beaks for capturing insects.
Natural Selection
• Darwin proposed a process called “natural
selection”.
• Natural selection states that members of a
species that are best suited to their
environment survive and reproduce at a
higher rate than other members of the
species.
Species Variation
• There are four things that mainly contribute to
variation among species.
• 1. Genetics
• 2. Geographic isolation
• 3. Interspecies Interactions
• 4. Climate
Species Variation
• The more variation you have in a species, the
better the survival rate.
• ????????????????????????????????????????
• WHY DO YOU THINK MORE VARIATION
PROMOTES BETTER SURVIVAL RATE IN A
PARTICULAR SPECIES?
SPECIES VARIATION
Variation comes from the gene pool.
In order for new traits to develop, you must
have time! It takes 100’s of years for new traits
to evolve, they don’t occur automatically.
• New traits develop in a species because a
different set of characteristics becomes more
of an advantage in a particular climate setting.
• Sometimes genetic material changes and this
causes a new variation in a species.
• A change in genetic material is called a
“mutation”
• Genetic variations are passed on to future
generations.
Mutations can be:
1. Harmful: Ex- a color change may prevent an
animal from being camouflaged.
2. Neutral: Eye color, fur length, ear size (these
don’t affect survival)
3. Helpful: being small or large, faster runners,
color that blends in with surrounds, claws for
burroughing
• Sometimes a mutation occurs that makes an
individual better able to survive than other
members of the group. This is called an
adaptation.
• EXAMPLE: a slight change in the shape of a
tail fin may increase a fish’s chance of
survival by helping it swim faster.
Geographic Isolation
• The term “geographic isolation” means
separated by land forms or water.
How Can Species Become Isolated?
1. Natural disasters: flooding, volcanic
eruptions, fire
2. Human influence: building strip malls might
prevent animals from migrating
3. Continental drift
4. island
5. Movement from one area to another
How can species become isolated?
4.
5.
6.
7.
Movement from one area to another
Island
Under water
Mountains create a
barrier
Species isolation
• The changes that occur in an isolated
population may be referred to as “separation”.
• If species become isolated from other group
members, new traits may evolve that help the
species survive in its particular location.
• Species interaction occurs within different
species.
1. Predator – Prey (hawk and mouse_
2. Parasitism: One species helped, the other is
harmed (tapeworm and human)
3. Mutualism: Both Benefit (termite and
protozan)
4. Commensalism: One helped the other
harmed (barnacle on whale)
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Changes don’t occur
because they are
wanted or needed,
but because
they become more
advantageous for
survival.
Climate change leads to a loss of
species
• Our planet is warming faster than at any time in
the past 10,000 years. With these changes,
species have to adapt to new climate patterns
(variations in rainfall; longer, warmer summers
etc).
• Global warming resulting from human emissions
of greenhouse gases. The consequences include
habitat loss; shifts in climatic conditions and in
habitats that surpass migrational capabilities;
altered competitive relationships.
Changes already underway
• Evidence suggests that the warming of the
past century already has resulted in marked
ecological changes, including changes in
growing seasons, species ranges, and patterns
of seasonal breeding.
• Global warming has the potential to cause
extinctions in a majority of the world's
especially valuable ecosystems.
Growing need for adaptations
• The fate of many species in a rapidly warming world
will likely depend on their ability to migrate away from
increasingly\ less favorable climatic conditions to new
areas that meet their physical, biological, and climatic
needs.
• Depending on a species responses to the
warming, especially their ability to migrate to
new sites, habitat change in many ecoregions
has the potential to result in catastrophic
species loss.
• Global warming is likely to have a winnowing
effect on ecosystems, filtering out species that
are not highly mobile and favouring a less
diverse, more "weedy" vegetation and
ecosystems that are dominated by pioneer
species, invasive species.
• Scientists have estimated that most species on
this planet (including plants) will have to "move"
faster than 1,000 metres per year if they are to
keep within the climate zone which they need for
survival.
• Many species will not be able to redistribute
themselves fast enough to keep up with the
coming changes.
• These species, as far as we know given present
knowledge, may well become extinct.