Transcript Species Variation

Species Variation
Obj.6 Describe evidence of species
variation due to climate, changing
landforms, interspecies interaction, and
genetic mutation.
•
•
Adaptation- a characteristic that
improves an individual’s ability to
survive and reproduce in a particular
environment.
Adaptations may be physical (change
in appearance), such as a long neck
or striped fur. Adaptations may be
behaviors that help an organism find
food, protect itself, or reproduce.
•
•
•
•
Scientists think that Earth has changed over
time. Scientists estimate that Earth is 4.6
billion years old.
Scientists think that as populations have
changed over time(adaptations), new
species form other species die out (go
extinct).
Newer species descend from older species.
Evolution- process in which populations
gradually change over time.
•
•
•
Evidence that organisms evolve can be
found by comparing living organisms to
each other and to the fossil record.
The process of evolution is indicated by
fossil records and common ancestry.
It was proposed that evolution happens
through a process called natural selection.
•
•
•
•
•
Natural selection- the process by which individuals that are
better adapted to their environment survive and reproduce
more successfully than less well adapted individuals do;
The four parts of natural selection are:
1. Overpopulation ( some eggs survival –other do not)
2. Inherited Variation (Every individual has its own
combination of traits)
3. Struggle to Survive (some die because of predators,
starvation, and disease)
4. Successful Reproduction (those best adapted to the
environment have many offspring that survive)
•
•
Speciation- formation of new species as a result of evolution
The three steps of speciation are:
1. Isolation (division) (part of a population becomes separated
from the rest)
2. Adaptation (the separated group may evolve different sets of
traits )
3. Division (two separated groups may become very different;
groups may not be able to interbreed anymore)
•
•
Extinct-describes a species that has died out
completely.
Most scientists think that the extinction of dinosaurs
happened because of extreme changes in the
climate of the Earth. These changes could have
resulted from a giant meteorite hitting the Earth or
forces within the Earth could have caused many
volcanoes and earthquakes.
•
Genetic Resistance-When an
organism changes or adapts to factors
such as the environment, antibiotics,
insecticides, and pollution to survive.
•
•
•
•
Isolation- refers to species being separated.
Isolated populations can be unable to interact with each other
because of geographic boundaries like an ocean or mountain.
They can develop unique characteristics and cannot breed.
Two populations can be isolated if they feed at different times
or reproduce at different times of the year.
Two or more populations may evolve differently from each
other.
•
Isolation stops populations from
interbreeding so new species evolve.
•
Survival of the Fittest-When an
organisms survives through
adaptations such as biologically,
physically, philologically, to enhance
survival and reproduction rates.
Relationships with other
organisms
•
Symbiotic relationships:
– Mutualism: both organisms benefit
– Parasitism: one is helped (the parasite)
and the other is harmed (the host).
– Commensalism: one benefits and the
other is not helped nor harmed.
•
If organisms prey on each other the
prey population has to outnumber the
predator population in order for them
to survive.
How do organisms impact
tour environment?
•
By studying an organisms behaviors
and impacts in their environment, we
can better manage our planet.
•
Organisms can modify the
environment positively and negatively.
•
•
Humans can negatively modify the
environment by building new roads,
buildings, cutting off rivers, polluting
the environment.
These things can change wildlife’s
way of living and can often lead to
extinction.
•
Bacteria and fungi can positively
modify the environment by breaking
down dead and decaying materials,
but they can negatively affect
organisms by causing infections and
sickness.
•
•
Plants give us food and oxygen but
they can overtake certain areas and
become invasive species.
An invasive species is a non-native
plant that invade and outgrow the local
plants.