Download Evolution* Change over Time

Evolution Change over Time
Natural Selection Process by which
inherited characteristics are passed
on more frequently and that enhance
the survival and reproduction of
future generations.
Alters the genetic make up of
populations through time
Charles Darwin
and Alfred Russel
Wallace
•Both independently
proposed the concept of
natural selection as a
mechanism for evolution
•Premises for Natural
Selection:
•Organisms face a
constant struggle to
survive and reproduce
•Organisms tend to
produce more offspring
than can survive
•Individuals of a species
vary in their
characteristics
Adaptation
• From one generation to
the next, traits that lead
to better survival and
reproductive success in
a given environment is
called adaptation.
• An adaptive trait is a
trait that promotes
success
• These could be
mutations, which are
accidental changes in
DNA, which gives rise to
genetic variation in a
species
• New traits can also
come from sexual
reproduction , with the
mixing of genes in the
offspring
Examples
• Peppered Moth
– Light colored moths lost
their camouflage with the
Industrial Revolution,
where the darker moths
stayed hidden
• Italian Wall Lizard
– When a section of this
species was cut of on a
isolated island, the lizard
changed to a more
vegetarian lifestyle when
there was not an
abundance of insects to
eat
• Darwin’s Finches
– Beak development
changed with the
availability of seeds and
their locations they were
found in
• Blue Moon Butterfly of
the Samoan Islands
– A parasite was affecting
the males in this species,
and eventually, a resistive
gene was found in a few
males and those survived
to a reproductive age
The Selection Process
• Natural Selection
– Selective pressures from
either the environment
or other populations
that affect the species
can lead to small or large
variations in
populations, leading to
small or large changes in
their evolutionary track
• Artificial Selection
– Species are bred based
on given traits that
people want to maintain
• Examples
– Dogs
– Crops
– Bacteria (insulin)
Biodiversity
• Variety of life across all
levels of biological
organizations
–
–
–
–
Communities
Populations
Species
Genes
• Over 1.8 million species
have been described, but
scientists estimate that
there are over 100 million
species all over the world
Speciation Process by which new species are
generated
• Allopatric Speciation
– New species are formed
from a physical separation
of populations over a given
distance
– Specimens from the same
species cannot mix with
other populations.
– This is long term and will
take many generations to
complete
– If or when the species
comes back together, they
can no longer breed with
each other
Speciation Continued
• Allopatric speciation
can occur in several
ways:
– Large glacial sheets
– Mountain Ranges may
rise
– Major Rivers change
course
– Warming or cooling
trends may move whole
populations
Speciation Continued
• Sympatric Speciation
– When a species becomes
reproductively isolated
within the same
geographic region
– Examples
• Some populations may
only breed at certain
times of the year
• Some populations may
only feed and mate on
certain species of plants