Transcript Evolution of Living Things

Evolution of
Living Things
Adaptation
• Characteristics
that helps an
organism
survive and
reproduce in its
environment
• When disturbed,
they inflate their
bodies. A
conspicuous spadelike tubercle on
each foot pushes
soil to either side as
the frog shuffles
backward into the
ground. They spend
much of the year
underground, but
come to the surface
after a heavy rain to
breed.
Squirrel monkeys move
through the trees by
leaping. They have
thighs that are shorter
relative to their lower
legs; this allows more
jumping force. They
distribute a musky
glandular secretion
throughout their fur
(especially on tail) as
scent to mark territory
or to leave a trail for
others of the troop to
follow as they go
through the trees. This
odor turns away
hunters who might
otherwise kill them for
food.
• Very agile. Furry pads on
feet are good for rock
climbing. Will actively dig
for water, sometimes up
to one meter deep;
however, they conserve
body water by hiding in
hollows under granite
boulders during hottest
part of day. Wallaroos are
the kangaroo best
adapted to heat and
dryness.
Heat sensors along the upper lip as well as its
keen sense of smell help it to find prey. As
with other snakes, the python's loosely hinged
jaws can be stretched far apart, enabling it to
swallow animals with bodies much larger in
diameter than the python's head. They are
good climbers and have prehensile tails.
To open the Abalone shell they place a small rock on their
chest and smash the shell against it. Sea otters are one of the
few mammals, beside humans, that use tools. They will use
strands of kelp to tie themselves into the kelp beds for a
secure night's sleep. Air trapped in their fur keeps them warm
and buoyant
Adaptations:
Cockroach
and
chameleon
• Group of
organisms
that can
mate with
on another
to produce
fertile
offspring
Species
Do Species change over
time?
• Evolution: process by which
populations accumulate
inherited changes over time.
•
Evolution
Could birds
have
evolved
from
dinosaurs?
Evidence of Evolution
• Fossil Record:
provide a historical
sequence of life
• Fossils are
solidified remains
or imprints of
once living
organisms
Vestigial Structures
• Remnants of once useful structures.
• Whales possess a femur and pelvis, but
these bones are no longer useful to the
mammals
Comparing Organisms
• Comparing skeletal
structures
• Comparing DNA
• Comparing embryonic
structures
• Comparing DNA:
• All organisms contain the same
limb bones- humerus, radius,
ulna, etc, but they evolved to
look different over time in
length.
• Homologous structures
are structures from
different organisms that
look similar because the
organisms descended
from common ancestors
(according to evolution).
Comparing Embryonic
Structures
• Scientists look at
embryos of
different
organisms and
find that many
embryos
resemble one
another.
Before Darwin
• French Scientist
Jean Baptiste de
Lamark ( 17741829)
• “inheritance of
acquired
characteristics”
• Passed acquired
traits to their
How does Evolution Happen?
Charles Darwin:
• 1831 he went on
voyage on the HMS
Beagle for five years.
• He observed
thousands of species
and collected many
different types of
fossils.
• Finches living on
Galapagos Islands differed
slightly from the finches in
Ecuador.
• Darwin concluded from his
years of research that
individuals having
advantageous variations
are more likely to survive
and reproduce than those
without the advantageous
variations… Evolution by
Natural Selection.
Natural Selection
•The process by which organisms
with favorable variations survive
and reproduce at a higher rate.
•Darwin learned from farmers and
animal and plant breeders
•Selective breeding: breed only
individuals that have desired traits.
• Darwin was aided in his research by the
book Principles of Geology, written by
Charles Lyell, where he learned the age
of Earth.
• Darwin also learned from Thomas
Malthus’ essay on the Principle of
Population, which helped him realize that
animal species often produced too many
offspring, and starvation, disease, and
predators affected their population.
• Then in 1858, Russell
Wallace (1823-1913) came
up with the same idea,
therefore, Darwin finished
his book The Origin of
Species in 1859.
Theory of Natural Selection
explains how a population
changes over many
generations in response to its
environment.
Formation of new species:
• Speciation: when two
populations can become so
different that they can no
longer interbreed.
1. Separation:
• Populations become isolated
from one another
2.Adaptation:
• When the environment changes
so may the population that lives
there.
3. Division
– Two populations over time may
become so different they can no
longer interbreed