Transcript Section 15.2 Summary– pages 404-413

Jean-Baptiste Lamarck – “Inheritance of
Acquired Characteristics”
• Thought that organisms could
change during their lifetime and
pass those changes onto their
offspring.
.
•. His theory does not work, but it
involved the environment
• Ex. The long neck in a giraffe
Charles Darwin (Father of Modern Evolution)
1. Darwin on the HMS Beagle
•
1831, the 22-year-old Darwin gets a job as a naturalist on a
British ship to tour the world for 5 years.
•
His job is to study, collect, observe, and record nature.
2. Galapagos Islands
•
Found off the west coast of South America
•
Darwin’s most interesting finds are here.
13 different species of finches (birds), all with different beaks.
•Tortoises with very long necks.
•
How Natural Selection works:
a) All organisms produce more offspring than
survive.
b) All organisms exhibit variation.
c) Environment selects those individuals best
suited for survival.
d) Variations favored by selection are inherited and
passed on to the next generation.
e) Over long periods of time, successful variations
produce differences that result in new organisms.
Natural
Selection
“Survival of the
Fittest”
Adaptations
• Mimicry – Structural adaptations
that allow one species to look like
another.
• Camouflage – Adaptation that
allows species to blend in with it’s
surroundings.
Walking stick camouflage
Anatomy
Homologous Structures – Structure features with a
common evolutionary origin.
• Ex. Forelimbs of a whale, croc, and bird.
Many similarities.
•Analogous Structures – No
evolutionary origin, but share the
same function.
•Bird wing and insect wing
• For example, insect and bird wings probably
evolved separately when their different
ancestors adapted independently to similar
ways of life.
• Another type of body feature that suggests an
evolutionary relationship is a vestigial
structure—a body structure in a present-day
organism that no longer serves its original
purpose, but was probably useful to an
ancestor.
Vestigial Organs –
Functionless parts of an
organism.
Eyes in a cave dwelling
salamander.
What in humans?
• Many organisms have vestigial structures.
• Vestigial structures,
such as pelvic bones
in the baleen whale,
are evidence of
evolution because
they show structural
change over time.
• Recall that an adaptation is any variation
that aids an organism’s chances of survival
in its environment.
Physiological adaptations can develop rapidly
Non-resistant
bacterium
Antibiotic
Resistant
bacterium
The bacteria
in a
population
vary in their
ability to resist
antibiotics.
When the
population is
exposed to an
antibiotic, only
the resistant
bacteria survive.
The resistant
bacteria live
and produce
more resistant
bacteria.
Breeding organisms with specific traits in order
to produce offspring with identical traits is
called _______.
A.
B.
C.
D.
natural selection
adaptation
mutation
artificial selection
What is the difference between artificial
selection and natural selection?
How does mimicry differ from camouflage?
• In nature, physical barriers can break large
populations into smaller ones.
• Geographic isolation occurs whenever a
physical barrier divides a population.
• A new species can evolve when a population
has been geographically isolated.
• When geographic
isolation divides a
population of tree frogs, the
individuals no longer mate
across populations.
• The formation of a river
may divide the frogs
into
two
populations.
The Evolution of Species
• Over time, the divided
populations may become two
species that may no longer
interbreed, even if reunited.
Diversity in new environments
• When an ancestral species evolves
into an array of species to fit a number of
diverse habitats, the result is called
adaptive radiation.
Loxodonta
africana
Elephas
maximus
0
1
2
Elephas
3
4
Mammuthus
primigenius
Loxodonta
Mammuthus
5
Primelephas
6
Ancestral species
about 55 million years ago
Extinct
mamo
Amakihi
Crested
honeycreeper
Kauai
Niihau
Possible
Ancestral
Lasan finch
Molokai
Oahu
Maui
Lanai
Akialoa
Kahoolawe
Akepa
Akiapolaau
Akikiki
Liwi
Hawaii
Apapane
Maui
parrotbill
Palila
Ou
Grosbeak
finch
Why are the Galapagos Islands rich in unique
species of organisms?
.
Geographic isolation has helped to keep the
islands’ species unique.
Convergent Evolution
Organisms that evolve similar
adaptations because they occupy similar
niches or habitats yet are not related.
They may look similar because they do
the same thing, such as dining on ants,
hunting in high grasses or swimming in
the dark.
Convergent Evolution
Dolphins and sharks are
unrelated organisms that
have evolved similar traits
because they share similar
environmental pressures.
Would these be
considered analagous
or homologous
structures?
Why do some insects and bacteria evolve
adaptations more rapidly than other species?
Insects and bacteria are examples of species that
reproduce in large numbers and many times in a
relatively short span of time, allowing
adaptations to be more easily observed.
\
Are the fangs of a rattlesnake and the fangs of
a spider homologous structures or analogous
structures, and why?
\
The fangs of these organisms are analogous
structures. They share the same function in each
organism, to deliver venom, but the organisms
do not share a common evolutionary origin.
Why is the presence of pelvic bones in the
baleen whale considered to be evidence of
evolution?
Pelvic bones are evidence that whales once
possessed hind limbs. Since whales now
have no hind limbs, their loss must be the
result of an evolutionary change.