Download Applied Bio Ch. 14.2 Evidence ppt notes

Evidence for
Evolution
Concept 14.2 pp 299-304
Fossil Record
• Fossils- preserved remains of
organisms from the past- extinct.
• Most- sedimentary rocks• Chronological collection of fossil
remains
• Each rock layer represents a
particular time period.
• Older fossils are found at the
bottom.
• Prokaryotes- oldest form of lifefound in rocks believed to be 3.5
billion yrs old.
Sedimentary Rock Layers
Terms
• An extinct species- a species
that no longer exists.
• Paleontologist- a scientist that
studies fossils.
• Studying fossils of ancestral
life- links past and present.
Geographical
distribution
• Patterns of geographical distribution
make sense in terms of evolution
• Geographic distribution is a clue to
how species may have evolved.
• Explains why we see related species
today in a particular area.
• Ex.- Australia- many pouched
mammals (marsupials) and few
placental animals.
Hypothesis_____.
Homologous structures.
• Definition- the presence of similar
structures in different species that
share a common ancestor.
• Examples- forelimbs of mammals
have the same skeletal parts even
though the function is completely
different.
• Human arm, cat forelge, whale flipper,
bat wing
• These structures have become adapted.
The forelimbs of all mammals consist of the same skeletal
parts. The hypothesis that all mammals descended from a
common ancestor predicts that their forelimbs would be
variations of the structural form in that ancestor
•
Vestigial Structures
• Definition- a remnant of a homologous
structure that once had an important
function in the ancestral species but
no longer has a function in modern
related species.
• Often vestigial structures are reduced
in size.
• Example – whale hipbones
• Hypothesis- whales descended from land
organisms that had 4 limbs.
• Natural selection favors survival of
individuals with genes for reduced
versions of these structures.
Comparison of Embryonic
Development
• Closely related organisms have
similar stages of development.
• All vertebrates evolved from a
common ancestor.
• Example- pouches on side of throat
• Fish-gills
• Birds and primates-bones of skull
Molecular Biology
• DNA sequences
• A common genetic code shared by all
species.
• Unrelated species show more
differences in DNA sequence.
• If 2 species have genes and protein
sequences that match closely then
they have a more recent common
ancestor.
• If 2 species have more differences in
DNA and protein sequences then no
close common ancestor.
Hemoglobin amino acid sequences-
Concept Check 14.2
• 1. Why are older fossils generally in deeper
rock layers than younger fossils?
• 2. How can evolutionary theory explain
why Australia is home to relatively few
native placental mammals?
•
3. What are homologous structures?
• 4. What can you infer about species that
differ significantly in their DNA sequences?
Reviewing Concepts
Multiple Choice
Choose the letter of the best answer.
• 1. Which of the following is an incorrect match?
• a. Lyell—suggested physical changes to Earth result
from geologic processes occurring over long periods of
time.
b. Lamarck—proposed that organisms adapt to their
environment.
c. Darwin—developed the theory of natural selection
as a mechanism of change in species.
d. Malthus—thought that characteristics acquired
during an organism's lifetime can be passed on to the
next generation.
• 2. Which of the following provides clues about the size
and structure of once-living organisms?
• a.
b.
c.
d.
fossils
DNA and proteins from the organisms
vestigial structures
development of embryos
• 3. What statement is not an observation or
inference on which Darwin's theory of natural
selection is based?
• a. Variations among individuals exist in a
population.
b. Poorly adapted individuals never produce
offspring.
c. Individuals whose inherited characteristics give
them advantages in their environment will generally
produce more offspring.
d. Species living today descended with modification
from earlier species.
• 4. Artificial selection is similar to natural selection
in that both processes
• a.
b.
c.
d.
were suggested by Darwin.
adapt species to their environments.
occur over many millions of years.
depend on variation among individuals.