Download CH 22: DESCENT WITH MODIFICATION

CH 22: DESCENT WITH MODIFICATION-DARWIN
I.
Important concepts
A. evolution-the processes that have transformed life from its earliest forms to what forms occur
today
B. natural selection-states that a population of organisms can change over time when certain
individuals with certain inheritable traits leave more offspring than other individuals
C. evolutionary adaptations result from interaction between organism and its environment/are
inherited traits that increase organisms’ chance to survive/reproduce in that environment
II.
History
A. Theologists-believe that a divine being is the creator of all living things
B. Taxonomy-developed by Linnaeus for naming and classifying life
C. Fossils-impressions of past life in sedimentary rock that showed that older fossils were in
lowest stratum Opponents to evolution believe that a catastrophe killed all organisms in that
particular layer rather than evolutionary change of the species
D. Gradualism-geological change is cumulative but slow (what we see today is the result of years
and years)
E. Uniformitarianism-geological processes that have been occurring in the past are the same that
are occurring today
F. Lamark-scientist who believed organisms evolved because they willed it- they wanted to
improve Ex. Arnold Schwartzenegger’s big biceps will increase his survival and will be passed
onto his offspring or the giraffe stretched its neck and will pass its long neck to offspring
III. The Origin of Species
A. Descent with modification
1.
all organisms are related by some ancestral life that lived in the past and as time
passed and descendants of that life moved into different habitats, they acquired new
traits/adaptations to fit them to that environment
2.
Darwin used Linnaeus’ classification system and saw certain species more related to
each other than to others
B. Natural selection and adaptation
1.
the success in reproduction due to interaction between environment and that
variability within a population living that environment, and resulting in adaptation of
the organisms within that environment
2.
important points of natural selection
a.
populations evolve not individuals (population-group of interbreeding
individuals of the same species and share a common geographic area)
b.
natural selection works only on an inheritable trait
c.
natural selection works in sync with the environment-one adaptation may
work in one habitat and not in another
3.
Ex.Fig 22.6-finch beak length changed over time based on availability of seed sizesduring wet season, abundance of large and small seeds (they eat small seeds first),
during dry season, less abundance, more large seeds, bigger beaks
**Note that environment did not create beak size, all beak sizes were present, and the ones
that could open and eat the seeds outlived and had more offspring than those that couldn’t –
natural selection has no set direction
4. Darwin derived many of his ideas from artificial selection done by farmers or breeders of
animals and plants.
IV. Evidence of evolution
A. Biogeography- geographic distribution of species
1. closely related species tend to be found in the same geographical regions even if on
Different continents.
2. Some island species may look the same but are completely different organisms (endemic
Organisms are found only in certain areas and no where else- Australia and the marsupials,
Hawaiian fruit fly species, finches of Galapagos, Devils hole pupfish in NV)
B. Fossil record-record shows fossils of various age and presence of transitional fossils
C. Comparative anatomy
1.
homologous structure p449 fig22.14 – similarities in structure resulting from a
common ancestor
2.
vestigial organs or structures- organs/structures not used by organism so although
still present, is smaller and not used ex. tail bone in human
D. Comparative embryology
1. fig 22.15 pg 449 vertebrates embryos go through similar development
E. Molecular biology
1. looks at genes among organisms p450 fig 22.16 shows how the hemoglobin protein
differs among organisms
F. Recent signs of evolution
1. Wild guppy populations- their development and maturity correlate to the predators that eat
them. Certain predators prey on juvenile guppies so these guppies reached maturity faster. In
other pools, the predators ate the more mature guppies so these guppies matured slower.
2. Drug-resistant HIV-the drug 3TC interferes with the virus’ ability of reverse transcriptase
to pick up the proper nucleotides. It chooses 3TC instead and so will not be able to reproduce.
Now there are some strains of HIV that can recognize the 3TC and normal nucleotides so it will
choose the nucleotide and continue to divide.
*know the difference between “just a theory” and a “scientific theory”
Vocabulary
Artificial selection
Catastrophism
Endemic
Evolutionary adaptation
Gradualism
Homologous structures
Paleontology
Taxonomy
Vestigial organs
biogeography
descent with modification
Evolution
Fossils
homology
Natural Selection
Sedimentary rock
uniformitarianism