Transcript Chapter 1 Notes

Chapter 22 Notes
Descent with
Modification: A Darwinian
View of Life
Concept 22.1
Darwin made two points in The Origin of
Species.
- the species on the earth today
descended from ancestral species
- the mechanism for evolution is
natural selection
Concept 22.1
Natural Selection: populations can change
over time if individuals with certain
traits have more offspring than other
individuals
The result of natural selection is
evolution
- the genetic composition of a
population changes over time.
Concept 22.1
Western culture resisted evolutionary
views of life
In the 1700’s, biology in Europe and
America was dominated by natural
theology
- dedicated to discovering the Creator’s
plan for studying nature
Concept 22.1
Carolus Linnaeus sought to discover order
in the diversity of life.
- specialized in taxonomy: branch of
biology that focuses on naming and
classifying the diverse forms of life
- his system of taxonomy became a
focal point in Darwin’s arguments for
evolution
Concept 22.1
The study of fossils also helped lay the
groundwork for Darwin’s ideas.
Fossils: impressions from the past found
in sedimentary rocks formed from the
sand and rocks of seas and lakes
Concept 22.1
Concept 22.1
Concept 22.1
Gradualism helped paved the way for
evolution
James Hutton: explained geologic
features through gradualism
- change is the cumulative product of a
slow but continuous process
Concept 22.1
Charles Lyell: incorporated gradualism
into uniformitarianism
- geologic change occurs at a constant
rate
Concept 22.1
Lamarck placed fossils in an evolutionary
context
Jean Baptiste Lamarck: published his theory of
evolution in 1809
Remembered for his mechanism of evolution
- first idea was use and disuse
- second was inheritance of acquired
characteristics
Concept 22.2
Darwin study of evolution first began as a
naturalist on the HMS Beagle
- travel around the world observing and
documenting the types of plants and
animals at the various locations
- he did not understand the scope of
the findings until after returning to
England
Concept 22.2
Concept 22.2
Darwin chose not to publish his findings
until prompted by Alfred Walace in
1858
The next year Darwin published The
Origin of Species
Concept 22.2
The Origin of Species developed two main
points
Descent with Modification:
- as populations spilled into new
environments, modifications become
prominent over time
- helped fit organisms into ways of life
Concept 22.2
Natural Selection:
- nature chose what features are
beneficial and give an increased chance
of survival
The history of life is like a tree.
- each fork of the tree is an ancestor
who is common to others from that fork
Concept 22.2
Concept 22.2
Summary of Darwin’s main ideas
-Natural selection is differential success in
reproduction
-Occurs through an interaction between
the environment and the variability
inherent among the individual
organisms making up a population
Concept 22.2
The product of N.S. is the adaptation of
populations to their environment.
Connection between N.S., the struggle for
existence, and the capacity of
organisms to “overreproduce.”
- Thomas Malthus (1798)
Concept 22.2
Artificial selection: the breeding of
domesticated plants and animals
N.S occurs between individuals and the
environment, but only populations (not
individuals) evolve.
N.S. can amplify or diminish only
heritable variations (not acquired
characteristics)
Concept 22.3
Evidence of N.S. provides evidence for
evolution
Insecticide-Resistant Insects
- natural selection causes the evolution
of resistance to insecticides
- only a few insects are resistant to
the first wave insecticide
Concept 22.3
- those reproduce and pass on the
gene to the second generation
- eventually the whole population
will be resistant
- Drug-resistant HIV
Concept 22.3
Concept 22.3
Homology: similarity of characteristics
resulting from common ancestry
Anatomical Homologies
- the forelimbs of mammals have the
same skeletal structures (homologous
structures)
Concept 22.3
- vestigial structures: structures of
marginal, if any, importance to the
organism
-ex. pelvis and leg bones of snakes
Embryological Homologies
- all vertebrate embryos have
pharyngeal pouches some time in their
development.
Concept 22.3
Concept 22.3
Molecular Homologies: all species of life
use the same machinery of DNA and
RNA
- the more similar the animals, the
more similar the genetic material
Concept 22.3
Concept 22.3
Biogeography: the geographic
distribution of species
- first suggested evolution to Darwin
- species tend to be more closely
related to others from the same area
than to others with the same way of
life, but from other areas
- ex. sugar glider (of Australia)
Concept 22.3
Concept 22.3
Islands often have a large amount of
biodiversity
They have many endemic species found
nowhere else in the world
Small changes can be seen in an island
chain or archipelago
Concept 22.3
Concept 22.3
The Fossil Record
The succession of fossil forms is
compatible with other types of evidence
for evolution
- ex. prokaryote fossils are older than
eukaryote fossils
- ex. fish fossils, amphibians, reptiles,
mammals and birds
Concept 22.3
Many fossils link older fossils with modern
species.
- ex. change in skull shape and size