Download Evolution and Diversity: Sometimes, differences between organisms

Evolution and Diversity: Sometimes, differences between organisms of the same
kind provide advantages for surviving and reproducing in different environments.
These selective differences may lead to dramatic changes in characteristics of
organisms in a population over extremely long periods of time.
KEY IDEA: The diversity and changing of life forms over many generations is the
result of natural selection, in which organisms with advantageous traits survive,
reproduce, and pass those traits to offspring.
I.
New traits may result from new combinations of existing genes or from
mutations of genes in reproductive cells within a population.
a. 4 principles of natural selection:
b. In order for natural selection to occur, some organisms must have
traits that are more advantageous than others.
c. Variation may result from:
i. Genetic recombination during meiosis
1) Way homologous chromosomes line up (independent
assortment)
2) Crossing over
ii. Contributions of each parent to offspring during sexual
reproduction
iii. Mutations
d. Differential reproductive success
e. POPULATIONS, not individuals, evolve
i. Gene pools
ii. Change in genetic make-up of a population changes over time
f.
Natural selection:
i. Peppered moths & Industrial Revolution
ii. Other examples
iii. Adaptations
g. Evolution is NEVER based on NEED
i. Individuals that do not possess favorable traits may die off
ii. Populations/Species may go extinct
II.
Molecular evidence (e.g. DNA, protein structures, etc.) substantiates the
anatomical evidence for evolution and provides additional detail about the
sequence in which various lines of descent branched.
a. Various types of evidence support evolution (think “What did T. rex
taste like?”
i. Fossil record
ii. Anatomy
1) Homologous structures
2) Vestigial structures
iii. Geographic patterns
1) Uniqueness of Australia
iv. Molecular Evidence
1) Common bases in DNA
2) Common gene sequences in related organisms
3) Similarities in amino acid sequences of proteins
b. Technology can be used to determine evolutionary relationships among
species
i. Gel electrophoresis/DNA Fingerprinting
ii. DNA sequencing
iii. Protein sequencing
III.
The principles of evolution (including natural selection and common
descent) provide a scientific explanation for the history of life on Earth
as evidenced in the fossil record and in the similarities that exist within
the diversity of existing organisms.
a.
Changes in species do not follow set pattern or timeline
i. Gradualism vs. Punctuated equilibrium
ii. Adaptive radiation
b. All species on Earth today descended from common ancestor
i. Life 1st appears in fossil record 3.5 bya
ii. Fossil record provides evidence for ancient life forms
1) Fossil record incomplete
iii. Prokaryotes  eukaryotes (endosymbiosis)
iv. Unicellular  Colonial  Multicelluar organisms
c. Phylogentic Trees/Cladograms
IV.
Evolution occurs as a result of the following factors: (1) ability of a
species to reproduce; (2) genetic variability of offspring due to mutation
and recombination of genes; (3) finite supply of resources required for
life; (4) natural selection, due to environmental pressure, of those
organisms better able to survive and leave offspring
a. Evolutionary process is influenced by:
i. Environmental pressures
ii. Genetic drift/chance events
iii. Mutation
iv. Competition for resources
b. Implications of environmental changes:
i. Volcanic eruptions
ii. Global climate change
iii. Pollution