Download 1.A.4 Evidence of Evolution

1.A.4 Evidence of Evolution
Biological evolution is supported by
scientific evidence from many
disciplines, including mathematics.
Warm-Up
1. Compare and contrast natural selection vs. artificial
selection.
2. What are the key ideas of natural selection?
Warm-Up
2. Define and give an example for the following:
• Homologous structure
• Vestigial structure
• Analogous structure
Scientific evidence of biological evolution
uses information from geographical,
geological, physical, chemical and
mathematical applications.
Molecular, morphological and genetic
information of existing and extinct organisms
add to our understanding of evolution.
Fossils show change over time.
How rocks and
fossils are dated
Relative dating: dating a fossil relative to other fossils,
without knowing its actual age.
• Strata at one
location
correlated to
strata at another
location
Dating fossils using the relationships within
phylogenetic trees
Absolute dating: Determining a Fossil’s Age
in Years
• Radiometric Dating
• Mathematical
Calculations
Radiometric dating – dating using
decay of radioactive isotopes
• Radioisotopes
have a half-life:
the number of
years it takes for
50% of the
original sample to
decay.
• Incredibly reliable
method for
dating; only 1%
error rate!
How Radiometric Dating Works:
Carbon-14 is a very important radioisotope
• An organism accumulates some carbon-14 in its body when it is alive
• When the organism dies, the carbon-14 will start decaying to become
nitrogen-14
C-14 is used to date fossils up to 75,000 years old
• For older fossils, radioisotopes
with longer half-lives are
necessary
• Can also date the rocks that
fossils are found in
Mathematical calculations can take into
account information from chemical
properties and/or geographical data.
Graph of Uptake of Trace Elements
by Diffusion of a Fossil
Magnetic reversals can be used to date
rocks when other methods fail.
― Occur when the earth’s north and south magnetic
poles reverse.
Morphological homologies represent
features shared by common ancestry.
Homologous Structures: arisen from
common ancestor.
• Same structure, but different function
Analogous Structures: no recent common
ancestor; due to convergent evolution.
• Same function, but different structure
What do all of these organisms have in common?
Vestigial structures are remnants of
functional structures, which can be
compared to fossils and provide evidence
for evolution.
Vestigial Structures in Humans:
• Tailbone
• Wisdom teeth
• Vomeronasal organ (secondary sense of smell
found in some animals)
• Ear-orienting muscles
• Goosebumps
Biochemical and genetic similarities, in
particular DNA nucleotide and protein
sequences, provide evidence for evolution
and ancestry.
Example: Analysis of sequence data
sets
The universal
genetic code:
implies that all
life on earth
ultimately
descends from
a common
ancestor.
Mathematical models and simulations can also
be used to illustrate and support evolutionary
concepts: ex) Hardy-Weinberg Equilibrium.
Example: Graphical analyses of allele
frequencies in a population
Biogeography: geographic distribution of
species
• Closely related species are usually found in the
same geographic region
Comparative embryology: embryos of
vertebrates share many anatomical
homologies