Transcript No Slide Title

More on microevolution
• Movie (Simpsons)
Evolution Evidence
• Fossil: Remnant or impression of organism that
lived in the past
• Mostly in sedimentary rocks
Grand Canyon
Evolution Evidence
• Fossil types:
– Organic: coal (reduced carbon: burns!).
Evolution Evidence
• Fossil types:
– Source energy
Coal seam
Evolution Evidence
• Fossil types:
– Thank “Lumpy Coal”.
Evolution Evidence
• Fossil types:
– Amber: fossil resin (conifer trees)
Evolution Evidence
• Fossil types:
– Jurassic Park! Mosquitoes in amber to get dinosaur
DNA
Evolution Evidence
• Fossil types:
– Mineralize hard parts: “petrification” replaces
organic molecules with rock
Evolution Evidence
– Ex, Petrified Forest National Park, Arizona.
Evolution Evidence
• Fossil types:
– Cast: Original structure dissolves but sediments
retain shape
Casts of
squid-like animal
called an ammonite
Evolution Evidence
• Fossil types:
– Casts: footprints!.
Dinosaur footprints from Montana
Evolution Evidence
• Principle of superposition: Old rocks lower,
young rocks higher.
Evolution Evidence
• Principle of superposition: Old rocks lower,
young rocks higher.
• “Relative dating”: age fossils relative to each
other.
Evolution Evidence
• Fossils show how life evolved
Cool
fossils
• Dinosaurs!
• Reptiles
dominated
Mesozoic Era.
Cool fossils
• Dinosaurs!
• Movie stars today!.
T. rex skull
Cool fossils
• What killed them off?
Asteroid impact.
Cool fossils
• Crater
image
(buried
under ocean
sediment)
• (Earth
owee!).
Evolution Evidence
• Radioactive dating: Decay radioactive isotopes
determines time since formation
Evolution Evidence
• Radioactive dating: Decay radioactive isotopes
determines time since formation
Start 1 isotope, which
gives off radioactivity and
becomes another isotope
(predictable rate)
Evolution Evidence
• Radioactive dating: Decay radioactive isotopes
determines time since formation
Rate measured by “halflife”: time for half original
material to decay.
Evolution Evidence
• Radiocarbon dating: Radioactive Carbon-14
– Half-life (5370 years): good 4 fossils < 60,000 yr
old
Shroud of Turin (1988)
1260-1390?
Evolution Evidence
• Potassium-Argon dating: Radioactive Potassium
forms Argon (volcanic rocks)
• Half-life 1.3 billion years: good 4 fossils
millions years old.
• Relative ages
converted to
absolute ages
(years)
– Humans only in
last 2 million
years.
Evolution Evidence
• “Vestigial structures”: Nonfunctional remnants
of useful structures.
Evolution Evidence
• Ex, some snakes: pelvis/leg bones
• Human coccyx (“tailbone”).
pelvic girdle
coccyx
(bones
where
many
other
mammals
have a
tail)
small bone
attached to
pelvic girdle
thighbone
attached to
pelvic girdle
Evolution Evidence
• Blind cave organisms. Vestigial (nonfunctional)
eyes.
Blind crayfish
Evolution Evidence
• Blind cave organisms. Vestigial (nonfunctional)
eyes.
Blind cave salamander
Blind cave fish
Evolution Evidence
• Comparative anatomy: Same structures, modified
to current use
• Ex, vertebrate forelimbs
Evolution Evidence
• Comparative embryology (embryology: study
of early stages of development): Embryos
related organisms go through similar stages
Evolution Evidence
• Comparative embryology (embryology: study
of early stages of development): Embryos
related organisms go through similar stages
fish
reptile
bird (chicken)
mammal (human)
Evolution Evidence
• Molecular biology: compare DNA (nucleotide
sequence) or proteins (amino acid sequence)
Evolution Evidence
• Molecular biology: compare DNA (nucleotide
sequence) or proteins (amino acid sequence)
• Similarity reflects relatedness.
Evolution Evidence
• Ex use: What is a quagga?
• Native South Africa
• Extinct by 1880s (hunting)
One of 23 skins
in museums
Quagga stallion
(drawing)
Only quagga photographed
alive (in London Zoo, 1870)
Evolution Evidence
• Horse or zebra?
Plains zebras
from South
Africa
Przewalski’s horse
from Mongolia
Evolution Evidence
• DNA from museum
skin: quagga type of
zebra
Evolution Evidence
• Experimental evidence
– Natural selection: peppered moths (England)
– Dark and light forms (1 gene)
Dark moth
Light moth
Evolution Evidence
• Experimental evidence
– Final twist: Pollution controls changing balance
again!.
Evolution Evidence
• Experimental evidence
– Natural selection: Galapagos Islands
Evolution Evidence
• Experimental
evidence
– Natural selection:
Galapagos islands
– Finch species eats
seeds.
Galapagos Islands :
telephoto view from the
space shuttle!
Evolution Evidence
• Experimental
evidence
– Bill size
changes:
food supply
changes
with
climate.
Evolution Evidence
• Experimental evidence
– Guppy experiment: guppies
native to Trinidad
Evolution Evidence
• Experimental evidence
– Guppy experiment
– Involves sexual selection: males colorful. Attractive
to females but helps predators find males!
Evolution Evidence
• Experimental evidence
– Experiment: Move guppies to low predator site.
Male tails became larger/more colorful
Evolution Evidence
• Artificial selection: Humans cause evolution by
our activities
– Intentional: Control breeding to change traits
Evolution Evidence
• Intentional: Control breeding to
change traits
• Ex: dog breeds.
Evolution Evidence
• Natural selection also caused evolution of
dog-like species
Evolution Evidence
• Intentional artificial selection
– Ex, wild mustard now cabbage, broccoli, kohlrabi,
brussel sprouts, cabbage, cauliflower, etc.
Wild
mustard
Foods you should eat more of!
Evolution Evidence
• Artificial selection: Humans cause evolution by
our activities
– Unintentional: Usually species we try to kill!
– “Antibiotic resistance”: bacteria evolve to be
unaffected by antibiotics
Evolution Evidence
• Ex, bacterium causes tuberculosis (TB)
– Some strains now resistant to most
antibiotics.
Chest x-ray of TB patient
TB bacteria
Evolution Evidence
• Antibiotic resistance solutions:
– Use antibiotics only when needed
– Develop new antibiotics!
Evolution Evidence
• Unintentional
artificial selection:
• Insecticide
resistance
Evolution Evidence
• Solutions:
• Look for new chemicals
• Use “biocontrol”: natural enemies fight pest
species.
Biocontrol
• Biocontrol ex:
Cassava mealybug
control
• Cassava important
crop in Africa.
Biocontrol
• Cassava attacked by
pest (mealybug)
• Caused large losses.
Biocontrol
• Parasite wasp found
(attacks mealybug)
• Now mealybug
under control.
Final Point
• Humans: our gene pool is changing (we are
evolving)
Final Point
• Human evolution
• Ex: medical advances allow us to keep people
with genetic disorders alive
• But pass defective genes to offspring…….