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 animalcalled 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 “half-life”: 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 (boneswhere manyother mammalshave a tail)

small boneattached topelvic girdle

thighboneattached topelvic 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

Only quagga photographedalive (in London Zoo, 1870)

Quagga stallion(drawing)

Evolution Evidence• Horse or zebra?

Plains zebrasfrom 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.

Wildmustard

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.

• Cassava attacked by pest (mealybug)

• Caused large losses.

Biocontrol

• Parasite wasp found (attacks mealybug)

• Now mealybug under control.

Biocontrol

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…….