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Transcript of Evolution 3
Evolution Evolution is "so overwhelmingly established that it has become irrational to call it a theory."
-- Ernst Mayr (1904-2005) Fossil
Layers of sedimentary rock contain fossils.
New layers cover older ones, creating a record over time.
Fossils can be dated using radioactive decay
The fossil record show that a succession of organisms have populated Earth throughout a long period of time.
Support (proof?) for a VERY old Earth. Homologous structures:
Similarities in characteristics resulting from common ancestry
Similar structure, similar development, different functions
Evidence of close evolutionary relationship (recent common ancestor) Comparing DNA & protein structure.
Life uses a universal genetic code!
All organisms use DNA as their genetic material.
The code used by ALL ribosomes is universal. A bacterium can make a human protein if given the proper recipe. Artificial selection (aka "selective breeding") can use variations in populations to create vastly different “breeds” & “varieties”.
This has been used by humans for livestock and crop production since before recorded history Biogeography Observed
Evolution Insecticide & drug resistance:
Insecticide doesn’t kill all individuals.
Resistant survivors reproduce.
Resistance is inherited.
Insecticide becomes less & less effective Vestigial organs:
Structures that serve little or no function.
Remnants of structures that were functional in ancestral species
Deleterious mutations accumulate in genes for non-critical structures without reducing fitness Analogous structures:
Similarities in adaptations resulting from similar evolutionary pressures.
Different structures, different development, similar functions
Evidence of Convergent evolution Comparative embryology:
Similar embryological development in closely related species.
All vertebrate embryos have similar structures at different stages of development Building “family” trees:
Closely related species (branches) share same line of descent until their divergence from a common ancestor. As this happens, genetic differences accumulate.
Fewer differences in DNA/protein sequences = more recently diverged. Genome sequencing:
What can whole genome sequence data tell us about evolution of humans?
Primate Common Ancestry? The original evidence that informed Darwin & Wallace.
Organisms found in a particular area tend to be more closely related to eachother than they are to organisms found in other areas. Peppered Moths:
Dark vs. light variants
What was the selection factor?
Early 1800s = pre-industrial England
lichen growing on trees = light colored bark
Late 1800s = industrial England
factories = soot coated trees
killed lichen = dark colored bark
Mid 1900s = pollution controls
clean air laws
return of lichen = light colored bar Big Questions Make Sure You Can How Science
Works The major ways science differs from other modes of thought:
Evidence- All ideas are not created scientifically equal. Evidence is required. Spectacular claims require spectacular evidence
Falsifiability- Scientific thoughts can NEVER BE PROVEN (only supported). Scientific thoughts can be disproven easily (happens all the time) Hypotheses vs. Theories vs. Laws:
Hypothesis: A Testable statement about the universe.
Theory: A major unifying framework, supported by all evidence currently known.
Law: A deduced fact that will always hold true if given certain conditions (not typically used in Biology).
Tiktaalik: a transition fossil between fish and amphibians Archaeopteryx: Dinosaurs to Birds "Lucy": an Australopithecus Transitional Fossils:
Show evolutionary links between groups of organisms A fossilized flower from the Eocene (~50mya) Analysis of fossilized ankle bones places cetaceans (whales, dolphins, porpoises) in a lineage with other even-toed ungulates A Geological History of the Earth 1996 1956 Homology in the tetrapod limb plan Homology in insect head anatomy Homology in Great Ape Skeletons: People used to think whales were fish!
The Fools! (Closer to "legless Hippos") I am not a fish! Look familar? Homology informs Phylogeny Convergence in Human and Octopus Eye Wings have evolved multiple times (flying is a good niche) They look similar because they both swim fast Human Eye (Blind spot) Octopus Eye (no blind spot) Insect Pterosaur Bird Bat Flipper Jaws The controversial human appendix Useless Goosebumps Notice Anything in common? Map of human genome Similarities between human and chimpanzee chromosomes Fancy Pigeon breeding was the Pokemon of 19th century Europe Native Americans bred Teosinte into Corn Phylogeny of Domesticated Dogs & Cats Demonstration of variation in domesticated species Map of Biogeographical Zones Convergence in Squirrel like mammals (Naked Mole Rat) DNA Mapping Protein sequence comparrison Why is evolution a scientific theory?
How does evidence from multiple scientific disciplines and domains support the modern theory of evolution?
Explain why evolution is a product of the scientific process.
Explain how each area of evidence described in this presentation lends support to the modern theory of evolution, and provide examples from each area.