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Evolution - constancy & change

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Page 1: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Evolution- constancy & change

Page 2: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Modern Evidence for Natural Selection

1. fossil records – organisms change over time

2. biogeography – related organisms in same area

3. comparative anatomy – homologous structures

4. comparative embryology – similar embryos

5. molecular biology – similarities in DNA, proteins

6. artificial selection – selective breeding

Page 3: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Phylogeny & Molecular Systematics

• Phylogeny – study of evolutionary relationships

• Molecular Systematics – study of molecular structures (DNA, protein) to determine evolutionary relationships

*animals, including humans, and fungi, are more closely related to each other than either are to plants

Page 4: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

• Occam’s Razor (law of parsimony) - "All other things being equal, the simplest solution is the best."

• Used to justify a phylogenetic tree that represents the smallest number of evolutionary changes

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Occam’s Razor & Parsimony

Page 5: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Comparison of hemoglobin

Cladogram (phylogeny)- shows ancestral relationships

Page 6: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Cladogram

- primate DNA comparisons

Page 7: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms
Page 8: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Molecular Clocks• DNA or protein comparisons to

estimate the length of time that two species have been evolving independently

Molecular Systematics

Page 9: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Primate evolution

• Humans have 99.99% similarity

• Humans and chimps have 98% similarity

Page 10: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms
Page 11: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

“Ontogeny recapitulates Phylogeny"

The embryonic development of a species (ontogeny) is a replay of its evolutionary history (phylogeny).

- 1866 Ernst Haeckel

Page 12: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Comparative Embryology (faked)

Page 13: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Drawings vs. photographs

Page 14: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Comparative Anatomy

Page 15: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Animal developmental characteristics

p.371

•body plan

•symmetry

•body cavity

•digestive tract

•segmentation

Page 16: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

mono-, para-, or polyphyletic

monophyletic – all descendants

paraphyletic - not all descendants

polyphyletic - last common ancestor is NOT within group

Page 17: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms
Page 18: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Monophyletic includes the most recent common ancestor of a group of organisms and all of its descendants

Polyphyletic does not include the common ancestor

Paraphyletic includes most recent common ancestor, but not all of its descendants

Page 19: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Restriction Maps

1717

1310

43

1. Gibbon is least similar; chimp is most similar.

Page 20: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Skull Morphology

humandeer cat dog bear gorilla

brain size

teeth types

brain to face ratio

meat-eaters

mammals

herbivore

Page 21: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Skull Morphology

humandeer cat dog bear gorilla

brain size

teeth types

brain to face ratio

meat-eaters

mammals

herbivore

Page 22: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Restriction Maps2. Changes will go back and forth as

environment changes.

3. Neutral changes will accumulate.

4. Advantageous changes will accumulate more often.

5. Two closely related organisms will have fewer genetic differences.

Page 23: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Animal Development& Phylogeny

Page 24: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Animal developmental characteristics

p.371

•body plan

•symmetry

•body cavity

•digestive tract

•segmentation

Page 25: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Tissue Organizatio

n

1. no tissue - no specialized fxn

2. tissue - specialization

Page 26: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Body Symmetry

1. radial - looks same cut from any side at top

2. bilateral - looks same cut from 1 side at top

Page 27: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Body Cavity1. acoelomate

- no body cavity, digestive tube connected to muscle

2. pseudocoelomate - partial cavity

3. coelomate - digestive tube separated from muscles

Page 28: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Digestive Tract

1. protostome

- spiral cleavage

- blastopore-->mouth

2. deuterostome

- radial cleavage

- blastopore-->anus

http://www.mun.ca/biology/scarr/141993_Protostome_vs_Deuterostome.jpg..jpg

Page 29: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Comparative Embryology• closely related organisms go through

similar stages in their embryonic development

*all vertebrate embryos have gill slits: – gill slits in fish form gills– human gill slits form the Eustachian tubes

connecting the middle ear with the throat

Page 30: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Comparative Anatomy

Page 31: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Vestigial Structures – pelvic bones in whale

- eye sockets in blind salamanders

Page 32: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Convergent Evolution -similar solutions to similar “problems”

Analogous structures• similar functions, no evolutionary relationship;

different internal structure & development

*flight - bird vs bat vs insect

*reproduction - marsupials vs placentals

*aquatic vertebrates - dolphins vs fish

Page 33: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Artificial selection

• breeding

Page 34: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Artificial selection• pesticide resistance• antibiotic resistance

Page 35: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms
Page 36: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Natural Selection“survival of the fittest”?

Page 37: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Charles Darwin • (1809-1882) British naturalist • 1831-1836 Voyage on HMS Beagle• collected specimens of fossils as

well as living; observed the various adaptations of plants and animals

• breeding experiments

• 1859 “On the Origin of Species by Means of Natural Selection”

Page 38: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

“Origin of Species” Key Points

1. descent with modification • all species evolved from ancestral species

and were not specially created; diverse modifications accumulated over millions of years

2. natural selection • mechanism of evolution; a consequence of

interactions between individual organisms and their environment

Page 39: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Natural Selection Requires…

1. Variation - individuals within a population show variation in their characteristics

2. Overproduction / competition - environmental resources are limited

3. Survival / reproduction – only those best suited to environment will survive to reproduce and pass on favorable variations

Page 40: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Historical Views of Origin of LifeCreationism (Judeo–Christian):

Earth is ~6000 years old and was populated by unchanging life forms made by the Creator during a single week

Greek philosophy (Aristotle ~350 BC):

scala naturae (scale of increasing complexity) – species were fixed in form, did not evolve

Page 41: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Carolus Linnaeus• (1707 – 1778) Swedish

physician, botanist

• father of taxonomy — developed the binomial nomenclature system

• organized organisms into categories based on similar physical features

Page 42: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

James Hutton• (1726-1797) Scottish geologist

• proposed geological gradualism – change is the cumulative product of slow, continuous processes

*canyons are formed by erosion from rivers

Page 43: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Georges Cuvier• (1769-1832) French anatomist

• founder of paleontology – study of fossils

• proposed catastrophism – periodic catastrophes result in mass extinctions; migrating species repopulate the area

Page 44: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Charles Lyell• (1797-1875) geologist• “Principles of Geology”

proposed uniformitarianism – geological processes are uniform and balanced throughout Earth

*processes that build mountains are eventually balanced by the erosion of mountains by wind and water

Page 45: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Jean Baptiste Lamarck

• (1744-1829) naturalist• evolution is driven towards

complexity and perfection (organisms became better adapted to their environments)

• 1809 proposed inheritance of acquired characteristics: – use and disuse

*giraffes

Page 46: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Reverend Thomas Malthus

1. all species over-produce

2. competition for resources

3. only a fraction survive to reproduce

4. eventually populations reach carrying capacity

•(1766-1834) studied human overpopulation:

Page 47: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Stephen Gould • 1972 proposed theory of

punctuated equilibrium- based on fossil record: little change occurs, then rapid localized speciation occurs

• exaptation – shifts in function of a trait during evolution*mammalian limb

Page 48: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Michael Behe

• 1992 irreducible complexity(argument for intelligent design) – biological systems are too complex to have evolved through natural selection

– evolutionary pathways may contain one or more unselected steps

Page 49: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

The Subtleties of Natural Selection

• individuals do not evolve; populations do

• only heritable variations can be changed

• an adaptation to a set of conditions may be useful or detrimental, under different circumstances

Page 50: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Modern Examples of Natural Selection

• Kettlewell - observed peppered moths

• Grants on the island of Daphne Major - observed shifts in the frequency of beak sizes over short periods of time

• Antibiotic resistance in bacteria

• How do genetic variations arise in nature?

Page 51: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

Industrial Melanism – Peppered Moths

•1848 Kettlewell’s observations – moths are darker in polluted areas

Page 52: Evolution - constancy & change. Modern Evidence for Natural Selection 1.fossil records – organisms change over time 2.biogeography – related organisms

1973 Grant - change in finch

beak size