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30 Cards in this Set
- Front
- Back
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• Charles Darwin
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On the Origin of Species by Means of Natural Selection
o Many species presently inhabiting earth are descendants of ancestral species that were different from the modern species o Natural selection→ populations change over generations if individuals that possess heritable traits leave more offspring than other individuals |
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• Evolutionary adaptation
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accumulation of inherited characteristics that enhance an organism’s ability to survive and reproduce in specific environments
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• Evolution
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• Evolution→ change over time in the genetic composition of a population
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• Aristotle
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• Aristotle→ greek philosopher who said species are fixed (unchangeable)
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• Old Testament
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• Old Testament→ species were individually designed by God and therefore were perfect at the start of their existence
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• Carolus Linnaeus
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founder of taxonomy (branch of biology dealing with classifying and naming organisms)
o Identified similarities between different species o Didn’t realize that those similarities were b/c of evolution though |
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• Paleontology
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• Fossils and sedimentary rocks give evidence for evolution
study of fossils |
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• Georges Cuvier
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developed modern day paleontology and geology
o Studied rock layers in regions around Paris o He noted that the deeper he dug, the more the fossils differed from modern life forms o Observed that species disappeared and appeared from one rock layer to the next o Advocated for catastrophism-→ each boundary between strata (rock layers) represents a catastrophe like a flood or drought that destroyed many of the species living at the time • These periodic catastrophes were usually confined to local geographic regions which were repopulated by species immigrating from other areas |
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• Gradualism
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• Gradualism→ profound changes in species occur slowly over time
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• James Hutton
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proposed that Earth’s geologic features could be explained by gradual mechanisms currently operating in the world
o geologist o Valleys are formed by rivers wearing through rocks o Sedimentary rocks with marine fossils are formed by particles that had eroded from the land gradualism advocate |
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• Charles Lyell
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o Leading geologist
o Theory of uniformitarianism • The same geologic processes are operating today as in the past and at the same rate o Built on Hutton’s ideas o Influenced Darwin’s theory→ if change can occur on the land over time, then change can occur on populations over time |
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• Jean Baptiste de Lamarck
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o Inheritance of acquired characteristics
o Giraffe example→ giraffes use their necks a lot to reach high trees- they stretch their necks out and pass along their long necks to new generations o He was wrong- no evidence that acquired characteristics can be inherited |
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• John Henslow
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Darwin’s professor
o Recommended that Darwin go with Captain Robert FitzRoy on a voyage on the Beagle around the world o Darwin would conduct his studies on the Beagle o Mission of the beagle was to chart poorly known stretches of the S. American coastline |
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• Wallace
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sent Darwin his manuscript on evolution
o Developed a theory of natural selection, but was too afraid to publish it o Wallace asked Darwin to read his paper and critique it o Wallace had the same theory of natural selection as Darwin, but Darwin published it first |
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• Descent with modification
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original term for evolution
o All organisms are related through descent from a common ancestor o As the common ancestor spreads out into different environments over a long time, they accumulate diverse modifications as they adapt to their environments o Tree of life |
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Ernst Mayr
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3 inferences and five observations
• Obs. #1 o Population sizes increase exponentially if all individuals that are born reproduce successfully • Obs. 2 o Populations tend to remain stable in size except for seasonal fluctuations • Obs. 3 o Resources are limited • Infer. 1 o Having more individuals than the environment can support leads to a struggle for existence among individuals in a population o Only a fraction of offspring survive to reproduce • Obs. 4 o No two individuals are exactly alike • Obs. 5 o Genetic variation is heritable • Infer. 2 o Survival depends on inherited traits o Individuals whose inherited traits give them an advantage in their environment will survive and reproduce more easily • Infer. 3 o The unequal ability of individuals to survive and reproduce leads to gradual change in a population- favorable characteristics accumulate over generations |
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• Thomas Malthus
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o Human suffering like disease and famine happen when population exceeds resources
o Capacity to over-reproduce applies to all species of animals o When populations exceed resources, bad things happen |
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• Artificial selection
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selection controlled by humans
o Dogs are artificially selected o Artificially selected animals/plants bear little resemblance to their wild ancestors |
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• Guppy example
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o Killifish pool
• Killifish eats small guppies • Guppies are therefore larger and older at sexual maturity, because the small ones are eaten up o Pike fish pool • Pikes eat big guppies • Guppies are smaller and younger at sexual maturity so they can reproduce before being eaten o Scientists took pike fish guppies and put them with killifish • Over time, the guppies became larger and older at sexual maturity because the small ones were eaten up b4 they could reproduce o Shows natural selection and evolution |
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• Drug resistant HIV
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o Whenever you develop a vaccine or a drug, you’re selecting for drug resistant diseases
o Eventually, pathogens will evolve to resist the drug, because those pathogens that survive the drug will continue to reproduce o They developed many HIV drugs, but many of the drugs don’t work anymore because the HIV virus evolved to resist the drug |
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• Homology
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• Homology→ certain characteristics in related species have an underlying similarity even though they may have different functions
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• Anatomical homologies
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• Anatomical homologies→ the bones in mammalian hands/arms are structurally similar, but have different functions
wings arms paws fins |
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• Homologous structures
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• Homologous structures→ structures that are similar amongst related organisms
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• Comparative embryology
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• Comparative embryology→ all vertebrae embryos look the same in their early stages across all species
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• Vestigial organs
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structures of marginal importance in organisms
o Remnants of structures that served important functions in the organism’s ancestors o Ex: humans have a tailbone, but no tail o Snakes have bones that resemble bones used for walking |
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• Molecular homologies
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o Similarities amongst organisms at the molecular level
o All living things have DNA and RNA • It’s likely that all species descended from a common ancestor o Human DNA is 50% the same as banana DNA o Human DNA is extremely similar to monkey DNA o Amino acid sequence of hemoglobin is very similar across all vertebrate species • Our hemoglobin amino acid sequence is 95% identical to a monkey and 14% identical to a fish |
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• Biogeography
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• Biogeography→ geographic distribution of species
• Closely related species tend to live in the same geographic region • Australia, for example, has a lot of exotic species that are only found in Australia |
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• Convergent Evolution
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o When two species are isolated from each other, but evolve similarly
o Ex: sugar gliders live in Australia and flying squirrels live in North America→ but they both evolved to look similar o Natural selection explains why similar adaptations can evolve independently among distantly related species |
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• Endemic
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• Endemic→ species that are found nowhere else in the world
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• Fossil record
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o Fossil record→ history of fossils
o Oldest known fossils are prokaryotes o Evolutionary transitions leave signs in the fossil record o There is fossil evidence to support the fact that birds descended from one branch of dinosaurs |
