Evidence for evolution
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Evidence for Evolution. Fossils. Evidence for evolution. Fossils. Show: Evolution Primer: How do we know evolution happens?. Evidence for evolution. DNA All life uses the same 4 DNA bases: thymine, adenine, guanine, cytosine

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  • Show: Evolution Primer: How do we know evolution happens?


Evidence for evolution2
Evidence for evolution

  • DNA

  • All life uses the same 4 DNA bases: thymine, adenine, guanine, cytosine

  • Biochemical pathways trace evolutionary relationships just as fossils do


Evidence for evolution3
Evidence for evolution

  • Sense of smell

  • All mammals have many genes for smell—about 3 % of all their genes

  • In humans, that’s about 1,000 genes.

    • BUT 300 genes in humans are useless-DO NOT work

    • WHY?

  • Whales, dolphins also have odor genes useful in air, but not water

    • BUT: NONE of the genes in whales and dolphins works. Whale’s blowhole is used for breathing, not smelling.


Evidence for evolution4
Evidence for evolution

  • Homology: characteristics that organisms share from a common ancestor

  • Good example: limbs of tetrapods


Evidence for evolution5
Evidence for evolution

  • Biogeography: the geographic distribution of species tells stories that geology and evolution can shed light on

  • e.g.: Dinosaurs that can’t swim, but are found on several continents  says those continents were once connected


The finches on the Galapagos are thought to have evolved from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.


Evidence for evolution6
Evidence for evolution from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Artificial selection

    • Humans can mimic the selection process, bend evolution to our will (sometimes!!) and produce useful plants and animals.

    • Check out corn (teosinte)


Adaptations
Adaptations from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Traits that are successful in their environment

  • An adaptation to one environment may be NEUTRAL or UNFAVORABLE in another environment

  • May be simple—heavier coat in colder climate—or complex—the mammalian eye


Again
Again: from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Adaptations are specific to the environment.

    • A zebra’s coat pattern is camouflage in the African savannah. It would not be advantageous in a North American grassland.

    • Running speed is advantageous for a cheetah on the savannah. But cats in the rainforest (e.g., jaguar) are not fast. Strength and stealth are more important than speed there.


Adaptation examples mimicry

How could such mimicry evolve? from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

What is the advantage to the orchid?

Is there a cost or benefit to the wasp?

Some orchids (a kind of flower) mimic wasps. They look enough like a female wasp to fool males into ``mating’’ with them and thus transfer their pollen

Adaptation examples: mimicry


Adaptation examples more mimicry
Adaptation examples: more mimicry from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Katydids have evolved a body form that looks like a leaf.

  • Why? What is the advantage to the katydid?


Adaptation examples still more mimicry
Adaptation examples: still more mimicry from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Non-poisonous king snakes mimic poisonous coral snakes

  • Many examples of mimicry in nature


Speciation
Speciation from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • One species evolves into another OR splits into two.

  • How can this happen?

    • Geographic isolationallopatric speciation


Biodivrsity patterns hotspots
Biodivrsity patterns: hotspots from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.


Birds in south america
Birds in South America from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.


History of life
History of life from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • As previous picture shows:

    • Complex creatures and structures have evolved

    • But simple life forms still common and dominate in many habitats ``Earth still belongs to the bacteria’’

    • Speciation generates diversity; extinction reduces it


Extinction
Extinction from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • The disappearance of a species from Earth

  • Local disappearance is called extirpation


  • 99% of ALL species that have ever existed are extinct from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.


Extinction1
Extinction from a single species of ancestral finch, probably the generic sort of seed-eating finch shown in the center. When a population of finches was reproductively isolated on one of the islands, it adapted over time to feed on a new food source. After time, it was sufficiently different from its ancestor to be considered a new species.

  • Two kinds:

  • Background: the regular, consistent, extinction of species over millions and hundreds of millions of years

    - Result of environmental change, species interactions

  • Mass: the relatively sudden extinction of a great number of species in a short period of time (few million years, or less)


This graph shows extinction rates. You can see that five times in the last 600 million years, the rate has spiked up. Those are MASS EXTINCTIONS. The last one is when the dinosaurs died. Between mass extinctions, there is a more steady extinction rate, called BACKGROUND EXTINCTION.


6 th mass extinction
6 times in the last 600 million years, the rate has spiked up. Those are MASS EXTINCTIONS. The last one is when the dinosaurs died. Between mass extinctions, there is a more steady extinction rate, called BACKGROUND EXTINCTION.th mass extinction?

  • We are in the midst of a 6th mass extinction.

  • First one caused by human activity.


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