Evidence for Evolution
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Transcript of Evidence for Evolution
Evidence for
Evolution
Evidence for Evolution•Homology•Convergent evolution•Vestigial structures•Selective Breeding•Fossils•Embryology•DNA
Homology– Evidence of a Common Ancestor
• All of these evobots used the same red pieces that were present in their ancestor but not in earlier generations.
Homology– Evidence of a Common Ancestor
Vertebrate Limb Homology
Homology– Evidence of a
Common Ancestor
• We can see the steps between the reptile jaw and the human ear– they use what appear to be the same bones.
Homology– Evidence of a Common Ancestor
• When we see very similar parts in many living things, we gain evidence of their common ancestor and its characteristics.
• This is especially true when similar parts have different functions
Convergent Evolution
Divergent Evolution• Most evolution appears to be divergent– those closest to
the ancestral state are the most similar and organisms become more different as they evolve.
• This is not always the case. Sometimes, organisms come up with similar solutions to the same environmental problems.
Convergent Evolution
Convergent EvolutionSimilar Structures for Similar Environments
Convergent Evolution
• Most evolution is Divergent (species with similar traits have a common ancestor)
• According to Natural Selection, species evolve traits that help them survive in an environment.
• Sometimes, the requirements to survive in an environment are so strong that several VERY DIFFERENT SPECIES evolve traits that function in similar ways. This is convergent evolution.
Vestigial Structures
• Structures that are no longer useful, such as our appendix,, or the fingers on a whale are vestigial structures. They are evidence that these creatures evolved from other creatures that used these structures.
Vestigial Structures
Vestigial Structures
Other Flightless Birds with Wings
Kakapo(New Zealand)
Kiwi(New Zealand)
Cassowary(New Giunea)
Vestigial Structures
Vestigial Structures
Vestigial Structures
Vestigial Human Characteristics
Spine Structure and tailbone
Body Hair and Goosebumps
Eyes in Blind, Cave-Dwelling Creatures
Selective Breeding• We humans have been selecting characteristics of pets and domesticated plants and animals for thousands of years. In many cases, we have dramatically changed how species look and behave.
• In some ways, animals do this too both through sexual selection and natural selection itself.
Selective Breeding or Artificial Selection
Selective Breeding or Artificial Selection
Selective Breeding in Agriculture
Cows are bred for beef or milk production (Video).
Corn has been selectively bred for 600 to 10000 years by people in North America.
Selective Breeding
Animals Do Selective Breeding too! Sexual Selection
Peacock Colors
Bowerbird Nests
Animals Do Selective Breeding too! Sexual Selection
In many animal species, females choose males that win competitions with other males. Alleles that help them win these competitions are then selected for.
Animals Do Selective Breeding too! Sexual Selection
Pollinators “select” flowers that are more appealing. Bees tend to select blue and purple flowers whereas humming birds prefer red.
Natural Selection as a form of Selective Breeding–
Just on Accident
Fishes “select” the angler fish with the most attractive lure--- by getting eaten by them!
Natural Selection as a form of Selective Breeding–
Just on Accident
Any prey species, inadvertently selects characteristics in a predator that allows the predator to catch and eat them.
Fossils
• There are fossils of many creatures that no longer exist today. They often show intermediate forms between species that exist today and their ancestors.
• We also see that fossils deeper in the earth only show simpler creatures with more advanced life forms closer to the surface.
Archeoptryx
Archeoptryx
Fossils
Whales in the Fossil Record
Whale Fossils– Migration of the Blowhole
Whale Fossils– Migration of the Blowhole
Fossil Human Ancestors
Fossils
Fossils
Embryology
•Embryos of some animals show traits that are not present in adults such as gills and tails in humans. These are evidence that these traits were found in our ancestors.
Embryology
Tail in Human Embryo
Hind Limb buds in Dolphin
DNA Similarities If you look at the DNA of living creatures
you can see the similarities. Many sections of DNA are don’t code foe
anything at all. These sections are similar to working or useful sections in other creatures.
Even in human DNA, you can see the broken parts of code that were important in an organism long ago
DNA Similarities
DNA Similarities
PseudoGenes Pseudogenes are sections
of chromosomes that resemble functioning genes in related creatures, but lack start codons (or promoters) and are never translate into proteins.
For example, genes for gills may be present in mammals, but in a non-functional, mutated, broken form.
Predictable Differences in DNA Humans and other chimps split from dogs
long before they spit from each other. We would expect to see more genetic
similarities between chimps and humans than either would have with dogs.
We would ALSO expect humans and chimps to show similar difference from chimps, and they do.
Evidence for Evolution•Homology•Convergent evolution•Vestigial structures•Selective Breeding•Old Earth •Embryology•Fossils•DNA