Prove It Biogeography Homologous and Analogous Structures Fossil record biogeography The geographic distribution of plants and animals over the surface of the Earth Pangaea 270 million years ago all of the planets land mass was combined into one super continent ID: 1006492
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1. Common ancestryFinding the proof
2. Prove It!BiogeographyHomologous and Analogous StructuresFossil record
3. biogeographyThe geographic distribution of plants and animals over the surface of the EarthPangaea270 million years ago all of the planet’s land mass was combined into one super continent200 million years ago it broke apart forming the current continents
4. biogeographyOceans separated land masses leading to species isolationIsolated populations developed unique mutations and adaptations, eventually becoming their own species.
5. biogeographyA microcosmic example of this isolation are the Kaibab and Abert squirrels on the Northern and Southern rims of the Grand Canyon The canyon prevents gene flow from one population to the other.The squirrels’ many similarities suggests a common ancestor whose population was split during the last ice age.Kaibab squirrelAbert squirrel
6. Homologous and Analogous structuresHomologous - Different organisms with similar structures due to common descentExample: forelimb in a cat and a whaleAnalogous - Different organisms with similar structures due to similar environmental challenges and selective pressuresExample: moth wings and bat wingsShow what you know!Homology vs Analogy
7. Living things are remarkably similar at the cellular and molecular level. These fundamental similarities are most easily explained by evolutionary theory: life shares a common ancestor. Humans and bananas share 50% of their dnaMolecular/cellular homology
8. All organisms are made of cellsAll cells are remarkably similar in structure and functioncellular homology
9. Comparing Animal and Plant CellsAnimal CellPlant CellVariety of ShapesOne or more small vacuolesCentriolesLysosomesOften have cilia or flagellaCell MembraneCytoplasmER (smooth and rough)RibosomesMitochondriaGolgi apparatusNucleusCell WallRectangularOne large, central vacuoleRarely have lysosomesPlastidsChloroplastsRarely have cilia or flagella
10. The DNA code is a homology linking all life.DNA and RNA possess a four-base code that provides the recipe for all living things. In some cases, transferring genetic material from the cell of one living thing to the cell of another, results in the recipient following the new instructions.Molecular homology
11. Developmental homologySimilarities between embryos of different species suggests shared ancestry; even across different classes of animals (Reptilia, Mammalia, etc).
12. Developmental homology ExampleToothed whales have full sets of teeth throughout their livesBaleen whales (such as the Blue whale) only have teeth in the early fetal stage. This suggests that both toothed and baleen whales share a common ancestor.
13. Anatomical homologyComparing the structure and function of the same bones in different species provides a rough estimate of how far back the common ancestor was.
14. Fossil recordA way for scientists to see the small adaptations that happen in species over timeProvides much proof for common ancestry between animals Enables scientists to better pinpoint when certain species existed and help determine whether they may be related to other species.
15. Dating the Fossil recordDepth at which fossils are found helps determine relative age (“older” or “younger” than other fossils)Older fossils are found deeper, as shown in sedimentary rock
16. Radiometric datingA technique used to date materials such as rocks or carbon, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.
17. Evolutionary TreesRepresent evolutionary relationships among a set of organisms or groups of organisms, called taxa (singular: taxon)Tree tips represent groups of descendent taxa (often species) and tree nodes represent common ancestors
18. Evolutionary TreesPhylogeny, Phylogenic Tree, and CladogramTerms often used interchangeably A tree structure that represents the evolutionary relationships within a group of organismsClade - a group of organisms that includes an ancestor and all descendants of that ancestor
19. Evolutionary TreesClick here to make your own tree: Reconstructing Trees
20. List the three methods scientists use to prove common ancestry.Give an example of geographic isolation and to what might it give rise?What is the difference between a homology and analogy?Why is the fossil record important to scientists?Dig Deeper!