Presentation on theme: "Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth."— Presentation transcript:
Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth.
Geologic History Geologic time- time that began when earth was formed until present day
200 Million Years Ago 150 Million Years Ago 100 Million Years Ago 50 Million Years Ago Present Evolution of the Earth with Time: Continental Drift
Important Terms Evolution- gradual change in a species over time- sci. theory Theory-well-tested explanation that explains a wide range of observations. Adaptation- any trait that helps an organism survive and reproduce
Natural Selection- the process by which individuals that are better adapted to their environment are more likely to survive and reproduce. Charles Darwin
Natural Selection cont. Over a long time, natural selection can modify a population enough to produce a new species Helpful variations accumulate in a species while unfavorable ones disappear.
Speciation When a group of individuals remain separated from the rest of the species long enough to evolve different traits HOW this happens- Pangaea /Continental Drift Landform isolation- river, mountain, water. (ex. Squirrels of N. Grand Canyon) Australia
A Problem with Traditional Classification Traditional classification systems relied on body structure comparisons only Due to convergent evolution, organisms that are quite different from each other evolve similar body structures. Convergent Evolution Convergent Evolution : Process by which unrelated organisms independently evolve similarities when adapting to similar environments.
A Problem with Traditional Classification Example: The Crab, The barnacle, & The limpet The barnacle and the limpet have similarly shaped shells & look alike The crab has a very different body form Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.
Related This incorrect because crabs and barnacles are actually related
12 TRADITIONAL CLASSIFICATION CLADOGRAM AppendagesConical Shells Crab Barnacle Limpet Crab Barnacle Limpet CrustaceansGastropod Molted exoskeleton Segmentation Tiny free-swimming larva Section 18-2 Traditional Classification Versus Cladogram Go to Section:
Crustaceans Even though they do not look a like, crabs & barnacles are actually related Gastropods Molted Exoskeleton Segmentation Free swimming Larva
Evolutionary Classification Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities Evolution Classification Evolution Classification : Is the strategy of grouping organisms together based on their evolutionary history.
If these three species belong to the same genus, they are descended from a common ancestor. Genus species Felis domestica leo margarita Sand cat` Lion Domestic Cat Felis domestica Felis leo Felis margarita
Classification Using Cladograms Cladogram Cladogram : A diagram that shows the evolutionary relationships among a group of organisms.
Crustaceans Using Cladograms, you can see that crabs and barnacles share similar characteristics because they both molt & are segmented Gastropods Molted Exoskeleton Segmentation Free swimming Larva
Crustaceans You can also see that ALL have a free swimming larval stage Gastropods Molted Exoskeleton Segmentation Free swimming Larva
Modern Evolutionary Classification Similarities in DNA and RNA The genes of many organisms show important similarities at the molecular level that can be used as criteria to help determine classification. 19
Modern Evolutionary Classification Molecular Clocks A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently. Comparison reveals more DNA in common, the more recent the common ancestor 20
Terminology Classification Assigning organisms to different catagories based on their relationship Taxonomy The science of naming organisms Systematics Determining evolutionary relationships of organisms Phylogeny Evolutionary history 21
Phylogenetic Tree Shows evolutionary relationships More historical than cladogram 22
24 Birds Mammals Reptile Amphibian Fish Four Limbs Amniotic Egg Endothermic Fur Feathers Vertebrae
Monophyletic A group of all the descendants of a common ancestor The common ancestor is in the group Example: Birds and Reptiles Ancestor was a bird like reptile 25
Polyphyletic group that has some similarities Contains organisms that have not descended from a common ancestor Based on physical characteristics instead of evolutionary evidence Example: Flying vertebrates- pterosaurs, birds, mammals 26
Cladogram Evolutionary relationship of a group of organisms Each clad (group) share something in common Ancestral traits are the oldest Derived traits evolved later 27
Cladogram for Transportation Wheels are the most ancestral Wings are the most derived 28
Construct a Cladogram 29
Gorilla Four limbs Fur Lost tail 30
Tiger Four limbs Fur Tail 31
Lizard Four limbs Tail 32
Fish Tail 33
Chimpanzee Four limbs Fur Lost tail 34
Clad With 4 Limbs 35
Clad With Fur 36
Clad With No Tail 37
Characteristics for Constructing Cladogram Tail is the most ancestral Four limbs is the oldest derived trait Fur is a later derived trait Loss of tail is the most derived trait 38
39 GorillaChimpanzee Tiger Lizard Fish Four Limbs Fur Tail Lost
Gorilla Tail? How do we know the gorilla lost its tail? 40