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phylogeny.notebook Phylogeny is the origin and evolution of a species The degree of relatedness among organisms can be determined by examining developmental, structural,and molecular traits. Ancestral relationships can be mapped out like a family tree (called a phylogenetic tree). Each branch represents a more recent ancestor, and the length of the branch indicates time. phylogeny.notebook Bryophytes (mosses) Plant Evolution Seedless Gymnosperms (conifers) Vascular Plants Angiosperms (flowering) (ferns) Early Flowering Plants Early Seed Plants Early Vascular Plants Millions of Years Origin of Plants Algal Ancestors Phylogenetic trees, such as this one, illustrate evolutionary relationships. phylogeny.notebook Developmental • similarities in stages of embryonic development reveal relatedness • the developing embryos of a chicken and a human look almost identical!!!! phylogeny.notebook Structural • organisms that share similar anatomical characteristics are more closely related than those that do not • Corresponding organs and body parts that are alike in structure and origin are homologous structures • a large number of shared homologous structures is considered evidence that two species are closely related to each other • related species share a common ancestor from which the "shared derived characters" evolved phylogeny.notebook example of homologous structures: These shared derived characters (like bones) evolved from a common ancestor species that had a similar set of limbs! phylogeny.notebook Molecular • similarities at the molecular level reveal relatedness • DNA, mitochondrial DNA, and protein structures DNA mitochondrial DNA protein structure phylogeny.notebook Cladograms (CLAYdoegrams) • A phylogenetic tree shows the shared derived characteristics of different species and the degree to which they are related. • Species are the tips of the branches and the shared derived characters of the homologous structures are shown along the branches by a solid square. • The species that was a common ancestor to both branches is shown with an open circle. phylogeny.notebook Example Cladograms Close relationships are shown by a recent fork from the supporting branch. The closer the fork in the branch between two organisms, the closer the relationship. phylogeny.notebook This cladogram is superimposed over a Venn Diagram that shows what characteristics species have in common. Complete the Venn diagram by dragging each species to the appropriate circle. Wolf: carnivore House Cat: purrs Horse: hair Leopard: retractable claws phylogeny.notebook Horse: hair Wolf: carnivore Leopard: retractable claws House Cat: purrs This information can be drawn out from a simple data tab which species that indicates has each trait: Place an "x" in the box if the animal has the characteristic: What do you notice about the total # of X's and the position in the Venn Diagram?
