Back to Unit Page Unit Textbook Chapter Animations & Images Expert Interview Transcripts Unit Glossary Related Resources View Text Only List Animations Cladogram An example of a cladogram, which depicts the relatedness of taxonomic groups; uses the Order Cetacea, whales, as an example. View Animation Still New Theoretical Approach in Whale Phylogeny A phylogeny depicting the new picture of whale ancestry. View Animation Still Genetic Data Demonstrates how scientists use genetic data to build a phylogeny and determine relatedness between a group of organisms. View Quicktime Movie Tree of Life -- Lateral Gene Transfer Diagram Revised "tree of life" with all groups divided into their domains. Includes information about lateral gene transfer and the endosymbiosis of bacteria that became mitochondria and chloroplasts. View Animation Still Images Ambulocetus, an archaic whale An artistic reconstruction of Ambulocetus, an ancestor to modern whales, based on fossil evidence Anthrax phylogeny A phylogenetic representation of the various anthrax isolates from laboratories around the world Anthrax rods Scanning electron micrograph of Bacillus anthracis rods in the human spleen Anthrax spores Spores of Bacillus anthracis Artiodactyl An artist's rendering of an ancient artiodactyl, a group of split-hoofed animals that were the ancestors to camels, hippos pigs, and probably modern whales Bacillus anthracis Transmission electron micrograph of Bacillus anthracis, the bacterium that causes anthrax Bacillus anthracis Photomicrograph of Bacillus anthracis, the bacterium that causes anthrax Carl Woese's data An autoradiogram of a gel electrophoresis separation and visualization of ribosomal RNA, part of Carl Woese's research that led him to reorganize the Tree of Life into three domains rather than five kingdoms. Chloroplasts A photomicrograph of chloroplasts, key cellular structures found in plants, which originally existed as free-living bacteria Five-kingdom vs. three-domain tree of life Old "tree of life," based on five kingdoms, transformed into new tree built from three domains, based on rRNA evidence. Genome of Bacillus anthracis A graphical representation of the DNA sequence of Bacillus anthracis Gingerich's revised picture of whale evolution In the revised picture of whale evolution, cetaceans evolved from the artiodactyls, and not the mesonychids, as previously thought. The closest living relative to whales is now thought to be the hippo. Haeckel's evolutionary tree A tree-like representation by Ernst Haeckel, a nineteenth-century evolutionary biologist Kutchicetus, an archaic whale An artistic reconstruction of Kutchicetus, an ancestor to modern whales, based on fossil evidence Megabat Photograph of an example of a megabat, the African fruit bat. Mexican freetail bat Photograph of an example of a microbat, the Mexican freetail bat. Monophyletic, paraphyletic, and polyphyletic trees Examples of monophyletic (top), paraphyletic (middle), and polyphyletic (bottom) trees. Monophyly and diphyly of bat evolution Alternative possibilities of bat phylogeny. Top: Bats form a monophyletic clade, in which flight evolved once in mamals. Alternately, bottom, bats are diphyletic, and flight evolved twice in mammals. Pachyaena An artist's rendering of Pachyaena, an example of the extinct group of animals called mesonychids. Once thought to be the ancestors of modern whales, it now appears that this is not the case. Parsimony Three possible unrooted trees are shown. The top tree assumes nine changes in character state occurred (each change is represented by a mark), the middle tree assumes ten changes, and the bottom tree assumes eleven. Because the top tree assumes the fewest changes, it is the most parsimonious tree. Phillip Gingerich Archaeologist Phillip Gingerich working in the field in 1991 Phillip Gingerich Archaeologist Phillip Gingerich working in the field in 1991 Phylogeny of Bacillus anthracis A phylogenetic representation of Bacillus anthracis and related bacteria Plasmid DNA A photomicrograph of plasmid DNA, a small circular form of DNA found in bacteria Unrooted tree and possible rooting points Panel A shows an unrooted tree. Panels B, C, D, and E should be the resulting rooted trees, when root is placed in each of the corresponding positions.

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