Phylogeny and Systematics - Application of Biology - Lecture Slides, Slides of Biology

Download Phylogeny and Systematics - Application of Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! AP Biology Chapter 25. Phylogeny & Systematics An unexpected family tree. What are the evolutionary relationships among a human, a mushroom, and a tulip? Molecular systematics has revealed that— despite appearances—animals, including humans, and fungi, such as mushrooms, are more closely related to each other than either are to plants. Docsity.com AP Biology Phylogeny & Systematics • Phylogeny – evolutionary history of a species – based on common ancestries inferred from • fossil record • morphological & biochemical resemblances • molecular evidence • Systematics – connects classification system to phylogeny by categorizing & naming organisms Docsity.com AP Biology Fossils Docsity.com AP Biology Building phylogenies • Morphological & molecular homologies – similarities based on shared ancestries • bone structure • DNA sequences – beware of analogous structures • convergent evolution marsupial mole placental mole Docsity.com AP Biology Evaluating molecular homologies • Aligning DNA sequences – more bases in common = more closely related – analyzed by software Docsity.com AP Biology Illustrating phylogeny • Cladograms – patterns of shared characteristics Classify organisms according to the order in time at which branches arise along a phylogenetic tree Docsity.com AP Biology Molecular Systematics • Hypothesizing phylogenies using molecular data – apply principle of parsimony • simplest explanation • fewest evolutionary events that explain data hypothetical bird species 3 possible phylogenies (there are more) Docsity.com AP Biology Parsimony • Choose the “tree” that explains the data invoking the fewest number of evolutionary events Docsity.com AP Biology Of Mice and Men… • Evolving genomes – now that we can compare the entire genomes of different organisms, we find… • humans & mice have 99% of their genes in common • 50% of human genes have a close match with those of yeast! – the simplest eukaryote Docsity.com AP Biology Molecular clocks Trace variations in genomes to date evolutionary changes Rate of change is calculated and then extrapolate back What does this assume? HIV-1M samples were collected from patients between early 1980s & late 1990s. The gene evolved at a relatively constant rate. Concluded that HIV-1M strain first infected humans in 1930s. Docsity.com AP Biology Universal Tree of Life • 3 Domains – Bacteria – Eukarya – Archaea Docsity.com