BCOR 012 1st Edition Lecture 8 Outline of Last Lecture I Definition of phylogeny and phylogeny data II Hierarchy of Life III Key Points about Phylogenies IV Shared Characters V Clades phyletic groups VI Types of characters used for Phylogenetic Trees Outline of Current Lecture I Microevolution and macroevolution connection II Major Characters used for Phylogenetic trees cont III Homology vs Analogy IV Brief Lecture Review of Past Lectures V Introduction to Chapter 25 Cell Theory Current Lecture Microevolution macroevolution Question How is a speciation event macroevolution influenced by the four forces of microevolution o A pre or postzygotic barrier is present preventing gene flow o Each species change is due to natural selection pushes separation of species a possible beneficial mutation to one of the species being created o Genetic drift bottleneck and founder effect Major Types of Characters Used to Construct Phylogenetic Trees Shared ancestral characters found in a clade on a tree that is being analyzed and seen in older clades Shared derived characters evolutionary novelties to a particular clade o Both are relative to the taxa we are analyzing and looking at Depending on the row of characters in a table of characters determines if the character is a shared derived character or a shared ancestral character Out group a taxon that is known to have diverged before the lineage that contains the group of taxa being studied In group the group of taxon being studied These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Shared ancestral characters of the whole group of taxa is the shared trait that is found furthest to the left on a phylogenetic tree Phylogenies are inferred from morphological and molecular data Morphological and genetic similarities in species are due to homologies Homology vs Analogy Homology similarity in different species due to a shared ancestry Analogy similarity in different species due to CONVERGENT evolution Analogous structures are NOT helpful when making trees for the organisms are NOT closely related Only homologous structures are useful in making phylogenetic trees Brief Review of Past Lectures Variation is what a population must contain in order for evolution to occur otherwise the population will remain the same always Maximum likelihood is used to determine best phylogenetic tree Natural selection is a directed change in a population or species to make a better fit species Sources of variation mutation recombination sexual reproduction are different than the mechanisms of evolution Polyploidy in animal kingdom is rare and usually leads to an unviable organism o Plants can handle being polyploidy for they reproduce differently than animals and can reproduce both asexually and sexually Polyploidy affects sympatric speciation Chapter 25 History of Life We still haven t answered the question of how did life arise from non life Cell Theory cells are an organism s basic unit of structure and function Cell Theories 3 Components I II III Life cannot exist beneath the level of the cell All organisms are composed of cells All cells arise from preexisting cells via cell division A cell contains 4 biological molecules I II III Carbohydrates Proteins Nucleic Acid DNA RNA IV Lipids Possible Processes that may have produced the 1st cells I II III IV Abiotic synthesis of small organic molecules Small molecules joined together to form macromolecules Formation of proto cells precursor of first cell Origin of replication molecules RNA made inheritance possible a It is hypothesized that RNA came before DNA