Biology 112 Basu Tamu Exam 1 Questions and Answers correct

Biology 112 Basu Tamu Exam 1 Questions and Answers correct Phylogeny - the evolutionary history of a species & its relationship to other species - shown as a "tree" Types of Phylogenetic trees a) Rooted: single lineage (at base) represents common ancestor b) Unrooted: show relationships but not a common ancestor Three Domains of life All life can be classified into three domains: Bacteria, Archaea, and Eukarya. Proposed by microbiologists Woese, Kandler and Wheelis - Bacteria: cells do not contain a nucleus. - Archaea: cells do not contain a nucleus; they have a different cell wall from bacteria. - Eukarya: cells do contain a nucleus. Include the plants, animals, fungi, and protists Rooted Phylogenetic Tree - A root indicates that an ancestral lineage gave rise to all organisms on the tree - A branch point indicates where two lineages diverged - A lineage that evolved early and remains unbranched is a basal • taxon - When two lineages stem from the same branch point, they are sister taxa - A branch with more than two lineages is a polytomy Clade a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor (monophyletic groups) Cladistic Analysis grouping organisms in a way that reflects their evolutionary relationship - monophyletic, paraphyletic, polyphyletic monophyletic consists of an ancestral species and all of its descendants paraphyletic consists of an ancestral species and some, but not all, of its descendants polyphyletic includes distantly related species but does not include their most recent common ancestor Taxonomy grouping or classifying species together based on similarities & differences (subjective!) taxonomic classification system (also called the Linnaean system after its inventor, Carl Linnaeus) Consists of a hierarchy of groupings, called taxa (singular, taxon) • Organisms that shared obvious physical traits, such as number of legs or shape of leaves were grouped together • After the common beginning of all life, scientists divide organisms into three large categories called domains: Bacteria, Archaea, and Eukarya • Within each domain is a second category called a kingdom • After kingdoms, the subsequent categories of increasing specificity are: phylum, class, order, family, genus, and species Advantages of phylogenetic classification - Tells evolutionary history. - Does not "rank" organisms and does not suggest that 2 identically ranked groups are comparable. - Linnaean classification "ranks" groups of organisms artificially into kingdoms, phyla, orders, etc. REVIEW RECALL Homologous structures • Similar due to evolutionary origin (same ancestral source) • Based on genetics and developmental origin Analogous structures • Similar due to functional or ecological constraints/pressures • Characters can be very similar in appearance due to evolutionary convergence Principle of maximum parsimony Using many characters to develop an accurate cladogram (phylogenetic hypothesis) often results in many possible trees • Use principle of "maximum parsimony" to choose best tree • fewest evolutionary events • events occurred in the simplest, most obvious way • Starting with all of the homologous traits in a group of organisms, scientists look for the most obvious and simple order of evolutionary events that led to the occurrence of those traits.