Lecture 12 Ch 22 Sections 22 1 22 4 Pre read Ch 1 Section 16 1 Ch 26 Sections 26 1 26 6 A phylogeny portrays the evolutionary relationship among organisms All life on earth shares a common ancestor Viruses not on tree viruses aren t living Natural selection and some random events generated biodiversity Organisms can have adaptations due to occurrences in the environment Evolutionary history is depicted on a phylogeny Key features 6 Some form of compartmentalization cellular organization Aqcuire and use energy for growth and metabolism Genetic material that is either the same or similar Heredity the ability to pass on information Capable of reproduction Some sort of internal regulation homeostasis occurs Phylogenetic tress describe relationships through common ancestry The common ancestor of all living things had features essential to life Lineages When a split occurs lineages develop Lineages diverge splitting event Tips are taxa taxon Common ancestor at root nodes Nodes are speciation events Each dot is a new trait Evolutionary relationships Time on horizontal axis Phylogenetic trees describe relationships through common ancestry Common ancestor Descendants Monophyly A monophyletic group clade is an ancestor and all of its descendants Phylogenies can be depicted differently Same processes and relationships Can be drawn up and down Can use a V Evolutionary history of an organism influences how traits evolve Homologos homology Things that we share with other species Example mitochondria Ancestral vs Derived outgroup Ancestral traits are something that you would see in the ancestor Example nucleus mitochondria Derived traits are new traits found only in the group that has them Example plants acquire chloroplasts Synapomorphy vs homoplasy Synapomorphy is a shared derived trait Example nucleus Homoplasy is a shared trait that is not due to a common ancestor Example wings in bats insects and birds Convergent evolution Different organisms evolve the same trait independently of each other Example wings in bats and birds Evolutionary reversal Lose a trait Example protist loss of mitochondria Phylogenies are constructed using parsimony and synapomorphies 0 absent 1 present Parsimony is building a tree with the least amount of changes Outgroup is the organism with all 0 s Phylogenies can be constructed with many types of data Physical characteristics morphology Paleontology fossils Behavior Development Molecular data DNA Biodiversity is organized into groups Taxonomy systematics Taxonomy organizing things into groups and then naming them Systematics studying and classifying biodiversity Binomial nomenclature Linnaeus Phylogenies monophyletic groups are used to classify organisms What are the groups of organisms Evolutionary hierarchy Polyphyletic Does not include the common ancestor Example bacteria all of the different prokaryotes Paraphyletic Almost every group and the common ancestor Example protists Phylogenies can help us understand the past How often has self compatibility evolved in one group of plants Linanthus Outcrossing vs self fertilization Genetic mechanism 3 alleles Phylogenies can be used to understand ancient traits What colors could dinosaurs see Ancestral state reconstruction Archosaurs Opsin visual pigment Protein that changes shape when exposed to light Organisms with opsins are capable of hunting at night Living species that still have opsins are nocturnal hunters Phylogenies can be used to understand where diseases came from From what animal did humans acquire HIV How many times Twice once from chimps and once from sooty mangabeys Phylogenies can be used to date evolutionary events When did HIV arise in human populations Molecular clock Phylogenies can be used to test hypotheses Did April s boyfriend physician attempt murder by injecting her with HIV Yes he did Hypothesis 1 April s HIV sequences are more like patient Hypothesis 2 April s HIV are more like a random sample