Phylogeny and Systematics5 Kingdom classification system in use through the late 1900sMoneraProtista (unicellular, eukaryotes)Plantae (photosynthesis, multicellular eukaryote)Fungi (feed by absorption, eukaryote, most are multicellular)Animalia (eukaryote, multicellular, feed by ingestion)Place according to similar homologous structuresOutdated, no longer used, used through 1900sNow it’s the three domains (eukaryotes, bacteria, archaea)Prokaryotes are different from ProtistaThree Domain SystemDr. Woese by sequencing certain segments of all species DNADNARNA(rRNA)proteinsBacteria and Archaea used to both be in Monera which was very wrong, they are differentWithin the three domains are multiple kingdomsBacterial kingdoms (Bacteria)Archaean kingdoms (Archaea)Protistan kingdoms, Plantae, Fungi, Animalia (Eukarya)BacteriaArchaea (DNA, RNA sequence more similar to Eukarya than Bacteria)EukaryaClassificationsTaxon (taxa)- the named taxonomic units at any level in this taxonomic hierarchyMost inclusive- domainLeast inclusive- species (homo sapien)Did King Philip Come Over For Gumbo Sunday?Domain (Eucarya)Kingdom (Animalia)Phylum (Chordata)Class (Mammalia)Order (Carnivora)Family (Felidae)Genus (Panthera)Species (Panthera pardus)Panthera- genusPardus- specific epithet that refers to one species in the genus PantheraLinnaeus convinced us to use a hierarchical classification systemDarwin provided us with the mechanism by which evolution results in descent with modificationThese two bring us to phylogenetics- reconstructing the evolutionary relationships among organismsMacroevolution and PhylogenyPhylogenic tree- hypothesized genealogy traced back to the last common ancestor (the most recent) through hierarchical, dichotomous branchingCladistics- the principles that guide the production of phylogenic trees (cladograms)Able to date species in two ways:1. Radiometric dating of fossils (more accurate)2. Observation of differing nucleotides in strands of DNA of different species with common ancestorsNode- branch point; speciation eventLineage (clade)- an entire branchA clade is a monoplyletic group, an ancestral species and all its descendantsA paraplyletic group consists of an ancestor and some of its descendantsA polyphyletic group lacks the common ancestor of species in the groupThe fossil record is especially valuable, and the only option for many extinct taxa.Cladistic principles allow us to construct hypothesized phylogenetic treesCladistic AnalysisFossils provide morphological data for extinct species, whereas comparisons of multiple types of traits- including molecular do so for extant speciesSimilar characters (morphological, behavioral, molecular, etc. traits or features) suggest relatednessBut, not all similarity derives from common ancestry. Convergent evolution can produce superficially similar traits that lack homologyAs a general rule, the more homologous characters shared by two species, the more closely related they are.Sequences of DNA and RNA (nucleotides) and proteins (amino acids) and used as characters; as a general rule, the more recently what two species were same species, the more closely their characteristics should be.Cladistic Analysis (family trees that show relationship between extinct and alive creatures)All similar charactersAnalogiesHomologiesShared primitive characters (ancestral)Unique to mammals- eyes (insects also have them)Shared derived characters (unique to a clade)Unique to mammals- body hairThis is significant because these traits that are specific describe that part of the family treeThe sequence of branching in a cladogram then represents the sequence in which evolutionary novelties (shared derived characters) evolvedCladistic AnalysisIngroup vs. outgroupIngroup- the group whose relationships we are trying to resolveOutgroup- a species (or group) known to have an older more recent common ancestor with the ingroup than the ingroup’s most recent common ancestorAn outgroup helps identify shared ancestral and shared derived characters (unique to a clade)All come from one line and break off part of a node marking a speciesParsimony and Occam’s RazorOccum’s Razor- the simplest answer is the most likely answerThe most parsimonious tree is the one that requires the fewest evolutionary events (appearance of shared derived characters)On this most parsimonious cladogram, each key character originated (evolved) onceSometimes these are wrong (dolphin goes with tuna or leopard)Have to choose the least number of evolutionary traitsLook at example in powerpointMacroevolution and PhylogenySometimes the most parsimonious arrangement for one character is not the most accurate overall…As you incorporate other data you have to change your thoughtsCannot tell ageDon’t confuse the age of a clade with the age of its component species*************************************************************The Hidden World of MicrobesMicrobes- too small to be seen clearly without a microscopeProkaryotes range in size 0.2-1.0micrometersUnicellular eukaryotes range in size 10-100 micrometersHow big is a micrometer- 1/1,000,000 of a meterThe period is about 1000 micrometersThe chloroplast of eukaryotic plant cells, plasmids, bacteria, and cyanobacteria has circular chromosomes in structureEukaryotic nuclear DNA is linearThe mitochondria of eukaryotic cells is circular (mitochondrial DNA)People have 2 genomes: nuclear DNA- linear, mitochondrial-circularPlants have 3 genomes: chloroplast- circular, nuclear DNA- linear, mitochondrial-circularMutualistic symbiotic relationship (ecoli and colon of a human) both benefit from living togetherParasitic symbiotic relationship (when human eats ecoli from deer meat) one benefits and the other is harmedInfluenza attacks the respiratory system in humans, but the digestive system in birdsOther “biological” entities (not really living things cannot replicate on their own)- even smaller than bacteriaNot organismsViruses- small (0.05-0.2 micrometers) and come in many different shapes1. Genome- genetic information. Can be either single-stranded or double stranded DNA or RNA. (chicken pox, varicella zoster- double stranded DNA, HIV- single stranded RNA, influenza- single stranded RNA)2. Capsid- protein coat which surrounds and protects genome3. Envelope- membrane (phospholipid bilayer) which surrounds the capsidHijack cells- highly specific for organism it infectsVirus must 1. Find host cell 2. Gain entry 3. Release genome/replicate 4.
View Full Document
Unlocking...