Bio 1202 – Exam 2 - Bio 1202 Exam 2 5 kingdom...

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Bio 1202 – Exam 2 02/28/2012 ° 5 kingdom classification systems in use through the late 1900’s – Monera, Protista, Plantae, Fungi, Animalia ° Woese’s 3 domain system – bacteria, archaea, eukarya ° - domain is the most inclusive (most members), species is the least inclusive (least members) ° taxon (taxa) – the named taxonomic unit(s) at any level in this taxonomic hierarchy - have to say the genus and species together – ex: homo sapien Linnaeus convinced us to use a hierarchical classification system. Darwin provided us with the mechanism by which evolution results in descent with modification. Together they came up with: 1) taxonomy – naming and classifying organisms, 2) systematics – naming and classifying organisms according to their evolutionary relationships, and 3) phylogenetics – reconstructing the evolutionary relationships among organisms (systematic phylogenetics) Phylogenetic tree – hypothesized genealogy traced back to the last common ancestor (i.e., the most recent through hierarchical, dichotomous branching) Cladistics – the principles that guide the production of plyogenetic trees, aka, cladograms Node – branch point, represents major speciation event Lineage (or clade) – an entire branch A clade is a monophyletic group – an ancestral species and all of its descendants Paraphyletic group – consists of an ancestor and some of its descendants A polyphyletic group lacks the common ancestor of two The fossil record is especially valuable, and the only option for many extinct taxa. Convergent evolution can produce superficially similar traits that lack homology with one another *Not all similarity derives from common ancestry! Analogous characters do not share common ancestry
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As a general rule, the more homologous characters shared by two species, the more closely they are related. Sequences of DNA & RNA (nucleotides) and proteins (amino acids) are used as characters; as a general rule, the more recently two species shared a common ancestor, the more similar their sequences. The sequence of branching in a cladogram then represents the sequence in which evolutionary novelties (shared derived characters) evolved. - shared derived characters – unique to a clade Ingroup – the group whose relationships we are trying to resolve (ex: looking at all animals that have a backbone, that’s the ingroup) Outgroup – a species (or group) known to have an older most recent common ancestor with the ingroup than the ingroup’s most recent common ancestor - helps identify shared ancestral and shared derived characters (unique to a clade) Sometimes the most parsimonious arrangement for one character is not the most accurate overall… - you do not know the age of a species from a cladogram The Hidden World of Microbes Microbes – too small to be seen clearly without a microscope - prokaryotes range in size 0.2-1.o micrometer - unicellular eukaryotes range in size 10-100 micrometers - How big is a micrometer? – 1/1,000,000 of a meter - The ‘period’ at the end of a sentence is about 1,000 micrometers - Very few bacteria cause disease Other “biological” entities – even smaller than bacteria
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