Bio 201 F11 Lect 9 (True) v2nr

Bio 201 F11 Lect 9 (True) v2nr - Biology in the News[see...

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Unformatted text preview: Biology in the News [see folder on BB] •  •  •  •  There have five mass ex:nc:ons in the last 540 million years; are we currently undergoing the sixth? The conclusion from a newly published study is yes: in mammals with risk of ex:nc:on is >50% over the next three genera:ons and look over the next 1000 years (assuming all of them are ex:nct) then the ex:nc:on level goes up to the same % of species involved in previous mass ex:nc:ons but it is not too late to avert a mass ex:nc:on in mammals: only 1‐2% of the ex:nc:ons have actually taken place ‐ in the past 500 years it is es:mated that ≥80 mammal species have gone ex:nct (among 5570 species) similar studies are needed in other hPp:// groups of organisms cntn_id=118804&WT.mc_id=USNSF_51&WT.mc_ev=click st mid term exam 1 •  •  •  •  •  •  •  •  Wed. September 28th in class covers material through Friday 9/23 lecture (first 10 lectures) prac:ce ques:ons will be posted; review sessions listed on next slide Be on :me –  >10 min late will not be allowed into room Bring only your ID and pencils –  All other materials have to be lea on periphery of the room 35 mul:ple choice ques:ons + 3 bonus bio news ques:ons lowest of the three mid terms is dropped, avg. of other 2 = 60% of your grade Only documented medical/family/accident excuses accepted •  we need to be NOTIFIED before end of the day on the day of the exam Exam 1 Review Sessions •  •  •  •  •  •  •  held in Life Sciences 026 Friday 9/23 ‐ 3:00 ‐ 4:00 ‐ Alvin Ho Monday 9/26 ‐ 2:00 ‐ 3:00 ‐ Safa Abdelhakim Monday 9/26 ‐ 4:00 ‐ 5:00 ‐ Harrison Dai Tuesday 9/27 ‐ 8:30 AM ‐ 9:30 AM ‐ Redwan Ahmed Tuesday 9/27 ‐ 10:30 ‐ 11:30 AM ‐ Dana Opulente Tuesday 9/27 ‐ 2:00 ‐ 3:00 ‐ Dana Opulente •  BRING YOUR QUESTIONS; TA’s do not make presenta:ons What is a phylogeny? •  Also called a phylogeneBc tree •  Illustrates the hypothesized rela:onships among a set of taxa (singular = taxon) More recent !me ancient Two criBcal and longstanding pursuits •  Taxonomy – systemaBc naming and ordering of taxa •  SystemaBcs – science of classificaBon and reconstrucBon of phylogeny Taxonomy DelimitaBon, naming, idenBficaBon LaBn binomial Felis catus ‐always italicize Genus name Felis Specific epithet catus Taxonomy DelimitaBon, naming, idenBficaBon, classificaBon Genus Felis Mephi*s Lutra Canis Taxonomy DelimitaBon, naming, idenBficaBon, classificaBon Family Felidae Mustelidae Canidae Taxonomy DelimitaBon, naming, idenBficaBon, classificaBon Memorize the taxonomic levels in order. All of these levels are taxa. Taxon is defined operaBonally; depending on what level you are interested in. Taxonomy DelimitaBon, naming, idenBficaBon, classificaBon animals Species/Species Genus/Genera Family Order Class Phylum / Division Kingdom Domain La*n binomial La*n ‐idae (highly taxon‐specific) (highly taxon‐specific) (highly taxon‐specific) plants ‐aceae ‐ales ‐opsida ‐phyta species nomenclature •  Genus_name species_name or G. species_name •  e.g. Homo sapiens or H. sapiens •  genus name first, capitalized – each genus has one or more species •  species name second, non capitalized –  this is called the specific epithet •  italicize both PhylogeneBc SystemaBcs ClassificaBon according to evoluBonary relaBonships PhylogeneBc SystemaBcs PhylogeneBc SystemaBcs Phylogeny construc:on depends on iden:fying homologous characters Bird and bat wings as wings are not homologous. They are homoplaseous (adj.; noun = homoplasy, homoplasies); i.e. they evolved independently BUT, their bones are homologous Two different origins of similarity Homology Similarity due to common ancestry –  Shared ancestral similarity –  Shared derived similarity Homoplasy Similarity due to other reasons (independent evoluBon of similar traits) Similarity can be misleading: Homoplasy Similarity can be misleading: Homoplasy we are now quite certain that this phylogeny is correct therefore the four‐chambered hearts of birds and mammals represent a homoplasy Phylogenies are based on shared derived characters •  Shared, derived characters = “synapomorphies” salamander Amnio:c egg Mammary glands snake mouse human Assump:ons in building phylogenies •  Characters are chosen such that –  Derived traits only evolved once in the set of taxa under considera:on –  No reversals (loss of a derived character) back to ancestral state •  Outgroup is established as branching off earlier than all the other taxa –  From independent data Phylogenies can be constructed from many types of characters/traits •  •  •  •  •  Morphology Development/embryology Behavior Physiology Molecules –  DNA and protein sequences Make sure you understand how this works ‐ ‐ ‐ ‐ many ways to construct phylogenies •  most require soaware/computa:on •  we will illustrate some of the concepts using one of the first methods: Unweighted Pair Group Method with Arithme:c mean (UPGMA) –  on a very simple data set ...
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