TPP109 Lecture Notes - Lecture 3: Biogeography, Archaea, Phylogenetic Tree
15 May 2019
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Why no penguins at N pole and no polar bears @ S pole?
• Both poles: cold, snow-capped, surrounded by ocean
• Distribution of organisms shows evolutionary history (their connection to related
species)
o Above: main pieces of evidence Darwin used to support his theory of
descent w/ modification
• *Biogeography: study of natural geographic distribution of species
o Explains why species are where there are
• Penguins first appeared near New Zealand while PB only live in arctic
• Arctic & Antarctic weren’t always so far away from each other
o Happed bc of *plate tectonics
Are creatures that look alike always closely related?
• Exp: Polar bears share traits w brown bears (they’re cousins), evidence they have
a common ancest.
• Species that aren’t related may have similarities bc of natural selection
(*convergent evolution)
How many species are there on Earth and how do scientists keep track of them?
• Modern estimates: 5-30 mil.
o App. 1.5 mil: formally described
▪ Many found in diversity hot spots (exp. Rain forests)
• To keep track…
o *Taxonomy (process how sci.s identify/name/classify org.s)
o Use smaller categories (get more exclusive as you go down list)
▪ Sometimes choosing categ. is complicated
1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
• *Vertebrates: anim.s w/ rigid backbone
Is a croc. more closely related to a bird or lizard?
• B/c all land vertebrates: 4 limbs & same forelimb bones shows all have common
acnest.
• Biolgsts. want categ.s to reflect *phylogeny (actual evolutionary history of
organisms)
