BIOL1003 Lecture Notes - Lecture 5: Graduated Cylinder, Phylogenetic Tree, Uniformitarianism
BIOL1003: Module 1 Evolution
Lecture 5 – Darwin, Owen and Homology
• Darwi did’t just appear, uilt o preursors
o Lyell's uniformitarian geology, Linnaeus's nested hierarchy
• He started with smaller projects, and gradually built up expertise and authority
o Uplift of the Andes, origin of coral atolls
• Publication was very important
• You cannot understand evolution without understanding some geology, ecology, etc.
• Evolution has many meanings
o Gradual can mean stepwise, graduation, graduated cylinder
• Best definition of evolution is "decent with modification"
Darwin's Career
• A page from Darwin's notebook from 1837, he draws the first biological phylogenetic tree
o Why the nest of hierarchy exists (Linnaeus)
• Population - gave a reason for population competition
• in 1858 Darwin and Wallace - joint readings of natural selection papers
• 1859 - Origin of Species
• Did’t etio huas util 11 i The Decent of Man, a selection in relation in sex
• Perhaps is the last scientist to cover so many fields (experimental botany, barnacle work as
well as the theory of natural selection)
Darwin After the Beagle
• Mockingbirds - thought they were just varieties of different mockingbirds
o John Gould - said that these were in fact different species (different island, different
mockingbirds)
o Same with finches - the morphological differences made Darwin think they were
different species
• Gould said that they were in fact the same, very closely related to each other than
anything else
o 2nd edition of the voyage of the Beagle - hints that Galapagos Islands animals were
unique, and must have come up after the dawn of time
• Darwin needed to establish himself as a traditional naturalist - so he decided to study
barnacles
o Studied barnacles for 8 years, classifying living and fossilised barnacles
o Recently discovered that barnacles are more closely related to ccrustaceans than
molluscs
• Richard Owen
o Coined the word "dinosaur"
o Defined homology
• Same organ in different animals under every variety of form and function
• On the Nature of Limbs - the penta
• Similarities between the limbs of a fin, wing, arm, leg, etc. Although differ in
function
• Different from analogy - which is similarities in limbs that can be attributed to
similarity in function
• Extended from limbs, and said the whole vertebrae as a massive example of
analogy (skull, spine, ribs)
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