BIOL1020 Lecture Notes - Lecture 2: Jean-Baptiste Lamarck, Lamarckism, Binomial Nomenclature
Lecture 2 - Evolution !
Taxonomy: the way to classify groups in biological systems !
History !
Aristotle (384–322 BCE) !
•father of taxonomy, developed Scala Naturae: “Ladder of life”, based on function and
complexity of organisms. !
•He organised all things in the natural world, living and non-living. !
•The ladder went from "lower" forms of matter to "higher" forms of matter. !
•Everything has a place and species cannot switch places. !
•The implication of this is that species are immutable.!
Carl Linnaeus (1701-1778) !
•Developed hierarchies based on morphological characteristics (E.g. color, pattern, bones,
organs) !
•He pioneered binomial nomenclature (E.g. Homo sapiens)!
Both Aristotle and Linnaeus operated under the “Doctrine of fixed species” – all forms of nature
were fixed and could never change. !
Jean Baptiste Lamarck (1744-1829) !
•refuted this by developing the theory of Lamarckian Evolution.!
•He believed that an organism’s traits could change throughout its lifetime through use and
disuse, and that this new trait could easily be passed on to offspring !
•E.g. Giraffe’s long necks were the result of continually stretching to reach high places; these
long necks were then passed down through the generations. !
•The problem was that in reality, it is very hard to pass on a trait even though the organism can
change trait through its life time.!
Charles Darwin (1809-1882)!
•questioned the Doctrine of fixed species but with an alternate theory!
•Formulated the theory of evolution by natural selection.!
•There was a shared common ancestor and different environmental conditions led to individual
evolutionary changes of each species. After millions of years, they still retained the core
“homologous structure”. !
Diversity and unity through evolution !
•After an environmental change, a physical trait may give a survival advantage (E.g. presence of
an antibiotic resistance gene in bacteria) !
•Organisms with that trait are going to be be “selected for” in that environment, but not
elsewhere without that selective condition.!
•Environmental change —> selective pressure over time —> new species $
DNA!
•the physical traits mentioned above in evolution are passed on through DNA!
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Document Summary
Taxonomy: the way to classify groups in biological systems. Carl linnaeus (1701-1778: developed hierarchies based on morphological characteristics (e. g. color, pattern, bones, organs, he pioneered binomial nomenclature (e. g. Both aristotle and linnaeus operated under the doctrine of xed species all forms of nature were xed and could never change. After millions of years, they still retained the core. Some facts about dna: 4 nucleotides make up the whole genetic sequence, bigger organism does not mean bigger genome. It is the complexity of the organism that determines the size of the genome. Prokaryotes: greek word pro (before) + karyon (nut or kernel, they do not have a nucleus, do not have membrane bound organelles, bacteria and archaea. Eukaryotes: greek word eu- (good/true) + karyon (nut or kernel, they have a nucleus and organelles, animals and plants. Cytoplasm: semi- uid matrix, contains chemicals of cell sugars, amino acids, proteins, organelles (in eukaryotes)
