EPS SCI 15 Lecture Notes - Lecture 4: Second Voyage Of Hms Beagle, Philosophie Zoologique, Banteng
29 Apr 2018
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Lec 4: Evolution
April 12
WHY EVOLUTION?
● we have so many different species of animals on Earth
○ pie chart of us, cows, reptiles, fish, birds → we’re such a small part of the world
○ there are tens of thousands of species of insects in the world
● “Nothing in biology makes sense, except in the light of evolution”
○ there are many different types of cow that share very similar features, and exist in
the same Genus (ex. cow, guar, yak, banteng, zebu)
○ there are very different animals that superficially look very different to one
another (ex. emu, ostrich, rhea)
○ why are there such strange and different and exotic animals in Australia?
○ why aging?
● Goals:
○ Explain Darwin’s idea
○ Explore phylogenies
THE ORIGIN OF “THE ORIGIN OF SPECIES”
● many medieval naturalists believed in spontaneous generation and transmutation
(one
type of life form would turn into another type)
○ geese would fly away during winter and return later in the year → never saw
goslings (believed that particles turned into geese)
○ Jean-Baptiste Lamarck
- believed that spontaneous generation creates life, and
moves up the “chain of being”
■did not believe in common descent
■ wrote Philosophie Zoologique
(1809) → many people pushed against this
idea
○species immutability
- species were fixed (ex. mice make mice, people make
people, etc.)
■ strong proponents = Georges Cuvier, Richard Owen, geologist Charles
Lyell
■ distinct idea from a “literal” reading of the Bible’s Genesis
● there was growing evidence for evolution (in a broad sense) → but there was no ideas
for a mechanism (similar to original problem for continental drift hypothesis)
○Charles Darwin
- liked exploring and looking at (naturalist)
■ part of wealthy family → afforded him certain opportunities, like becoming
the naturalist for a significant voyage
○Beagle Voyage (1831)
- Darwin set off from Europe towards parts of South
America, Galapagos, and Australia
■ recorded plants / animals (what life was like in other parts of the world)
■ endemic species
: species that is unique to a certain region
●(ex. Rhea is endemic to South America)
● one type of flightless bird in one region, and another type of
flightless bird in another region
■saw that some animals that currently existed shared many similarities with
fossils, or extinct animals (ex. sloths, anteaters, armadillos)
■ Galapagos Islands
● some birds had large, hard beaks → ate seeds
○ other birds had very narrow beaks → ate cacti
● some tortoises had longer necks → fed on taller cacti
○ other tortoises had shorter necks → fed on lower-lying
shrubs
■The Origin of Species
(1859) - Darwin spent lots of time gathering
evidence for his hypothesis (written 28 years after the voyage)
● examined different breeds of pigeons
DARWIN’S THEORY OF EVOLUTION
●common ancestry
: all things share common ancestry in the past
○ ex. Why are there so many cow-like creatures?
■ all of these animals share a relatively recent common ancestor
■ Aurochs (Bos primigenius
) = common ancestor
●natural selection
: the differential survival and reproduction of individuals due to
differences in phenotype → certain traits allow for higher chance of surviving to
reproduce
○phenotype
: observable traits (ex. behavior, metabolism, physiology,
development, morphology, etc.)
○1) variation
■ (ex. green frogs and yellow frogs)
○ 2) competition
■ (ex. easier for snakes to see yellow frogs than green frogs)
○ 3) heritability
■ (ex. green frogs produce green frogs, yellow frogs produce yellow frogs)
■ more green frogs surviving means that they can reproduce and pass on
their genes
● Implications of Natural Selection: there is no long-term goal → depends based on the
environment at the time (certain processes favor certain characteristics)
○ individuals do not evolve, populations do
○ phenotypes that do not increase fitness will be removed over time by natural
selection
■ (ex. blind mole rat)
■ Darwin would hypothesis that. given enough time, their eyes would fully
cease to develop because they have no use for them (vestigial structures
)
○ ecological & geographic isolation often leads to new species
Document Summary
We have so many different species of animals on earth. Pie chart of us, cows, reptiles, fish, birds we"re such a small part of the world. There are tens of thousands of species of insects in the world. Nothing in biology makes sense, except in the light of evolution . There are many different types of cow that share very similar features, and exist in the same genus (ex. cow, guar, yak, banteng, zebu) There are very different animals that superficially look very different to one another (ex. emu, ostrich, rhea) Many medieval naturalists believed in spontaneous generation and transmutation (one type of life form would turn into another type) Geese would fly away during winter and return later in the year never saw goslings (believed that particles turned into geese) Jean-baptiste lamarck - believed that spontaneous generation creates life, and moves up the chain of being . Wrote philosophie zoologique (1809) many people pushed against this idea.
