AntA01 Lecture 2
Evolution: Descent with Modification
What is Evolution?
Natural Selection – five traits
-Change in frequency of genetics
-Adapting to your Environment
-Survival of the fittest
Evolution works on POPULATIONS not INDIVIDUALS
A species evolves
What is a species?
- a group of creatures that can breed together and can produce viable and fertile offspring
- Species may be quite similar in appearance (eg: deer) or quite variable (dogs)
- Giraffes are an exception to shared behavioural traits relating to social groups etc. since the
giraffes from East Africa and others from South Africa have different behaviours like mating
rituals which they cannot read so they don’t mate even though they are genetically identical.
- Before the enlightenment period
- He boarded the SMS Beagle that he
- Afraid of commiting heresy
- 1 book = The origin of species
- 2 book = the descent of man
- Story of genesis
- Darwin questioned the origin of man
- Tried to figure out the origin of the world calculating the age of the earth using the generations
in the bible. He found the earth around 6000 yrs old.
- After this, the enlightenment period began George Cuvier
- Geologist who found strange morphologies of rock and to this he decided that there were
massive catastrophes that occurred in the past to create rivers, mountains, etc
- Reverend Burnet – you can see processes in action (not necessarily catastrophic) they are just
slow (such as erosion)
- People come up with ideas but were scared of heresy
- Def’n: The processes that work on the planet in the past also occur today
- Buffon: there were 6 different epochs in the world but he was forced
- Hutton: world was probably 100,000’s of yrs old
- Lyell: looked at the deposition rate of the mississipi delta and tried to guess the age of the world
- Reverend Chalmer: Change the topic of the discussion to maybe Ussher was wrong
- Establish the classifications of species the way we know today (7 layers)
- Binomial system (genus and species naming system)
- He named humans in the system
- He was a very devout man
- Known for comparative anatomy – arm (radius and ulna) and 5 fingers
- He noticed that we are a very primitive sort of mammal
- They found that people not named in the bible – they treated them very badly
- Handaxes- They are made of stone and are stones and huge – but the bible says that tool use
came from recent times
Life on Earth had Changed
- They found fossils which they couldn’t account for from the bible
- Strata – deposits
- They found that the bottom layer is older than the top layer
- Question in the 1800’s changed to: How did the Earth change and how did species change
- Darwin was not the first to come up with change
- HOWEVER Lamark was NOT mechanism of change since his ideas were not right
- Number 2 is wrong!! There is no end goal!! HE thought that eventually humans become angels
and worms could eventually become human etc. - Number 3 is slightly wrong since if you change something about yourself doesn’t mean that if
you have a child they will also be born with this too.
Darwin and Wallace
- Natural Selection: variation already exists in populations
- Survival of the fittest increases frequency of trait
- VARIATION IS RANDOM!!! THERE IS NO DIRECTION!!!
Case Study: Grant and Grant 2002
- Darwins finches- they are related but they have slight changes depending on what they eat
- Santa Cruz- insect eating finches
- Drought lasted 10 years
- At the end of the 10 years the finches looked more like the seed eating finches no longer like
insect eating finches.
- Immediately after this drought, insects came back and now again it went back to insect eating
finches beak--> THERE IS NO DIRECTION!!!
- No direction which is the definition of natural selection
- In order to be successful, you have to reproduce and survive
- Unfavourable variations usually don’t survive or are not able to reproduce so they are removed
- Natural Selection is the MECHANISM OF EVOLUTION
HOWEVER! The Mechanism works on GENES!!!!