Lecture 1 - Introduction to the module & evolution Flashcards
What 2 problems did Charles Darwin solve in his book - “Origin of species”
- The problem of history
- The problem of design
What is an example of the problem of history?
A human arm, a bat wing, and a horse leg all contain a humerus, ulna and metacarpals - yet all are different shapes and serve different purposes
What is a molecular level example of the problem of history?
Cytochrome C (a protein molecule)
Similarity of the protein between humans and Rhesus monkeys - around 103 similarities
The more similar animals look, the more similair the structure of Cytochrome C
How did Darwin solve how to explain relatedness though his theory of evolution?
Proposed that what underpinned the relatedness of species was TIME - since they shared a recent common ancestor - solved the problem of history
What is the problem of design?
That species look like they are perfectly designed and well adapted for their surroundings - i.e fennec fox in summer, arctic fox in winter - no explanation for how and why they adapt
What is a very complex example of the problem of design?
Bat - hunt their prey using echolocation which requires neurochemistry to receive and perceive the sounds, have to turn off their own hearing - people thought that the only way this occurs is if someone had designed bats
What is an example of the problem with design where the design doesn’t make sense?
Whale pelvis - serves no purpose to the whale (known as a vestigial structure)
How did Darwin solve the problem of design?
Realised that adaptation is explained by slight changes over generations.
-Useful adaptations more likely to be retained
-Useless ones more likely to disappear
What are Darwin’s 4 main theories?
- Variation
- Heredity
- Competition
- Natural Selection
What are homologies?
Similarities between organisms due to common ancestry
What is an example of an homology?
The human pelvis and the whale pelvis - at one point the human and whales had the same ancestry
That humans, bats and horses all have a humerus and ulna
What are analogies?
Similarities due to parallel selective pressures
What is the Modern Synthesis?
Mendel’s work was understood to have provided the mechanism for Darwin’s theory to work, and the mathematical foundations of evolutionary theory worked - 1930s
What is a real world example to prove the theory of evolution?
Drought led to changes in sizes of food - birds beaks size increased due to only large seeds/foods available - birds with smaller beaks died due to not being able to eat - less reproduction but more big beak sizes of offspring
What is the misunderstanding of “there are gaps in the records”?
General public argue this
Best evidence is living animals, i.e looking at homologies and analogies
Fossils are an added bonus to evoultion
What is the misunderstanding of “Things are too complex to arise like this”?
Natural selection is not a chance thing - retain the positive complex abilities
What is the common misunderstanding of “Evolution is only in the past”?
Evolution is not only in the past, explanations help show why things occur in the present day.
i.e a common example is that nausea and vomiting at pregnancy have been selected for as they benefit the survival of the foetus - less chance of miscarriage
What are patterns of homology and divergence best explained by?
Descent with modification from a common ancestor.
