Earth Science Midterm

Lectures 1-11

What does natural selection imply about survival and offspring?

An organism best equipped to survive its environment is most likely to bear offspring and those offspring will pass on advantageous traits to their offspring

How are traits passed on according to Mendels Law of Particulate Inheritance?

Traits are passed on like “particles”, not as a “fluid”. Factors are discrete entities that are not diluted.

What were the two main things Darwin’s Origin of Species did?

1. Summarized all the evidence in favour of the idea that all organisms have descended with modification from a common ancestor building a strong case for evolution

2. It suggested for the first time natural selection as a mechanism of evolution

What does the school of Modern Synthesis attempt to explain?

It explains how evolution works at the level of genes, phenotypes, and populations.

What organism did Thomas Hunt Morgan study for genetics research?

Fruit fly, Drosophila Melanogaster

What striking variation do Drosophila (fruit fly) show?

Eye colour

What does Hardy Weinberg equilibrium concept show?

This concept shows a mathematical baseline for a non evolving population

What did Fisher, Haldane, and Wright conclude?

They recognized that natural selection is the only evolutionary mechanism compatible with the new discoveries in genetics

What did John S. Haldane develop?

He developed mathematical models of allele frequencies in individual genes in theoretical and natural populations

What did Ronald A Fisher study?

He studied the statistics of gene flow - the mixing of genes between populations

Who were the Major players in mathematical theory of population genetics?

1. John Haldane

2. Ronald Fisher

3. Sewall Wright

What does genetic drift imply?

It means that changes in a populations genetic makeup can happen due to pure luck not just natural selection

What is bottleneck effect?

When a population is sharply reduced in size by a natural disaster or other non ongoing selective factor

What is the founder effect?

When a small group spilts off from a main population to start a new colony leading to changes in genetic composition

What did Fisher, Haldane, and Wrights work integrate?

• Mendels theory of inheritance

• Genetics as the cause of continuous variation

• Genetics as a factor that allows variation to be maintained

What was the significance of Step 1 (Integration) in the Modern Synthesis?

It established that Darwin’s natural selection and Mendels concept of particulate inheritance are compatible.

Modern Synthesis (example)

Evolution of “Simpsons Horses”

Who discovered the double helical structure of DNA

Francis Crick and James Watson

Whose experimental data was crucial to the discovery of DNAS structure?

Rosalind Franklin