Intro pt 2 (Meg- finished)

Question 1

Outline Charles Darwins theory

Answer 1

1. Populations change over generations
2. Gradual change
3. Speciation- change over generations mean they will eventually become so different that they become different species
4. Natural selection- part of reason why speciation occurs
5. Common descent

Question 2

What was the missing part of Darwins theory?

Answer 2

Inheritance not truly understood by Darwin- suggested blending inheritance which is incorrect

Question 3

What is blending inheritance?

Answer 3

= average of parents characteristics e.g. tall dad + short mum = medium-sized off-spring

Question 4

Name some sources of evidence of evolution

Answer 4

• Universally shared features
• Hierarchical classification (phylogeny)- morphology used originally but DNA used more nowadays
• Fossil record
• Biological relationships, geological history and geographical distributions
• Evolutionary processes can be observed directly in natural + artificial selection work (e.g. domestication) e.g. finches, malaria

Question 5

What does the fossil record represent?

Answer 5

represent extinct species that can be used to determine how species looked in the past vs how they look now

Question 6

Galapagos Islands- tortoises

Describe an example of evidence for evolution

Answer 6

Galapagos giant tortoises differ in shell shape among islands- have evolved to fit the different habitats among the different islands

Question 7

Darwins finches

Describe a method used to see evolution in action

Answer 7

Darwin’s finches- beak size in Geospiza fortis = medium ground finch observed for many years (30 years):

1. Birds arrived on Galapagos 3 million years ago + rapidly diversified like…
2. G fortis on Daphne major (= relatively untouched island)- so can measure every type of seed that finches are eating + mark and follow every individual

Question 8

Darwins Finches

Describe the results of Darwins finches experiment?

Answer 8

RESULTS =
- Beak size is heritable + makes a difference between life and death
- Drought 1977- plants all died = no seeds available so had to eat seeds harder to open
- Next years, beak size = 8-11mm survived as they were able to open seeds and then after = 9.7mm = 15% bigger
- 5 years later- lots of rain = more seeds = beak size decreased
- Correlation between average depth of parents beak and average depth of offsprings beak = evolution as heritable trait
= 1st time measured effects of natural selection had been observed in wild population

Question 9

What do present day studies of Darwins finches studies involve + what has been discovered?

Answer 9

Present day studies- apply modern genomic methods to finches by sequencing the genomes and discovered 2 different species have hybridised and made new species
= speciation- sometimes happens quick enough it can be observed

Question 10

Describe the role of Alfred Russel Wallace in evolution

Answer 10

produced similar ideas to Darwin- went to South East Asia and noticed biogeographic line (Wallace’s line) where on one side = certain types of fauna and on the other = other times of fauna

Question 11

Since Darwin, why was it thought that irish elk had enormous antlers and how has that thought changed post darwin?

Answer 11

Since Darwin- extinct Irish elk had enormous antlers = e.g. orthogenetic momentum that drove species to evolve maladaptive feature that caused extinction
But since 1940s this has been rejected and instead suggested that huge antlers were probably due to animals overall large size from natural selection caused by competition among males for females

Question 12

Who was involved in modern synthesis of Neo-Darwinism?

Answer 12

• RA Fisher
• Haldane
• Sewall Wright
• Stebbins, Simpson, Dobzhansky
• Mendel rediscovery

Question 13

What is modern synthesis / neo-Darwinism a combination of?

Answer 13

combination of mathematical approaches + genetics + Darwin’s theory

Question 14

How did the rediscovery of mendels work contribute to modern synthesis?

Answer 14

Rediscovery of works of Mendel- put into context with Darwin’s studies to understand how inheritance worked

= Theoretical advances e.g. mathematical theory of population genetics + experimental tests of theory

• adaptive evolution works by natural selection acting on Mendelian genetic variation

Question 15

Describe the 2 most famous examples of hard evidence for evolution by natural selection

Answer 15

• Peppered moth- lived on bark of trees which became blacker due to pollution = less predated on when moth had darker form which increased during industrialisation = frequency of darker moths decreased after Clean air act
• Snails have different coloured forms- believed to be entirely random but actually are a result of natural selection

Question 16

Since the 1960s, what extra elements were added to Darwins theory?

Answer 16

Neutral theory
Random genetic drift
Sex
Kin selection

Question 17

Name some people who contributed to Darwins theory since the 1960s + what did they contribute?

Answer 17

• Motoo Kimura – neutral variation = DNA changes that have no effect on survival prospects- encompassed by random genetic drift- in every generation there is random sampling of variation
• Stephen Jay Gould- Spandrels have no adaptive function = just a consequence of biology
• Mayr = very important in defining species (biological concept)
• Williams
• Smith = thought deeply about evolution of sex which Darwin’s theory lacked
• Hamilton = involved in kin selection

Question 18

Define: neutral theory

Answer 18

suggests that most of the genetic variation in populations is the result of mutation and genetic drift and not selection

Question 19

What are spandrels?

Answer 19

= byproducts of evolution. They arise due to the evolution of one trait, but this unintended trait may not have any function.

Question 20

Describe the role of Patrick Matthew in evolution

Answer 20

Note of caution-1st to elaborate principle of natural selection- - Is diversification of species a result of different living conditions?- those better suited to the environments they occupy will live longer and in turn more likely to reproduce and pass on their favourable genes = gradually species will acquire best possible adaptations – same as natural selection but has no impact

He further states- descendants of same parents, can be very different and in many generations time can even become distinct species that are incapable of breeding

Question 21

Why does the credit for theory of evolution go to Darwin and not Patrick Matthew?

Answer 21

In science = credit goes to person who can convince the world of an idea not the 1st to come up with the idea

Question 22

Was lamarck completely wrong?

Answer 22

Lamarck’s theory of inheritance completely wrong, but modern articles discuss epigenetics = something encountered in one generation that imprints on genes which is then passed onto next generation

Question 23

Name some examples of other people involved in development of theory of evolution

Answer 23

• George Cuvier
• Cuvier + Lamarck- sacred ibis
• Scottish-English gentlemen
• Etienne Geoffroy Saint
• Comte de Buffon

Question 24

Describe the role of George Cuvier in evolution discovery

Answer 24

George Cuvier (=comparative anatomist) - 1769-1832 = founder of palaeontology + believed in catastrophism = earths major geological features arose through sudden catastrophic large scale events rather than slow gradual change- not observed or testable

• Principles of correlation of parts = can inspect single bone and determine class + maybe genus of animal in which it belonged
• Understood each areas had particular fauna
• Proved extinction
• Still opposed idea of evolution

Question 25

Describe the sacred Ibis story

Answer 25

Egyptians had keen interest in Ibis bird- suggested to be because they controlled invasion of flying snakes but was discovered that they eat shellfish
1. Mummified bird sent to Paris
2. Discovered to be modern ibis species by Cuvier + Lamarck

Question 26

How did Cuvier and Lamarcks view differ on the discovery of the modern Ibis species?

Answer 26

Cuvier = Ancient remains of Ibis species identical to modern Ibis species = evidence for fixity of species

Lamarck = Instead suggested gradual change of species overtime by evolution

Question 27

Name all the scottish-English gentlemen

Answer 27

• Erasmus Darwin
• Charles Lyell
• Robert Chambers
• Patrick Matthew
• Thomas Malthus

Question 28

Describe the role of Erasmus Darwin in the discovery of evolution

Answer 28

Erasmus Darwin (=Godfather of Charles Darwin)- suggested all species descended from minute aquatic filament in a poem + in latter work suggested earth and life on it has been evolving for millions of ages before mankind

Question 29

Describe the role of Charles Lyell in the discovery of evolution

Answer 29

Charles Lyell (= geologist)- champion of uniformitarianism in principles of geology = all the processes that have generated geological patterns which are still in operation nowadays- which can be testable and suggests gradual change- had influence on Darwin but not considered to be an evolutionist

Question 30

Describe the role of Robert Chambers in the discovery of evolution

Answer 30

Roberts Chambers- principle of progressive development- hypothesised that new species arise from old ones as he observed species changed overtime which was gradual and unlinked to catastrophes- considered 1 of 2 pre-Darwinian 19th century British evolutionists

Question 31

Describe the role of Etienne Geoffroy Saint in the discovery of evolution

Answer 31

Comparative anatomist- father of principle of connection
- Not considered evolutionist as didn’t distinguish between similarities (homologous = share similar evolutionary origin but not similar function) due relationships and those due to convergence (analogous = share similar function but not evolutionary origin)

Question 32

Describe the role of Comte de Buffon in the discovery of evolution

Answer 32

suggested species could change over generations but rejected that they could evolve into other species