lecture 2 - more evidence

Question 1

oceanic islands

Answer 1

these islands have island-specific species. they have special adaptive traits for that island. They are similar to the species on the nearest landmass. they lack land mammals, reptiles and freshwater fish

Question 2

what are marsupials and where did they originate

Answer 2

pouch animals- came from south America- walked across Antarctica and came to Australia- proof in fossils of pouched mammals in Antarctica

Question 3

convergent evolution

Answer 3

This occurs when two geographically isolated species in two different locations evolve to have similiar appearance due to similiar environmental conditions.

Question 4

examples of natural selection

Answer 4

peppered moth

lizards in the Caribbean islands

Question 5

importance of genetic sequence data

Answer 5

suggests that all organisms have the same ancestors

track evolution by comparing gene sequences- explain why species split

Question 6

molecular clock

Answer 6

This is a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged- genetic difference accumulate at a constant rate-some mutations form junk DNA because DNA is redundant and this is not seen by random selection. this junk DNA is the best molecular clock to see evolutionary patterns.

Question 7

olfactory receptors

Answer 7

68% doesn’t work in dolphins and whales- stop codon( pseudogenes) - proof of evolution by natural selection

Question 8

lactose intolerance

Answer 8

lactase persistence levels depend upon the geographical areas- areas in the UK did not have cow milk and hence large amounts of lactose intolerance

Lactase persistence shows strong evidence of natural selection.

Question 9

neutral theory

Answer 9

A large fraction of new mutations do not have an effect on the evolutionary fitness of an individual, so they would not be favoured or disfavoured by natural selection.

Question 10

example of convergent evolution

Answer 10

distantly related animals with similar traits- eg: North American porcupine and crested porcupine, last common ancestor 45 mya with no quills- both species developed quills separately

Question 11

divergent evolution

Answer 11

This is effectively speciation. Occurs when two groups of the same species evolve and look different due to different environmental conditions

Question 12

State which type of mutations can be described as being selectively neutral

Answer 12

Mutations found in non coding DNA. These do not code for protien, so do not change phenotype of organisms. Such mutations are not selected and hence evolve randomly.