Natural Selection and Evolution

Question 1

Definition of evolution?

Answer 1

-change in gene frequencies over time

Question 2

Definition of natural selection?

Answer 2

-sifting of variation to produce adaptations

Question 3

Definition of genetic drift?

Answer 3

-random sampling of individuals over time

Question 4

Definition of founder effect?

Answer 4

-small group of individuals ‘bud off’ or survive by chance

Question 5

What are the different types of evidence for evolution?

Answer 5

• fossil record
• observations of similarities and differences between living species
• natural selection acting within species
• evolutions in action (observing changes in real time)

Question 6

What are fossil records?

Answer 6

• intermediate forms are present continuously in the fossil record
• order of fossils suggests evolutionary perspectives
• some species around today appear ‘unchanged’ from when their evolutionary history began

Question 7

What are observations of similarities and differences between living species?

Answer 7

• analogous
• homologous (e.g. structure ends with 5 digits but is used for different purposes)
• study of developmental patterns may illustrate evolutionary patterns
• vestigial structures suggest evolutionary descent (limbs are no longer adaptive but remains are seen in skeleton)
• phylogenetic approaches (understanding evolution by comparing features of extant species)
• 2 changes are more likely to have occurred than 4 changes
• problems with evolutionary classifications based on external features
• universal homology is more reliable than looking at external features
• phylogenetic approaches (aspects of species historical past and current ecology can explain…)

Question 8

What is natural selection acting within species?

Answer 8

• selection is a designing agent
• only mechanism known to cause the evolution of adaptations that make individuals fitter
• acts to sift variants of behaviour, favouring those that provide their bearer with greater representation in next generation
• explains why individuals are well adapted to environment
• selection for survival
• selection for reproductive share (most adaptations are complex and have appearance of design that can’t arise via random processes)

Question 9

What are evolutions in action (observing changes in real time)?

Answer 9

• can be produced experimentally

- on small-scale evolution can be observed ‘in action’

Question 10

What’s a phylogenetic tree?

Answer 10

• a diagram showing inferred evolutionary relationships
• any characteristic can be used to infer relationships and build a tree
• the closer the branches are the more similar they are than those with sequences separated over longer evolutionary distance