Natural Selection and Evolution Flashcards
1
Q
Definition of evolution?
A
-change in gene frequencies over time
2
Q
Definition of natural selection?
A
-sifting of variation to produce adaptations
3
Q
Definition of genetic drift?
A
-random sampling of individuals over time
4
Q
Definition of founder effect?
A
-small group of individuals ‘bud off’ or survive by chance
5
Q
What are the different types of evidence for evolution?
A
- fossil record
- observations of similarities and differences between living species
- natural selection acting within species
- evolutions in action (observing changes in real time)
6
Q
What are fossil records?
A
- 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
7
Q
What are observations of similarities and differences between living species?
A
- 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…)
8
Q
What is natural selection acting within species?
A
- 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)
9
Q
What are evolutions in action (observing changes in real time)?
A
- can be produced experimentally
- on small-scale evolution can be observed ‘in action’
10
Q
What’s a phylogenetic tree?
A
- 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