2: Evidence for evolution Flashcards
What is artificial selection? Give some examples
→ human generated evolution
Examples:
Pigeons, dogs
Wheat: originally Eichorn → heritage wheat → modern wheat
Beta Vulgaris → beetroot, chard
= all still same species e.g dogs can breed with wolves
Give an example of how artificial selection can create new species
Hybrid between Primula verticillata & Primula floribunda
Speciation through alloployploidy → the hybrid has double the chromosome number of the parents
‘Instant speciation’
More common that you think: 40-70% of plants are polyploids
What is Bergmann’s rule?
animals get larger further North
What is Allen’s rule?
animals in colder climates have thicker limbs
What is Lack’s rule?
the clutch size of each bird species has evolved to an evolutionary optimum
What is Rensch’s rule?
sexual dimorphism increases with av. body size
What do differences in space demonstrate?
Past speciation
Example:
Diff species. But distantly related
Now inhabit similar locations
Give an example of instant speciation in animals
- House sparrow: very widely distributed
- Spanish sparrow: restricted distribution
- Italian: even more restricted, just in Italy
- House & Spanish sparrow species interbred = hybrid, Italian sparrow
= Now a distinct species
What can the fossil record be used for? (In relation to evolution)
→ mapping evolution through deep time
Can trace inter-relationships and transitional forms (e.g transition between dinos and birds)
More recent: preserved animals in permafrost and peat
What are homologous characters?
Give an example
= traits inherited from a common ancestor
Existence of these characters provides evidence for evolution from common ancestors
E.g Limbs of bats and birds (each have 2 pairs), are homologous = common ancestor
But, their wings did evolve independently and are structurally different = non-homologous
What are vestigial characters?
Give an example
= Extant organisms have structures with no function
Presence provides evidence for evolutionary relationships and evolutionary change
E.g Whales possess pelvis bones, linking them to terrestrial mammals, eyes of cave dwelling fish become vestigial = change in response to environ
What is the ‘universal homology’?
Genetic code
Describe experimental evolution. Give an example
→ Generating evolution in the lab
Using fast-reproducing organisms
Richard Lenski et al. proliferated E.coli for 73,500 gens
- 12 founding pop.s and all showed the same evolutionary response to conditions
- Experimentally imposed stresses lead to evolutionary changes that can be measured
- Can be used to test evolutionary theories
