7 Evidence For Evolution Flashcards
What is artificial selection?
There is large variation in species generated by human-driven selection
Selection based on morphology and desirable characteristics
e.g. pigeons, dogs, crops
How has artificial selection generated a new species - Primula kewensis?
New species is a hybrid between parental species P. verticilliata and P.floribunda
Speciation through allopolyploidy - the hybrid has a doubled chromosome number
Leads to instant speciation
Why was artificial speciation used as an example by Darwin?
Species are not immutable - change is possible
Accumulation of small changes
Directional change through selection
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?
Clutch size of each species has evolved to an evolutionary optimum
What is Rensch’s rule?
Sexual dimorphism increases with average body size
What do the biogeographical rules tell us?
They don’t always work
But tell us that there are common adaptive responses of organisms in different places
How can fossils act as evidence for evolution?
Fossils contained within layers of sedimentary rock
Fossil evidence allows tracing of inter-relationships, transitionary forms, and evolutionary links between major groups
Also preserved animals e.g. in permafrost
Can sequence the DNA of bones
How are homologous characters evidence for evolution?
The existence of homology shows that different groups have evolved from common ancestors
As well as showing where they have diverged
What is an example of a homologous character?
Forelimbs of birds, bats and humans show homology - comprised of same bones
Limbs of bats and birds
- They inherited these from a common ancestor
- However differences in structure means at the same time their wings are non-homologous
What are vestigial characters?
Structures that serve no function
- Presence serves as evidence of evolutionary relationships and evolutionary change
What is a universal homology?
The genetic code
How can evolution be experimented on?
Using fast-reproducing organisms - can demonstrate evolution under lab conditions
e.g. proliferating E.coli for 73500 generations
- Experimentally imposed stresses lead to evolutionary changes that can be measured
