Flashcards in 5. Introducing Evolution Deck (22):
'Evolution' has several meanings, but what is the gist of the word?
gradual development of something
What is the biology specific definition of 'evolution'? When does evolution, therefore, occur?
- changes that occur in living organisms over many generations
- when heritable characteristics of a species change
Has the theory of evolution been proved?
- but there is very strong evidence
What can happen to populations within a species? What happens if this occurs?
- they can become separated and unable to breed with each other (because of geography)
- they evolve differently and their characteristics diverge
How long does it take for populations of the same species to develop different such different characteristics that they can no longer interbreed? What has happened when this is the case?
- but thousands of years or more
- the two populations are said to be different species (if they can no longer interbreed)
What do taxonomists do?
classify living organisms into species
What do taxonomists argue about (not a joke)?
whether populations in different geographical areas are part of the same species or are different species
Why do the arguments between taxonomists occur?
there is continuous variation in the amount of difference to populations
What idea does evolution not fit with?
creationism - distinct species being created and not evolving
How many groups of vertebrates have limbs? What are the names of the groups?
Of the vertebrates that have limbs, how are the limbs used?
variety of ways:
Vertebrates (with limbs i.e. not fish) use their limbs in a variety of different ways. What is the same in all of them?
the basic bone structure
What is the vertebrate limb structure known as?
the pentadactyl limb
What is the most plausible explanation for the pentadactyl limb?
all vertebrates share an ancestor that had pentadactyl limbs
If many different vertebrates evolved from one ancestor with the pentadactyl limb, how come the limbs developed in wildly different ways? What type of evolution is this?
- the vertebrates adopted different types of locomotion (movement) so the limbs developed differently to suit the type of locomotion
- adaptive radiation
What is adaptive radiation?
- the diversification of a group of organisms into forms filling different ecological niches (dictionary definition not IB)
What are homologous structures?
structures (like the pentadactyl limb) that have evolved from the same part of a common ancestor
What would call a 'structure that has evolved from the same part of a common ancestor'?
a homologous structure
What are the features of a homologous structure?
- similarities of structure
- despite the differences in function
Can homologous structures be explained in any way but evolution?
- not really
Draw a diagram of a pentadactyl limb structure. (p63)