micro and macroevolution Flashcards
what is co-speciation
a form of coevolution in which the speciation of one species dictates the speciation of another species
what are clades
aka a monophyletic group is a group of organisms composed of a common ancestor and all its lineal descendants
what is meant by the term analogous
structures which have separate evolutionary origins but are superficially similar as a result of convergent evolution
define convergent evolution
the independent development of similar traits or features in unrelated or distantly related species
define macroevolution
looks at evolution on a grand scale looking at the over-arching history of life
what are the four mechanisms of change
- mutation
- migration
- genetic drift
- natural selection
what are the different patterns of macroevolution
1) stasis
2) character change
3) lineage splitting
outline the pattern of macroevolution - stasis
no change for a long period of time e.g. the coelacanths
outline the pattern of macroevolution - character change
when lineages change quickly or slowly
outline the pattern of macroevolution - lineage splitting/ speciation
the formation of a new and distinct species in the course of evolution
what is microevolution
evolution on a small scale within a single population = narrowing the focus to one branch of the tree of life
define a population
a group of organisms that interbreed with each other = all share a gene pool
what are the two ways of detecting microevolution
- a change in gene frequency in a population
- a group of organisms that share a common gene pool
what is the problem with the definition of a population referring to interbreeding individuals
hard to apply to organisms that reproduce only or mainly asexually
also many species form hybrids etc
define speciation
a lineage splitting event that produces two or more sperate species
how can speciation occur
1) allopatric speciation
2) reduction in gene flow
what is allopatric speciation
when species are separated and become geographically isolated from each other
how can speciation occur as a result of reduced gene flow
if a population extends over a large range and mating throughout the pop is not random there is reduced gene flow
how long ago did mammals evolve
200 million years ago
how long ago did animals evolve
600 million years ago
