unit 6 concept 2 PATTERNS OF EVOLUTION Flashcards
patterns of evolution (7)
speciation
extinction
gradualism
punctuated equilibrium
divergent evolution
convergent evolution
coevoution
Speciation
forming of a new species by evolution for a pre-existing species
for speciation to occur… (3)
-some sort of isolation MUST occur
- gene pools gradually become different and are no longer able to reproduce
at this point the 2 groups are different species
Species
group of organisms that can successfully interbreed and produce viable, fertile offspring
Extinction
elimination of a species
2 types of extinction
gradual extinction and mass extinction
gradual extinction
occurs at a slow rate
- affects a few species at a time
eg. climate change, natural disasters
gradualism thoery
slow constant changes over a long period of time
- peppered moths
Mass extinction
occurs whena catostrophic event changes the enviornment suddenly
- effects many species across LARGE areas / global change
eg. massive volcano, metoer, tsunami
punctuated equilibrium
bursts of change followed by periods of stability
- eg. changes to mammal population during mesozoic and paleozoic eras
- Mammals rapidly evolved to fill these new niches
Divergent evolution
a number of different species arise from one common ancestor
- new environments caused differences to evolve in populations
adaptive radiation
a type of divergent evolution occurring on a small scale over a shorter period of time
divergent evolution vs adaptive radiation
write it out
Convergent evolution
when unrelated species evolve similar characteristics because they live in similar environments
coevolution
when 2 populations form a specialized relationship and thus change in response to each other
- eg. flower and insects that pollinate them
symbiotic relationships
- parasitic
- mutually beneficial
- competitive
Red queen theory
species need to evolve continuously to keep up with other evolving species
- because changes in one species leads to changes in another
