Mechanisms (Evolution) Flashcards
traits
can be preferentially selected for or against which can cause rise of a new species
disruptive selection
two extreme traits are preferentially selected for
moderate traits slowly become less common and then disappear
stabilizing selection
extreme traits are preferentially selected against
moderate traits become more common and extreme traits become less common and slowly disappear
directional selection
when a trait moves slowly over time towards one extreme
4 ways of evolving
divergent, convergent, parallel, coevolution
divergent evolution
when two or more related species become more and more dissimilar
ex. red fox and kit fox
red fox and kit fox
example of divergent evolution
evolved differently because of their environments
red fox- farmland and forests
kit fox- deserts
convergent evolution
unrelated species become more and more similar
adapting to the same environment
American cactus and African euphorbia
example of convergent evolution
adaptations help to store water and protect themselves from predators
parallel evolution
2 species with similar characteristics evolve similar traits in a similar timeframe
might be due to being exposed to similar/identical selective pressures
aren’t necessarily interacting with each other
coevolution
joint evolution of 2 or more species in close interaction
evolution of predators and their prey
example of coevolution
bats and the flowers they pollenate
example of coevolution
bats adapt to be better at retrieving pollen
flowers adapt to be lighter in colour so the bats can see them better
species
the event by which a new species arises
Ernst W. Mayr’s definition of a species
- can breed or reproduce with one another
- produces offspring of both sexes that are capable of reproducing offspring of both sexes
- do not ordinarily breed with organisms from another group