Download 17.4

17.4
Macroevolution
large scale evol. Patterns
Extinction
more than 99% of org. that were, are
not
Extinction
Mass extinction
food webs wiped out
cretaceous period- huge asteroid
Most mass extinctions
several causes
Adaptive radiation
Several species can evol. From one
species
ex: darwin’s finches (13 species from
1)
Convergent evolution
unrelated org. react to similar env.
And evolve to look very alike
Ex- many unrelated aquatic species
have similar body shapes
Coevolution
org. that are evolving in response to
each other
Flowers and insects (pollinators)
Ex- orchid changed to have pollinator
40 cm down the flower--- insect with
40 cm structure to get nectar
Punctuated equilibrium
unlike what Darwin thought (slow
changes) there is a time with no
change and then period with a lot of
changes
Changes in dev. genes/body plans
One change in one gene can turn on or
off dif. Characteristics
Ex- ancient insects wings on all
segments, modern insects have one
segment with wings