Transcript Macroevolution - CPBiologyClass

Macroevolution
-Evolution of species-
What is macroevolution?
• Macroevolution: major biological
changes evident in the fossil record
– Includes origin of different species
(speciation), extinction, and evolution of
major new features in organisms
– Species: members of pop’s that can
interbreed to have fertile offspring
Why aren’t horses and donkeys
considered the same species?
+
Horse
=
Donkey
Mule
• Because their offspring (mules) are
sterile (can’t have more offspring)
Reproductive barriers
• Reproductive barriers keep 2 closely
related species that live in the same
environment from interbreeding
– Creates reproductive isolation
Types of reproductive barriers
• Timing – the 2 similar species have
different breeding seasons
• Behavior – the 2 similar species have
different mating behaviors (courtships,
mating songs/calls)
• Habitats – the 2 similar species live in
different habitats of the same location
– Bottom feeder vs. Open water feeder
Geographical isolation
can create speciation
• Geological processes constantly
change and rearrange Earth’s
features
– Possibly creating geographical isolation
(separation of pop’s as a result of
geographical change or an arrival of a
pop to a geographically isolated area)
Example of Geographical Isolation
Harris’ antelope squirrel
White-tailed antelope squirrel
North rim
South rim
GRAND CANYON
Geographical Isolation
• Isolating the pop. by a geographical
barrier can lead to speciation
– We can apply microevolution (genetic
drift and Natural Selection) to the
evolution of the new species
– Ex. Darwin’s finches
Continental drift & Macroevolution
• Continental drift:
the movement of
the Earth’s
continents as a
result of plate
tectonics
Plate tectonic basics
• The Earth’s surface is broken up into
large plates, which float on molten
lava
– As the plates shift, they cause:
• Earthquakes, volcanoes, and
mountain building
• The continents to move (relative to
each other)
Pangaea
• 250 million years ago, the
Earth’s continents are
believed to have been 1
large landmass (Pangaea)
• 180 million years ago,
Pangaea drifted apart into 2
isolated continents
– Species on each
continent would’ve
encountered their own
evolution