Evolution & Biodiversity Biodiversity=richness of living species
Varieties of species that exist Genetic diversity Species diversity Habitat diversity
Plants begin invading land
Evolution and expansion of life
First fossil record of animals
Age of reptiles
Age of mammals
Insects and amphibians invade the land
Modern humans (Homo sapiens) appear about 2 seconds before midnight
Recorded human history begins 1/4 second before midnight
Origin of life (3.6–3.8 billion years ago)
How’d I get here?
noon
midnight
Natural Selection• AKA – Survival of the fittest
• Let’s look at Sneaky Cricket!
• The best adapted to environment survive and reproduce; passing on the desired trait
• Mutations can cause desired trait
• 3 steps to natural selection: – Gene mutation – Desired trait “selected” – Reproduction cause evolution for that trait
Why evolve?• SURVIVAL!!
• Niche: where an organism fits into it’s habitat (lives, eats)
• Generalist species: have a general niche; can live and eat more of a variety; less competition
• Specialist species: have a specific niche and food. Are more at risk!
It’s time to move on• Speciation: two different species evolved
out of one. Might be due to new geography.
• Extinction: no members of species left on Earth
• Extirpation: no members of that species left in area. (wolves in Iowa)
• Species: to be in the same species, must be capable of bearing fertile offspring! – Horse + donkey = mule (sterile) – Lab + German Shepherd = fertile dog
How does a new species emerge?Allopatric:
populations segregated by a geographical barrier; can result in adaptive radiation (island species)
Sympatric: reproductively isolated subpopulation in the midst of its parent population (change in genome);-polyploidy in plants (wheat)-cichlid fishes
Adaptive RadiationAdaptive Radiation
Continental drift has played a major role in macroevolution-Pg. 527
Continental drift is the slow, incessant movement of Earth’s crustal plates on the hot mantle
Figure 15.3A
PacificPlate
NorthAmerican
Plate
NazcaPlate
SouthAmerican
Plate
AfricanPlate
EurasianPlate
Splitdeveloping
Indo-AustralianPlate
Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events)
Antarctic Plate
Adaption of Butterfly http://www.nbclearn.com/portal/site/
learn/changing-planet
This movement has influenced the distribution of organisms and greatly affected the history of life
– Continental mergers triggered extinctions
– Separation of continents caused the isolation and diversification of organisms
– Rate : 1-2 cm/yearFigure 15.3B
Mil
lio
ns
of
ye
ars
ag
o
EurasiaCE
NO
ZO
ICM
ES
OZ
OIC
PA
LE
OZ
OIC
North America
AfricaIndiaSouth
America
AntarcticaAustra
lia
Laurasia
Gondwana
Pangaea
Continental Drift/Plate Tectonics
Pangea (Paleozoic)
Laurasia Gondwana (Mesozoic)
Europe -S. America Greeland -Australia N. America -Africa (Cenozoic)
**First Proposed by Alfred Wegner (1912)**Later Reproposed in the 1960’s after WWII and sonar mapping of the
ocean floor
Figure 15.3D
NORTHAMERICA
SOUTHAMERICA
EUROPE
AFRICA
ASIA
AUSTRALIA
= Living lungfishes
= Fossilized lungfishes
Macroevolution
Macroevolution consists of the major changes in the history of life The fossil record chronicles these changes, which have
helped to devise the geologic time scale
ExtinctionExtinctionThe elimination a species The elimination a species from the earthfrom the earth
Background Extinction RateBackground Extinction Rate - - relatively constant rate of relatively constant rate of extinction in the fossil recordextinction in the fossil record
Mass ExtinctionMass Extinction - major loss - major loss of species: climate change, of species: climate change, humans, catastrophieshumans, catastrophies
Mass Extinctions
- These mass extinctions may have been a result of an asteroid impact or volcanic activity
Every mass extinction reduced the diversity of life But each was followed by a rebound in diversity Ex. Mammals filled the void left by the dinosaurs
Six Mass Extinction Events in the last 600 million years
(2) of the major extinctions are:-Permian (90% of all marine species went extinct)-Cretaceous (Killed the dinosaurs)
How Do Humans How Do Humans Affect Extinction Affect Extinction Rates?Rates?
SimplifySimplify ecosystems ecosystems (monocultures/disturbed (monocultures/disturbed habitats) habitats)
StrengthenStrengthen pest pest populationspopulations
EliminateEliminate predators (can predators (can create new pests)create new pests)
How Do Humans How Do Humans Affect Extinction Affect Extinction Rates?Rates?
IntroduceIntroduce new species new species (starlings)(starlings)
OverharvestOverharvestInterferInterfer with chemical with chemical cycling and energy flow cycling and energy flow (UV/ozone, heat pollution)(UV/ozone, heat pollution)
Let’s read about the most recent mass extinction…
And look at rat evolution…