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 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 Pacific Plate North American Plate Nazca Plate South American Plate African Plate Eurasian Plate Split developing Indo-Australian Plate Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events) Antarctic Plate

Adaption of Butterfly  n/changing-planet n/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/year Figure 15.3B Millions of years ago Eurasia CENOZOIC MESOZOIC PALEOZOIC North America Africa India South America Antarctica Australia Laurasia Gondwana Pangaea

Continental Drift/Plate Tectonics Pangea (Paleozoic)  LaurasiaGondwana (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 NORTH AMERICA SOUTH AMERICA 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

Extinction  The elimination a species from the earth  Background Extinction Rate - relatively constant rate of extinction in the fossil record  Mass Extinction - major loss of species: climate change, humans, 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 Affect Extinction Rates?  Simplify ecosystems  (monocultures/disturbed habitats)  Strengthen pest populations  Eliminate predators (can create new pests)

How Do Humans Affect Extinction Rates?  Introduce new species (starlings)  Overharvest  Interfer with chemical cycling and energy flow (UV/ozone, heat pollution)

Let’s read about the most recent mass extinction…

And look at rat evolution…