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…