AP ENVIRONMENTAL SCIENCE

BIODIVERSITYBIODIVERSITY

3.6 BILLION YEARS OF EVOLUTION ON PLANET EARTH HAS CREATED THE MILLIONS OF SPECIES THAT INHABIT THE EARTH TODAY

THE ELEMENTS OF BIODIVERSITY

Species Richness the total number of different

species in an ecosystem

Species Evenness the extent to which each

species is well represented in the ecosystem

Species Diversity: the number or variety of different species in a particular region

WORLD WIDE SPECIES RICHNESS

• In a study, ecologist Holger Kreft of the University of California, San Diego and his colleagues looked at what they termed “endemism richness”, or the number of unique species combined with the overall number of species around the world.

• The researchers were surprised to find that islands from Micronesia to the Atlantic—just 3.6 percent of the surface of the planet—boasted plant endemism richness 9.5 times higher than the continents and more than 8 times higher for vertebrates.

SPECIES RICHNESS OF LARGE MAMMALS IN NORTH AMERICA

GENETIC DIVERSITY

• The variation in DNA composition among individuals within a species.

GENETIC DIVERSITY

Provides the crucial raw material for adaptation to local conditions.

Populations with low genetic diversity are vulnerable to environmental change, disease, and ultimately to extinction.

ECOSYSTEM DIVERSITY

• Ecosystem diversity refers to variety at levels above the species level, such as ecosystems, communities, habitats, or landscapes.

• A coral reef contains far more biodiversity than the same area of an agricultural farm.

HOW MANY SPECIES ARE THERE?HOW MANY SPECIES ARE THERE?

Good Question – Hard to Know

Currently there are about about 1.5 million1.5 million described.

The highest estimate is around 100 million.100 million.

The lowest around 5 million. 5 million. The best estimate might be

around 10 million10 million. It means we've only known

about a small fraction of what is presently there.

HOW MANY SPECIES ARE THERE?HOW MANY SPECIES ARE THERE?

Estimates of biodiversity are incomplete becauseDifficulty of estimating

certain groups microbes, nematodes,

fungi, protists, and soil-dwelling arthropods.

Many areas of Earth still remain little exploredDeep oceanTropical rainforest

HOW MANY SPECIES ARE THERE?HOW MANY SPECIES ARE THERE?

To illustrate: In a famous study conducted in Panama, 19 trees were "fogged" with insecticide and the dead were collected as they fell through the canopy.

Nearly 1,200 species of beetles alone were collected. Of those, 80 percent were not known to science.

HOW MANY SPECIES ARE THERE?HOW MANY SPECIES ARE THERE?Many of the species that are

currently being discovered live in areas that have never before been explored

Hydrothermal vents along the floor provide energy for bacteria that use this energy like plants use the energy of the sun.

They form the base of a giant food web thousands of feet below the surface.

Now scientists believe there could be as many as a million species just in on the ocean floor.

UNEVEN SPECIES DISTRIBUTION

BUGS RULE THE PLANET!

LATITUDINAL GRADIENTLATITUDINAL GRADIENT

Species richness gradually increases as one approaches the equator

HYPOTHESIS: LATITUDINAL GRADIENT

The variable climates of polar and temperate latitudes favor organisms that can survive a wide range of conditions.

Such generalist species have expansive niches; they can do many things well enough to survive, and they spread over large areas.

HYPOTHESIS LATITUDINAL GRADIENT

In tropical latitudes, abundant solar energy, heat, and humidity induce greater plant growth, which supports more organisms.

The stable climates of equatorial regions favor specialist species, which have restricted niches but do certain things very well.

Together these factors are thought to promote greater species richness in the tropics.

Where Is Declining Biological Where Is Declining Biological Diversity the Greatest Problem?Diversity the Greatest Problem?

THREATENED SPECIES

Top Six Hot Spots1 Hawaii2 San Francisco Bay

area3 Southern

Appalachians4 Death Valley5 Southern California6 Florida Panhandle

Concentration of rare species

High Low Moderate

EXTINCTION OF SPECIES

PANDA SAYS: SEE YA LATER

– STUDY HARD