AP Environmental Science Biodiversity AP Environmental Science

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

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. Figure 11-01 Title: The concept of biodiversity encompasses several levels in the hierarchy of life. Caption: Species diversity (middle frame of the figure) refers to the number or variety of species. Genetic diversity (bottom frame) refers to variation in DNA composition among individuals within a species. Ecosystem diversity (top frame) and related concepts refer to variety at levels above the species level, such as ecosystems, communities, habitats, or landscapes. Notes: Keywords: ecology, biodiversity

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. Figure 11-01 Title: The concept of biodiversity encompasses several levels in the hierarchy of life. Caption: Species diversity (middle frame of the figure) refers to the number or variety of species. Genetic diversity (bottom frame) refers to variation in DNA composition among individuals within a species. Ecosystem diversity (top frame) and related concepts refer to variety at levels above the species level, such as ecosystems, communities, habitats, or landscapes. Notes: Keywords: ecology, biodiversity

How Many Species Are There? Good Question – Hard to Know Currently there are about 1.5 million described. The highest estimate is around 100 million. The lowest around 5 million. The best estimate might be around 10 million. It means we've only known about a small fraction of what is presently there.

How Many Species Are There? Estimates of biodiversity are incomplete because Difficulty of estimating certain groups microbes, nematodes, fungi, protists, and soil-dwelling arthropods. Many areas of Earth still remain little explored Deep ocean Tropical rainforest

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? 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 Figure 11-05 Title: In the left portion of the figure, we see that three-quarters of known species are animals. Caption: The central portion subdivides animals, revealing that nearly three-quarters of animals are insects and that vertebrates comprise only 3.9% of animals. Among vertebrates (right portion of figure), nearly half are fishes, and mammals comprise only 9%. As noted, most species are not yet discovered or described, so some groups may contain far more species than we now know of. Data from Groombridge, B., and M. D. Jenkins. 2002. Global biodiversity: Earth's living resources in the 21st century. UNEP-World Conservation Monitoring Centre. Cambridge, U.K.: Hoechst Foundation. Notes: Keywords: ecology, biodiversity, taxonomy

BUGS RULE THE PLANET!

Latitudinal 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. Figure 11-07 Title: Ecologists have offered many hypotheses for the latitudinal gradient in species richness, and one set of ideas is summarized here. Caption: The variable climates (across days, seasons, and years) 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. In tropical latitudes, the 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. Notes: Keywords: ecology, biodiversity, niches, species

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. Figure 11-07 Title: Ecologists have offered many hypotheses for the latitudinal gradient in species richness, and one set of ideas is summarized here. Caption: The variable climates (across days, seasons, and years) 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. In tropical latitudes, the 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. Notes: Keywords: ecology, biodiversity, niches, species

Where Is Declining Biological Diversity the Greatest Problem?

Threatened species Top Six Hot Spots 1 Hawaii 2 San Francisco Bay area 3 Southern Appalachians 4 Death Valley 5 Southern California 6 Florida Panhandle Figure 11.18 Threatened natural capital: biodiversity hot spots in the United States. The shaded areas contain the largest concentrations of rare and potentially endangered species. Compare these areas with those on the map of the human ecological footprint in North America shown in Figure 4 on pp. S14–S15 in Supplement 4. (Data from State Natural Heritage Programs, the Nature Conservancy, and Association for Biodiversity Information) Concentration of rare species Low Moderate High

Extinction of species

PANDA SAYS: SEE YA LATER – STUDY HARD