Biodiversity – diversity of life

•Variety of ecosystems–coral reefs, rainforests

•Variety of species

•Variety of genes among individuals of a species

–color, height

• Kingdoms: – Monera – bacteria (no cell nucleus)– Protists – single-celled organisms– Fungi– Plants multi-celled organisms– Animals

• Table/ classification of organisms

Hierarchical nomenclature

What is a species?

• Common definition: A species is reproductively isolated from every other species in nature.

• 1.6 million species have been described and recorded.

• Total number of species?30 – 100 million

Species estimates

• High estimates came about in the 1960-1970s when new communities were discovered.

• Rain forest canopy

• Deep ocean hydrothermal vents

How many species are there?

Speciation – creation of new species

• Populations evolve by becoming genetically different.– Genetic drift– Natural selection

Genetic diversity

• Caused by mutations – errors in duplication of the genetic code.

• Mutations are often bad, in which case they are not passed on to the next generation.

• But mutations can also be helpful, in which case they are passed on to offspring and genetic diversity of the population increases.

Example: sickle cell anemia

• Substitution in the gene sequence for hemoglobin in humans

• Valine instead of glutamic acid in 2 places

• Red blood cells are different• Homozygous – sickle cell anemia• Heterozygous – protection

against malaria.• This genetic “defect” persists

because there are advantages.

Natural selection

“Survival of the fittest!”

More “fit” organisms tend to be more successful and their genes are more likely to be passed on.

Fit = best adapted

Success = have more offspring

Example: Peppered moth

Pre-industrial England, moths were predominantly white, with black moths (mutation) rare.

Moths rest on tree trunks during the day, and are eaten by birds.

In industrial areas, pollution turned tree trunks black. In these areas black moths eventually became dominant.

Geographic isolation

• Reproductive isolation is induced by a barrier such as a river, glacier, rising ocean.

• Population is split into two groups, each of which undergo genetic drift and natural selection.

• May eventually become separate species.

Species adaptation

• Organisms become adapted to a certain “lifestyle.”

• Ecological niche – functional role in an ecosystem– Range of environmental conditions.– Types of resources used.– Interactions with living and non-living

matter.– Role in flow of energy and cycling of

matter.

Species tolerances

Ecosystems

• an assemblage of different species and their physical environment, all organized in a way that each population of organisms obtains energy and nutrients through specific pathways within the ecosystem. Each species has a distinct ecological niche.

Example ecosystem: Rocky intertidal

Ecosystem components

1. Functional groups of organisms a. Producers (autotrophs)fix energy and

inorganic nutrients into organic forms that are accessible to other organisms.

b. Consumers (heterotrophs) get energy and nutrients by consuming the producers.

c. Decomposers (heterotrophs) get energy and nutrients by decomposing all other organisms that have died.

Energy transfer

2. Unidirectional transfer of energy from one functional group to another until it is dissipated from the ecosystem as heat

Energy is transferred in one direction, from producers to consumers to decomposers.

After decomposers have extracted energy from dead organic matter, the energy is no longer available within the ecosystem.

Nutrient cycling

3. Cycling of nutrients among the various groups of organisms through trophic (feeding) interactions Unlike energy, nutrients do not move unidirectionally through the ecosystem. They are recycled through the activity of decomposers, which return the organic nutrients to their inorganic forms.This process is called mineralization. The mineral nutrients are then available again to producers and microbes that can use them.

Fig: ecosystem

Example ecosystem: Rocky intertidal

Complex species interactions within an ecosystem – food webs

Simple food web

• Energy flow diagrams represent energy movement between trophic levels.

• Changes in species population sizes can affect species in other trophic levels in the food web.

autotrophs

1° consumers

top predators

2° consumers

Increase in autotrophs. . .

Decrease in autotrophs. . .

Primary productivity is an important control on ecosystem productivity

Change in top consumer. . .• overfishing

Keystone species

• If that species is removed there are dramatic changes in and population densities of all the other species in the community.

• Keystone species are usually predators• No comparable changes appear when

other species are removed from the ecosystem.

The kelp forest ecosystem

• Kelp forests along the Pacific coast.

• 30 – 40 m water depth– Determined by light availability

• Found almost exclusively at areas of upwelling– Require high nutrient concentrations

• Water temperatures cooler than 20oc

fig/ distribution of kelp and mangroves

slide/ kelp forest

• Gas – containing sacs to keep them buoyant

• Grow as much as 50 cm a day

• Continue to grow once they reach the surface

• Supports diverse community

• Provide – Food– Protection/ hiding place from predators– Substrate/ habitat

slide/ sea urchin

slide/ otter in kelp bed

fig/ otter,urchin, kelp circle

otters eat sea urchins

sea urchins eat kelp

kelp provides habitat for otter

fig/ graphs of urchin vs. kelp

With otters Without otters

The role of sea otters in kelp communities

• A ‘keystone’ predator

• Sea urchins graze kelp beds

• Otters keep sea urchin populations under pressure– Keep the sea urchin populations from growing

too large and destroying the kelp.

• What happens if you remove the otters?– Intensive hunting of otters in 1800s led

decline of kelp forests.

(Altered) Yellowstone ecosystem

• Missing the natural top predator (wolf)

• High population levels of bison and elk grazers.– Destroy habitat, diminish food resources.– Increased disease.– Unstable population sizes.

Increased grazing pressure in Yellowstone

Wolves

• Top predator• Typical feast and famine diet• Pack of 6 will consume about 2 elk and one

deer a month.– Select ill and weaker animals, which controls

disease and strengthens the population– Control population density of prey.– Provide food for other animals – ravens, eagles,

grizzlies.

Reintroduction program

• Reintroduction program began in 1995.

• Yellowstone had 22% more visitors in June 1995.

• Wolves now have viable populations (producing offspring).

• Beginning to prey on bison as well as elk.

Activity: Should we drill in the Artic National Wildlife Refuge?

pretty picture

Comparison of ANWR to Continental US

Map

Pictures

Muskoxen

Snow geese

Predators

Porcupine caribou

Vegetation

Oil