Ecosystem Balance Ch. 6

Relationship in Ecosystem Energy is cycled in ecosystems…… Predator: hunts other organisms Prey: the hunted Praying mantis Increases in a prey generally lead to increase in predator populations

Population Changes

http://www.rpdp.net/sciencetips_v2/images/l12c2/lynx-hare_cycle.gif

Parasitism One organism feeds on tissues/body fluids of another (the host) Parasite Harmful to hosts, but usually don’t kill Live on the body of host Density dependent Population size of parasite depends on population of host

Symbiosis Two species live closely together Examples Parasitism: one species benefits, other is harmed Aphids and plants Commensalism: benefits one species and doesn’t really affect the other Barnacles and whales Mutualism: both species benefit Plants and insects that pollinate them

Use the information below to answer the following. Aphids are insects that feed on fluids from the stems of plants. After the aphids ingest the plant fluids, they excrete a liquid called honeydew. Ladybugs eat aphids, which are a source of protein for the ladybugs. Which of these terms best describes the relationship between the ladybugs and the aphids? A. mutualism b. parasite–host C. predator–prey D. commensalism Praying mantis

A few examples of parasites are tapeworms, fleas, and barnacles A few examples of parasites are tapeworms, fleas, and barnacles. Tapeworms are segmented flatworms that attach themselves to the insides of the intestines of animals such as cows, pigs, and humans. They get food by eating the host's partly digested food, depriving the host of nutrients. Fleas harm their hosts, such as dogs, by biting their skin, sucking their blood, and causing them to itch. The fleas, in turn, get food and a warm home. Barnacles, which live on the bodies of whales, do not seriously harm their hosts, but they do itch and are annoying. Some parasitic animals attack plants. Aphids are insects that eat the sap from the plants on which they live. Parasitic plants and fungi can attack animals. A fungus causes lumpy jaw, a disease that injures the jaws of cattle and hogs. There are also parasitic plants and fungi that attack other plants and fungi. A parasitic fungus causes wheat rust and the downy mildew fungus attacks fruit and vegetables. Some scientists say that one-celled bacteria and viruses that live in animals and harm them, such as those that cause the common cold, are parasites as well. However, they are still considered different from other parasites. Many types of parasites carry and transmit disease. Lyme disease is trasmitted by deer ticks.

Ecological Succession What happens to a lawn or garden overtime if it is not cared for?

Ecological Succession Succession: changes overtime to a landscape Types: Primary Secondary Aquatic Island

Primary Succession Sequence of organisms coming to a lifeless habitat First: colonization by new organism Pioneer Community: 1st to colonize On Land: rocks are colonized by lichens Lichens: fungus and an alga Secrete acids to break down rock form organic material Help to form soil Second: formation of soil Third: grasses and small plants (block light so no more lichen) Fourth: shallow root trees Fifth: deep root trees Climax Community: undergoes no more growth/change (stable)

Secondary Succession Occurs in area after a disturbance eliminates most organisms, but doesn’t destroy soil Usually after human disturbances (fires) Resembles later stages of primary succession Will also eventually result in climax community Example:grasslands

Aquatic Succession Starts as a nutrient –poor lake Supports few organisms Overtime water plants begin to grow near the shore Becomes more nutrient-rich lake fills with sediment and becomes a marsh Land plants move in; ultimately turns into a forest

Island Succession New islands can form after volcanoes erupt New organisms’ ancestors came there by water, wind, or hitching a ride Majority have large bird populations Offspring evolves to fill several niches Usually is little competition for food/resources because few organisms New species tend to form because mates may be difficult to come by and available niches Ecological succession

Stability in the Ecosystem Stability: measure of how easily an ecosystem is affected by a disturbance and how quickly it returns to it original condition after the disturbance. Equilibrium: disrupted ecosystem returns to a state of balance

Disruptions Major disruptions can cause drastic changes-even complete destruction of the ecosystem A new ecosystem will eventually evolve Dinosaurs Were believed to go extinct due to the impact of a large object from space After the dinos were gone, many different kinds of mammals evolved

Chaos Theory Chaos Theory: ecosystems may be sensitive to very small changes Now: species are becoming extinct at faster rates Reasons: Human population growth Habitat destruction Introduction of foreign species Pollution of fresh water

Biomes Biome: a major type of ecosystem with distinctive temperature, rainfall, and organisms Land (terrestrial) amount of precipitation and temperature Water (aquatic) Water depth, nutrients, nearness to land Biomass: total mass of organic material

Figure 9k-1: Figure 9k-1: Distribution of the Earth's eight major terrestrial biomes. Legend is below. (Adapted from: H.J. de Blij and P.O. Miller. 1996. Physical Geography of the Global Environment. John Wiley, New

Land Biomes Desert Tundra Coniferous forest Deciduous forest Rain forest Savanna Temperate Woodland and Shrubland Steppe and Prairie Very little water; small amt biomass Forests: contain 75% Earth’s biomass

Rain Forests Cover 6% surface, but contains 50% biomass Most diverse Tropical Dry Forest: rainy season followed by dry season

Temperate Woodland and Shrubland Precipitation varies Located only 5 areas-all on shorelines Contain chaparral: low plants that contain flammable oils Catch fire easily  some plants have seeds that can only germinate after being exposed to fire