Ecology NotesPart 2

limiting factors and natural selection

oLimiting factor: factor that restricts life, reproduction, or distribution of organisms; Ex: food, temperature, water, etc.

oNatural selection : survival of the fittest; those species that are better able to survive in their environment will pass on their genes to offspring which in turn will be better able to survive

oAfter long periods of time, may lead to changes in organism

Identify the types of resources• Natural resources: part

of natural environment, Ex: soil, water, crops, oil, gas, wildlife

• Renewable resources: replaced or recycled by natural processes (biodegradable) Ex: plants and animals

• Nonrenewable resources: available in limited amounts, Ex: fossil fuels

6 Environmental Changes

1. Pollution: air, water, noise

2. Global Warming: Earth’s atmosphere heating up due to trapped gases (fossil fuels)– Ex: Arctic, where rising

temperatures and melting ice are dramatically changing the region’s unique landscapes and wildlife

3. Acid Rain: transformation of sulphur dioxide (SO2)

secondary pollutants such as sulphuric acid

4. Ozone Hole:Ozone shields us from damaging UV sunlight. Ozone is affected by Chlorofluorocarbons (CFC)

5. Greenhouse Effect: Earth's atmosphere contains trace gases, some of which absorb heat.

• water vapor, carbon dioxide, methane, ozone, and nitrous oxide = "greenhouse gases."

6. Extinction:a species no longer exists

Describe factors that affect population size.

Predation: predators limit number of prey; pick out old, sick, young

Competition: compete for resources; water, food, living space, mates

Parasitism/disease

Environmental changes: pollution, thermal warming, unfit water all affect population size

May cause species to become threatened(rapid decline) or endangered (extinction possible)

Describe population growth.

Exponential growth: occurs when number of individuals increases rapidly; produces J-shaped curve on graph

Logistical (linear) growth: S-shaped curve; shows steady growth; slows after populations reach carrying capacity

Describe carrying capacity.

Carrying capacity: the number of individuals that an environment can support

Limits the population size

Affected by temperature, food supply, reproduction, hunting, etc.

# of yeast cells

Time in hours

• Limiting Factors – factors that limit the survival, distribution, or reproduction of organisms thus affecting the population size

• Density-dependant factors – competition, predation, parasitism, and disease (numbers matter!)

• Density-independent factors – weather, natural disasters, human activities (numbers do not matter!)

Human Population Growth • Human population growth is in exponential

growth phase for world population. Countries have different growth rates which can be determined by examining age structure diagrams.

Succession. Succession: changes that take

place in a community.

Primary: occurs where no soil existed; creates new colonies; pioneer species move in; continues to grow until limiting factors become too great

Secondary: disturbance of some kind changes existing community; “old” species die and new species move in; associated with natural disasters

Climax Community - the stable, mature community that undergoes little change

Succession

Biomes and the Biosphere

Biomes - ecosystems with similar climate (temperature and precipitation levels) and types of biotic factors (plants and animals)

Tropical Rain Forest

• Poor soil, heavy precipitation, much biodiversity, levels of niches including the canopy, under story, and forest floor

Desert

• Poor sandy soil, very little precipitation, extreme temperatures, specially adapted organisms

Grasslands

• Rich soil, very little precipitation, extreme temperatures, specially adapted organisms

Temperate deciduous forests

• Rich soil, moderate precipitation and temperature, trees that lose their leaves, abundant wildlife

Coniferous forests

• Acidic soil, moderate precipitation and cold temperatures, conifers or cone-bearing trees and abundant wildlife

Tundra

• Poor soil, permafrost, very little precipitation and cold temperatures, treeless, small plant species, migratory animal species

Aquatic Biomes

Fresh water: Very low salt content, flowing in rivers and streams, or standing in ponds and lakes. Plankton, microscopic algae act as producers.

Aquatic BiomesEstuary: moderate salt

content due to mixing of fresh and salt water where rivers flow into the ocean

Marine: high salt content. Aphotic zone is dark while Photic zone allows for photosynthesis, Large variety of species

Aquatic Biomes

Intertidal zone: area at the coast between high and low tide marks. Organisms here are adapted to being exposed to air and dealing with waves and strong currents

Aquatic Biomes

Coral reefs: Warm shallow tropical seas contain reefs built from the calcium carbonate skeletons of coral. Huge diversity of species