Population Dynamics How do populations change Population Dynamics

Population Dynamics – How do populations change?

Population Dynamics - Characteristics • Density • Distribution – Random (deer) – Clumped (bison) – Uniform (bear) • Ranges

Population Dynamics – Limiting Factors • Density – Independent » abiotic i. e. weather, fire, etc. – Dependent » biotic i. e. disease, competition, parasites

Limiting Factors in an Ecosystem Limiting factors are things that prevent a population from growing any larger. Density-Dependent Competition-Predation. Parasitism. Crowding/Stress-Food, space, nesting sites Density-Independent Weather-Fires. Droughts/Floods-Human activities

Density-Independent Natural factors affecting Habitat that are positive or negative • • • Extreme Cold Fires Heavy Snow Drought Overpopulation Flood

Population Dynamics – Growth Rates • Population Growth Rates – emigrate - moving out – immigrate - moving in – exponential model - r strategists – logistic model - k strategists – carrying capacity

Carrying Capacity The maximum number of individuals of a population that can be supported by the environment

Exponential growth In a population showing exponential growth the individuals are not limited by food or disease. Example: locust, mice, etc. If the rate of reproduction per individual remains constant through time, then the rate at which the population increases is a multiple of the number of individuals in the population.

Logistic growth In most real populations both food and disease become important as conditions become crowded. There is an upper limit to the number of individuals the environment can support ("carrying capacity“). Populations in this kind of environment show what is known as logistic growth. S curve. A population can grow exponentially only for short periods of time, because it would very quickly deplete all the resources necessary for its survival. Over long periods of time, populations tend to attain an equilibrium population size which is determined by the available resources.

Population Dynamics – Reproductive Patterns • Reproductive patterns – K (carrying capacity) strategists - live in stable environments. » few offspring, longer lives » Logistic (S curve) growth – r (rate) strategists - live in environments that fluctuate » many off spring, short lives. » exponential (J curve) growth

Thoughts to consider… • Has, or could, climate change make the limiting factors change? How would this affect your biome? • What impact do humans have on this function?

How do ecosystems form and change over time?

• Ecosystems are constantly changing in responds to human and natural disturbances. • Ecological Succession is the change that occurs. • 2 types of succession

Two types of succession 1. Primary Succession 2. Secondary Succession

Primary succession 1. Begins with soil formation 2. Generally slow, many 1000 s years 3. Volcanic eruptions, bare rock 4. never had a community living

Pioneer Species First species to populate the area.

SOIL FORMATION Pioneer Species

Secondary Succession • Reestablishment after disturbance • Faster

• The following natural events are examples of factors which begin secondary succession anew: • A) Forest Fires • B) Disease • C) Climatic Conditions - Hurricane, tornado, drought, windstorms, etc. . . . • D) Human Disturbance - Roadsides, clear cutting, yards, etc. .

5 th year 1 st year 10 th year 2 nd year 20 th year

Primary or Secondary?

• Old growth forests are forests whose natural cycles of growth have not been disturbed by logging, building roads or clearing.

How have humans impacted the ecosystem?

Biodiversity refers to the number and variety of species, of ecosystems, and of the genetic variation contained within species. Threats to Diversity & Human Impact

1 -Habitat loss 2 -Over-hunting

3 -Pollution • Air • Water

Algal Bloom 3 -Pollution

4 -Invasion of non-native species Kudzu is an invasive species

Global Warming (proposed) 5 -Climate change

5 -Climate change

Possible consequences of Global Warming • Rising sea levels • Increasing ocean temperatures • Severe weather Global Warming Clip 5 -Climate change

6 -Population Growth U. S. : 306, 297, 506 World: 6, 775, 939, 586 as of Apr 26, 2009

7 -Over use of Non Renewable Resources • A non-renewable resource is a natural resource that cannot be produced, re-grown, regenerated, or reused on a scale which can sustain its consumption rate. Non-renewable Oil Natural Gas Coal Uranium Renewable Solar, Wind, Geothermal, Biomass, Hydro

Biological Magnification Process by toxins become more concentrated with each successive trophic level of a food web

The theory of global warming suggests that a trend toward warmer temperatures on Earth will cause glaciers to lose mass. A major consequence of glacial melting is A B C D flooding coastal regions destruction of fossil records increased saltiness of the ocean increase in atmospheric carbon dioxide

Ecology: Organisms in Their Environment Video

You should know: • the relationship of the individual to a population, a community, an ecosystem and a biome • know the flow of energy through an ecosystem and required components of a successful environment • food chains • food webs • energy pyramids • nutrient cycling – Be able to explain the negative impact humans have had on Earth – pollution – proposed global warming – explosive population – pesticide and herbicide usage – resource consumption, renewable and non-renewable