Biosphere Key Benchmark SC.912.L.17.5

Analyze how population size is determined by:Birth

DeathImmigration Emigration

Limiting Factors ( Biotic and Abiotic)

Students will Use Data and information about Population dynamics

Students will Use graphs and charts to analyze Population change

Learning Goals

Students need to Explain a change in Carrying Capacity

Students must Identify positive/ negative consequences from a reduction in biodiversity

Students should determine effects of Limiting Factors

Questions may include catastrophic events, but the student’s only concern is with the consequence of the event, but not the catastrophe itself.

Example: If a flood washes away valuable topsoil and destroys large tracts of land, which graph shows the effect on the native grass population.Students should be able to choose a graph with a down sloping line to indicate a population reduction.*If a trophic level is altered, what is the direct effect on trophic levels above and below?

Content Limitations

Students often think that a catastrophic event or even a change often leads to extinction, when they really need to think in terms of

POPULATION REDUCTION

It is imperative to have students resist going to the extreme as this will enhance their ability to analyze changes in a more realistic manner.

Student Misconceptions

Type One: low infant mortality and many survive to old

age Type Two: Chance of survival is equal at all ages

Type Three: high birth rate and high infant mortality

Basic Survivorship Curves

See graph on page 439 in Textbook Type One curve is shaped like the top of a

football. Most individuals live to maturity and death is usually at older ages.

Type one is indicative of large mammals Type Two shows a down sloping diagonal

which indicates an equal chance of dying regardless of age. Indicative of many birds.

Type Three shows an instant drop indicating high birth rate and high infant mortality. Indicative of fish and insects

Survivorship Curve Reference

4 Factors Effecting Population Size Birth Death Immigration EmigrationStudents must be able to analyze a population growth graph and determine which of the 4 factors explains the direction of the graph line.

Population Growth Factors

Gives us information about species interaction

1. Clumped dispersion: facilitates mating and protection2. Uniform dispersion: indicates intra-species competition and limited resources3. Random dispersion: Individuals are spread randomly

Population Dispersion Patterns

Exponential Growth:Characterized by a “J” curveIndicates very few predators.Ample food supplies Logistic Growth :

Characterized by a ‘S” curveIndicates limited resources Predators are presentCarrying Capacity is reached

Population Growth Curves

See textbook page 441

J curve of Exponential Growth shows a steep rise in numbers over a short period of time.

Indicative of ample resources like food and shelter

Indicates few to No predators

Population Growth Curves

The “S” curve of Logistic Growth is more reflective of most populations in that initially there is a burst in numbers, but as resources are limited and predators are present, the population line goes horizontal indicating carrying capacity has been reached.

Population Growth Curve

Students need to remember that a Growth Curve or a Growth Pattern is not set in stone

Change is DYNAMIC

Change is the Norm Nothing is Fixed Variation Occurs

Cause and Effect are your primary focus

Student Misconceptions

Primary succession establishment of an ecosystem from bare rock First organisms in are pioneer species.

Secondary successionReestablishment of a damaged ecosystem Plants and organisms that remain start the processReestablishment begins with previous inhabitants

*** see questions 7, 14, 21, 23,

Succession

Benchmark Focus: Know seasonal variations Climate zones and Seasonal changes Succession

Content LimitationsNo need to know characteristics of individual biomes Only understand consequence of change in climate or changes due to a catastrophic event.******

Biomes

I want my students to know biomes based on

“ EST “ Wettest Hottest Driest Newest Largest Most Diverse (est) keep the theme going

However, just in case:

Greatest Diversity Highest Rainfall amount (wettest) Highest Avg. Temp Highest Density of living things

Tropical Rain Forest

Largest Land Biome 4 Season Climate with a Severe Winter Dominant Plant: Conifer Trees

Taiga

Newest/ Youngest Biome Created by retreating glaciers from Ice Age Coldest Biome Second driest Treeless Only Biome with Permafrost

Tundra

Driest Biome/ Least amount of Rainfall Largest Daily Temperature shift between Night and Day Most sparsely populated

Desert

Temperate tells you it has a 4 season Climate

Deciduous Trees indicate a true winter Noted for multiple Strata: some say 3: Trees, Shrubs, Ground coversome say 5: Trees, Sapling, Shrub, Herb, Ground cover

Temperate Deciduous Forest

Focus should be on life in the aquatic systems as a function of:

Chemistry - oxygen levels-nutrient cycling and seasonal variation

Oxygen levels due to water temperature “Turn over” as a result of density differences Light – sunlight is the major abiotic factor Salinity Temperature Depth

Marine/Aquatic Systems

Oxygen levels fluctuate with Temperature Colder water has higher levels of oxygen. Salt water is more DENSE than fresh water Cold water is more DENSE than warmer

water Nutrient Turnover is often the result of

temperature and density differences occurring as a result of Seasonal Change

Aquatic System interactions

Students do not need to have particular knowledge of individual marine zones

See Ecology Population3 questions 8, 9,25 and 30

Content Limitations