Option G:Ecology and Conservation

Chpt. 18: pages 552 - 600

Biodiversity

The variability of organisms from all sources.

Includes variability within species, between species, and of ecosystems.

Biodiversity includes genetic variation within species, the variety of species in an area, and the variety of habitat types within a landscape.

Community Ecology G.1

Plants and animals are affected by different factors that determine their distribution

Populations can be sampled to determine diversity and distribution of organisms

G.1.1 Factors affecting plant distribution

Temperature Light Soil pH Salinity Nutrient content of soil

G.1.2 Factors affecting animal distribution

Temperature Water Breeding sites Food supply Territory

Random Sampling

Samples must come from all parts of the habitat

Each organism must have an equal chance of being selected.

Quadrat Method

A quadrat is a square of a particular size. Size depends on the type of area being surveyed and type of organism being studied

Steps of quadrat method

Map area of interest Determine size of quadrats Place a grid with numbers over map Use a random numbers table to

choose squares for sampling Count organism of interest in

selected squares Average the number of the

organisms in your selected squares

Multiply the average number of the selected organism times the number of quadrats on the map

The transect technique

Used for studying how the distribution of plants in an ecosystem is affected by abiotic factors

Steps to perform a transect on a beach

Run a tape from the tide line to the dunes at right angle to the water

Every 10-20 meters along tape mark a quadrat (each being the same size)

Identify and count plant species of interest in each quadrat

Measure abiotic features (T, light, soil pH, moisture, mineral content) in each quadrat

Examine pattern of distribution

Niche – an organisms role in the ecosystem

Includes Where the organism lives What and how the organism eats How the organism interacts with other

species

Spatial habitat-the specific area an organism inhabits

Feeding activities – affect the ecosystem by keeping other populations in check

Interactions Competition Predator/prey Parasitism Mutualism

Parasitoid wasp larva and corpse of caterpillar (skin and hair)!

Unsuspecting caterpillar!

Read pages 558-559 for examples of interactions between species.

Homework! Research these interactions and find

3 MORE examples of each!

Competitive Exclusion

No two species in a community can occupy the same niche

Demonstrated by Gause in 1934 using two species of Paramecium grown in separate cultures thrived

When grown together one species died and the other survived. One out competed the other for resources

Gausian hypothesis of competitive exclusion – when 2 species have a similar need for the same resources, one will be excluded

If animals have the same niche one of two things will happen:

Competitive Exclusion – one species will be driven to local extinction

Resource Partitioning – one species may evolve to use a different set of resources

Fundamental vs. Realized Niche

Fundamental niche – the potential mode of existence, given adaptations of the species

Realized niche – the actual mode of existence, results from adaptations of the organism and competition

Biomass

The total mass of organic matter (carbohydrates, lipids, proteins)

Water is inorganic so all material must be dried to measure biomass

Measured as dry mass in g/m2/y or gm-2y-1

Measuring biomass

Must collect animals and determine their biomass using a table (based on size and weight)

Plants can be collected, dried and weighed

Measuring biomass of a terrestrial ecosystem

Measure total area of ecosystem and divide into plots

Select a plot to sample Measure size of each plant species (trees,

low growing vegetation). Cut all vegetation on the plot

Dry all plant samples Use a mathematical model to show

relationship between weight and height of each plant and its biomass

Sample other plots by measuring size and height of plants. Use mathematical model to find biomass

Collect animals by trapping. Weigh and measure. Use table to determine biomass

Average data for all species per plot Multiply average times number of plots to

find biomass of entire ecosystem Repeat seasonally or yearly to study

changes