option g: ecology and conservation chpt. 18: pages 552 - 600
TRANSCRIPT
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