Download Ecology-Option G - IB BiologyMr. Van Roekel Salem High School

Ecology-Option G
IB Biology 2
Van Roekel
G.1 – Community Ecology
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G.1.1 Outline the factors that affect the distribution of plant species, including
temperature, water, light, soil pH, salinity and mineral nutrients.
G.1.2 Explain the factors that affect the distribution of animal species, including
temperature, water, breeding sites, food supply and territory.
G.1.3 Describe one method of random sampling, based on quadrat methods, that
is used to compare the population size of two plant or two animal species.
G.1.4 Outline the use of a transect to correlate the distribution of plant or animal
species with an abiotic variable.
G.1.5 Explain what is meant by the niche concept, including an organism’s spatial
habitat, its feeding activities and its interactions with other species.
G.1.6 Outline the following interactions between species, giving two examples of
each: competition, herbivory, predation, parasitism and mutualism.
G.1.7 Explain the principle of competitive exclusion.
G.1.8 Distinguish between fundamental and realized niches.
G.1.9 Define biomass.
G.1.10 Describe one method for the measurement of biomass of different trophic
levels in an ecosystem.
What is a community?
• Community - A group of
interdependent
organisms, or different
populations, living and
interacting with each
other in the same
habitat.
• Distribution of
organisms is affected by
abiotic and biotic
factors
Factors Affecting Distribution of Plant
Species
• Temperature
• Water
• Light
• Soil pH
• Salinity
• Mineral Nutrients
Temperature & Water
• Foredune: High temps, little water  less
variety of plants
– Marram Grass: long roots, long narrow leaves
that curl, both features help find/save water and
resist heat
• Mature Dune: Cooler temps, moist condition
 numerous variety of plants
– Ferns: survive in low temps and moist conditions
Light
• Marram grass requires constant sunlight,
found in sunny areas of dune
– Long narrow leaves reduce water loss, poor ability
to capture sunlight
• Ferns found in shady areas of mature dune
– Wide leaves captures small amount of light
Marram Grass & Ferns
Soil pH
• Soil pH changes in different locations, allows
for different plant life
– Marram grass in pH of 7.5 of Foredune & Yellow
Dune
– Grey Dunes have lower, more acidic pH, Heather
plants thrive here
Salinity
• Foredunes catch salt spray from ocean
– Marram grass and Lyme grass can live in salty
environments
• Grey dunes as less salty
– Shrubs, mosses, and lichens live here
Mineral Nutrients
• Mineral nutrients refer to the minerals and
nutrients found in the soil
– Mature dunes contain the most because soil has
been building up for hundreds of years, support
large trees and variety of organisms
– Grey dunes contain some mineral nutrients
supports small shrubs, mosses, and lichens
– Foredune and yellow dunes contain little mineral
nutrients
Factors affecting distribution of animal
species
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Temperature
Water
Breeding sites
Food Supplies
Territory -
Temperature
• Animals have different adaptations to live in
hot and cold environments
– Sand Wolf Spider: lives in foredune, can survive
hot temps by burrowing in sand
– Woodland Spider: lives in mature dune, can
survive cooler temps, but would die in foredune
Water
• Animals can be specifically adapted to live in
wetlands
– Necessary for survival: laying eggs, food, etc..
– Blue Heron hunts in wetlands
• Animals do not need wetlands/abundance of
water for survival
– Woodpeckers, found in mature dunes and eat
insects living in trees
Breeding Sites
• Wetlands necessary for Blue Heron to breed
– Food source
– Protection from sun and wind
• Mature Dunes and trees necessary for
woodpeckers to breed
– Branches used for nesting sites
– Food source
Food Supply
• Some animals adapt to feed on specific food,
others are more wide-ranging and can travel
to find variety of food sources
– Raccoons go anywhere on dune where food is
– Rabbits build burrows in foredune and live near
Marram grass, which they eat
Territory
• Some animals live in specific areas and remain
separated from each other
– Use variety of mechanisms to mark territory
– Coyotes mark territory by urination, which
separates different groups of coyotes
– Studies have shown that territories do not overlap
Random Sampling
• Used to compare populations of different
species in a community
• Take a random sample and use it to estimate
total number of organisms
• Samples must come from all around habitat
• KEY TERM:
Random Sample – each organism has an
equal chance of being selected for the count
Quadrat Method
• Quadrat method –
– Map entire area (dune
example)
– Determine size of the
quadrats
– Place a grid with numbers
around entire area
– Choose which squares to use
to make sample
– Count number of “whatever”
in sample quadrant
– Count number of “whatever
else”
– Calculated averages of each
then multiply average by total
number of quadrants
Transect Method
• Most commonly used for
studying how the
distribution of plants in
an ecosytstem is affected
by abiotic factors
• Looking at Sand Dunes,
dunes nearest sea are
youngest, dunes farthest
inland are oldest
Transect Method
• Right angle from sea, lay tape all they way up
the dunes
• Ever 10-20 meters, mark out a quadrat
• Identify and could plant species of interest in
each quadrat
• Measure abiotic features (temp, light, etc…)
• Determine pattern of distribution from
youngest to oldest dune and examine
correlations
The Niche Concept
• Organisms have particular roles, or niches, in
their ecosystem
• The niche concept includes:
– Spatial Habitat: where the organism lives, every
organism has a particular space in the ecosystem that
is its spatial habitat
– Feeding Activities: What an organism eats affects the
ecosystem by keeping other populations in check
– Interactions w/ others: Include competition,
herbivory, predation, parasitism, and mutualism
Interactions between Species
• Competition: Occurs when two species rely on
the same limited resource in an ecosystem
• 1 species will be better adapted than the other to
benefit from resource
– Coyotes and Red foxes both eat small rodents and
bird. Expanded farming has led to overlapping
environments and more competition between the two
– Natterjack toad (Bufo calamita) competes with the
common toad (Bufo bufo) for resources in coastal
dunes in the UK
Interactions between Species
• Herbivory: occurs when a herbivore (primary
consumer) feeds on a producer (plants).
• Interaction between plants and animals:
– Rabbits eat Marrum Grass
– Monarch butterfly larvae eat leaves of milkweed
plant
Interactions between Species
• Predation: predator (consumer) eats another
consumer.
• Interaction between two animals, the
predator and the prey, each of which affects
the other
– Canadian Lynx preys on arctic hare, changes in
numbers of either population are followed by
changes in the other
– Blue Heron is a predator on frogs
Interactions between Species
• Parasitism: occurs when one organism lives on
or in a host and depends on the host for food.
The host is harmed by parasite
– Plasmodium is a parasite that causes malaria in
humans. Reproduces in liver and red blood cells
and uses mosquitos as vectors to transmit from
humans to humans
– Leeches are parasites in ponds that puncture the
skin of host and secrete an enzyme that prevents
clotting. Hosts are humans or other mammals.
Interactions between Species
• Mutualism: occurs when both organisms benefit
from the relationship
– Lichens (fungi) have mutualistic relationships with
algae. Algae photosynthesize and make
carbohydrates, fungi absorb mineral ions needed by
algae
– Rhizobium is a nitrogen fixing bacteria that lives in the
roots of leguminous plants such as beans and peas.
Bacteria fixes nitrogen that the plant uses to make
proteins, the plant makes carbohydrates that bacteria
use for food
Mutualism
• Clownfish and sea anemones live together. Clownfish
live in area of tentacles of poisonous anemone.
Clownfish is covered with mucus that protects from
sting of anemone and lure other fish to tentacles of
anemone. Clownfish eat remains of fish and nibble
off remains of dead sea anemone tentacles
The Principle of Competitive Exclusion
• States that no two species in a community can
occupy the same niche
• When two species have a similar need for the
same resources, one will be excluded
• One species will die out and the other will
survive
The Principle of Competitive Exclusion
• Demonstrated by Russian ecologist G.F. Gause
in 1934
• Use 2 species of paramecium, P. aurelia and P.
caudatum
– When two were kept separate both survived
equally well
– When in the same culture, P. caudatum died out
and P. aurelia survived
– P. aurelia out-competed P. caudatum
Fundamental and Realized Niche
• Fundamental Niche: the potential mode of
existence, given the adaptations of a species
• Realized Niche: the actual mode of existence,
which results from adaptations and competition
with other species
• Red Fox fundamental niche is the edge of a forest
and all organisms it interacts with. Its realized
niche is narrower because of the disappearing
forests and differing species, as well as increased
competition
Biomass
• Biomass: the total mass of organic matter,
with consists of compounds such as carbs,
lipids, and proteins
• Measured as dry mass of organic matter of
living organisms in grams per meter squared
per year [(g * m-2)/ y]
Measuring Biomass
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Measure total area of ecosystem
Divide are into small plots
Choose one plot to sample
Measure size of each plant species (height and diameter) including trees
and low growing vegetation. Cut down all vegetation on that plot.
Dry all samples in drying oven
Use mathematical model to show relationship between each plant species
and its biomass
Sample other plots by measuring size and height of plants
Apply mathematical formula to find biomass
Set traps for animals in plot to weigh and measure organisms
Use tables to determine their biomass
Average data for all species per plot
Multiply average per plot by number of plots
Repeat seasonally or yearly to study changes in a community over time