C.1 species and community

http://therainforestguide.weebly.com/
Essential idea: Community structure is an emergent property of an ecosystem.
C.1 Species and Community

Understandings
Statement Guidance
C.1 U.1 The distribution of species is affected by limiting factors.
C.1 U.2 Community structure can be strongly affected by keystone species.
C.1 U.3
Each species plays a unique role within a community because of the
unique combination of its spatial habitat and interactions with other
species.
C.1 U.4
Interactions between species in a community can be classified
according to their effect.
C.1 U.5
Two species cannot survive indefinitely in the same habitat if their
niches are identical.
C.1 A.1
Distribution of one animal and one plant species to illustrate limits of
tolerance and zones of stress.
C.1 A.2 Local examples to illustrate the range of ways in which species can
interact within a community.
C.1 A.3 The symbiotic relationship between Zooxanthellae and reef-building
coral reef species.
C.1 S.1 Analysis of a data set that illustrates the distinction between
fundamental and realized niche.
C.1 S.2 Use of a transect to correlate the distribution of plant or animal
species with an abiotic variable.

Factors affecting the distribution of species:
Plants Animals
temperature
water
light (intensity/wavelength) breeding sites
soil pH food supply
soil salinity territory
mineral nutrient availability

Temperature Water Food
Body size (specifically SA:Vol
ratio) will determine an animal's
ability to conserve heat – a large
SA:Vol ratio means that heat is
easily lost to /gained from the
environment
Apart from drinking to maintain
cells’ osmotic balance water can
be required as a habitat,
transport medium, a place to lay
eggs, a source of dissolved
oxygen, food maybe filtered from
water (e.g. corals), and as a
coolant. [See 2.2 Water for
details]
Animals maybe specialized so
that they will only consume a
particular species of animal or
plant, e.g. the caterpillars of the
Small Tortoiseshell butterfly eat
only nettle plants.
Homeotherms (organisms that
maintain a stable internal body
temperature) can colonize a
wider range of habitats than
poikilotherms (internal
temperature varies considerably)
Seasonal or geographical
variation in food directly affects
abundance of the population
Detail on how the factors affecting the distribution of animal species:

Detail on how the factors affecting the distribution of animal species:
Breeding sites Territory
Breeding sites need to provide protection
for eggs, juveniles, and nesting adults.
Animals may mark territories, e.g. by
urinating or marking trees
Sites are often rich in food or other
resources necessary for juveniles, and
breeding adults
Territories can be established by
individuals, breeding pairs or groups
Juveniles may have specialized
environmental requirements different from
the adults, e.g. dragonfly nymphs live
underwater
Territories maybe temporary (e.g. just for
the duration of breeding cycle) or
permanent
Establishment of territories can lead to
intra-specific (within species) or inter-
specific (between species) competition

Example: Water
deep-sea vent, high
temperature and
pressure, no light,
organisms are
adapted to getting
there energy from
chemicals released
from the magma.

Food Supply: hypersaline lakeNutrient poor,
water is clear, oxygen rich; little productivity by
algae, relatively deep with little surface area.
Example: Water effect on the distribution of animals deep-sea mussels living on the "shore" of
the Brine Pool (extremely salty environment). These mussels use methane as their primary
source of food, but also filter small particles from the water.
http://oceanexplorer.noaa.gov/explorations/02mexi
co/background/mussels/media/brinepool.html

Intertidal Zone: Alternately submerged and
exposed by daily cycle of tides. Often
polluted by oil that decreases biodiversity.
Example: Waters effect on the
distribution of animals in the intertidal
zone. Mussel and star fish have
adapted to an environment of harsh
extremes. Water and salinity levels
availability varies with the tides.
Intertidal zone's have high exposure to
the sun, the temperature range can be
anything from very hot with full sun to
near freezing in colder climateshttp://people.stfx.ca/rscrosat/biol
ogy311/MUSSEL_SEASTAR.jpg

Temperature Water Light
Metabolic pathways are
controlled by enzymes, which
have optimal temperatures, too
high and the enzymes will
denature
Needed to maintain cell turgor Plants that grow in shade (lower
light intensity) contain more
chlorophyll, they have darker
green leaves
High temperatures increase the
rate of evaporation (and hence
transpiration)
Needed for photosynthesis and
respiration to occur
Plants, e.g. Kelp (algae), appear
brown, not green, and have
pigments that are adapted to
absorbing the blue wavelengths
as red wavelengths do not easily
penetrate water
Xerophytes, e.g. Cacti are adapted
to low water conditions,
hydrophytes, e.g. rice, are
adapted to waterlogged soils
Detail on how the factors affecting the distribution of Plant species:

Soil pH Soil salinity Minerals nutrient
availability
pH affects the availability
of mineral nutrients, e.g.
minerals can either be
bound more strongly in the
soil or leeched from the
soil more easily at different
pHs.
High salinity either makes
uptake of water (osmosis)
by plants more difficult, or
in extremes causes water
loss
Waterlogged soils
encourage denitrifying
bacteria and lower the
nitrogen availability to
plants
pH may affect the
decomposition of organic
matter, and hence the rate
at which nutrients are (re-
)cycled and made available
to plant
Halophytes, e.g. Mangrove
trees, are adapted to high
salinity soils
Weathering of rocks often
increases the availability of
nutrients in the soil
Detail on how the factors affecting the distribution of Plant species:

Tropical Forest: Vertical stratification with trees in canopy blocking light to bottom
strata, making light the limiting factor for those plant.

Desert: Sparse rainfall (less then 30 cm per year) makes water the limiting factor, plants and
animals. Both must adapt for water storage and conservation.

Temperate Rain Forest: Old growth forests nutrients are locked into the trees
making the soil nutrient poor.

Permafrost (Permanent frozen ground), bitter cold, low rain fall, high
winds and thus no trees. Has 20% of land surface on earth.

Keystone Species Concept
• In ecological communities there are little
players and big players. The biggest players
of all are referred to as keystone species.
• A keystone species may be defined as one
whose presence/ absence, or
increase/decrease in abundance, strongly
affects other species in the community.
• Evidence usually comes from addition or
removal experiments.
Example: Kelp forests (Keystone species: Sea
Otters)
• Can grow two feet per day
• Require cool water
• Host many species – high biodiversity
• Fight beach erosion
Kelp forests threatened by
• Sea urchins
• Pollution
• Rising ocean temperatures
Removal of the keystone in the arch
will cause the structure to collapse.

Keystone Species
Sea Otters: are a keystone species in
the kelp forests. They eat many
invertebrates, but especially sea
urchins. If there are too many sea
urchins, they will eat too much of the
kelp and destroy it.

Endangered Southern Sea Otter
Keystone species: plays a role affecting many
other organisms in ecosystem
specifically sea otters eat sea urchins that would
otherwise destroy kelp forests
• Kelp forests provide essential
habitat for entire ecosystem
• ~16,000 around 1900
• Hunted for fur and because considered
competition for abalone and shellfish
• 1938-2008: increase from 50 to ~2760
• 1977: declared an endangered species

http://www.vanaqua.org/files/1013/2018/0738/otter-eat.jpghttps://en.wikipedia.org/wiki/Mangrove
Red mangrove: This tree
grows along the shoreline
in the tropics and its roots
protect the soil from
erosion. The roots also
offer protection to small
animals, including reef
fish.

Keystone modifier species, such as the Grizzly bears:
As predators, bears keep down the numbers of
several species, like moose and elk. They also carry
and deposit seeds throughout the ecosystem. Bears
that eat salmon will leave their dropping and the
partially eaten remains that provide nutrients such as
sulfur, nitrogen and carbon to the soil. https://www.pinterest.com/pin/330170216403151039/

Wolves: Are a top predator, wolves are
important in many habitats. Wolves keep
deer populations in check and too many
deer will eat small trees, which leads to
fewer trees. In turn, there would be
fewer birds and beavers and the whole
ecosystem would change.
http://www.glogster.com/keishaa2014/el-parque-nacional-yellowstone/g-6m1qgcf75nvsgkiibvrkga0

ECOLOGICAL NICHE
• It is more than just the physical place (‘address’) where a species
lives, it also includes its role in the system (its “occupation /
lifestyle”). It is its total role in the ecosystem.
• A species functional role (“place”) in a community in relation to
other species which includes
Space and territory
Nutrition and feeding habits
Interactions and relationships with other organisms
Reproductive habits
Its role and impacts in the habitat or ecosystem
C.1 U.3 Each species plays a unique role within a community because of the unique
combination of its spatial habitat and interactions with other species.

Two types of Niche’s
• Fundamental Niche: the total range of physical, chemical and biological factors
a species can utilize / survive if there are no other species affecting it
• Realized Niche: the actual mode of existence, which results from its adaptations
and competition with other species. Because species never live under ‘perfect’
conditions but where an ‘acceptable’ ECOLOGIC SUM of conditions exists.
Competition II
Competition I
Competition
III
Realized Niche
C.1 S.1 Analysis of a data set that illustrates the distinction between
fundamental and realized niche.

C.1 U.4 Interactions between species in a community can be classified
Type of Interaction Sign Effects
mutualism +/+ both species benefit
commensalism +/0 one species benefits, one is
unaffected
competition -/- each is negatively affected
predation(includes herbivory,
parasitism)
+/- one species benefits, one harmed
Types of Species Interactions
An ecological community is a group of actually or potentially interacting species, living
in the same place
A community is bound together by the network of influences that species have on one
another.
There are four main classes of two-way interactions, and many possible pathways of
indirect interaction.

Mutualism is where two members of different species benefit
and neither suffers. Examples include rumen
termite/protazoa that digest cellulose

Commensalism is an ecological relationship, in which one species
benefits from an association with another organism, while the other
organism receives no benefit, but is not harmed

• Predation are consumers the eat other consumers. Predators have evolved to
find, catch, kill, eat and digest it prey.
Anteater Ant

• Parasitism is the relation between the host and the parasite. The parasite
gains an advantage at the cost of the host, causing harm to the host which
may lead to death. Examples of parasites are some viruses, fungi, worms,
bacteria, and protozoa.
Bass
Lamprey

Herbivory
Primary Consumers that feed only on plant material. Considered
predators of plants. These relationships can be harmful or beneficial.
Ladybug and a caterpillar are examples of herbivories

Interactions Between Species (Two types)
• Competition is when two species need the same resource such as a
breeding site or food. It will result in the removal of one of the
species. There are two major types of competition

I. Intraspecific competition A form of competition in which individuals of the
same species compete for the same resource in an ecosystem. This tends to have a
stabilizing influence on population size. If the population gets too big, intraspecific
population increases, so the population falls again.

II. Interspecific competition A form of competition in which
individuals of different species compete for the same resource in an
ecosystem.

Competitive Exclusion
• No two species in a community can occupy the
same niche
Species A niche
Species B niche
C.1 U.5 Two species cannot survive indefinitely in the same habitat if
their niches are identical.

Principle of Competitive Exclusion
• Where two species need the same resources and will compete until one species is
removed.
• One would be more capable of gathering more resources or reproducing more
rapidly until the other was run out of existence.
• Experiments with paramecium populations in the lab of Ecologist G.F. Gause
demonstrated this concept scientifically.
*The niche concept was investigated in some classic experiments in the 1930s
by Gause. He used flasks of different species of the protozoan Paramecium,
which eats bacteria and yeast.
Experiment 1

P. aurelia
P. caudatum
• Conclusion: These two species of Paramecium share the same niche, so they
compete. P. aurelia is faster-growing, so it out-competes P. caudatum.

• In the second experiment he took P. caudatum and had it compete
with a second type of Paramecia. It is important to understand the
distribution in experiment 2.
• P. caudatum lives in the upper part of the flask because only it is
adapted to that niche and it has no competition. In the lower part of
the flask both species could survive, but only P. bursaria is found
because it out-competes P. caudatum.
Experiment 2
Conclusion: These two species of Paramecium have slightly different
niches, so they don't compete and can coexist.

C.1 A.1 Distribution of one animal and one plant species to illustrate
limits of tolerance and zones of stress.
http://imgkid.com/purple-saxifrage.shtml
Purple Mountain Saxifrage: Melting
glaciers are indicators of climate change,
but when it comes to biodiversity in the
Alps, scientists are more concerned
about the fate of fragile mosses and
flowers. Alpine plants are one group
expected to be highly susceptible to the
impacts of climate change

http://www.greenglobaltravel.com/wp-content/uploads/babyseaturtles.jpg
Sea Turtles: lay their eggs on beaches,
many of which are threatened by rising
sea levels. Climate change also threatens
the offspring of sea turtles, as nest
temperature strongly determines the sex:
the coldest sites produce male offspring,
while the warmer sites produce female
offspring.
This nest-warming trend is reducing the
number of male offspring and seriously
threatens turtle populations.

Shelford's law of tolerance
A law stating that the abundance or distribution of an organism can be controlled by
certain factors (e.g. the climatic, topographic, and biological requirements of plants
and animals) where levels of these exceed the maximum or minimum limits of
tolerance of that organism.
http://www.ic.ucsc.edu/~wxcheng/envs23/lecture8/ecosystem

C.1 A.2 Local examples to illustrate the range of ways in which species
can interact within a community.
Atlantic Silversides: With a life cycle said to be only two years, the young of last year are now
the breeders of this year. Having reached a size of 4'' to 5'', they begin returning to the bay in
late winter. As the waters warm they travel throughout the bay and middle estuary, breeding as
they go, eventually returning on the same path till exiting for the inlet and surf in early July
followed closely by Bluefish that pursued them into the bay. For the rest of the year it's the
young of the year they left behind that will dominate the forage fish of the bay.

Bluefish, ranges in the western North Atlantic from Nova Scotia and Bermuda to Argentina. They
travel in schools of like-sized individuals as warm water migrants. They generally move north in
spring and summer to centers of abundance in the New York of the Atlantic Silversides

C.1 A.3 The symbiotic relationship between Zooxanthellae and reef-building coral reef
species.
• The relationship between the
algae and coral polyp facilitates a
tight recycling of nutrients in
nutrient-poor tropical waters.
The coral provides the algae with:
• a protected environment - coral
polyps secrete calcium carbonate
to build the stony skeletons which
house the coral polyps (and
zooxanthellae)
• compounds they need for
photosynthesis
The algae provide the coral with:
• Oxygen
• helps the coral to remove wastes
• Supplies the coral with glucose,
glycerol, and amino acids
(products of photosynthesis)

Most reef-building corals have a
mutually beneficial symbiotic
relationship with a microscopic
unicellular algae called zooxanthellae
that lives within the cells of the coral
C.1 A.3 The symbiotic relationship between Zooxanthellae and reef-building coral reef
species.
http://felixsalazar.com/pages/2013/01/macro-reef-dwellers-a-retrospective/

Random Sampling
Using Quadrats to compare the population of plant or animal
species
• The validity of results obtained from the various sampling
methods is dependent upon the adoption of random sampling
techniques
• Strategies for avoiding bias through random sampling utilise a
number of approaches – these include random sampling using
a grid
• A grid is created by laying out tapes at right angles to one
another to form the axes of the gridded area
• Pairs of random numbers are used to provide the coordinates
for locating quadrats

Quadrat is a frames, constructed from wood or metal, are used to
investigate the distribution of species
Subdivided quadrat frame
for determining % cover of
species
Square quadrat frame
for determining population
densities

Transects
• A transect is a line, created with string or a tape, along which systematic sampling
is performed
• Transects are particularly useful for sampling areas where there is a transition of
species from one habitat to another as environmental conditions change
• Transect studies are used to investigate gradients such as zonation on rocky
shores and changes in the species diversity across sand dunes
• A line transect is one in which all individual organisms touching the tape/string
are recorded
• The most commonly used belt transect involves laying a tape through the area of
study and sampling the population with quadrats positioned at regular intervals
alongside the tap

Belt transect Survey of a Dune System
A belt transect was used to investigate the distribution of three
species of grass commonly found on sand dunes
The transect line stretched from the high water mark to the
inland area and 1m x 1m quadrats were used to determine the
number of individual plants of each grass species along the
profile

Present the results as a bar chart

0
10
20
30
40
50
60
70
80
90
100
0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 55-60
Distance from high water mark (m)
Numberofplantsperm
2
Sand couch grass
Marram grass
Sand fescue

Bibliography / Acknowledgments

C.1 species and community

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