Option C: Ecology

and Conservatio

nKáren KrmoyanIB Biology SLMrs. Mariam

Ohanyan18 October 2016

C.1 Species and Communities

Limiting Factors

Distribution of species Range of Places that the Species InhibitsWhat?

Limiting Factors

Affected by

Abiotic (Non-Living) Factors Biotic (Living) Factors

Sunlight availability, water availability, soil type, air/water temperatures

Abundance of a prey animal, predators, a competitor for a resource, a parasite

Examples of limiting factorsPlant species Animal Species

Black Mangroves (tree type)

● Mean temperature of 20०C● pH = 5.3-7.8● Thrives in waterlogged soils

with no/little oxygen● Tropical or subtropical

areas

Dog Whelk (sea snail)

● Saline water required● Mean temperature = 0-

20०C● Lower to middle parts of

rocky shores

Ecological Model: Environmental Gradients & Population Level of

Species

Using transects to depict the distribution of plant/animal

species

Quadrat sampling and transect sampling performed simultaneously

A transect is a method of sampling at regular positions in an ecosystem, to investigate whether the distribution of

the plant or animal species is correlated with an abiotic variable.

Ecological Niches

Spatial Habitat Interactions

Where a species inhabitsHow the species affects and is affected

by other species in the community, including nutrition

● Each species has its role in the niche.● A suitable habitat for thriving in the habitat

(abiotic variables within limits of tolerance)

Competitive Exclusion Principle

PLAN AThe superior species will cause the other species to be lost from the ecosystem.

Two species cannot survive

indefinitely in the same habitat

if their ecological niches are identical.

PLAN BOne or both of the competitors will narrow down their niches to avoid competition

Types of Ecological Niches

Fundamental Niche Realized Niche

The niche that the species could POTENTIALLY occupy (POTENTIAL

mode of existence)

The niche that the species actually occupies (ACTUAL mode of existence)

6 Types of Interactions Between Species

1 HERBIVORYPrimary consumers feed on producers

Harmful for producers, but reduces competition among consumers

EXAMPLE: bisons feed on grasses

2 COMPETITION One species using a resource reduces its availability for others

EXAMPLE: red oak and sugar maple

6 Types of Interactions Between Species

3 PREDATIONOne species is a prey for another animal

One consumer feeding on another consumer

EXAMPLE: apple snails are prey of Everglades kit

4 PARASITISMOne species acts as a host to another species (parasite) that harms the host

The parasite feeds off the host

EXAMPLE: leeches are parasites to many mammals

6 Types of Interactions Between Species

5 MUTUALISM Both species living in close association benefit from their interaction

EXAMPLE: flowering plants pollinated by insects

6 COMMENSALISMOne species benefits and the other relatively

unaffected (neither harmed nor helped) by the relationship

EXAMPLE: ‘air plants’ of the US use trees as places to grow (the tree not harmed or benefitted)

Application: zooxanthellae and reef-building coral reef species

An example of Mutualism

Zooxanthellae Photosynthetic unicellular algae that live inside coral tissues

Zooxanthellae photosynthesize and provide nutrients for the coral

Corals provide the algae with protective environment and

substance for photosynthesis

Keystone SpeciesA keystone species exhibits a strong,

disproportionate control over the structure of the community.What?

Removal Experiment→ Paine first conducted an experiment (removing the sea star from its original habitat)→ Result: mussel took over its place and excluded algae and other invertebrates from the environment (ORIGINALLY, sea stars prevented the mussels)

C.2 Communities and Ecosystems

Trophic levelsAn organism’s trophic level is its feeding position in a particular

food chain.N.B. The organism can occupy more than 1 trophic level based

on the food chains.

What?

Food chain

Food web

A single consequence of organisms, each of which consumes the previous one in that chain

A food web shows all the possible food chains in the community.

Pyramids of energy as models

Unit: KJ/m2 year

Shows energy transfer from one trophic level to another

Limitations of the model:- Energy transfer varies

over seasons- Diet dependent on reason

and/or opportunity

The impact of climate on ecosystem type

Climate is a property that emerges from the interaction of a number of variables including temperature and precipitation.

What?

Temperature affects cell respiration, photosynthesis, decomposition, transpiration,

productivity.

Precipitation affects photosynthesis, decomposition, productivity.

High rainfall and high temperature → tropical rainforestsHigh rainfall and low temperature → temperate rainforests

Low rainfall and high temperature → grasslandLow rainfall and low temperature → desert

Interpreting a Whittaker climograph

Shows the relative combination of temperature and precipitation in the area and the likely ecosystem that will emerge in different conditions.

Gersmehl nutrient cycle diagrams

Energy conversion ratios

Food conservation ratio is the quantity of dietary input in grams required to produce a certain quantity of body mass in livestock of fish.

What?

- Production in plants happens due to photosynthesis.- Production in animals happens when they digest food

Gross production - total amount of organic compound produced per unit area per unit time

by a trophic level in an ecosystem.

Net production - the amount of gross production remaining after subtraction of the amount used

for respiration by the trophic level.

Conversion rate = intake of food (g) / net production of biomass (g) Used to assess the sustainability of food production practices

SuccessionsSuccession → the changes that transform ecosystems over time

(species and abiotic environment)

Abiotic environments limit the distribution of living organisms, while organisms have

an effect on abiotic factors.

Changes in the environment (starting with rocks)

Soil develops and more species occur

At a place where there is already an ecosystem present (disturbance and

change in conditions)Climax community ~ slower changes,

relatively stable

Primary succession Secondary succession

Closed ecosystems

Open Closed Isolated (theoretical)

energy

energy

matter matter

energy

energy

C.3 Impacts of Human on Ecosystems

Alien and invasive speciesSpecies that are native to an area are called

endemic.Species that are not native to an area and are introduced by humans are called alien.

Alien species that increase in number and spread rapidly are called invasive.

Competitive exclusion and absence of predators

Competition between endemic and alien species

Stimulates

Cane toads introduced in Australia and affect the population of mosquitos.Zebra mussel introduced in the North American Great Lake systems

Biomagnification

toxin

toxin toxin

toxin

toxin

toxin

Bioaccumulation

Biomagnification is the process by which chemical substances become more concentrated at each trophic level. [Predator consumer larger

quantities of prey]

Devastating effects on top carnivores (e.g.

ospreys) due to biomagnification

Ethical issue

The benefits and risks of DDT use

Benefits Costs

Combatting diseases such as malaria (DDT killed insects, bacteria, and viruses harmful to

humans)

Plastics in the oceanPlastic - a number of different polymers used

in different disposable consumer items.

Macroplastic → large visible debris ~ e.g. nets, buoys, buckets, trash

→ Degradation of macroplastic → microplastic (invisible, yet omnipresent)

Consequences● Bioaccumulation and

biomagnification of plastic at sea● Concentration of toxins

● Animals eat / become entangled in plastic pollution

Named examples:● Laysan albatross (contacts

the large volumes of plastic in the beaches)

● Leatherback turtle

C.4 Conservation and Biodiversity

Indicator species

Occur only when specific environmental conditions are

present

Example: understorey plants

in a forest → indicator of soil fertility, water

drainage

Biotic index calculationSimpson’s reciprocal index

D = N*(N - 1) / Sum (n*(n-1)),Where D = diversity index,

N = total number of organisms,n = number of individuals per species

Aim: COMPARE THE RELATIVE FREQUENCY OF DIFFERENT SPECIES (especially, indicator species)

Conservation types

Endangered species removed from their

original habitat→ Botanical garden,

captive breeding

In situ conservation Ex situ conservation

Endangered species remain in their original

habitat→ Terrestrial, aquatic,

and marine nature reserves established

Biodiversity

Richness EvennessComponents of Biodiversity

Biogeographic factors (e.g. size of the habitat, connectedness of nature reserves, shapes of nature reserves) affect the biodiversity of the ecosystem.

Thank You!