Summary (Ecology)

Ecology & Nutrient Cycle

 

What is Ecology?

- How life processes adapt to its surrounding/environment

- How different species are being distributed

- How an ecosystem change overtime

- How materials and energy move through the system of interacting organisms and their environment

- How biodiversity is being influenced by the environment

*Biodiversity – It is a term we use to describe the variety of life on Earth. It refers to the wide variety of ecosystems and living organisms: animals, plants, their habitats and their genes.

 

Individual --> Habitat --> Population  --> Community  --> Ecosystem

Habitat

Place where an organism lives is called habitat.

 

Population

A group of organism of the same species living in a particular habitat

Community

All the population of organisms living and interacting with each other in a single habitat

Ecosystem

A community with its abiotic environment make up an ecosystem

Examples of Communities:

- Leaf litter Community

Producer: Plants  --> Primary Consumers: Snail, Woodlouse, Earwig, Millipede -->Secondary Consumers: Beetle Larva, Beetle  --> Tertiary Consumers: Wolf Spider

- Pond Community

 

Organisms are interdependent. Energy is being transferred from one organism to another mainly through feeding. Sun is the main source of energy. Solar energy is being absorbed and it is being passed on in the form of chemical energy. Most of the energy is being lost eventually as heat. Energy flow is non-cyclical

Abiotic Environment

It means the physical features of the surrounding

1) Light Intensity

- It can affect the distribution and growth of both plants and animals.

- If there is excess light the plant might grow shorter where as if there is lesser light the plant will grow taller

- Green plant exists only where there is an adequate supply of light. Some plants develop adaptations to reach the light

- Certain plant have adapt so that they can block of excessive light, some plants have a dense covering of hairs on the leaf epidermis called the hypodermis. This will screen off excessive heat reducing the rate of transpiration

2) Temperature

- Temperature affects the rate of reaction of enzymes which control metabolic or physiological activities of plants and animals

- Temperature too high or too low will kill an organism

3) Amount of water

- Water is one of the basic necessities for all living thing

- Without water, no organism can live long

- It can affect both plants and animals affecting the flora and fauna

- Amount of water depends on the amount of rain and the pattern which rains falls throughout the year

- Examples of adaptations to droughts are camels (they can drink large amount of water when water is available and can go for long periods without water) xerophytes (a type of plants that reduce rate of transpiration, stem becomes fleshy to store water and stems also take over photosynthesis)

- Hydrophytes are for plants that live in very wet places

4) Oxygen content

- Oxygen is required for aerobic respiration

- lack of oxygen slows down metabolism

Some fishes adapt to the low oxygen water by coming up to the surface of the water to breathe in air

5) Salinity (salt concentration) of water or soil

- Many fishes that live underwater  tend to lose water through osmosis as seawater contain a higher
concentration of salt than the cytoplasm in the animal cell

- Marine fishes normally have a waterproof coating consisting of closely-fitted scales covered by a slimy mucous material to prevent water loss

6) Humidity

- High humidity slows down the rate of transpiration in plants but is also critical to the survival of epiphytes and organisms living in and places

7) Wind Speed

- High wind speed may break the stems of certain plants and may dissipate humidity

8) Wave action

- Prevents marine organism from settling down to feeding

9) Type of substratum

Clayey, sandy or rocky substratum influences ability of plants and sessile organisms to anchor themselves

10) pH level of soil and water

- Seawater has a pH of 8

- During the day it is more alkaline because the plants will use up the carbon dioxide

- During the night the plants respire making the seawater more acidic

Biotic Environment

- Arise from the interaction between organism

- Biotic influence may limit the distribution and abundance of organism

- Crucial elements to shape an ecosystem

- Mutualism

Both organism benefits 

- Commensalism

One benefit one does not receive benefit nor negative effect 

- Competition

Both receive negative effects

- Exploitative Relationship

Comes in three forms (Predation, Parasitism and Herbivory) One benefit one receive negative effects

- Ammensalism

One remain unchanged one receive negative effects

Feeding Relationship

- A food chain starts with a photosynthesizing organism which passes energy in a form of chemical energy to the organism that eats it

- Food web consist of interlinked food chains in the same ecosystem

The different consumers:

1. Autotrophs

Using inorganic molecules (such as carbon dioxide) and energy derived from either sunlight (photoautotrophs) or other inorganic molecules

2. Primary Producers

Primary producers are autotrophic organisms that supply energy to all other organisms in the food chain/ food web.

3. Heterotrophs

Heterotrophs are organisms which use organic molecules both as a source of carbon and as a source of energy, and acquire these molecules by feeding on other organisms

4. Consumers

Consumers are heterotrophic organisms that depend ultimately on the producers as energy sources.

5. Herbivores

Organisms with a strict diet consisting of plant matter only.

6. Primary Consumers

Organisms that feed directly on producers

7. Secondary Consumers

Consumers which feed on the herbivore/primary consumer

 

8. Tertiary Consumers

Consumers which feed on the secondary consumer

9. Carnivores

Organisms with a strict diet consisting only of other animals. The dominant consumer in an ecosystem is usually a carnivore.

 

10. Omnivores

Organisms that feed on both plant matter and on other animals.

11. Decomposers

Organisms which release enzymes to break down large molecules in dead organic matter into smaller ones which can then be recycled

 

Conservation

Man has greatly altered natural habitats. The ecosystem is in a delicate state of balance. Disturbance to the natural balance may result in increased rate of species extinction ad the organisms might be unable to adapt fast enough to rapid changes. Food webs become destabilized and an entire ecosystem may collapse. This in turn affects mankind as we obtain our food and resources from the natural environment.

Why must we conserve?

- Prevent extinction

- Maintain a stable and balanced ecosystem

- Prevents disruption of natural cycles

- Prevents global warming

- Maintain large gene pool

- Conserve marine life as a food source

- Scientific value

- Maintain biodiversity

Biodiversity

Biodiversity is the variety of living organisms (i.e. distinct biological species) and their range of behavioral, ecological, physiological and other adaptations in an area such as an ecosystem.

Consists of three levels:

1.Genetic diversity

- Genes determine character traits such as green eyes, brown eyes, ability to roll tongue etc.

- Thus together, the many individuals of a species contribute to the genetic diversity of that species.

2.Species diversity

- Total variety of biological species in a given place.

- Two organisms are considered as members of two different species if they are unable to produce a viable offspring that is itself capable of reproduction.

- E.g. chimpanzees, gorillas, humans, tigers, elm trees, orchid plants, bracket fungi, Pseudomonas bacteria, Amoeba

3.Ecosystem diversity

- The variety of ecosystems found in the biosphere.

- The destruction of one ecosystem, will destroy many of the organisms that live within it, decreasing both species and genetic diversity.

Addition of a new species

Extinction due to:

- Introduction of natural predator

- Introduction of competitor

- Depletion of food and water resources

- Sterility

- Low birth rates

- Environmental stressors

- Loss of habitat

- Poaching for food or pet trade

Removal of species

Addition of new species may also destabilize an ecosystem

Example: Biological Pest Control 

A method of pest control involving the release of the natural predator of the pest. These predators prey on the pest (by predation, herbivory or parasitism) and decimate the pest population.

Disadvantage

•Predator may also prey on local endemic species

•Pest population may not be controlled

•Pose as competition to other species