Ecology is the study of interaction and relationships between the organisms and the biotic as well as abiotic environment. Every organism is interdependent. Energy is transferred form one organism to another mainly through feeding. The sun is the main source of energy for Planet Earth, as the solar energy is absorbed by the sun and passed on to other organisms as chemical energy. However, most of this energy is eventually lost as heat and the energy is non-cyclical too.
Terms used for ecology:
Habitat: the place where an organism lives
Population: a group of organisms of the same species living in a particular habitat
Community: All populations of organisms living and interacting with each other in a particular habitat.
Ecosystem: A community and its abiotic environment
Abiotic Factors that will affect the livelihood of organisms living in a community or ecosystem:
Temperature and pH: Extreme temperatures and pH disrupts the hydrophobic, hydrophilic, ionic interactions and proper functioning of enzymes, and will cause them to lose their shape and functionality.
Oxygen Content: Oxygen is required for aerobic respiration, thus a lack of oxygen will slows down metabolism.
Humidity: High humidity slows down the rate of transpiration in plants but is crucial and critical to the survival of epiphytes and organisms living in arid places.
Amount of water: Affects number and location of flora and fauna. However, it is affected by rain pattern
Wave action: Prevents marine organisms form settling down and feeding
Wind Speed: High wind speed may break the stems of certain plant species but will dissipate humidity
Light Intensity: Low light intensity retards plant growth, but high light intensity may bleach chlorophyll and impairs the ability of plants to photosynthesize
Salinity: Affects osmotic balance in many aquatic animals and coastal plant species
Type of substratum: Clayey, sandy or rocky substratum will influences ability of plants and sessile organisms to anchor themselves
Biotic Environment
Mutualism:
Both organisms benefit. For example, Lichen is made up of algae and fungus. The algae make food for the fungus while the fungus takes in water for the algae.
Commensalism:
One party benefits while the other remains neutral. For example, Remora fish help to clean and eat parasites from sharks’ gills.
Exploitative relationships (Predation, Parasitism, Herbivory):
One party benefits while the other had a fitness disadvantage. For example, the snake had a fitness advantage when it feed on the rabbit, but the rabbit had a fitness disadvantage.
Competition:
Both party had a fitness disadvantage. For example, both snake and eagle have similar feeding habits, thus both had a fitness disadvantage.
Ammensalism:
One party had a fitness disadvantage while the other is neutral. For example, a smaller plant had a fitness disadvantage when it is shaded out by a tall tree, as it could not receive sufficient amount of sunlight, but the tall tree was neutral as it did not affect the tree.
Feeding Relationship:
Feeding relationship is shown through a food chain, which is a sequence of organisms, starting with a photosynthesizing organism, through which energy is passed as one organism is eaten by the next in the sequence.
Examples of food chain:
grass -> rabbit -> fox
grass -> zebra -> lion
grass -> grasshopper ->bird -> snake
Food chains can be then interconnected to form a more complex food web, which comprises interlinked food chains involving organisms from the same ecosystem.
Terms used in food web:
Autotrophs: Organisms that are capable of synthesizing organic molecules, such as glucose, using inorganic molecules, such as carbon dioxide, and energy derived from sunlight.
Primary Producers: Autotrophic organisms that supply energy to all other organisms in the food chain/ food web. Note that all primary producers are autotrophic but not all autotrophs are primary producers.
Heterotrophs: 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.
Consumers: Heterotrophic organisms that depend ultimately on the producers as energy sources.
Primary Consumers: Organisms that feed directly on producers
Secondary Consumers: Consumers which feed on the primary consumer
Tertiary Consumers: Consumers that feed on the secondary consumers
Herbivores: Organisms that only feed on plant matter
Carnivores: Organisms that only feed on other animals
Omnivores: Organisms that feed on both plant matter and other animals
Decomposers: Organisms which release enzymes to break down large molecules in dead organic matter into smaller ones which then can be recycled.
Conservation
Man has greatly altered natural habitats when they exploit the natural environment for fossil fuel, wood and other natural sources. This may result in increased rates of species extinction as organisms are unable to adapt fast enough to the rapid changes. When a species go extinct, food webs become destabilized and an entire ecosystem may collapse. Thus, this will eventually affect mankind as we obtain our food sources from the natural environment.
Thus, conservation is important for the following reasons:
-prevent extinction of plant and animal species
-maintain a stable and balanced ecosystem, prevent disruption of natural cycles such as carbon and water cycle, prevent global warming
-maintain large gene pool so as to preserve favourable genes; helps to improve agricultural produce or crops with better resistance to diseases
-conserve marine life as a food source
-scientific value – study of evolution
-nature appreciation – recreational purposes such as hiking, fishing, skiing
-maintain biodiversity – economical (rice, pineapple and banana are food plants developed from rainforest plants), medical (Quinine, an anti-malarial drug is found from the bark of Cinchona), industrial (latex is tapped from rubber trees and used to make tyres) purposes
Effects of selective addition/removal of species
The dynamic flow of energy, nutrients and intricate interactions between organisms and their environment establishes a state of delicate balance in the ecosystem, which changes only gradually over time. This state of balance gives stability and self-sustainability to an ecosystem.
Such stability and self-sustainability requires:
-A constant input of energy
-Presence of producers which are able to harness this source of energy, converting it into chemical energy required to power the rest of the food chain
-Continuous circulation of matter between the biotic and abiotic components of an ecosystem
By altering any of the above requirements, the stability of an ecosystem may be disrupted. An example is the addition or removal of species from an habitat, such as the use of biological pest control.
Natural predators of the pest may be introduced to effectively control the pest population. However, care must be taken when selecting the natural predator so that they may not offset the local ecological balance. This may happen if the natural predator target unintended prey, and compete with the indigenous species.
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