Fundamentals of Ecology, Biology tutorial


Essentially, ecology is like a society, only it is much bigger than ours; ecologists are like economists, only they examine economy of nature instead of that of human. Ecology in three basic scales after introductory section: population, community, and ecosystem.

Ecological Community:

The community is included all different populations interacting in area. The example of the community is the coral reef where many populations of fishes, crustacea and corals exist and interact. Ecologists attempt to know at level how different relationships like predation and competition are influencing organization and evolution of the community.

Composition and Diversity:

Communities differentiate from each other by two features: composition and diversity. Composition of the community is simply listing of different species in community. Diversity digs deeper than mere composition in that it involves both species richness(the number of species) as well as evenness (the relative abundance of different species).

A species' spreading range is based on its tolerance for such abiotic factors in the environment as temperature, light, water availability, salinity, and so forth. To determine a species' tolerance range, we plot the species' ability to survive and reproduce under a particular gradient of environmental conditions, resulting a bell-shaped curve.

Habitat and Ecological Niche:

Each species plays role in the community, eats or be eaten, lives or let live. They dwell in particular positions both in the spatial sense (where to live) and functional sense (what is the part). The habitat is the environment wherein organism lives and reproduces, while ecological niche is functional role organism plays in community, incorporating habitat and interactions with other organisms. As organism's niche is influenced by abiotic factors (like climate and habitat) and biotic factors (like parasites, competitors, and predators) concurrently, generally two kinds of niches are looked at separately by ecologist, fundamental niches and realized niches.


Competition for resources, predator-prey, parasite-host, and other kinds of interactions incorporate species in a system of dynamic interacting populations. Competition for restricated resources between two species has negative effect on population abundances of both species. In predation and parasitism, abundances of predator and parasite are expected to increase at expense of that of prey and host, as predators feed on prey and parasites get nutrients from host.

a) Competition among Populations:

Interspecific competition happens when members of different species attempt to use same resource such as light, space, or nutrients which is in limited supply, or when niches overlap. If it is unlimited, no competition would have been triggered. Competition leads to many possible outcomes.

b) Predator-Prey Interactions:

In predation, one organism, known as predator feeds on another, known as prey. With common sense, there must be no dispute on that relationship between lion and zebra is that of predation. This might be little bit surprising, but in the broader sense, predaceous consumers comprise not only animals but also herbivores which feed on plants. The interacting pattern between populations of predator and prey, cycles of fluctuation that one drives other and vice versa. Population of prey increases as that of predator decreases, as fewer prey are being eaten. At carrying capacity of environment, number of prey reaches summit and stops growing.

c) Symbiotic Relationships:

The symbiotic relationship, or symbiosis is one in which members of two populations interact very closely. Parasitism resembles predation in that organism known as parasite derives nourishment from another known as the host (just as predator derives nourishment from its prey), although parasites also take hosts as habitats and springboards to transmit themselves to other hosts. Parasites appear in all kingdoms of life. Commensalism is the symbiotic relationship in which one species is benefited and other is neither benefited nor harmed.


Ecosystem extends the community by involving also abiotic environment, which is, physical and chemical environment. Energy flow and nutrient cycling (cycling of chemicals) are important features in understanding how ecosystems function. The ecosystem frequently comprises cycles and flows which involve dozens of living things and non-living matters. Ecologists focus not only on organic living things of the ecosystem, but also those fundamental inorganic conditions and materials which are vital for living things to survive.

Abiotic components:

Abiotic components are such physical and chemical factors of the ecosystem as light, temperature, atmospheric gases (oxygen, nitrogen, carbon dioxide are the most significant), water, wind, soil. These specific abiotic factors represent geological, hydrological, geographical, and climatological characteristics of the particular ecosystem. Separately:

  • Water, which is at the same time essential element to life and a milieu
  • Air that gives oxygen, nitrogen, and carbon dioxide to living species and permits dissemination of pollen and spores
  • Soil, at the same time source of nutrients and physical support. Salinity, nitrogen and phosphorus content, ability to retain water, and density are all important.
  • Temperature that must not exceed certain extremes, even if tolerance to heat is important for some species

Biotic Components:

Organisms are biotic components of the ecosystem. In ecosystems, living things are categorized after way they get their food. Autotrophs generate their own organic nutrients for themselves and other members of community; thus, they are known as the producers. There are basically two types of autotrophs, chemoautotrophs and photoautogrophs. Chemautotrophs are bacteria which get energy by oxidizing inorganic compounds like ammonia, nitrites, and sulfides, and they utilize this energy to synthesize carbohydrates.

Energy Flow:

Everything requires energy for motion, living things are no exceptions. Sun is crucial source of energy for every ecosystem. Energy flow of the ecosystem begins the moment photosynthesizers capture sun light and transform it in the stock of organic compound like glucose which stores heat and energy for later use, and ends until energy is used up or released in surroundings in metabolic processes. In between them, energy transfers from one organism to another at aid of food webs, each of the organisms receiving only the small percentage of total energy carried in one being consumed,

a) Primary Productivity and Secondary Productivity:

About 1% to 2% of the solar energy which falls on the plant is converted to food or other organic material. Primary productivity is term utilized to describe amount of organic matter the ecosystem produces from solar energy inside given area during the given period of time. Related to concept, gross primary productivity is total amount of organic matter produced by all autotrophs in the ecosystem, including which used by themselves. Net primary productivity, on the other hand, is stated as total amount of energy fixed per unit of time minus amount of energy expended by metabolic activities of photosynthetic organisms in community, denoting amount of organic matter produced by autotrophs which is available for heterotrophs.

b) Food Webs and Trophic Levels:

Food webs refer to complicated feeding relationships which exist among organisms in natural ecosystem. Ocean food web is just grazing food web which starts with green plant, or producer. This ocean food web shows that krill and other herbivorous plankton feed on phytoplankton, producer, whereas birds and fish feed on krill, but they are in fact omnivores as they also feed on plankton; squid hunts fish for food while enjoying some plankton once in a while as well. These herbivores and omnivores all give energy and nutrients for the number of different carnivores, like seals and whales.

Another sort of food web known as detrital food web, compared with grazing food web, it is food web more involved with decomposition procedures, and more involved in abiotic components of the ecosystem.

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