The living organisms in a given specific geographical area live together with other organisms and interact among themselves as well as with the environmental factors. The organisms are extremely diverse and range from single cellular entities to highly complex multicellular organisms. They interact irrespective of their dissimilarities for the benefit of each other and continue their propagation in the specified environmental conditions. Abiotic factors like temperature, humidity, sunlight, and nutrient availability influence the survival of living organisms. Changes in the quality or quantity of the abiotic or biotic components can influence the living of other organisms. The ecosystems are organised into different levels for understanding and learning purposes.
Studying nature is complex because of its extreme diversity. The ecosystem is the basic unit of nature that is functional having two inseparable components. The biotic and abiotic components are inseparable and each of which cannot exist without the other one. Because of the extreme diversity in living organisms and their interactions are studied at different levels.
Organisms are single beings and a group of genetically related organisms that can breed naturally and produce fertile offspring capable of continuing their number is called species. Each species can be unicellular or multicellular organisms however, they pose a set of unique characteristics that may be different in sexes.
Organisms within a species may look similar with some physical differences like sexual characters. Although the genetic make-up is not entirely the same for organisms within a species, there are many common genes and proteins resulting in unique characteristics for the individual organisms within a species. Species are the taxonomic level and fall below the genus. In general, species is the second word in the scientific name. For example, Homo sapiens is the scientific name for humans. The species name is “sapiens” and it is the single existing species of humans on earth. H. floresiensis, H. habilis, and H. neanderthalensis are the human ancestral species that once existed on earth.
The organisms of the same species compete among themselves for the limited and shared resources. It can be food, mate, or territories also.
Images coming soon
A population is a group of genetically related individuals breeding among themselves and living together in a particular geographical region for a specified time interval. Organisms of a particular species can inhabit different regions on earth. And those sets of individuals of the same species inhabiting one particular geographical area are referred to as a population.
For example, Common house sparrows live in different regions in India. However, they may be geographically isolated because of some isolating barriers like hills or mountains. All those sparrows inhabiting that geographically bound area are studied as a population. They compete for food and mates for the limited available resources in that specified area.
Population size is influenced by density, migrations into and out of the geographical area, number of births and deaths. Sometimes there can be factors affecting the population size. They can be biotic factors like predators, parasites or abiotic factors like natural disasters which diminish many populations at a time.
Images coming soon
Community refers to all the diverse groups of individuals of different populations interacting among themselves and sharing a specific geographical area. The diversity among the individuals may range from single cellular microbes to complex multicellular animals. For example, forests in tropical regions are inhabited by dense trees and diverse herbivores and carnivores living there. Apart from these, there exist microbial populations of bacteria, algae and fungi all of which constitute the community.
The populations in a community interact continually for survival. The interactions are parasitism, commensalism, predation and mutualism. Organisms in a community can compete for resources and it can be interspecific competition.
A community can be influenced by the diversity of organisms, their numbers, and interactions between them. These factors change over time scale and as a result, the community also experiences changes which is called ecological succession.
Images coming soon
Species, population and community are all interrelated terms in the hierarchy of ecology.
Although there exist some genetic variations among individuals, species and populations are groups of genetically related organisms that can breed naturally.
Population and community relate to organisms in specified geographical regions. The organisms experience similar environmental conditions and share abiotic components for their survival.
Species, populations and communities comprise living organisms which form biotic components and are continuously affected by the abiotic factors essential for their survival.
| Character | Species | Population | Community |
|---|---|---|---|
| Definition | Group of genetically related organisms that can interbreed naturally and produce fertile offspring. | Group of genetically related organisms living within a specific geographical area that can interbreed naturally and produce fertile offspring. | Group of diverse organisms of different species living within a geographical area. |
| Size | small | relatively larger than species. | Largest of all the three. |
| Organisms | one species. | single species. | multiple species. |
| Similarity between organisms | behaviourally and morphologically similar. | behaviourally and morphologically similar. | behaviourally and morphologically dissimilar. |
| Genetic constitution | similar to a major extent | similar to major extent | dissimilar |
| Competition | intraspecific | intraspecific | interspecific |
| Interbreeding | interbreed naturally | interbreed naturally | no interbreeding |
| Relationship in between organisms | intraspecific competition for food, mate and territory. | intraspecific competition for food, mate and territory. | predation, parasitism, symbiosis, commensalism. |
Ecosystems are units of ecology composed of biotic and abiotic components that interact with one another to lead a successful living. Ecosystems are complex to study and hence categorised to different levels. A species is a group of similar organisms that can interbreed and produce fertile offspring. A Population is a relatively larger group than the species and includes all the organisms of the same species within a geographical region. While a community is still a larger group of diverse organisms living in a geographical region. Although the levels may vary, there is an equal contribution of abiotic as well as biotic factors for the success of ecosystems.
Q1. How is the population size affected?
Ans. Population size is the number of individuals living in a defined area. Various factors like nutrient availability, species competition, number of deaths and births, immigration and emigrations affect the population size in general.
Q2. Do migration have any effect on the genetic variability of a population?
Ans. Immigration is the movement of individuals into another geographical population. It can bring new alleles which can lead to genetic variability.
Q3. What abiotic factors influence organisms in an ecosystem?
Ans. Abiotic factors like light, temperature, water, humidity, pH, salinity and soil nutrients influence the biotic components that are the living organisms within ecosystems.
Q4. What is meant by population density?
Ans. Population density is the number of individuals of a particular species inhabiting a unit area within a specific geographical region.
Physics
Biology
Chemistry
Mathematics
Economics
Psychology
Environmental Science
Social Studies
Fashion Studies
English