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Community structure and community function are two of their most important qualities. Community structure refers to a biotic composition, whereas community function refers to the community's energy flow, resilience, and resistance. Apart from these qualities, communities have a few things in common. Species diversity, species interactions, spatial organisation, periodicity, the ecotone-edge effect, and ecological successions are all examples of these. A community can be as little as a pond or a tree, or as large as a biome, which is a regional or global biotic association.
Read Also: Difference Between Pathogens and Parasites
| Table of Content |
Key Terms: Community, Environment, Spices, Biome, Ecology, Biodiversity, Mutualism, Parasitism, Commensalism, Habitat, Biotic components
Also Read: Biodegradable and Non-biodegradable Substances
What is community?
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A community in biology is a collection of interacting organisms that may or may not be of the same species as long as they share a shared habitat. Mutualism, parasitism, commensalism, or predation are some of the symbiotic relationships they have with one another. In ecology, a community is defined as the association of a group (or groups) of species that co-inhabit a geographic area over time.
To be more specific, an ecological community is an assemblage of living creatures that have symbiotic interactions with one another and hence function as an ecological unit to some extent. In general, a community is one that is constructed on a healthy, eco-friendly, and holistic design with the goal of living in harmony with the environment and other living things.
Properties of Community
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Recognizing a biological community can be difficult due to the fact that assemblages of organisms can occasionally overlap. Nonetheless, they have distinguishing characteristics, such as community structure and function.
- The biotic components of a community are referred to as community structure. It includes species variety and abundance, as well as the trophic interactions established by community members.
- Energy flow, resilience, and resistance are all aspects of community function. The route of energy, for example, as it passes through the various trophic levels of a food chain, is part of the energy flow in society. Two crucial characteristics are resilience and resistance.
Read More: Food chains and webs
Community Types
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A community can be characterised as open or closed. An open community is one in which organisms, particularly plants, are dispersed and so open to new invasion. A closed community is defined as one in which the organisms are clustered together. As a result, no more organisms may live in the area.
Interactions of Various Types
Organisms engage in a wide range of interactions. The following are examples of reproductive and behavioural interactions:
- When one creature, the predator, consumes all or part of the body of another organism, the prey, it is known as predation. Herbivory is predatory behaviour where the prey is a plant. Predator and prey population dynamics are influenced by each other.
- Mutualism is simply described as a partnership in which both species benefit from one another. This link might exist either inside a species or between two species. Symbionts are species that share this relationship.
- Parasitism is a close interaction between species in which one creature, the parasite, lives on or inside another organism, the host, and is structurally adapted to this mode of existence. Animal parasites are extremely specialized, and they reproduce more quickly than their hosts.
- The rivalry between or among living organisms for space, resources, goods, mates, and so on is referred to as competition. It's one of several symbiotic partnerships that can be found in nature.
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Community Characteristics
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Aside from their distinguishing characteristics, communities share common characteristics that can aid in their identification. The following are some of the most important qualities of a community:
Species diversity
The complexity of species in a community is referred to as diversity. The species richness and evenness of the species can be used to determine it (i.e. the relative abundance of species). The amount of various species coexisting in a given area is referred to as species richness. In comparison to locations near the poles, areas around the equator have the greatest species richness because the natural circumstances (low seasonality and high rainfall) are more conducive to a wider range of species.
The relative abundance of species is another essential metric. It is the ratio of the number of individuals in a species to the total number of individuals in a given habitat. The relative abundance of foundation species is frequently the highest.
There is often a dominating population in a community that has more power than the others. Ecological dominants are the dominant species in a given ecosystem. As a result, they're also employed to name communities, such as oak woodland, grassland, and so on. The keystone species is another type of species that is unique. Because its extinction would result in the community's collapse, this species is considered a key. The importance of keystone species in preserving biodiversity and the community's structure cannot be overstated.
Check Important Notes for Endangered species
Species interactions
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In a community, species interactions might be direct or indirect. A direct interaction occurs when two interacting animals come into direct physical touch. An indirect interaction is a type of species interaction in which the interaction between two species is mediated by a third species. It's also possible for the interaction to be linear or circular. A competitive hierarchy exemplifies a linear interaction, whereas a competitive network exemplifies a circular relationship.
Spatial structure
A community's structure can be portrayed through zonation or stratification. A lake community, for example, can be separated into three zones: littoral zone, limnetic zone, and profundal zone, according to zonation. Different types of species can be found in each zone.
Stratification is the most prevalent structure. Various strata could occur as a result of the evolution of different animals. The sea, for instance, could be split into upper and lower strata. The upper layer is frequently dominated by autotrophs, whilst the bottom stratum is dominated by heterotrophs.
Ecotone
The presence of an ecotone can help distinguish adjacent communities. An ecotone divides two communities. Because it is frequently in a transitional condition, it is more likely to be denser and richer than the two communities close. Edge species are those that are confined near the ecotone. Streams that run through a meadow and estuaries where rivers meet the sea are examples of ecotones.
Read Further: Difference Between Species Population and Community
Community dynamics
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Communities may be affected by a disturbance (e.g., a volcanic eruption, a fire, an earthquake, etc.). After a shock, a once-stable society may be unable to return to its equilibrium condition. The original community may be replaced with a new one if this occurs. This is known as ecological succession.
There is primary and secondary succession. A community colonises a newly developed land in primary succession. After a disturbance, a new community replaces the first one in secondary succession.
Importance of community
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The importance of community is that it allows species to interact. Nutrition is one of the many reasons that species interact within a community. Photosynthesis, on the other hand, is how plants generate theirs. They do, however, rely on animals as one of the primary producers of carbon dioxide. In mammals, this gas is emitted as a waste product of metabolism. Plants, on the other hand, require it as a chemical reactant in the process of photosynthesis. In exchange, they emit oxygen, which the animals use to meet their metabolic demands. Members of the community may also provide a safe haven in addition to food.
Also Read: What are Living Organisms Made Up Of
Things to remember
- A community is a diverse group of creatures that share a shared environment and interact.
- Diversity (number of species), abundance (number of each species), and interactions among the many species are among the factors.
- Except for autotrophs, most species in a community rely on other organisms for nourishment.
- Abiotic variables have an impact on organisms' ability to survive and reproduce.
- Organisms in a community share the same habitat and grow in a controlled environment.
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Sample Question
Ques. What makes a community distinct? [4 Marks]
Ans. A community, like a population, has a set of traits, such as:
Species diversity: Each community is made up of a diverse range of creatures, including plants, animals, and microorganisms, all of which are taxonomically distinct from one another. In a community, the number of species and population abundance varies substantially. The study of species variety is an important part of community research.
Growth form and structure: Major categories of growth forms are used to describe the sort of community (e.g., trees, shrubs, herbs, mosses, etc). The community's zonation (horizontal layering) and stratification (vertical stacking) are determined by these various growth forms.
Dominance: A few species in a community exert a significant controlling impact due to their size, numbers, or activities. This is referred to as dominating species.
Succession: Each community has its own development history, which evolves over time as a result of a directional shift.
Trophic structure: Each community, which consists of autotrophic plants and heterotrophic animals, is a self-sufficient, perfectly balanced assemblage of creatures in terms of nutrition.
Ques. In biology, what exactly is a community? [2 Marks]
Ans. An interacting group of numerous species in a shared place, commonly known as a biological community in biology. A biological community, for example, is made up of trees and undergrowth plants that are home to animals and are rooted in bacteria and fungi-rich soil. Community ecology is a broad term that refers to a variety of ecological interactions that vary through time. The plant community, all trees, birds, squirrels, deer, foxes, fungi, fish in a forest stream, insects, and any other species dwelling or migrating seasonally make up a forest community.
Ques. What are the things that influence the Community's structure? [3 Marks]
Ans. Factors that influence community structure
- Climate patterns and location geography - distance from the equator, temperature variations, island or mainland communities, etc.
- Heterogeneity (patchiness) - Heterogeneity refers to more variance in the environment, which allows for increased species richness due to the usage of different habitats.
- Disturbance Frequency - Disruptive occurrences such as storms, landslides, and fires have an impact on the community structure. Species diversity would be higher in communities with a medium level of disturbance than in groups with frequent or infrequent disruptions.
- Interactions between species of many types, such as competition, predation, and mutualism, have the ability to form a community.
Ques. Explain how all communities have responded to their surroundings over time. [4 Marks]
Ans. Communities' reactions to the environment are as follows:
- Physiological or behavioural strategies are used by some creatures to preserve homeostasis (regulate).
- With changes in the external environment, the interior environment of the vast majority of animals and nearly all plants changes (conform).
- During unfavourable conditions, some creatures leave their homes temporarily and return when the conditions improve (migrate).
- Some organisms, such as hibernation and aestivation, put their metabolic activity on hold in order to escape stress.
Ques. What constitutes a community? [2 Marks]
Ans. The assemblage of interacting organisms (either of the same or different species) coexisting in a certain area and period is referred to as a community in biology. Species diversity, species interactions, spatial organisation, periodicity, the ecotone-edge effect, and ecological successions are all examples of these factors.
Ques. What is the relationship between species and communities? [2 Marks]
Ans. Mutualism, commensalism, competition, and predation are the four basic forms of two-way interactions seen in ecological webs (which include herbivory and parasitism). Changes in one species can have far-reaching consequences in a food web because of the multiple interconnections among species.
Ques. How do biotic factors impact communities? [2 Marks]
Ans. Biotic factors in a community can have an impact on organism numbers, but they are also necessary for the ecosystem's balance of life. In an ecosystem, food competition is an example of a biotic component. In the same habitat, a red squirrel and a grey squirrel will compete for the same food source.
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