Community Characteristics and Types o

Submitted to: environment science department

Submitted By:
Bhavana Avasthi
M.S.C First Year
Roll No. 2483007
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Table of Content
1. Introduction
2. Community Characteristics
3. Interspecific Relationships 3.1 Competition 3.2
Predation 3.3 Parasitism 3.4 Mutualism
4. Intraspecific Relationships 4.1 Cooperation 4.2
Competition 4.3 Cannibalism 4.4 Communication
5. Importance of Community Relationships
6. Threats to Communities
7. Conservation Efforts
8. Conclusion
9. References
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1. Introduction:

An ecological community is a complex and dynamic system encompassing all

populations of different species living together in a specific area at a given time.
These populations interact in intricate ways, shaping the community's structure and
function. Understanding the various types of inter and intra-specific relationships
within communities is crucial for comprehending the intricate web of life on Earth.

2. Community Characteristics:

Several key characteristics define an ecological community:

 Species diversity: The number of different species present in the community.

This metric is often measured using indices like Shannon's Diversity Index or
Simpson's Diversity Index.
 Species richness: This refers to the number of individuals belonging to each
species within the community. It provides a more detailed picture of
abundance and distribution compared to species diversity alone.
 Species evenness: This measure indicates how evenly the individuals of
different species are distributed within the community. A community with high
evenness implies that no single species dominates, whereas low evenness
suggests dominance by a few species.
 Community structure: This refers to the spatial arrangement of different
species within the community. It encompasses factors like vertical
stratification in forests, clumping behaviour in social animals, and territoriality
among competing species.
 Trophic structure: This describes the feeding relationships between different
species in the community. It is typically represented by a food web, illustrating
the flow of energy and nutrients through the system.
 Productivity: This refers to the rate at which the community produces organic
matter through photosynthesis or chemosynthesis. It is crucial for supporting
the entire trophic structure and determining the overall energy flow within the
ecosystem.

3. Interspecific Relationships:

Interspecific relationships encompass a wide range of interactions between different

species, each with distinct ecological consequences:

3.1 Competition:
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Competition occurs when two or more species require the same limited resources,
such as food, water, or space. This interaction can be:

 Direct: Involving aggressive interactions, such as territorial disputes or

resource guarding.
 Indirect: Where species compete for resources without direct contact, such as
allelopathy in plants.
 Exploitation: One species utilizes another species' resources, potentially
harming the exploited species.
 Apparent: Where one species inadvertently harms another species by
consuming the same resources.

Competition can lead to several outcomes:

 Competitive exclusion: One species outcompetes the other, leading to its

decline or even extinction.
 Resource partitioning: Species specialize in different niches or utilize
resources at different times to minimize competition.
 Character displacement: Competing species evolve different traits to reduce
competition and coexist.

Example: Lions and hyenas competing for prey in the African savanna. Lions may
directly attack hyenas to defend their kills, while hyenas may scavenge leftover prey
from lions. This competition can regulate prey populations and maintain ecosystem
stability.

3.2 Predation:

Predation occurs when one species (the predator) hunts and kills another species
(the prey) for food. This interaction plays a crucial role in:

 Regulating prey populations: Predators control prey numbers, preventing

overgrazing or overpopulation.
 Maintaining ecosystem balance: Predation ensures energy and nutrients flow
through the food web, sustaining diverse communities.
 Shaping prey evolution: Predation drives the evolution of anti-predator
adaptations in prey, promoting biodiversity and complex ecological
interactions.

Example: Wolves hunting deer in North American forests. Wolves control deer
populations, preventing overgrazing and maintaining the health of diverse plant
communities.

3.3 Parasitism:
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Parasitism occurs when one species (the parasite) lives on or in another species (the
host) and obtains nutrients from it without killing it. This interaction can have various
impacts on the host:

 Reduced fitness: Parasites can steal resources from the host, reducing its
growth, reproduction, and overall health.
 Disease transmission: Some parasites act as vectors for diseases,
transmitting harmful pathogens between hosts.
 Behavioural manipulation: Certain parasites manipulate the host's behaviour
to enhance their own transmission or survival.

Example: Tapeworms living in the intestines of humans. Tapeworms absorb

nutrients from the food humans consume, reducing their nutritional intake and
potentially causing health problems.

3.4 Mutualism:

Mutualism is a beneficial interaction between two species where both partners derive
some benefit from the relationship. Mutualistic interactions can be essential for the
survival and reproduction of both partners. Some common types of mutualism
include:

 Pollination: Plants attract insects or other animals to transfer pollen between

individuals, facilitating reproduction in return for nectar or pollen rewards.
 Seed dispersal: Animals consume fruits containing seeds and disperse them
through their faces, promoting plant colonization and range expansion.
 Symbiotic cleaning: Certain fish species clean parasites and other debris from
the bodies

4. Intraspecific Relationships:

Intraspecific relationships involve interactions between individuals of the same

species:

4.1 Cooperation:

Cooperation occurs when individuals work together to achieve a common goal, such
as:

 Raising offspring: Parental care and cooperative breeding in birds and

mammals.
 Hunting: Pack hunting in wolves and lions enhances prey capture success.
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 Building shelters: Ants and termites work collectively to build complex and
elaborate nests.
 Défense: Communal defines against predators in fish schools or bird flocks.

Cooperation can significantly enhance individual survival and reproductive success,

contributing to the overall population health and stability.

Example: Honeybee colonies exhibit intricate cooperative behaviour, with individual

bees specializing in tasks like foraging, brood care, and comb construction. This
collective effort ensures efficient resource utilization and colony survival.

4.2 Competition:

Competition can also occur between individuals of the same species, especially for
limited resources like:

 Mates: Male animals compete for females during breeding season, often
through displays of physical prowess or elaborate courtship rituals.
 Territory: Individuals defend territories rich in resources against
competitors, ensuring access to food, shelter, and potential mates.
 Social status: Individuals compete for dominance within social
hierarchies, influencing access to resources and reproductive opportunities.

Competition within a species can help regulate population size, promote resource
partitioning, and drive the evolution of adaptations for competitive advantage.

Example: Male deer engage in fierce battles during rutting season, locking antlers,
and demonstrating strength to win access to females. This competition ensures only
the strongest and fittest individuals reproduce, contributing to the long-term health of
the deer population.

4.3 Cannibalism:

Cannibalism occurs when an individual of a species eats another individual of the

same species. This behaviour can be driven by several factors:

 Nutritional stress: In harsh environments with limited food

availability, cannibalism can be a survival strategy, especially for juveniles or
weak individuals.
 Population control: Cannibalism can help regulate population size, preventing
overcrowding and resource depletion.
 Sexual selection: In some species, males may consume females after mating
to gain additional nutrients for sperm production.
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Example: Praying mantis females sometimes eat their mates after copulation. This
provides them with essential nutrients for egg production and enhances their
reproductive success.

4.4 Communication:

Communication is essential for intraspecific interactions, allowing individuals to:

 Share information: About resources, predators, potential mates, and territorial

boundaries.
 Coordinate activities: When hunting, raising young, or defending territories.
 Maintain social bonds: Strengthen social relationships and promote group
cohesion.

Communication can occur through various means, including:

 Vocalizations: Birds sing songs to attract mates or defend territories.

 Chemical signals: Pheromones are used by insects and other animals for
communication and social organization.
 Body language: Animals use visual cues like facial expressions and body
postures to communicate intentions and emotions.
 Tactile communication: Touch plays a significant role in social bonding and
communication in many species.

Example: Honeybees perform a waggle dance to communicate the location of food

sources to other bees. This complex dance conveys information about direction,
distance, and quality of the food source, ensuring efficient resource utilization by the
colony.

5. Importance of Community Relationships:

Community relationships play a fundamental role in maintaining the structure and

function of ecosystems. These interactions contribute to:

 Maintaining biodiversity: By promoting species coexistence and niche

specialization.
 Regulating population dynamics: Through predation, competition, and disease
transmission.
 Facilitating energy flow and nutrient cycling: Through the food web, ensuring
the efficient utilization of resources within the ecosystem.
 Promoting ecosystem stability: By maintaining a balance between different
species and functional groups.
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Understanding these relationships is crucial for managing human impacts on

ecosystems and conserving the delicate balance of life on Earth.

6. Threats to Communities:

Several human activities can disrupt and threaten the health and stability of
communities:

 Habitat loss and fragmentation: Destruction of natural habitats through

deforestation, urbanization, and agricultural expansion can lead to species
decline and extinction.
 Pollution: Contamination of air, water, and soil can harm species directly and
disrupt ecological processes.
 Climate change: Rising temperatures, changing precipitation patterns, and
extreme weather events can have severe impacts on plant and animal
communities.
 Overexploitation: Unsustainable practices like overfishing, logging, and
hunting can deplete populations and disrupt natural balances.
 Invasive species: Introduction of non-native species can disrupt communities
through competition, predation, and disease transmission.

These threats highlight the need for urgent action to protect ecosystems and ensure
the long-term survival of diverse communities.

7. Conservation Efforts:

Various conservation efforts are underway to address threats to communities.