Adaptation is any structural, functional, or behavioural characteristic of an organism that enables it to survive and reproduce successfully in a particular environment.
Definitions [56]
Definition: Ecology
Ecology is the branch of biology that studies the interactions among organisms and between organisms and their environment.
Definition: Biome
A biome is a large ecological region characterized by a particular climate and a group of associated plant and animal communities.
Define Percolation.
Percolation is the downward movement of infiltrated water through soil and rock layers.
What is light? Define it.
Light is a form of Energy i. e. The external physical cause that affects our eye to produce the sensation of vision.
Define the term:
Relative humidity.
The ratio between the amount of water vapor in the atmosphere and the amount of water vapor it can hold is Relative humidity.
Define the term:
Absolute humidity
The amount of water vapour in the atmosphere is called Absolute Humidity.
Define Humidity.
The amount of water vapour present in the air at a particular time and place is called Humidity.
Definition: Habitat
Habitat is the natural place or environment where an organism lives and grows under suitable conditions.
Define ecological niche.
Niche of an organism can be defined as the total position and function of an individual in its environment.
Definition: Niche
A niche is the functional role of an organism in its environment, including how it uses resources and interacts with other organisms.
Definition: Adaptation
Define Community.
A community is an assemblage of populations of different species living in the same area and interacting with one another.
Define the following term:
Parasitism
Parasitism is generally defined as a relationship between the two living species in which one organism is benefitted at the expense of the other. The organism that is benefitted is called the parasite, while the one that is harmed is called the host.
Define the following term:
Commensalism
An interaction in which one species benefits while the other is neither benefited nor harmed is called commensalism.
Define the Stenothermal organisms.
A species or living organism is only capable of living within a narrow temperature range.
Define Niche.
Niche describes the position of a species in an environment and also the functional role played by an organism.
Define mutualism.
The type of interaction in which both species are benefitted is called mutualism.
Mutualism refers to an interaction between two different species in which both benefit. (The term symbiosis is frequently used interchangeably with mutualism.)
Define Population.
Organisms of the same kind inhabiting a geographical area constitute the population.
Individuals live in groups in a well-defined geographical area, share or compete for similar resources, and potentially interbreed and thus form a population.
The population is defined as a group of individuals of a species occupying a definite geographic area at a given time.
Define the following term:
Camouflage
Camouflage, also called cryptic colouration, is a defense mechanism or tactic that organisms use to disguise their appearance, usually to blend in with their surroundings. Organisms use camouflage to mask their location, identity, and movement.
Define the following term:
Interspecific competition
Interspecific competition occurs when closely related species compete for limited resources such as food and habitat.
Define stenohaline species.
Species that tolerate narrow range of salinity are called stenohaline species.
Definition: Intraspecific relationship
Interactions occurring among individuals of the same species within a community.
Definition: Dominance hierarchy
A social arrangement in which individuals of the same species are ranked according to their dominance status.
Definition: Territoriality
A form of competitive interaction in which an individual or group occupies and defends a fixed area for a certain period.
Definition: Altruism
A type of social behaviour in which an individual sacrifices its own interest or safety for the benefit of other members of the group.
Definition: Interspecific relationship
Interaction between populations of two different species living in the same habitat.
Definition: Commensalism
An interspecific relationship in which one organism benefits, while the other is neither benefited nor harmed.
Definition: Proto-cooperation
It is a non-obligatory interaction between two different species in which both are benefited, but neither depends completely on the other for survival.
Definition: Mutualism
Mutualism is an interaction between two species in which both are benefited.
Definition: Predation
Predation is an interaction between two species in which one organism, called the predator, kills and feeds on another organism, called the prey, for food.
Definition: Parasitism
Parasitism is an interaction between two species in which one (known as parasite) obtains its food in ready‑made form from the other living organism (said to be host).
Definition: Competition
The rivalry between two or more organisms for the same limited resource, where the use of the resource by one reduces its availability to the other, is called competition.
Definition: Intraspecific Competition
Competition that occurs between individuals of the same species for limited resources is called intraspecific competition.
Definition: Interspecific Competition
Competition that occurs between individuals of different species for the same limited resources is called interspecific competition.
Definition: Interference Competition
A type of competition in which one organism directly prevents another from accessing a resource is called interference competition.
Definition: Exploitative Competition
A type of competition in which organisms share a resource but one uses it more efficiently than the other is called exploitative competition.
Definition: Amensalism
An interaction between two different species in which one organism is inhibited or harmed while the other remains unaffected is called amensalism.
Definition: Population
A group of organisms of the same species occupying a particular area at a particular time is called a population.
Definition: Demography
The scientific study of the size, structure and growth of a population, generally human population, is called demography.
Definition: Population Density
The number of individuals of a species present per unit area (or volume) at a given time is called population density.
Definition: Biotic Potential:
The inherent capacity of a population to increase in number under ideal environmental conditions is called biotic potential.
Definition: Population Growth
The increase in the number of individuals of a species in a given area over a period of time is called population growth.
Definition: Natality (Birth Rate)
The rate at which new individuals are added to a population through reproduction is called natality.
Definition: Mortality (Death Rate)
The rate at which individuals die in a population during a given period of time is called mortality.
Definition: Population Growth Rate (r)
The rate of change in population size per individual per unit time is called population growth rate.
Definition: Intrinsic Rate of Growth (rₘ)
The maximum growth rate of a population under ideal conditions with maximum reproduction and minimum mortality is called intrinsic rate of growth.
Definition: Fecundity
The reproductive capacity of a population measured as the number of births during a given period is called fecundity.
Definition: Immigration
The addition of individuals to a population from neighbouring populations is called immigration.
Definition: Emigration
The movement of individuals out of a population to other areas is called emigration.
Definition: Carrying Capacity
The maximum number of individuals that an environment can support or sustain with available resources is called carrying capacity.
Definition: Environmental Stochasticity
The unpredictable fluctuations in population size caused by random changes in environmental conditions such as weather, good years and bad years are called environmental stochasticity.
Definition: Age Distribution
The proportion of individuals belonging to different age groups in a population is called age distribution.
Definition: Age Structure
The arrangement or composition of a population based on different age groups is called age structure.
Definition: Age Pyramid
The graphical representation showing the proportion of individuals in different age groups of a population is called an age pyramid.
Definition: Sex Ratio
The proportion or ratio of males to females in a population is called sex ratio.
Definition: Bioenergetics
The flow and transformation of energy within a population is called bioenergetics
Key Points
Key Points: Levels of Ecological Organisation
- Organism: An individual living entity that interacts with its surroundings.
- Population: A group of individuals of the same species living in a defined area.
- Community: Different populations living and interacting together in an area.
- Ecosystem: A functional unit where organisms interact with the physical environment.
- Landscape: A land area containing a group of different ecosystems.
- Biome: A large ecological region defined by climate and dominant vegetation.
- Biosphere: The entire zone of life on Earth where all ecosystems exist.
Key Points: Organisms and Its Environment
- Organismic ecology studies how organisms are physiologically adapted to their environment for survival and reproduction.
- Variations in temperature, rainfall, and seasons lead to the formation of different biomes and habitats.
- Abiotic factors like temperature, water, light, and soil influence habitats, and organisms evolve adaptations to survive in them.
Key Points: Major Biomes of India
| Biome | Climate | Rainfall | Vegetation | Fauna | Major Regions |
|---|---|---|---|---|---|
| Tropical Rainforest | Hot and humid | Very high | Evergreen broad-leaved trees | High biodiversity, insects, birds, mammals | Western Ghats, North-Eastern India |
| Deciduous Forest | Warm with seasons | Moderate | Sal, Teak (leaf-shedding trees) | Deer, elephants, herbivores | Northern & Southern India |
| Desert | Hot or cold extremes | Very low (<500 mm) | Thorny shrubs, grasses | Black buck, chinkara, reptiles | Thar Desert, Rann of Kutch |
| Sea Coast | Humid and saline | Moderate to high | Mangroves | Dolphins, dugong, crocodiles, tigers | Eastern & Western coasts |
Key Points: Climatic Factors
- Climatic factors such as precipitation, temperature, light, humidity, and wind determine climate and vegetation types.
- Rainfall is the most important factor influencing plant distribution and types of vegetation.
- Availability of water affects plant growth, metabolism, photosynthesis, and animal distribution.
- In aquatic habitats, salinity influences organism survival; organisms may be euryhaline or stenohaline based on tolerance.
Key Points: Topographic Factors
- Altitude: With increase in altitude, temperature decreases and wind and humidity variations increase.
- Slope: Slope affects rainfall, sunlight exposure, soil moisture, erosion, and vegetation distribution.
- Exposure: Areas exposed to sun and wind support different vegetation compared to sheltered areas.
- Direction of mountain chains: Mountain ranges influence wind direction, rainfall patterns, and local climate.
Key Points: Soil Factors (Edaphic Factors)
| Factor | Description | Importance for Plants |
|---|---|---|
| Soil Composition & Texture | Soil contains mineral matter (40%), organic matter (10%), soil water (25%) and soil air (25%) | Determines soil fertility, drainage and root penetration |
| Soil Humus | Dark, decomposed organic matter formed by humification | Improves soil structure, aeration, water-holding capacity and nutrient supply |
| Soil Water | Present in soil pores and essential for plant cells | Helps in nutrient absorption, metabolism and maintains turgidity |
| Soil Air | Air present in soil pore spaces | Supplies oxygen for root respiration and microbial activity |
| Soil Temperature | Depends on sunlight and soil colour | Affects seed germination, microbial activity and metabolism |
| Soil Reaction (pH) | Soil may be acidic, neutral or alkaline | Influences nutrient availability and plant growth |
| Saline Soil | Soil with high salt concentration | Usually unsuitable for plant growth |
| Soil Cover | Living (vegetation) or non-living (litter, snow) | Prevents erosion, conserves moisture and regulates temperature |
Key Points: Responses of Organisms to Abiotic Factors
| Response | Description | Examples |
|---|---|---|
| Regulate | Organisms maintain a constant internal environment through physiological or behavioural mechanisms | Birds and mammals regulate body temperature (sweating, shivering) |
| Conform | Internal conditions change according to the external environment | Most plants, fishes, and invertebrates |
| Osmoregulators | Maintain constant body fluid osmolarity despite environmental changes | Freshwater animals, mammals |
| Osmoconformers | Body fluid osmolarity matches the surrounding medium | Most marine invertebrates |
| Migrate | Organisms move temporarily to avoid unfavourable conditions | Migratory birds moving in winter |
| Suspend | Organisms reduce metabolic activity or form resistant stages | Spores in microbes, seeds, hibernation, aestivation |
Key Points: Adaptation in Aquatic Plants (Hydrophytes)
| Type of Hydrophyte | Position in Water | Roots | Leaves / Stem | Examples |
|---|---|---|---|---|
| Free-floating | Float freely on water surface | Absent or reduced | Spongy stem, broad leaves | Eichhornia, Pistia |
| Rooted with floating leaves | Roots in mud, leaves float | Well developed | Long petiole, waxy leaves | Nelumbo, Nymphaea |
| Submerged floating | Fully submerged, not rooted | Absent | Thin, dissected leaves | Ceratophyllum |
| Submerged and rooted | Fully submerged, rooted | Poorly developed | Ribbon-shaped leaves | Hydrilla, Vallisneria |
| Amphibious and rooted | Waterlogged soil | Well developed | Adapted to water & air | Potamogeton, Marsilea |
| Emergent and rooted | Shallow water, shoots exposed | Well developed | Aerial shoots, strong stem | Sagittaria, Ranunculus |
Key Points: Adaptation in Grassland Plants (Mesophytes)
| Feature | Description | Advantage |
|---|---|---|
| Habitat | Moist, well-aerated soil with moderate humidity | Ensures normal growth conditions |
| Root system | Well developed | Efficient absorption of water and minerals |
| Stem | Aerial and profusely branched | Supports leaves and photosynthesis |
| Leaves | Large, broad, thin and variable | Maximises photosynthesis |
| Cuticle | Moderately developed | Prevents excessive water loss |
| Internal tissues | Well-developed mesophyll, vascular and mechanical tissues | Efficient transport and mechanical support |
Key Points: Adaptation in Desert Plants (Xerophytes)
| Type of Xerophyte | Habitat Condition | Main Adaptations | Key Features | Examples |
|---|---|---|---|---|
| Ephemeral annuals (Drought escapers) | Dry areas with short rainy period | Escape drought by short life cycle | Complete life cycle quickly | Argemone, Solanum |
| Succulents | Very dry habitats | Store water in organs | Fleshy stems/leaves/roots | Aloe, Opuntia, Euphorbia |
| Non-succulent perennials (True xerophytes) | Arid and semi-arid regions | Resist drought | Thick cuticle, sunken stomata | Acacia, Calotropis |
Key Points: Aquatic Adaptations (Hydrocoles)
| Adaptation | Structural Feature | Function | Advantage |
|---|---|---|---|
| Streamlined body | Elongated, compressed head, body and tail | Reduces water resistance | Easy and fast swimming |
| Fins | Paired (pectoral, pelvic) and unpaired (dorsal, anal, caudal) fins | Act as paddles and stabilisers | Directional movement and balance |
| Gills | Thin, vascular respiratory organs | Exchange of gases in water | Efficient respiration |
| Lateral line system | Sensory receptors along body | Detects water vibrations | Awareness of surroundings |
| Swim bladder | Air-filled sac (in bony fishes) | Maintains buoyancy and depth | Energy-efficient floating |
Key Points: Desert Adaptations (Xerocoles)
| Adaptation Aspect | Structural / Physiological Feature | Purpose | Example / Group |
|---|---|---|---|
| Water conservation | Impervious skin; dry excreta (uric acid, guanine) | Minimises water loss | Reptiles, insects |
| Respiration | Invaginated spiracle system | Reduces evaporation | Desert insects |
| Food & water source | Feeding on dry seeds or succulent plants | No need for drinking water | Desert rodents, birds |
| Temperature avoidance | Burrowing; nocturnal activity | Escape heat | Rodents, reptiles |
| Locomotion on sand | Long limbs, padded feet | Easy movement on hot sand | Lizards, mammals |
| Protection & senses | Protective colouration, spines; keen senses | Defence and survival | Desert mammals, birds |
Key Points: Volant Adaptations
| Adaptation | Structural Feature | Function | Advantage |
|---|---|---|---|
| Body shape | Boat / spindle-shaped body | Reduces air resistance | Smooth flight |
| Wings | Forelimbs modified into wings | Provide lift and propulsion | Enables flying |
| Feathers | Flight feathers and body feathers | Insulation and air support | Maintains body temperature and flight |
| Tail feathers | Fan-shaped rectrices | Steering and balance | Control during flight |
| Skeleton & muscles | Keeled sternum, strong flight muscles, hollow bones | Power and lightness | Efficient and sustained flight |
| Respiration & senses | Air sacs; well-developed cerebellum and eyes | Continuous oxygen supply and coordination | Balance, vision and endurance in flight |
Key Points: Cursorial Adaptation
| Adaptation | Structural Feature | Function | Examples |
|---|---|---|---|
| Body shape | Streamlined body | Reduces air resistance | Horse, deer |
| Forelimbs | Reduced or less developed in bipeds | Not involved in locomotion | Ostrich, kiwi |
| Hindlimbs | Long and strong | Provide speed and endurance | Tiger, horse |
| Limb bones | Reduction of ulna and fibula | Lightens limbs, increases speed | Deer, antelope |
Key Points: Fossorial Adaptations
| Adaptation | Structural Feature | Function | Examples |
|---|---|---|---|
| Body shape | Spindle-shaped body | Easy movement in burrows | Mole, rabbit |
| Head | Small, tapering snout | Helps in digging | Mole |
| Tail | Shortened tail | Avoids obstruction underground | Burrowing mammals |
| Sense organs | Reduced eyes and ear pinnae | Protection in dark habitat | Subterranean animals |
| Limbs & teeth | Short, stout limbs with strong claws; forward incisors | Efficient digging | Rat, mole |
| Behaviour | Hibernation | Survival during unfavourable conditions | Ground squirrel |
Key Points: Arboreal (Scansorial) Adaptations
| Adaptation | Structural Feature | Function | Examples |
|---|---|---|---|
| Body shape | Stout body with curved ribs | Balance and support on trees | Squirrel, lemur |
| Limb girdles | Strong and stout | Supports body weight during climbing | Sloth |
| Claws | Well-developed, sharp claws | Grasping branches | Rodents, lizards |
| Digits | Syndactyly (fused digits) | Firm grip | Some mammals |
| Adhesive pads | Sticky pads on fingers and toes | Clinging to surfaces | Tree frog |
| Tail / organs | Prehensile tail, spines or tubercles | Additional support in climbing | Chameleon, langur |
Key Points: Parasitic Adaptations
| Adaptation | Structural / Biological Feature | Function | Examples |
|---|---|---|---|
| Attachment | Suckers, hooks or adhesive structures | Firm attachment to host | Tapeworm, flukes |
| Organ reduction | Loss of locomotory, sense and digestive organs | Dependence on host for nutrition | Endoparasites |
| Multiple hosts | Use of intermediate hosts or vectors | Increases chances of survival | Plasmodium |
| Reproduction | Highly developed reproductive organs | Produces large number of offspring | Parasites |
| Life cycle | Polyembryony and complex life cycle | Ensures species continuity | Fasciola |
Key Points: Behavioural Adaptations in Animals
| Type of Adaptation | Description | Purpose | Examples |
|---|---|---|---|
| Migration | Seasonal two-way movement to new areas | Food, breeding, favourable climate | Arctic tern, locusts |
| Camouflage (Cryptic appearance) | Blending with surroundings | Protection and hunting | Grasshopper, stick insect |
| Mimicry | Resemblance to another species | Avoid predation or gain advantage | Viceroy butterfly, spiders |
Key Points: Population Interactions
- Organisms live in groups forming populations, and different populations together constitute a biotic community.
- Communities show species diversity, interdependence, dominance, and coexistence among different species.
- Communities interacting with their physical environment form an ecosystem with energy flow and nutrient cycling.
- All ecosystems together constitute the biosphere, the highest and most self-sustaining level of biological organization.
Key Points: Growth Models
- Exponential growth:
Population grows rapidly when resources are unlimited. - Logistic growth:
Population growth slows and stabilizes at the carrying capacity due to limited resources.
Key Points: Population Growth Curve
| Aspect | J-shaped Curve (Exponential Growth) | S-shaped Curve (Logistic Growth) |
|---|---|---|
| Meaning | Population grows rapidly under ideal conditions | Population growth slows and stabilizes due to limited resources |
| Resource availability | Unlimited | Limited |
| Environmental resistance | Absent or negligible | Present and effective |
| Growth pattern | Slow at first, then very rapid increase | Slow → rapid → slows down |
| Final population size | Continues increasing theoretically | Stabilizes at carrying capacity (K) |
| Occurrence in nature | Rare (e.g., bacteria in lab) | Common in natural populations |
Important Questions [5]
- Define the Stenothermal organisms.
- Define following term: Niche
- Mention the scientific name of protozoan parasite that causes Amoebiasis.
- The diagram given below shows the life cycle of a malarial parasite. Study it carefully and answer the questions that follows: Name the hosts in which the asexual phase and sexual phase of the life
- Some orchids live on the branches of mango trees. Name the type of interaction that exists between the mango tree and the orchid.
Concepts [59]
- Ecology and Biomes
- Levels of Ecological Organisation
- Organisms and Their Environment
- Biomes of India
- Major Abiotic Factors
- Climatic Factors > Precipitation
- Climatic Factors > Wind
- Climatic Factors > Temperature
- Climatic Factors > Light
- Climatic Factors > Atmospheric Humidity
- Climatic Factors > Fire
- Topographic Factors
- Atmospheric Factors
- Biotic Factors
- Soil Factors (Edaphic Factors)
- Soil Organisms
- Responses of Organisms to Abiotic Factors
- Habitat
- Niche
- Types of Habitats in the Biosphere
- Adaptations
- Adaptation in Aquatic Plants (Hydrophytes)
- Adaptation in Grassland Plants (Mesophytes)
- Adaptation in Desert Plants (Xerophytes)
- Aquatic Adaptations (Hydrocoles)
- Desert Adaptations (Xerocoles)
- Volant Adaptations
- Cursorial Adaptations
- Fossorial Adaptations
- Arboreal (Scansorial) Adaptations
- Parasitic Adaptations
- Behavioural Adaptations in Animals
- Population Interactions
- Interaction between Organisms
- Intraspecific Relationships
- Dominance Hierarchy (Pecking Order)
- Territoriality
- Altruism
- Animal Societies
- Communication
- Interspecific Relationships
- Positive Interactions > Commensalism
- Positive Interactions > Proto-cooperation
- Positive Interactions > Mutualism (Symbiosis)
- Negative Interactions > Predation
- Negative Interactions > Parasitism
- Negative Interactions > Competition
- Negative Interactions > Amensalism
- Concepts and Measures of Population Ecology
- Environmental Resistance
- Growth Models
- Population Growth
- Carrying Capacity and Its Role in Population Sustainability
- Environmental Stochasticity
- Population Growth Curve
- Population Age Distribution
- Sex Ratio
- Population Dispersal and Energy Flow (Bioenergetics)
- Life History Variation
