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INTRODUCTION TO ENVIRONMENT AND ECOLOGY
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Important Concepts
Environment
The environment encompasses all external elements, both living and non-living, that surround and influence an organism or a community of organisms.
It comprises the Earth’s atmosphere, hydrosphere (including oceans, lakes, and rivers), lithosphere (the Earth’s solid surface), and biosphere (the realm of living organisms). These components interact in intricate ways, creating a complex and interconnected system.
The environment plays a crucial role in
shaping the development, behavior, and overall well-being of all forms of life. It provides essential resources like air, water, food, and shelter, which are fundamental for the survival and sustenance of organisms.
Additionally, the environment serves as a dynamic stage for various ecological processes, including nutrient cycling, energy flow, and interactions between
Ecosystem
An ecosystem is a complex biological community and its physical environment, functioning as an interconnected unit.
It comprises living organisms (biotic factors) interacting with their non-living surroundings (abiotic factors).
Habitat
A habitat refers to the specific place or type of environment where a particular species or community of organisms naturally resides.
It encompasses the physical and biological conditions that characterize that particular area, including factors like climate, soil type, vegetation, and the presence of other species.
Habitats provide the necessary resources, such as food, water, and shelter, that organisms require for their survival and
For example, a coral reef can be a habitat for a diverse range of marine species, offering them the conditions they need to Ecosystems can range in size from small, like a pond, to vast, like a forest or a desert. They involve the flow of energy and cycling of nutrients among organisms and their
Ecosystem vs Environment vs Ecology
Ecosystem: An ecosystem refers to a specific biological community and its physical environment, interacting as a functional unit. It encompasses both living (biotic) and non-living (abiotic) elements.
Environment: The environment encompasses all external factors, both living and nonliving, that surround and influence an organism or a community of organisms. It includes the Earth’s atmosphere, hydrosphere, lithosphere, and biosphere.
Ecology: Ecology is the scientific study of the relationships between living organisms and their environment. It explores how organisms interact with one another and with their physical surroundings.
Ecology encompasses the study of individual organisms, populations, communities, and ecosystems.
Components of an ecosystem
Abiotic components
Ecosystems are intricate networks of life, where living organisms interact with their physical environment.
Among the fundamental elements that define an ecosystem, abiotic components play a crucial role.
These non-living factors provide the framework and resources that shape the distribution and behavior of biotic
Understanding abiotic components is essential for comprehending the dynamics of ecosystems.
Climate
Climate encompasses a range of factors such as temperature, precipitation, humidity, wind patterns, and seasonal variations.
These elements have profound effects on the organisms within an ecosystem.
For instance, a tropical rainforest and a desert have drastically different climates, leading to distinct plant and animal communities adapted to survive in those
Geology and Soil
The geological composition of an area, including rock types, mineral content, and soil structure, is a critical abiotic component.
It influences the physical structure of the ecosystem and determines the availability of essential nutrients for plants.
For example, limestone-rich soils support different vegetation compared to acidic, granite-based soils.
Topography
The physical features of the landscape, such as elevation, slope, and the presence of bodies of water, contribute to the unique characteristics of an ecosystem.
Topography influences water drainage patterns, creating different microclimates and habitats within a larger ecosystem.
Water
The presence and quality of water bodies, including rivers, lakes, ponds, and oceans, are vital abiotic factors.
They provide habitats for aquatic organisms and influence the types of organisms that can survive in the area.
Additionally, water availability affects temperature regulation, particularly in riparian ecosystems.
Light
Sunlight is a primary energy source for most ecosystems. The amount of sunlight an area receives impacts photosynthesis, the process by which plants convert light energy into chemical energy.
This energy forms the basis of the food chain, ultimately supporting all life within the ecosystem.
Nutrients
The availability of essential nutrients like nitrogen, phosphorus, and potassium in the soil and water is crucial for plant growth.
These nutrients are absorbed by plants and passed on through the food chain to herbivores, carnivores, and decomposers.
pH Levels
pH levels represent the acidity or alkalinity of soil and water.
Different species of plants and animals have specific pH requirements for
For instance, some plants thrive in acidic soils, while others prefer more alkaline
Disturbances
Natural disturbances like wildfires, storms, floods, and geological events, as well as human-induced disruptions such as deforestation and pollution, significantly impact abiotic components.
These events can alter soil structure, water availability, and nutrient levels, consequently influencing the composition of the ecosystem.
Atmosphere
The composition and quality of the air, including the presence of gases like oxygen, carbon dioxide, and trace gases, are crucial abiotic factors.
These atmospheric components play a vital role in respiration and photosynthesis, which are fundamental life processes for both plants and animals.
Weather
Short-term variations in atmospheric conditions, such as daily and seasonal weather patterns, also influence abiotic components.
Temperature fluctuations, precipitation levels, and wind patterns can affect the behavior, distribution, and reproductive cycles of organisms within an ecosystem.
Biotic components
Biotic components are the living organisms and biological entities that make up an These components interact with the abiotic (non-living) elements of the ecosystem to form a complex and interconnected web of life.
Biotic components can be categorized into several groups based on their roles and functions within the ecosystem.
The key biotic components include Producers
Producers, primarily plants, algae, and some bacteria, are autotrophic organisms that can convert sunlight into chemical energy through
They form the base of the food chain, as they produce organic matter from inorganic substances.
Consumers
Consumers are heterotrophic organisms that obtain their energy by consuming other organisms. They can be further divided into different trophic levels:
Primary Consumers (Herbivores): These organisms feed on producers (plants) and include animals like rabbits, deer, and
Secondary Consumers (Carnivores): These organisms prey on primary consumers and include animals like foxes, snakes, and birds of prey.
Tertiary Consumers: These are higher- level carnivores that feed on secondary consumers. Examples include apex predators like wolves, lions, and eagles.
Decomposers
Decomposers, such as bacteria, fungi, and certain insects, break down dead organic matter into simpler substances.
They play a crucial role in nutrient recycling, returning essential elements to the ecosystem for reuse by producers.
Detritivores
Detritivores, like earthworms and scavenging insects, feed on decaying organic material (detritus) and further aid in the decomposition
Predators and Prey
The interactions between predators and their prey are fundamental to regulating the population dynamics of species within an
Symbiotic Organisms
Symbiotic relationships involve two or more species living together, with various degrees of cooperation or dependence.
Competitors
Organisms of the same or different species can compete for limited resources such as food, water, and shelter.
Competition can drive evolutionary adaptations and influence the distribution of species within an ecosystem.
Keystone Species
Some species, known as keystone species, have a disproportionately large impact on the
Their presence or absence can dramatically affect the structure and function of the ecosystem.
Biodiversity
The variety of species in an ecosystem
contributes to its overall resilience and stability.
Greater biodiversity can enhance an ecosystem’s ability to withstand environmental changes.
Ecology
Ecology, the study of the relationships between living organisms and their environment, is guided by fundamental principles. These principles include the interdependence of species, the cycling of matter and energy, and the balance of
Levels of Organisations in Ecology
Individual and Species: The individual level focuses on a single organism and its interactions with its environment.
Species refer to a group of similar individuals capable of interbreeding and producing fertile offspring.
Ecologists study the characteristics and adaptations of individual organisms and how they define a species.
Population: A population consists of all individuals of the same species living within a specific area.
Ecologists examine population size, density, distribution, and factors affecting population growth and decline, including birth rates and death rates.
Community: A community comprises all the populations of different species coexisting within a defined area.
Ecologists investigate the relationships, such as predation, competition, and symbiosis, among these species and how they influence community structure and
Ecosystem: An ecosystem includes all the biotic (living) and abiotic (non-living) components within a particular area.
It studies the flow of energy and cycling of nutrients among organisms and their
Ecosystem ecology examines the interconnections between living and non- living factors.
Biome: A biome is a large, regionally defined terrestrial or aquatic ecosystem characterized by specific climate and vegetation types.
Biomes are often classified by factors like temperature, precipitation, and dominant plant species.
Examples include tropical rainforests, deserts, and tundra.
Biosphere: The biosphere encompasses the entire living component of the Earth, including all ecosystems and biomes.
It extends from the deepest oceans to the highest mountains and from the polar ice caps to the equator.
The biosphere represents the sum of all life on Earth and the ecological relationships that sustain it.
Principles of Ecology
Ecology is the study of interactions between organisms and their environment.
It encompasses a wide range of principles that govern the functioning of ecosystems and the diversity of life on Earth.
This brief overview will delve into some fundamental principles of ecology,
including adaptation, variation, speciation, mutation, natural selection, evolution, and extinction.
Adaptation: Adaptation is a cornerstone of ecology, referring to the process by which organisms evolve traits or behaviors that enhance their survival and reproduction in a specific environment.
These adaptations may be physical, physiological, or behavioral.
For instance, the long neck of a giraffe allows it to reach leaves high in trees, while the thick fur of an Arctic fox provides insulation against harsh cold climates.
Adaptations are the result of natural selection, where individuals with advantageous traits are more likely to pass them on to their offspring.
Variation: Variation is the diversity of traits present within a population of organisms.
This diversity arises from genetic differences, which can be inherited from parents or arise from mutations.
Variation is a crucial aspect of natural selection, as it provides the raw material upon which selection can act.
In a changing environment, having a range of traits allows a population to respond effectively to new challenges.
Speciation: Speciation is the process by which one species splits into two or more distinct
This occurs when populations of a species become isolated from one another, leading to genetic divergence over time.
Geographic barriers, such as mountain ranges or bodies of water, can contribute to this isolation.
Over generations, accumulated genetic differences can result in reproductive incompatibility between the separated populations, ultimately leading to the formation of distinct species.
Mutation: Mutation is the ultimate source of genetic variation in populations.
It involves changes in the DNA sequence of an organism.
While most mutations are neutral or harmful, some can be beneficial, providing the genetic diversity upon which natural selection acts.
Mutations can occur due to various factors, including exposure to radiation, chemicals, or errors in DNA replication.
Natural Selection: Natural selection is the driving force behind evolution.
It refers to the process by which organisms with traits that confer a reproductive advantage in a specific environment are more likely to survive and pass those traits on to their offspring.
Over time, this leads to the accumulation of advantageous traits within a population, as well as the adaptation of species to their respective habitats.
Evolution: Evolution is the overarching principle that unifies all of ecology.
It is the cumulative change in the genetic makeup of populations over generations.
Through mechanisms like natural selection, genetic drift, and gene flow, populations evolve and adapt to their environments. This process has led to the incredible diversity of life forms we observe today.
Extinction: Extinction is a natural part of the evolutionary It occurs when a species ceases to exist, either due to environmental changes, competition with other species, or other factors.
While extinction is a natural phenomenon,
human activities, such as habitat destruction, pollution, and climate change,
have accelerated the rate of extinction, posing a significant threat to biodiversity. Principles of Ecology
Ecosystem evolution is governed by specific principles:
Adaptation
Adaptation is the process by which organisms undergo genetic changes that allow them to better suit their environment, increasing their chances of survival and reproduction. It’s a fundamental concept in ecology and
Adaptations are important because they allow organisms to survive and reproduce in their
There are many different types of adaptations. Some examples include:
Morphological/Structural adaptations: These are physical changes in the organism’s body.
For example, a fish has gills to help it breathe in water, while a bird has wings to help it fly.
To reduce water loss through transpiration, many desert plants have thick cuticles on their leaf surfaces and deep pits for their stomata. Some desert plants, like Opuntia, have no leaves; instead, they have spines instead of leaves to prevent transpiration. The flattened stems perform the photosynthetic process because there are fewer leaves on the plant, which reduces the area accessible for transpiration.
In order to reduce heat loss, mammals from colder regions typically have shorter limbs and ears. (Allen’s Rule) Try to guess why an elephant has such large since elephants don’t perspire.
A hyperthermophile is a creature that thrives in extremely hot settings (60 °C). They use their flapping ears to dissipate heat and keep the rest of the body cool. For instance, deep-sea hydrothermal vents and hot springs have an abundance of Eubacteria and Archaebacteria
The kingdom Monera, which includes the least organised unicellular prokaryotic (genetic material is not contained within a membrane-bound nucleus) microorganisms on earth, includes archaebacteria (ancient bacteria), eubacteria (genuine bacteria), and cyanobacteria (blue-green algae). The ability of archaebacteria to survive in harsh environmental conditions is what sets them apart from other Monera groupings. The formation of a protective, lipid-linked cellular membrane by these creatures is facilitated by a unique protein, which is essential for enduring highly salty areas (halophiles), hot springs and acidic habitats (thermoacidophiles).
Physiological adaptations: These are changes in the organism’s internal functions. For example, a camel can store water in its body to survive in the desert, while a polar bear has thick fur to keep it warm in the Arctic.
When we are in the mountains, we need to breathe more Our bodies adapt to the new environment on the high mountain after a few days. Acclimatisation is the term used to describe these modest adjustments made over brief periods of time in an organism’s body to address minor issues brought on by changes in the environment. The body responds to reduced oxygen availability by producing more red blood cells, reducing hemoglobin’s ability to bind oxygen, and breathing more quickly.
Behavioral adaptations: These are changes in the organism’s behavior. For example, a deer will run away from a predator, while a wolf will hunt in packs.
Adaptations can be inherited or acquired. Inherited adaptations are passed down from parents to offspring. Acquired adaptations are changes that an organism makes during its lifetime, such as building up a tolerance to a toxin.
Desert lizards are physiologically incapable, unlike mammals. When their body temperature dips, they bask in the sun and take in heat, but when the outside temperature rises, they seek the shade. Some species have the ability to burrow under the ground in order to hide from the heat above ground.
Variation
Changes in genetic makeup brought on by the insertion or deletion of particular genes cause variations. Variations develop over time as a result of mutations, climatic changes, geographic barriers, etc. The variation within the human species is represented by the differences in skin colour, hair type (curly or straight), eye colour, and blood type among various ethnic groups.
Adaptive Radiation:
When the environment presentsnew challenges or opens up new environmental niches, animals undergo a process known as “adaptive radiation” in which they diverge from an ancestral species into numerous different forms.
Speciation
New species emerge through a process called speciation, and speciation occurs as a result of evolution.
Multiple populations make up a species. Geographical obstacles like mountains, oceans, rivers, etc. frequently cause disparate communities to remain apart.
Allopatric speciation:
Geographic isolation eventually results in speciation (also known as allopatric speciation or geographic speciation). After a considerable amount of time, the sub-populations undergo genetic drift and become reproductively isolated (they no longer cross-breed).
The sub-populations later become separate species since they are unable to interbreed even after the barrier is
Sympatric speciation:
There are no physical barriers that hinder populations of the same species from mating in sympatric speciation. However, it appears that a new species spontaneously emerges, perhaps based on a different food supply or trait.
Rhagoletis pomonella, or the Apple Maggot Fly
The apple maggot fly is a native of North America, and it used to eat hawthorn tree fruit as its primary food source.
Some of these flies started to infest apple fruit instead of hawthorn when European settlers brought apple trees to North
Over time, two separate populations of apple maggot flies appeared: one that continued to infest hawthorn fruit while the other focused more on infesting
The two groups were unable to reproduce as a result of this host preference divergence. Flies who liked apples mated with other flies who also liked apples, while flies that liked hawthorns married with other flies who also liked hawthorns.
Their genetic makeup, host preferences, and reproductive habits eventually diverged to the point that they could be classified as separate species.
Mutation
New genes develop in a population as a result of mutation (a change in genetic material brought on by a mistake in DNA replication). Recombination, which occurs every generation in a sexually reproducing population, is caused by meiosis and fertilisation. Members of the same species therefore exhibit “variation” and are not all the same.
Natural Selection
Darwin and Wallace’s theorised mechanism is Natural Selection. It is the method by which a species adjusts to its Variations, such as genes that enable the organism to better adapt to its environment, are chosen through evolution. Natural selection causes
certain genes to reproduce more frequently in a population. Children who are adapted to their immediate environment are more likely to survive, mature into reproductive adults, and pass along acceptable adaptations to their offspring.
Evolution
Evolution is the change that results in the emergence of new species. The organism becomes more suited to the current environment as a result. Natural selection, adaptability, variety, and other processes are all part of the evolution process. In 1859, Charles Darwin and Alfred Wallace put forth a convincing hypothesis of evolution. Neo- Darwinism is the name given to this theory as it has been expanded in light of genetics
Extinction
An environmental change or biological competition is the main cause of extinctions. When a species cannot evolve quickly enough to adapt to its environment, extinction The sixth mass extinction, known as the anthropogenic or human-induced extinction, is currently taking place.
Species Niche and Its Types
Definition of Niche: A niche is the specific role or function of a species within an ecosystem, involving all biological, physical, and chemical factors necessary for its survival, health, and reproduction. Each species occupies a distinct niche, making it crucial for conservation efforts to understand and address these unique
Types of Niches and Their Descriptions:
Habitat Niche: Refers to the specific location or environment where an organism lives, indicating its preferred habitat or ecosystem.
Food Niche: Describes the organism’s diet, what it consumes or decomposes, and its interactions with other species in terms of competition for resources.
Reproductive Niche: Outlines the organism’s reproductive methods and timing, including its reproductive strategies and the conditions under which it reproduces.
Physical & Chemical Niche: Covers the organism’s physical and chemical needs, such as temperature preferences, land shape and slope, humidity, and other environmental factors essential for its well-being.
Habitat vs. Niche:
Think of a species’ habitat as its home address, providing a specific location where it lives. In contrast, a species’ niche represents its role within its habitat – akin to its occupation and lifestyle, encompassing its behaviors, interactions, and the environmental conditions it requires. Although multiple species can inhabit the same physical space, each species carves out a unique niche. The concept of competitive exclusion underlines that no two species can indefinitely share the same niche within the same habitat; competition persists until one species displaces the other. For example, various pest insects might coexist on a single plant by targeting different parts of it for food.
Biome:
A biome represents a large-scale community of flora and fauna occupying a major habitat, such as tundras or rainforests. Distinct from habitats, which are smaller and can exist within biomes, a biome encompasses extensive areas with similar climate conditions, leading to shared characteristics among its plant and animal life, even across continents. The taiga forest biome, found across the northern hemisphere’s temperate zones, serves as an example, as does the temperate deciduous forest biome.
Ecotone:
An ecotone marks a transitional area between two distinct ecosystems or biomes, blending
elements of both. This transitional zone, which can vary in width, is a melting pot of biodiversity, exemplified by mangrove forests bridging land and sea. Estuaries, marshlands, and grasslands similarly illustrate the concept, serving as interfaces between freshwater and saltwater, dry and wet conditions, and forests and deserts, respectively.
Characteristics of an Ecotone:
Ecotones can range from narrow to broad and exhibit conditions that are intermediate compared to adjacent ecosystems, often resulting in heightened tension and diversity. These zones, whether they’re mangroves, wetlands, or grasslands, tend to be more productive than their neighboring ecosystems, supporting unique species in addition to those from adjacent communities.
Ecocline:
An ecocline is a gradual transition between two ecosystems, characterized by a continuous but gentle shift in species composition along an environmental gradient. This gradient may be related to changes in altitude, temperature, salinity, or depth, lacking a clear demarcation between ecosystems.
Edge Effect and Edge Species:
The edge effect refers to the phenomenon where an ecotone, or transitional zone, supports a higher biodiversity and population density than the neighboring ecosystems. This richness is attributed to the variety of ecological conditions present. Edge species thrive in these areas, benefiting from the ecotone’s diverse habitat. The edge effect is especially notable among bird populations in transitions between forests and deserts, for instance.
UPSC PREVIOUS YEAR QUESTIONS
1) On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion: (2013)
1. is bound in atmosphere as moisture and clouds
2. is found in freshwater lakes and rivers
3. exists as groundwater
4. exists as soil moisture
2) With reference to the water on the planet Earth, consider the following statements: (2021)
1. The amount of water in the rivers and lakes is more than the amount of groundwater.
2. The amount of water in polar ice caps and glaciers is more than the amount of
3. Which of the statements given above is/are correct?
a) 1 Only
b) 2 Only
c) Both 1 and 2
d) Neither 1 nor 2
