Introduction to Ecology PDF

Introduction to Ecology unit. Broadly, the ecosystem consists of two basic interacting components: the living, or biotic, and the I. Introduction...

Introduction to Ecology unit. Broadly, the ecosystem consists of two basic interacting components: the living, or biotic, and the I. Introduction nonliving (physical and chemical), or abiotic. No organism can exist by itself or without an environment. Characteristics of Ecosystem: Living organisms and their nonliving (abiotic) environment are inseparably interrelated and interact with each other. This 1. It is a major structural and functional unit of Ecology. module presents the basic concepts of ecology and ecosystems, including their definitions, hierarchy, 2. Its structure is related to its species diversity; the more components, interactions, and the difference between natural complex ecosystem have species diversity and vice and man-made ecosystems. You will be creating a poster that versa. summarizes your understanding of the concepts learned in 3. The relative amount of energy needed to maintain an this module. ecosystem depends on its structure. The more complex Key Concepts the structure, the lesser the energy it needs to maintain itself. ❖ Ecology is the study of relationships between organisms and environment. 4. It matures by passing from less complex to more complex state. Ecology is a science. Environment includes the physical and chemical conditions as well as the biological or living Consider a natural ecosystem, such as a forest. The physical components of an organism’s surroundings. Relationships (abiotic) component of the forest consists of the atmosphere, includes interactions with the physical world as well as with climate, soil, and water. The biotic component includes the the members of the same and other species. many different organisms – plants, animals, and microbes – that inhabit the forest. Relationships are complex in that The term ecology comes from the Greek words oikos, each organism not only responds to the abiotic environment meaning “the family household”, and logos, meaning but also modifies it, and in doing so, becomes part of the “management of the household”. broader environment itself. ❖ Organisms interact with the environment in the context of the ecosystem. Organisms interact with their environment at many levels. The physical and chemical conditions surrounding an organism – such as ambient temperature, moisture, concentrations of oxygen and carbon dioxide, and light intensity – all influence basic physiological processes crucial to survival and growth. An organism must acquire essential resources from the surrounding environment and in doing so must protect itself from becoming food for other organisms. It must recognize friend from foe, differentiating between potential mates and possible predators. All of this effort is an attempt to succeed at the ultimate goal of all living These are the basic units: I – abiotic substances, basic organisms: to pass their genes on to successive organic and inorganic compounds; IIA – producers, generations. rooted vegetation; IIB – producers, phytoplankton; III-IA – primary consumers (herbivores), zooplankton; III-2 – Ecosystem. The environment in which each organism secondary consumers (carnivores); III-3 – tertiary carries out this “struggle for existence” is a place – a consumers (secondary carnivores); IV – saprotrophs – bacteria and fungi of decay. The metabolism of the physical location in time and space. It can be as large and system runs on sun’s energy, while the rate of metabolism stable as an ocean or as small and transient as a puddle on and relative stability of the pond depend on the rate of the soil surface after a spring rain. This environment inflow of materials from rain and from the drainage basin includes both the physical conditions and the array of in which the pond is located. organisms that coexist within its confines. Organisms interact with the environment in the context of the ECOSYSTEM. The eco- part of the word relates to the environment. The -system part implies that the ecosystem functions as a collection of related parts that function as a  kinds of organisms interact with members of their own species as well as with individuals of other species. These interactions range from competition for shared resources to interactions that are mutually beneficial for the individuals of both species involved. Interacting populations make up a biotic community. Community plus the physical environment make up an ecosystem. All communities and ecosystem exist in the broader spatial context of the landscape/seascape – an area of land (or water) composed of a patchwork of communities and ecosystems. The highest level of organization of ecological systems is the biosphere – the thin layer around Earth that supports all of life. An organism refers to any living thing. A population is a group of individuals within the same species, within the same area, and that are capable of reproducing with one another. A community is defined as the populations of two or more Structural Features: species within the same geographical area and within the same time period. Biotic Structure An ecosystem is a community along with its abiotic (non- The plants, animals and microorganisms present in living) components, such as the water and air. an ecosystem form the biotic component. A biome is a large ecological area with similar climatic a) PRODUCERS: They are mainly the green plants conditions. A biome can have multiple ecosystems within it. which can synthesize their food themselves by making use of carbon dioxide present in the air and water The biosphere includes all living organisms along with the through the process of photosynthesis. spheres they interact with (lithosphere, hydrosphere, etc.). b) CONSUMERS: All organisms which get their organic food by feeding upon other organism. b.1 herbivores – plant eaters b.2 carnivores (meat eaters) b.3 omnivores (plant and meat eaters) b.4 Detritivores (detritus feeders or saprotrophs) c) DECOMPOSERS: They derive their nutrition by breaking down the complex organic molecules to simpler organic compound and ultimately into inorganic nutrients. ❖ Ecological systems form a hierarchy Ecological hierarchy can be understood as a natural system that ranks different organisms and living beings in the environment into groups based on their interactions with each other and the environment. Simply, it is an arrangement of all organisms and abiotic components present on Earth from the simplest to the most complex. Ecological systems can be viewed in a hierarchical Natural and Man-made (Artificial) Ecosystems framework from individual organism to the biosphere. Organisms of the same species that inhabit a given physical There are several differences between natural and artificial environment make up a population. Populations of different ecosystems, including sustainability, diversity and purpose.  A natural ecosystem has a diverse amount of species For example, Duck’s feet are for swimming and plants, whereas artificial ecosystems are limited. Behavioral Adaptation Natural ecosystems are self-sustaining and result from spontaneous natural reaction, while artificial An action that aids in survival ecosystems require the assistance of humans. Clown fish seek shelter from predators in sea A natural ecosystem is the result of interactions anemones. Sea anemones are poisonous to other between organisms and the environment. This process marine creatures occurs naturally over a period of time, whereas in an Lions stay together in a pride. As a group they can artificial ecosystem, human intervention is required. help each other hunt, care for the young and watch for An artificial ecosystem is not self-sustaining, and the danger. ecosystem would perish without human assistance. The PLANT AND ANIMAL ADAPTATION plants and animals need the help of humans to eat and survive. Plants: Plants have developed adaptations to survive in the hot and dry climate of the deserts. Most plants have long roots that go deep into the soil in search of water. Example: A farm is an artificial ecosystem that consists of A cactus has the following modifications: plants and species outside their natural habitat. Without 1. The leaves are modified as spines to minimize humans, this ecosystem could not sustain itself. water loss. The purpose of artificial ecosystems are recreational, 2. The stem is green, to make food for the plant. educational or profit. The purpose of natural ecosystems is simply natural circumstances. 3. The to stem is swollen and fleshy store water. Natural ecosystems contain more natural factors and 4. Cactus has a thick, waxy coating that prevents organisms. The relationships between organisms, each water loss and helps it to retain water. other and the environment in this ecosystem are more complex than that of artificial ecosystems. The Organism and Its Environment I. Introduction The physical environment directly influences the processes in plants and other living organisms, consequently, species of plants and animals are adapted to their environment. This module presents the variety of adaptations exhibited by plants and animals to variations in environmental conditions. An adaptation is defined as a physical or behavioral feature of an animal that helps them better survive in their environment. Animals: Desert animals have adapted themselves to live in Physiological Adaptations their habitat in the following ways. Physiological adaptations are internal or cellular features of 1. Camel’s long eyelashes and ear hairs protect an organism that enable them to survive in their the eyes and ears from sand. environment. 2. Fat stored in a camel’s hump acts as a food reserve. Snakes produce poisonous venom to ward off predators and to capture prey. 3. Its long legs keep its body away from hot sand. Dolphins are mammals and need to breathe air. 4. Broad feet help in walking on the sand without They spend their entire lives in the water and sinking in it. their bodies have adapted so that they can hold 5. It can drink a huge quantity of water at a time and their breath for several minutes. can stay without water for a long time. Its body loses very little water in the form of urine. Structural Adaptations 6. It can keep its nostrils closed to keep out sand. A body part that aids in survival Properties of a Population and Population Growth What is Population? A population is a group of individuals of the same species living and interbreeding within a given area. Key Features of Population Definition By requiring that individuals be of the same species, the definition suggests the potential for interbreeding among members of the population (in sexually reproducing organisms). This makes the population a genetic unit, defining the gene pool, which is the focus of evolution. The population is a spatial concept, requiring a defined spatial boundary—for example, the population of Darwin’s ground finch inhabiting the Island of Daphne Major in the Galápagos Islands. Examples of a Population People in a City Elephant Population. Fish Population in a Coral Reef WHAT IS POPULATION GROWTH? The term population growth refers to how the number of individuals in a population increases or decreases over MODELS OF POPULATION GROWTH time. This growth is controlled by the rate at which new individuals are added to the population through the processes of birth and immigration and the rate at which individuals leave the population through the processes of death and emigration. POPULATION GROWTH RATE Measure of how fast population has grown overtime. CHARACTERISTICS OF POPULATION A population has several characteristics or attributes which are a function of the whole group and not of the individual. Different populations can be compared by measuring these attributes. These attributes are population density, natality, mortality, distributions, etc. Demography - the study of the group characteristics of a population, their changes over time and prediction of future changes POPULATION DISTRIBUTION It is how individuals in a population are distributed in a given area.  Distribution is based on the presence and absence of individuals. GEOGRAPHIC RANGE VS. POPULATION DISTRIBUTION Population's geographic range encompasses all the individuals of a species. A spatial boundary within which all individuals in the RANDOM population reside. Organisms have an unpredictable distribution. This is typical A hypothetical population. Each red specie in which individuals do not interact strongly. dot represents an individual CLUMPED organism. The blue line defines the population distribution, or the area Organisms are clustered together in group. This may reflect in which the population occurs. patchy distribution of resources in the environment. This is the most common pattern of population dispersion. UNIFORM FACTORS OF POPULATION DISTRIBUTION Organisms are evenly spaced over the area they occupy. This is typical of species in which individuals complete for a scare HABITAT SUITABILITY environmental resources, such as water in a desert. Each species has a range of abiotic environmental and POPULATION ABUNDANCE resource conditions under which it can survive, grow, and reproduce. The primary factor influencing the distribution of Population Abundance a population is the occurrence of suitable environmental and resource conditions—habitat suitability. Abundance defines population size—the number of individuals in the population. CLIMATE Species Abundance is the sum total of individuals from a Temperature, precipitation, and seasonal changes given species within a given area. significantly impact where species can thrive, as different species have specific climate requirements. Species Richness considers the number of unique species in a certain region. FOOD RESOURCES The availability of food sources directly affects the distribution of herbivores, carnivores, and omnivores, influencing their population densities. COMPETITION Interspecific (between species) and Intraspecific (within species) competition for resources can limit population distribution, as species may POPULATION DENSITY be outcompeted in certain areas. Population density is the number of individuals per unit PATTERNS OF POPULATION area (per square kilometer [km], hectare [ha], or square DISTRIBUTION meter [m]), or per unit volume (per liter or m3). Crude Density 16, and 8. For the uniform population, any sampling unit gives a correct estimate (16). For the clumped population, Density measured simply as the number of individuals per the estimates are 32, 20, 0, and 12. unit area is referred to as crude density. The trouble with this measure is that individuals are typically not equally If a population is clumped, it is important to report an numerous over the geographic range of the population. estimate of variation or provide a confidence interval for the Individuals do not occupy all the available space within the estimate of density. In cases where clumping is a result of population’s distribution because not all areas are suitable. habitat heterogeneity (habitat is clumped), ecologists may As a result, density can vary widely from location to choose to use the index of ecological density for the specific location. areas (habitats) in which the species is found. Determining Density Mark-recapture When both the distribution (spatial extent) and abundance For mobile populations, animal ecologists must use other are small-as in the case of many rare or endangered species- sampling methods. Capturing, marking, and recapturing a complete count may be possible. Likewise, in some individuals within a population (known generally as mark habitats that are unusually open, density may be determined recapture) is the most widely used technique to estimate by a direct count of all individuals. In most cases, however, animal populations. Captured birds are marked with leg flags density must be estimated by sampling the population. as part of the effort to estimate population size and track survival rates of adults. Sampling Sampling is a selection of a smaller percentage of individuals from within a larger population that is used to estimate the attitudes and characteristics of the whole population. A method of sampling used widely in the study of Capture-recapture or mark-recapture methods are based on populations of plants and sessile (attached) animals involves trapping, marking, and releasing a known number of marked quadrats, or sampling units. Researchers divide the area of animals (M) into the population (N). After giving the marked study into subunits, in which they count animals or plants of individuals an appropriate period of time to once again mix concern in a prescribed manner, usually counting individuals with the rest of the population, some individuals are again in only a subset or sample of the subunits. From these data, captured from the population (n). Some of the individuals they determine the mean density of the units sampled. caught in this second period will be carrying marks (recaptured, R), and others will not. If we assume that the SESSILE ANIMALS ratio of marked to sampled individuals in the second sample CORALS (n/R) represents the ratio for the entire population (N/M), we BARNACLES can compute an estimate of the OYSTERS population using the following relationship. Multiplying the mean value by the total area provides an estimate of population size (abundance). The accuracy of estimates of density derived from population sampling can be influenced by the manner in which individuals are spatially distributed within the population. The estimate of density can also be influenced by the choice of boundaries or sample units. For example, suppose that in sampling a population of rabbits, a biologist captures and tags 39 rabbits from the population. After their release, the ratio of the number of The difficulty of sampling. Each area contains a population rabbits in the entire population (N) to the number of tagged of 16 individuals. We divide each area into four sampling or marked rab- bits (M) is N/M. During the second sample units and choose one at random. Our estimates of population period, the biologist captures 15 tagged rabbits (R) and 19 size will be quite different depending on which unit we select. For the random population, the estimates are 20, 20, unmarked ones a total of 34 (n). The estimate of population Human activities — wildlife management, conservation size, N, is calculated as... efforts, and habitat protection by humans directly impact species populations. Protected areas can support population For example, suppose that in sampling a population of growth. rabbits, a biologist captures and tags 39 rabbits from the population. After their release, the ratio of the number of rabbits in the entire population (N) to the number of tagged or marked rabbits (M) is N/M. During the second sample period, the biologist captures 15 tagged rabbits (R) and 19 unmarked ones a total of 34 (n). The estimate of population size, N, is calculated as… For work with most animals, ecologists find that a measure of relative density or abundance is sufficient. Methods involve observations relating to the presence of organisms rather than to direct counts of individuals. If these observations have some relatively constant relationship to total population size, the data can be converted to the number Immigration of individuals seen per kilometer or heard per hour. Such counts, called indices of abundance, cannot function alone — also known as in-migration. as estimates of actual density. — refers to the movement of people into a specific area or However, a series of such index figures collected from the country to live there. same area over a period of years depicts trends in abundance. HUMANS: Immigrants Counts obtained from different areas during the same year provide a comparison of abundance between different PULLING FACTORS habitats. Most population data on birds and mammals are based on indices of relative abundance rather than on direct Better opportunities counts. Better quality of living Better social services & benefits Better Infrastructure OTHER SPECIES: FACTORS INFLUENCING POPULATION EXPANSION BIRTH IMMIGRATION High/Rapid Birth Rate — refers to a situation where the number of births in a population is increasing significantly over a short period of time. This can lead to rapid population growth. HUMANS: Lack of access to education— individuals with limited access to education may have less knowledge & awareness about family planning, contraception, and the consequences of unplanned pregnancies. Economic factor — economic development, and resource availability (like food, water and shelter) play a critical role in supporting larger populations. OTHER SPECIES: Abundant resources — resource availability, like food, Abundant resources — resource availability, like food, water, & shelter play a critical role in supporting larger water, & shelter play a critical role in supporting larger populations. populations. Climate and Seasonal Changes — many species migrate to Political Factors find favorable climates, or following seasonal patterns, such — armed conflicts & violence can cause a significant rise in as birds flying south for the winter. death rates due to casualties, injuries, & the breakdown of healthcare systems. Environmental Factors — natural disasters (like earthquakes, floods, or hurricanes) Factors for Expansion and environmental pollution can increase death rates by causing accidents, injuries, or health problems. HUMANS: OTHER SPECIES: High/ Rapid birth rate Habitat Loss Lack of access to education —destruction of natural habitats due to natural disaster, deforestation, or pollution can lead to increased Economic factors (development, resource mortality as animals lose their homes & sources of availability) food/food shortage. Social services & benefits Better Disease Outbreaks Infrastructure — epidemics of diseases or parasites can spread rapidly among animal populations, causing significant Immigration increases in mortality. Better opportunities Overhunting and Poaching Better quality of living — excessive hunting or illegal poaching can reduce Social services & benefits animal populations and increase death rates, Better Infrastructure particularly for endangered species. Climate Change OTHER SPECIES: — changes in temperature, weather patterns, and sea levels can disrupt ecosystems and food sources, leading 1. High/ Rapid birth rate to increased deaths among species unable to adapt Abundant resources quickly. Human activities 2. Immigration Abundant resources Climate & Seasonal Changes FACTORS INFLUENCING POPULATION DECLINE DEATHS EMIGRATION Increasing Death Rate — this means that more people or animals are dying in a certain period of time. It indicates a rise in the number of deaths within a population. HUMANS: Poor healthcare facilities. — Lack of access to quality healthcare can result in higher death rates due to untreated illnesses and medical conditions. Disease Outbreaks — new or worsening diseases can lead to higher mortality rates if they spread rapidly and are difficult to control. Economic Factors — economic hardships, including poverty and lack of resources, can lead to inadequate nutrition, & poor living conditions.  Natural Disasters Poor infrastructure Security OTHER SPECIES: 1. High/ Rapid birth rate Habitat Loss Disease Outbreaks Overhunting and Poaching Climate Change 2. Emigration Habitat Loss Predation and Competition Climatic Condition MAINTENANCE OF POPULATIONS Habitat Conservation Protecting and restoring the natural habitats where species live. BENEFITS: Emigration — also known as out-migration. Biodiversity Preservation — refers to the movement of people leaving a specific area or country to live in another. Ecosystem Services HUMANS: Emigrants Species Survival PUSHING FACTORS 1. Less opportunities Regulation & Management 2. Natural Disasters 3. Poor infrastructure Implementing laws and policies to prevent overexploitation 4. Security and manage hunting or fishing. OTHER SPECIES: REGULATION Habitat Loss — destruction of natural habitats can lead to Hunting & Fishing migration as animals lose their homes & sources of food. Limits Protected Areas Predation and Competition— lack of resources is the Endangered Species Laws leading factor of competition. As it gets limited, competition for food and water intensifies, leading to stress, fighting, & MANAGEMENT even migration. Climatic Condition — when conditions become unsuitable, Monitoring they often seek more favorable environments. Habitat Restoration Control of Invasive Species Factors for Decline HUMANS: EXAMPLE: 1. Increasing Death Rate Wildlife Resources Conservation and Protection Act Poor healthcare facilities. (Republic Act No. 9147) Disease Outbreaks Economic Factors (lack of resources) Monitoring Regularly Political Factors (war) Environmental Factors (natural disaster) tracking population sizes and health to detect issues early. 2. Emigration KEY ASPECTS: Less opportunities Data Collection  Trend Analysis ▪ The smaller member of the interaction is termed the Health Assessment mutualist, whereas the larger species is called the host. Threat Identification ▪ Mutualism is an important interaction in ecology as well Research as evolution. Currently, it is assumed that about 80% of land species in a terrestrial ecosystem depend on Studying species' biology and ecology to understand their mutualistic interactions with fungi for nutrients. needs and threats. ▪ Examples: Lichen, Bee and Flower, Mycorrhiza, Acacia KEY ASPECTS: and Pseudomyrmex ants, Ficus and Fig Wasps. Understanding Species Ecology Population Dynamics Impact Assessment Types of Mutualism Genetic Studies Policy and Management Recommendations a. Obligate Mutualism Captive Breeding The interaction between different species where the Breeding species in controlled environments to support interaction is essential for their survival, and thus the populations in the wild. species are obligated or forced to depend on each other. KEY ASPECTS: Obligate mutualism is also termed exclusive mutualism as the interactions are very specific, and Breeding Programs the absence of the interaction results in the death of Habitat Simulation one or both species. Health Monitoring Behavioral Training Lichen: The algae provide nutrients to the fungus by Reintroduction producing organic matter by the process of photosynthesis. Long-Term Monitoring The fungus, in turn, protects the algae from the environment with the help of its filaments. Introduction to Species Interaction Species interaction refers to the direct and indirect b. Facultative Mutualism relationships between different organisms, which can occur between: The interaction between two or more species where the species benefit from the interaction but can also Plants and plants exist independently of each other. Plants and animals Facultative mutualism can be described in one of the Animals and animals, including microorganisms like three ways; resource-resource mutualism, service- bacteria and fungi resource mutualism, and service-service mutualism. In nature, no species exists in total isolation - all organisms Bee & a flower: In the interaction, the flowers of the plant interact with both the abiotic environment and other provide nectar to the bee, which acts as a source of nutrients organisms. for the bee. Types of Species Interaction The bees, in turn, provide a service of transferring pollen A. Symbiotic Relationships grains from one flower to another to aid the process of fertilization. Close interactions between organisms of different species. Types include: c. Trophic Mutualism ▪ 1. Mutualism: Both species benefit. (+, +) A type of ecological interaction that involves the transfer of energy and nutrients between two species. ▪ The term mutualism was used initially by Pierre-Joseph Trophic mutualism involves the resource-resource van Beneden in 1876 in his book Animal Parasites and interaction where the species provide resources to Messmates to indicate the meaning ‘mutual and among one another in the form of nutrients and energy. species’. Mycorrhiza: Mycorrhiza is the interaction between fungi Orchids And Trees: Orchids and epiphytic plants grow on and the roots of plants where the plants provide carbon to the tree branches, accessing sunlight and air without harming fungi, and the fungi provide nutrients. Mycorrhizas also the tree. improve water uptake and resistance against pathogens. Examples: Remora fish and shark, Orchids and Trees. d. Defensive Mutualism 3. Parasitism: One species benefit at the expense of the other. (+, −) Defensive mutualism is a type of service-resource relationship where one of the species provides A relationship between the two living species in which one nutrients whereas the other provides protection organism is benefitted at the expense of the other. against predators or parasites. In simple words, defensive mutualism can be explained Species Involved as a species defending the other for a reward. The host Acacia and Pseudomyrmex ants: Acacia plants produce newly enlarged thorns (also called bull’s horns) that contain This organism is harmed in the process, either through loosely arranged pith. The ants can easily chew and remove nutrient depletion, damage to tissues, or increased the pith to create a hollow interior. The small hole in the vulnerability to disease. thorn is used by the ant as a home. Parasite e. Dispersive Mutualism This organism benefits from the relationship by exploiting the host for food, shelter, or other resources. Dispersive mutualism is the interaction between insects or animals and plants where animals acquire nectar Examples: Dog and ticks, Rafflesia on vines. from the flower while facilitating the transfer of pollen Dog and ticks: Ticks, as parasites, benefit from feeding on grains. the dog's blood, while dogs suffer harm, potentially facing Dispersive mutualism is a service-resource mutualism serious health consequences if not treated. that enables the dispersal of the plant to new areas. Ficus and fig wasps: The flowers of Ficus are present on the Rafflesia on vines: Rafflesia, a parasitic plant without inside of the plant. The female wasps enter the fig flowers leaves, relies entirely on its host vine for nutrients. and carry the pollen grains to other flowers. The wasp lays eggs on the part of the flower which is nourished by the galls B. Non-symbiotic Relationships present in the flower. Interactions where organisms live apart. 2. Commensalism: One species benefit, the other is Types include: unaffected. (+, 0) A relationship between individuals of two species in which 1. COMPETITION (-, -) Organisms compete for one species obtains food or other benefits from the other resources. Competition can be defined as an without either harming or benefiting the latter. interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Species Involved Competition is for reproduction. often for a resource such as The host food, water, or territory in limited supply, or for access to females the organism that provides the benefit or support. Commensal Intraspecific competition: The competition between the organism that benefits from the relationship without member of the same species. This also includes the harming or helping the host. competition for mates. Remora fish and shark: The remora fish uses a suction Interspecific competition: The competition between disc to attach to sharks. It feeds on leftover scraps, while members of two different species. The results is that the shark is unaffected. neither species can obtain as many resources as they could in the Camouflage absence of the other species. Outer protection Chemical warfare Limited supplies of resources such as Foods, water, territory Warning coloration and etc. usually triggers one of two types of responses.: Deceptive looks Deceptive behavior COMPETITIVE EXCLUSION - One species uses the resources more efficiently, driving the other species to local INTERDEPENDENCE OF ORGANISMS WITH extinction. EACH OTHER AND THEIR ENVIRONMENT ORGANISMS RESOURCEPARTITIONING - Both species alter their use of the environment to divide the resources between them. 1. Energy Flow The chemical energy of food is the main source of energy required by all living organisms. This energy is transmitted to different trophic levels along the food chain. This energy flow is based on two different laws of THERMODYNAMICS: Based on the laws of thermodynamics: First law of thermodynamics, states that energy can neither be created nor destroyed, it can only change from one form to another. Second law of thermodynamics, states that as energy is transferred, more and more of it is wasted TROPHIC LEVELS The producers and consumers in the ecosystem can be arranged into different feeding groups and 1. The producers (plants) represent the first trophic level. 2. Herbivores (primary consumers) present the second trophic level. 3. Primary carnivores (secondary consumers) represent the third trophic level Examples: Intraspecific and interspecific competition. 4. Top carnivores (tertiary consumers) represent the 2. Predation (+, -): Predation is a biological last level. are known as trophic level or the feeding level. interaction whereby one organism (Predator) hunts and Feeds on another organism (Prey). Energy flow in ecosystem Organisms use their senses to locate objects and their prey. The energy flow in the ecosystem is one of the major factors that support the survival of such a great number of Some predators are: organisms. For almost all organisms on earth, the primary source of energy is solar energy. It is amusing to find that we receive less than 50 per cent of the sun’s effective FAST ENOUGH TO CATCH THEIR PREY radiation on earth. Most of the sun’s radiation that falls on HIDE AND LIE IN WAIT the earth is usually reflected back into space by the earth’s INJECT CHEMICALS TO PARALIZE THEIR PREY atmosphere. This effective radiation is termed as the Photosynthetically Active Radiation (PAR). Some prey may escape their predator by: Overall, we receive about 40 to 50 percent of the energy having Photosynthetically Active Radiation and only around 2-10 percent of it is used by plants for the process of 4. Some of the carbon that is not released back into photosynthesis. Thus, this percent of PAR supports the entire the atmosphere eventually become fossil fuels. world as plants are the producers in the ecosystem and all the 5. These fossil fuels are then used for man-made other organisms are either directly or indirectly dependent activities, which pump more carbon back into the on them for their survival. atmosphere The energy flow takes place via the food chain and food web. Nitrogen Cycle: Nitrogen is also an essential component of During the process of energy flow in the ecosystem, plants life. Nitrogen cannot be directly utilized by living being the producers absorb sunlight with the help of the organisms and has to be converted to other forms. chloroplasts and a part of it is transformed into chemical energy in the process of photosynthesis. Oxygen Cycle: Oxygen is essential for life. Aquatic organisms are dependent on oxygen dissolved in water. There are basically three different types of food chains in Oxygen is required for decomposition of biodegradable the ecosystem, namely – waste products. Grazing food chain (GFC) – This is the normal food chain Photosynthesis is the main source of oxygen present in that we observe in which plants are the producers and the the atmosphere energy flows from the producers to the herbivores (primary consumers), then to carnivores (secondary consumers) and Atmospheric oxygen is taken up by living organisms in so on. the process of respiration and release carbon dioxide which is used for photosynthesis by plants. Saprophytic or Detritus food chain (DFC) – In this type Water Cycle: of food chain, the dead organic matter occupies the lowermost level of the food chain, followed by the Water is an essential element for life to exist on earth. decomposers and so on. Water from oceans, lakes, rivers and other reservoirs is continuously converted to vapor by the process of Parasitic food chain (PFC) – In this type of food chain, evaporation and transpiration from the surface of plants large organisms either the producer or the consumer is Water vapors get condensed and return by precipitation exploited and therefore the food passes to the smaller and the cycle continues organism. The water falling on the ground is absorbed and stored as groundwater. 2. Nutrient Cycle Habitat and Niche “A nutrient cycle is defined as the cyclic pathway by which nutrients pass-through, in order to be recycled and reutilized. Temperature, sunlight, rainfall, types of soil, etc. and other The pathway comprises cells, organisms, community and abiotic factors determine the presence of organisms in an ecosystem.” area. These factors prevailing in an area determine the best- suited species for that environment. In the process, nutrients get absorbed, transferred, released and reabsorbed. It is a natural recycling system of mineral Habitat: Habitat is the best-suited condition for a species nutrients. and provides ideal conditions for a species to grow, adapt, reproduce and flourish. Includes cycles like: It is the energy or nutrient-providing area for an organism. 1. Carbon Cycle The habitat of a species describes the totality of abiotic factors to which the species is exposed in the area. Carbon is the main constituent of all the living cells. All the Niche: “Niche is defined as a functional role played by an organic matter and biomolecules contain carbon. organism in its ecosystem.” Following are the major steps involved in the process of the Three aspects of an ecological niche: carbon cycle: Spatial or habitat niche 1. Carbon present in the atmosphere is absorbed by Trophic Niche plants for photosynthesis. Hypervolume or multidimensional niche 2. These plants are then consumed by animals and carbon gets bioaccumulated into their bodies. Interconnectedness 3. These animals and plants eventually die, and upon decomposing, carbon is released back into the Interconnectedness means that everything in an atmosphere. ecosystem is linked and depends on each other in some  way. It’s like a big team where everyone has a role to 3. Same Habitat play, and if one member is missing, it affects the whole team. Changes in one element can affect the entire COMMUNITY STRUCTURE ecosystem. essentially the composition of a community, Plants and Sunlight including the number of species in that community. Plants use sunlight to make food through a process called photosynthesis. This process releases oxygen into the air. includes all of the patterns of interaction between these different species. Animals and Plants HOW DO WE MEASURE COMMUNITY Animals eat plants (or other animals that eat plants) for food. STRUCTURE? This provides them with energy. SPECIES RICHNESS Species richness is the number of Decomposers different species in a particular community. When plants and animals die, decomposers like bacteria and Communities with the highest species richness tend to be fungi break them down into nutrients. These nutrients go found in areas near the equator, which have lots of solar back into the soil. energy. Soil and Plants SPECIES DIVERSITY Species diversity is a measurement of species richness combined with evenness. It takes into Plants get nutrients from the soil to grow and continue the account not only how many species are present but also how cycle. evenly distributed the numbers of each species are. Oxygen and Animals FACTORS THAT SHAPE COMMUNITY Animals breathe in the oxygen released by plants during STRUCTURE photosynthesis. They exhale carbon dioxide, which plants 1. CLIMATE use for photosynthesis. The predictability or variability of climate can also affect Water and Life community structure – for instance, some species may be Water is essential for all living things. Plants absorb water unable to survive in a region with sporadic droughts or from the soil, animals drink water, and the water cycle sporadic drops below freezing. ensures a constant supply. 2. GEOGRAPHICAL FEATURES Predator-Prey The physical location and features of a habitat, such as The balance between predators (hunters) and prey (those altitude, proximity to water bodies, or the presence of hunted) helps control populations, ensuring the ecosystem mountains, influence the types of species that can inhabit the stays healthy. area. Biodiversity 3. HETEROGENEITY Different species of plants, animals, and microorganisms If there is more variation, or heterogeneity, in a community's contribute to the diversity and stability of an ecosystem. environment, this may allow for greater species richness because there are more distinct habitats to be occupied. The Ripple Effect of Changes: When something changes in an ecosystem, it can cause a ripple effect. For example, if a species disappears, it can affect other species that rely on it 4. FREQUENCY OF DISTURBANCES for food or shelter. This can disrupt the balance of the whole ecosystem The intermediate disturbance hypothesis suggests that communities with a medium (intermediate) level of COMMUNITY STRUCTURE disturbance may have greater species diversity than Community is a group of various species in a common communities with very frequent or very rare disturbance. location interacting with each other. COMMUNITY HAVE: 5. SPECIES INTERACTION 1. Different Species 2. Species Interaction Two species that compete intensively with one another may The food web forest comprises different components be unable to coexist in the same community, or a prey species such as producers, primary consumer, secondary may be unable to persist in a community that contains a consumers, scavengers and decomposes. highly effective predator. The Producers of the forest ecosystem are trees which are of different varieties, shrubs and also small plants that can produce their own food. Trophic Levels FOOD WEB OF GRASSLAND In a basic food chain, organisms are categorized into different trophic levels based on their position in the chain: The grassland food web begins with the primary producers, plants, wildflowers, and a few trees that provide leaves, seeds, and fruits. FOOD WEB IN TERRESTRIAL AND AQUATIC ECOSYSTEMS In terrestrial ecosystems, food webs involve organisms living on land, such as forests, grasslands, or deserts. Food The food webs web in terrestrial and aquatic ecosystems In aquatic ecosystems (freshwater or marine), food webs are based on What is Food web? organisms that live in water, and often include a larger role for microorganisms. Food web represents feeding relationships within a community (Smith and Smith 2009). Effects of Food Web Food web can be defined as, "a network of food Man is disturbing the food chain and making it short. chain which are interconnected at various topic levels, so as to from a number of feeding The shortening of food chain due to man's activities connections amongst different organisms of a leads to imbalance in the functioning of an ecosystem biotic community. and ultimately the biosphere. It is also known as "Consumer-resource system" Significance of Food web Types of food web representation Food webs distinguish levels of producers and consumers by identifying and defining the importance 1. Topological webs - These food web simply indicates a of animal relationships and food sources, beginning feeding relationship. with primary producers such as plants, insects and herbivores. 2. Flow webs - Bio-energetic webs, or flow webs, include information on the strength of the feeding interaction. Food webs are important tools in understanding that plants are the foundation of all ecosystems and food 3. Interaction webs - In interaction, the arrows show how chains, sustaining life by providing nourishment and one group influences another. oxygen needed for survival and reproduction. Different Food Web In short the food web provide stability to the ecosystem. SOIL FOOD WEB DOMINANT SPECIES The soil food web is the community of organisms living all are species that have large population size or occupies or part of their lives in the soil. Soil food web It describes a a significant proportion of the habitat within an complex living system in the soil and how it interacts with ecosystem. are generally the most abundant and have the environment, plants and animals. a substantial influence on the overall structure and AQUATIC FOOD WEB functioning of the ecosystem. Food chain which occurs in aquatic water is called aquatic food web. Aquatic food web WHAT MAKES A SPECIES DOMINANT? Examples: Algae-Protozoa-small insects. -Large aquatic Avilio et al (2019) provide a summary of the characteristics insects- small fish- Large fish or traits that make a species potentially dominant. FOOD WEB IN FOREST Types of Dominance: ELEPHANTS STARFISH SEA OTTERS EXAMPLE OF KEYSTONE SPECIES BEES WOLF 1. Dominance by resource acquisition MANGROVES (1) based on the resource-ratio hypothesis, the species with FOUNDATION SPECIES the lowest equilibrium resource requirement tended to be dominant, It is a species that has a strong role in structuring a community or ecosystem. (2) based on the competitive effect hypothesis, species with the highest resource uptake capability tended to be dominant These species provide essential habitat or resources for other organisms, influencing biodiversity and ecosystem (3) based on stoichiometric homeostasis, dominant species dynamics. are those with the highest stoichiometric homeostasis. KELP FOREST SEAWEED GRASSES EXAMPLE OF 2. Dominance by niche matching FOUNDATION SPECIES CORAL REEFS FOREST MANGROVES ARE BEAVERS CONSIDERED AS two possible mechanisms: FOUNDATION SPECIES? (1) niche specialization, where dominant species tended to keystone species maintain biodiversity Keystone species have specialized features or capability to utilize the most have a more significant impact on all other species in the abundant resource from its environment, and ecosystem. keystone species strongly affect the composition (2) niche modification, where dominant species has of communities in the ecosystem. Keystone species are characteristics that enable it to modify its environment and trophic and share a common collection of prey and predators, then create or form its new niche. DIFFERENCES BETWEEN KEYSTONES SPECIES 3. Dominance by stochastic processes AND FOUNDATION SPECIES entails the interaction between ecological and evolutionary KEYSTONES priority effects. Keystone species maintain biodiversity Stochastic processes are those having a random probability distribution or pattern. Keystone species have a more significant impact on all other species in the ecosystem. Species tended to prevail over the other species as being the first ones to arrive (successions) and thereby have the Keystone species strongly affect the composition advantage of diversifying and adapting earlier than the other of communities in the ecosystem. species. Keystone species are trophic and share a common KEYSTONE SPECIES collection of prey and predators. are species that have a massive impact on an FOUNDATION SPECIES ecosystem, such that if their presence is removed, foundation species maintain the structure of the the ecosystem will dramatically change. ecosystem. foundation species contribute to the may not be abundant species but they play a crucial role creation and maintenance of a landscape in order in maintaining ecosystem`s structure, function and to thrive by other species. biodiversity. foundation species are non-trophic and do not Dominant species influence ecosystems by outcompeting share a common collection of prey and predators. others for resources and occupying significant habitat space. INFLUNCES OF KEYSTONE SPECIES IN Conversely, keystone species have a disproportionately large COMMUNITY STRUCTURE impact relative to their population size due to their unique ecological roles. Their removal or introduction can 1. KEYSTONE SPECIES KEEPS COMMUNITIES drastically alter ecosystem structure and function, affecting IN BALANCE numerous other organisms. Controlling populations of other species that would Keystone species and Foundation species otherwise dominate the community or by providing critical resources for a wide range of species. KEYSTONE SPECIES Keystone species are those that provide vital ecosystem services which are essential for the 2. FEEDING RELATIONSHIP survival of other species in the ecosystem. This species critically maintains its structure. Dominant and keystone species influence the presence and abundance of other organisms through their feeding relationships. Feeding relationships — eating or being eaten — are called trophic interactions. 3. POPULATION CONTROL They regulate prey populations, preventing any single species from dominating and promoting biodiversity. Example: Coral Reefs (Coral Polyps) Dugongs Philippine Eagle Pufferfish 4. NUTRIENT CYCLING They enhance nutrient availability, supporting a diverse array of life. 5. PREDATION Predation can have large effects on prey populations and on community structure. Predators can increase diversity in communities by preying on competitive dominant species or by reducing consumer pressure on foundation species. 6. PLANT DIVERSITY Their activities can increase plant diversity, which in turn supports various herbivores and other species.