Basics of Ecology Learning Modules PDF

Photo Courtesy: https://www.google.com.ph/search?q=ecology+hd+nature+photo&tbm=isch&ved=2ahUKEwjWjdONmqvrAhUC9pQKHblOCI8Q2- Sarah Jane S. Jucal, MEd. Analyn C. Sa-an, MSci.  Human knowledge and understanding of the importance of relationship and interaction between organisms a...

Photo Courtesy: https://www.google.com.ph/search?q=ecology+hd+nature+photo&tbm=isch&ved=2ahUKEwjWjdONmqvrAhUC9pQKHblOCI8Q2- Sarah Jane S. Jucal, MEd. Analyn C. Sa-an, MSci.  Human knowledge and understanding of the importance of relationship and interaction between organisms and the environment play a vital role in human well-being and prosperity. Ecology is the scientific study of the interaction between organisms and their environment. Both biotic and abiotic factors are significant in maintaining balance in the environment. Biomes are the environments that have characteristics of not changing too much over time. There are few biomes in the world like Aquatic (rivers, streams, lakes, open sea zone, deep-sea zone, neritic zone) and Terrestrial (tundra, taiga, grassland, tropical rainforest, temperate rainforest, and desert). The energy that comes to the earth comes from the sun which means the sun is the source of energy for the ecosystem. The feeding relationship in an ecosystem is the food chain and food web. To maintain the ecosystem many biochemical cycles are going on like water, carbon, nitrogen, and phosphorus and limited nutrients. Most of the energy resources in our environment are affected by interacting populations of the same or different species, hence the growth of the size of the population of living things have a greater impact on the future state of a particular area or habitat. In this module, you will learn the following lessons: Lesson 1 – Basic Ecological Terminologies Lesson 2- The Ecosystem and Its Components Lesson 3 - Energy Flow in Ecosystem Lesson 4 – Population and Community Ecology Module Outcomes: At the end of the module, you must have: 1. defined ecological terms and concepts; 2. explained the components of Ecosystems; 3. described and differentiated the major types of the ecosystem; 4. examined the relationship of different organisms in an ecosystem; 5. illustrated and discussed the flow of energy in an ecosystem; and 6. discussed population and community ecology. |2 Before you start with the lessons in this module, familiarize yourself with the terms listed in Table 1. Table 1. Terms you need to know in this module. Any living organism that makes its own food by Autotroph converting simple inorganic molecules into complex organic compounds like carbohydrates, fats, and proteins An area of the planet that can be classified according to Biome the plants and animals that live in it. An organism that only eats animal tissue. Most predators Carnivore and scavengers are exclusively carnivorous. Some examples of carnivores include members of the feline family, like lions, tigers, and house cats, and birds of prey, like eagles, hawks, and owls Community A group of two or more populations of organisms from different species inhabiting the same location at the same time Consumers Animals of an ecological food chain that consume other organisms. Decomposer An organism that feeds on and breaks down dead or decaying matter in the process of ecological decomposition. |3 Detritivore An organism that consumes detritus, also known as decomposing organic matter, to obtain nutrients. All decomposers are detritivores, including fungi, worms, and some bacteria. Ecosystem A term describing all the living and nonliving things in a certain location. Food chain A simple, direct, and eating or trophic relationship among a group of organisms, where one organism, like a plant, is the food source for the next organism, like a cow, which in turn is the food source for the next organism, like a human, and so on. Food web A complex trophic relationship among a group of organisms, consisting of interactions among multiple food chains. A food web describes how multiple producers and consumers directly or indirectly interact in an ecosystem. Population A group of individuals of the same species inhabiting the same area. Producers Also known as autotrophs, make their own food. They make up the first level of every food chain |4  Lesson Outcomes At the end of the lesson, you must have: 1. defined ecological terms and concepts; and 2. explained the levels of organization from atoms to biosphere; Ecology is a scientific field of study that explores the interactions between organisms, like individuals, populations, or communities, and the abiotic components in the environment, like chemicals, temperature, climate, and landscapes. In studying these living and non-living components, some important ecological terms and concepts should be explained and understood. The living and non-living things are arranged from the simplest (atom) to most complex (biosphere) in the levels of the organization. Engage Investigate the picture Source:https://www.google.com/search?q=level s+of+biological+organization&source What do you know about this picture? |5 Explore Think of 10 commonly used ecological terms that you can still remember from your biology subject. List down and define them. Explain Ecology is a study of the relationships between living organisms, including humans, and their physical environment; it seeks to understand the vital connections between plants and animals and the world around them. In effect, it is a study of connections in nature. To enhance their understanding of nature, scientists classify matter into levels of organization from atoms to the biosphere. Ecologists focus on organisms, populations, communities, ecosystems, and the biosphere (Table 2) Table 2. Levels of Organization Parts of the earth's air, water, and soil Biosphere where life is found A community of different species interacting with one another and with Ecosystem their non-living environment of matter and energy Populations of different species living in a particular Community place, and potentially interacting with each other A group of individuals of the Population same species living in a particular place Organism An individual living being The fundamental structural Cell and functional unit of life Chemical combination of two Molecule or more atoms of the same or different elements The smallest unit of a chemical Atom element that exhibits its chemical properties |6 Elaborate In your local area, select a specific ecosystem then write the different levels of the organization as to (example, ecosystem- terrestrial, community - lions and elephants, population- lion, organism-lion). Ecosystem Community Population Organism Write a song with a tune of “Bahay Kubo” based on the organisms found in your chosen ecosystem. |7 Evaluate Name: Date: Program and Section: Score: I. Multiple Choice Direction: Choose the letter of the correct answer and write it on the space provided before each number. ___1.Any living organism that makes its own food by converting simple inorganic molecules into complex organic compounds like carbohydrates, fats, and proteins. A. Autotrophs C. Decomposer B. Consumers D. Detrivore ___2. The smallest unit of a chemical element that exhibits its chemical properties. A. Cell C. Molecule B. Atom D. Organism ___3. A complex trophic relationship among a group of organisms, consisting of interactions among multiple food chains. A. Food web C. Both A and B B. Food chain D. None of these ___4. An area of the planet that can be classified according to the plants and animals that live in it. A. Earth C. Biome B. Atmosphere D. all of the above ___5. Also known as autotrophs, make their own food. They make up the first level of every food chain. A. Producer C. Decomposer B. Consumer D. Detrivore ___6.It is a study of the relationships between living organisms, including humans, and their physical environment. A. Biology C. Ecology B. Geoscience D. None of these |8 ___7.What is the correct order of organization from least to most complex? A. Population-community-biosphere B. Atom-molecule-cell-organism C. atom-cell-molecule-organism D. cell-atom-molecule-organism ___8. A group of toads falls under which level of organization? A. Population C. Community B. Biome D. Biosphere ___9. A term describing all the living and non-living things in a certain location. A. Community C. Organism B. Population D. Ecosystem ___10. An individual living being. A. Community C. Organism B. Population D. Ecosystem |9  Lesson Outcomes At the end of the lesson, you must have: 1. defined an ecosystem; 2. differentiated biotic and abiotic components of an ecosystem; 3. explained the different major types of an ecosystem; 4. described the nature of each ecosystem;. The ecosystem is made up of both biotic (living) and abiotic components. These biotic and abiotic components interact to maintain equilibrium in an ecosystem. There are different types of ecosystems and each has unique environmental conditions characterized by a distinct climate, soil, topography and distribution of plants and animals. Engage Have you ever been on a team, a sports team, perhaps? What is it like? Is it different than trying to do something alone? How is it better? We are going to try to understand how things in the environment work together, similar to how a team works together to try to win a basketball or soccer game. We call this special interaction among people and living and non-living things, teamwork Explore Lists down at least five living (biotic) and non-living (abiotic) factors found in your area. Living (Biotic factor) Non-living (Abiotic factor) | 10 Explain I. Ecosystem An ecosystem is a group or community composed of living and non-living things that interacts with one another. They can be natural as well as artificial. Every ecosystem has two components, namely, biotic components and abiotic components. Biotic components refer to all living organisms in ecology while abiotically refers to the non-living things. These biotic and abiotic interactions maintain the equilibrium in the environment. II. Components of Ecosystem Biotic components are the living things that have a direct or indirect influence on other organisms in an environment. For example plants, animals and microorganisms and their waste materials. Abiotic components of an ecosystem include all chemical and physical elements i.e. non-living components. Abiotic components can vary from region to region, from one ecosystem to another. They mainly take up the role of life supporter. They determine and restrict the population growth, number, and diversity of biotic factors in an ecosystem. Hence they are called limiting factors. A terrestrial ecosystem consists of abiotic factors like climate, type of soil or rock, altitude, temperature, nutrients, and minerals, whereas abiotic components in an aquatic ecosystem include dissolved gases, depth of water, salinity, pH of water, light intensity, etc. III. The Significance of Biotic and Abiotic Components A. Biotic components can be classified into three categories:  Producers: These include all the autotrophs. They use light energy and synthesize food on their own, e.g. plants, green algae, etc.  Consumers: These include all the heterotrophs that directly or indirectly depend on producers for their food. Consumers are further categorized as herbivores, carnivores, omnivores and parasites.  Decomposers: These include saprophytes which act on dead matter and decay them for their nutrition. The relevance of biotic and abiotic components in an environment appears when they start interacting with each other. For example, biotic elements like plants provide food for other organisms. The soil is the abiotic element that supports the growth of the plants by providing nutrients and other essential elements. Biotic components depend on abiotic components for their survival and help in the formation of abiotic factors like soil, nutrients, etc. | 11 IV. Food Chains and Webs A food chain is a chain that shows how organisms are linked to each other through food. A food web (Figure 2.2) shows how two food chains are connected. A single food web consists of many food chains. Every food chain begins with producers and ends with top carnivores. Figure 2.1. A food chain showing the relationship of different organisms. Source:https://www.pinterest.ph/pin/802414858580466591/?nic_v2=1a2XfnW5s A food web links all of the food chains in an ecosystem together, showing a more holistic view of energy transfer in the ecosystem. Figure 2.2. A food web showing the relationship of different organism Source:https://www.pinterest.com.au/pin/141863456998136368/?nic_v2=1a2XfnW5s | 12  The energy flow from one level to another level in a food chain gives the trophic level of an ecosystem. The producers come at the first trophic level followed by herbivores (primary consumers), then small carnivores (secondary consumers) and large carnivores (tertiary consumers) occupy the fourth trophic level. V. Trophic Levels Each step in a food chain or food web is a trophic level. As you increase the trophic level, the amount of energy decreases. Figure 2.3. The trophic level and amount of energy as the level increases. Source: https://www.askiitians.com/revision-notes/class-10-science/our-environment/ VI. Major Types of Ecosystem: Biomes and Aquatic Life Zones Life exists on land systems called biomes and in freshwater ocean aquatic zones. As viewed from outer space, the earth resembles land and vast expanses of ocean. Biologists have classified the land (terrestrial) portion of the biosphere into biomes. Each of these large regions –such as forests, deserts, and grasslands- is characterized by a distinct climate and specific species. The watery part of the biosphere is divided into aquatic life zones, each containing numerous ecosystems. Examples included freshwater zones (such as lakes and streams) and ocean or marine life zones (such as coral reefs, coastal estuaries, and the deep ocean). Biomes consist of broad regional groups of related manageable units called ecosystems. A biome is one of several terrestrial environments, a habitat characterized throughout its extent by similar paths, animals, climate and | 13  social types. The distribution of animals and plant forms is determined largely by climate, topography and the soil. The same or very similar ecological niches may be occupied by different species in geographically separated biomes. VII. Major Types of Biomes A. Deserts Deserts generally occur in semi-tropical and temperate regions having rainfall of less than about 20 cm a year. Its climate has the least precipitations and is unpredictable from year to year. Precipitation is so slow that in some desserts, evaporation from soil and plant surface exceeds precipitation. There are two kinds of deserts:  Cool Deserts – these are dominated by sagebrush, rabbitbrush and smaller perennial plants  Hot Deserts – these are dominated by creosote, cacti, acacias, agave and yucca. Desert soil is largely unprotected by vegetation. It is subject to severe erosion from wind and occasional rain. It has a thin top layer of decaying plant materials called humus. Organisms of the desert have both structural and behavioral adaptations to meet their three most critical needs for survival: food, water, and heat. Plants with seasonal leaf production have water-storage tissues and thick epidermal layers that help reduce water loss. Animals live in burrows or rocky shelters to escape from the onslaught of the daytime heat. B. Grasslands Grasslands are dominated by grasses and a rich array of deep-rooted beautifully flowering non-grass species. They have a few trees because of inadequate rainfall and frequent grass fire that kill woody seedlings. C. Forests Forests are regions where trees grow as a result of adequate temperature and minimal precipitation of 75 centimeters or more. | 14 D. Tropical Biomes  Tropical Rainforest is a forest with high, fairly constant rainfall and temperature that permit trees to grow throughout the year. Annual rainfall may exceed 400 centimeters. This is a biome with the highest species diversity. The number of species in a given area may have almost 100 different species per hectare.  Tropical seasonal forest is also known as the monsoon forest. Seasonal rainfall is concentrated during part of the year after which follows as an increasingly pronounced dry season. The proportion of deciduous trees (trees that lose their lives for a season) increases as the length of the dry season increases.  Tropical savanna consists of grassland dotted with scattered small trees and shrubs such as acacias. Some savannas are entirely grassland; others contain many trees.  Tropical Thornwood, shrubland and tropical shrub. The proportion of trees depends on the competition between trees and the grass for water. The soil is more fertile than most tropical rainforests, but the rainfall is erratic. E. Temperate Biomes  Temperate deciduous forest occurs in a moderately humid area where precipitation takes place throughout the year but winters are cold restricting plant growth during summers. Most of the trees lose their leaves in autumn. They lose little water by transpiration in winter where their roots could not replace it from the frozen soil.  Temperate evergreen forest occurs where the condition favors conifers or broadleaf evergreens over deciduous trees. It has poor soil condition, frequent droughts, and forest fires  Temperate rainforest occurs in cold climates near the sea with abundant winter rainfall and summer clouds or fogs.  Temperate woodland occurs where the climate is too dry to support a forest yet provides sufficient moisture to support trees as well as grasses. Dominant trees are conifers, evergreens, flowering trees, and deciduous trees.  Temperate shrublands is represented by Chaparral communities that occur in all five regions of the world having a fairly dry climate with little or no summer rain.  Temperate grassland is also known variably as a prairie in North America, steppe in Asia, pampas in South America, and veldt in | 15  South Africa. The grasslands are natural ranges for grazing animals, but they must be treated with care or they degrade into shrubland. F. Taiga Taiga came from the Russian word meaning “primeval forest’. It is also called the boreal forest. It is dominated by conifers that can survive extreme cold winter. The trees in the taiga are further apart than in the forest and enough sunlight penetrates the forest floor to support an extensive ground cover for the shrubs. Most taiga precipitations are snow. The mammal’s grown hair or plumage makes them blend in a surrounding with white background. G. Tundra The tundra is a treeless biome that occurs far north in the Arctic regions where winters are too dry and cold to permit the growth of trees. It is a biome of low-growing plants where the water reaches plant roots for only a few months of the year because the soil is frozen for the rest of the time. The permanently frozen layer is permafrost Elaborate In your local ecosystem, illustrate a simple food chain and food web and label the trophic levels. | 16 Evaluate Name: Date: Program and Section: Score: I. Matching Type A. Match each item with the correct statement below. Write only the letter corresponding to your answer. a. temperate grassland d. tropical rain forest b. coniferous forest e. savanna c. tundra _____1. It has the greatest biological diversity of any land biome _____2. It has trees with cones _____3. It has a variety of grasses as its main plants _____4. It has mosses, lichens, and low growing shrubs in the warm season _____5. It has large grazing animals B. Match each item with the correct statement below. Write only the letter corresponding to your answer a. temperate deciduous forest d. savanna b. coniferous forest e. desert c. temperate grassland ____ 6. It has grass, but few trees due to fires, drought, and grazing ____ 7. It has many trees that do not change much seasonally ____ 8. It has organisms with special adaptations to a hot, dry climate ____ 9. It has clumps of trees and seasonal rains ____10. It has many trees that lose all of their leaves to save Supplementary Notes The following are suggested video links for further learning: https://www.youtube.com/watch?v=Bn41lXKyVWQ https://www.youtube.com/watch?v=E6WdEyt93vA https://www.youtube.com/watch?v=Mle5gmEpYys https://www.youtube.com/watch?v=Yy191KVBNP0 https://www.youtube.com/watch?v=pNxgY4Ru3gs https://www.youtube.com/watch?v=OUmHWrF8MnY | 17  Lesson Outcomes At the end of the lesson, you must have: 1. explained how energy flow in an ecosystem; and 2. illustrated and discussed the different cycles of matter; An ecological balance is maintained through the energy flow in the ecosystem. The energy that is found in food webs comes from the sun and transformed into chemical energy through photosynthesis. In an ecosystem, matter cycling happens when matter moves from one form to another or from one place to another. These cycles are also called biogeochemical cycles because they include a variety of biological, geological, and chemical processes. The four biogeochemical cycles are water, carbon, nitrogen, and phosphorus cycles. These biogeochemical cycles transport and store important elements to be used by living organisms. Engage What is the cycle? Do you ever wonder how energy is produced, utilized and returned in an ecosystem? Explore Explain briefly the life cycle of plants. (This is an example of what we call cycle) Illustrate a simple food chain. (This is how energy flows in an ecosystem) Explain I. Producers provide energy for other organisms in an ecosystem. All organisms must have a source of energy to survive. However, not all organisms obtain their energy by eating other organisms. Producers are organisms that get their energy from non-living resources, meaning they make their own food. Producers are also called autotrophs. In the word autotroph, the suffix -troph comes from a Greek word meaning “nourishment.” The prefix auto- means “self.” | 18 II. Consumers are organisms that get their energy by eating other living or once- living resources, such as plants and animals. Consumers are also called heterotrophs. In the word heterotroph, the prefix hetero- means “different.” Most producers need sunlight to make food. These producers depend directly on the sun as their source of energy. For this reason, all the consumers connected to these producers depend indirectly on the sun for their energy. III. Cycles of Matter: Matter is recycled within the ecosystem and it is done through Biogeochemical Cycles. This is the way that water, carbon, nitrogen, and phosphorus cycle through the atmosphere. A. Water Cycle All living things depend on water. It is through the processes of condensation, evaporation, and precipitation that water cycles pass through in the atmosphere. Source: https://en.wikipedia.org/wiki/Water_cycle#/media/File:Watercyc lesummary.jpg | 19 B. Carbon Cycle All living things are made up of carbon, which makes it important. In the carbon cycle, there are 4 major processes:  Photosynthesis, respiration, and decomposition. Photosynthesis is the process by which energy from the sun is used to form bonds of chemical energy that hold organic matter together.  Erosion and volcanic activity  Burial and Decomposition of dead organisms and their conversion into coal and petroleum  Human activities such as mining, cutting and burning forests, and burning fossil fuels, releasing carbon into the atmosphere as carbon dioxide. The key processes in the carbon cycle are: Carbon dioxide from the atmosphere is converted into plant material in the biosphere by photosynthesis. While organisms in the biosphere obtain energy by respiration and so release carbon dioxide that was originally trapped by photosynthesis. Respiration happens when plants convert the carbon in atmospheric carbon dioxide into carbon-containing organic compounds, such as sugars, fats, and proteins.) Figure 2.5. The Carbon cycle Source :https://www.windows2universe.org/earth/Water/co2_ cycle.html | 20 C. Nitrogen Cycle In the nitrogen cycle, there are two processes that help gaseous nitrogen come into our soil. Nitrogen fixation: bacteria which turn nitrogen gas into ammonia. This ammonia is then converted to nitrates and nitrites by other bacteria. Denitrification: process where bacteria convert nitrates into nitrogen gas. Figure 2.6. The Nitrogen cycle Source: https://www.fredericknewspost.com/news/environment/the- nitrogen-cycle-and-trees/article_892f760f-f004-58b8-a223-684 b5c3d9fdc.html | 21  D. Phosphorus Cycle Phosphorus helps form DNA and RNA Phosphorus does NOT enter the atmosphere (like water, carbon, oxygen and nitrogen) Phosphorus exists as phosphate and is found in rocks, soil and ocean sediments (sand) Phosphate is used by producers and then moves up through the food chain Figure 2.7. The Phosphorus cycle Source: https://qforquestions.com/sedimentary-cycle/phosphorus-cycle/ Elaborate Choose one among Nitrogen, Carbon, Phosphorus cycle then create a collage or a digital version (powerpoint, MSword, video) of cycle explaining each step. | 22 Evaluate Name: Date: Program and Section: Score: I. Multiple Choice Direction: Choose the letter of the correct answer and write it on the space provided before each number. ___1. What step of the water cycle is when plants gives off water vapor from photosynthesis? A. Evaporation C. Condensation B. Transpiration D. Sublimation ___2. Oxidation of ammonium salts to nitrites and further oxidation of nitrites to nitrates. A. Ammonification C. Nitrification B. Nitrogen fixation D. Decomposition ___3. Decomposition with the production of ammonia especially in the action of bacteria. A. Ammonification C. Nitrification B. Nitrogen fixation D. Decomposition ___4. Which part of the carbon cycle occurs when plants convert sunlight and C02 into oxygen and sugar? A. Photosynthesis C. Respiration B. Combustion D. all of the above ___5. Without phosphorus, living beings cannot grow, reproduce, or move. This is because phosphorus___________________. A. forms part of the structure of DNA and RNA. B. is needed for energy transport in cells. C. provides structure to cell membranes. D. All of the above ___6. Which nutrient cycle does not have a troposphere in its processes? A. Nitrogen C. Carbon B. Phosphorus D. Water | 23  ___7. Which of the following is known as the “sedimentary” cycle because its reservoir is sedimentary rocks? A. Sulfur C. Nitrogen B. Phosphorus D. Carbon ___8. The process by which a gas changes into a liquid? A. Precipitation C. Evaporation B. Condensation D. all of the above ___9. One of the main ways CO2 is removed from the atmosphere is ____. A. Photosynthesis C. Respiration B. Combustion D. Decomposition ___10. The process in which nitrogen is circulated and recycled is called? A. Sulfur Cycle C. Nitrogen Cycle B. Phosphorus Cycle D. Carbon Cycle Supplementary Notes The following are suggested video links for further learning: https://www.youtube.com/watch?v=jFjI6y46QRk https://www.youtube.com/watch?v=ccWUDlKC3dE https://www.youtube.com/watch?v=_dYkByQ9Kmg https://www.youtube.com/watch?v=DsCMYyQ0NWU https://www.youtube.com/watch?v=tm2LG5ScT1g | 24  Lesson Outcomes At the end of the lesson, you must have: 1. defined and differentiated population and community ecology; 2. identified the factors that affect the population growth; 3. described interactions between and within species in a community; and 4. calculated the index of diversity based on species richness and relative abundance. Humans have always been one of the greatest factors in the degradation of energy resources. The use of resources in the community is vastly affected by the growth of the size of the population of living things. Studying the degree of this growth may serve as a warning of what would happen in the future if living things especially humans will continue to increase their population dramatically. Engage In your understanding, what is Population? What is Community? Explore Watch the video link and answer the guide questions. Organism, Population, Community: What is the difference? https://www.youtube.com/watch?v=ClLHcSXzRos Guide Questions 1. What is the difference between Population and Community? 2. Give at least three examples of each concept Explain I. Population Ecology The population in human demography is a set of humans in a given area. In genetics, a population is a group of isolated interbreeding individuals. Population ecology is a group of similar species living in a certain place at the same time. Examples would be all the cats in the house, all the maya birds in the campus, all | 25 the narra tree in a province, all the tilapia in the Philippines and all the bees in the world. II. Population Distribution, Density and Size A. Population Distribution Characterized by where organisms are found on earth and are determined by biotic and or abiotic factors, it is also about where a particular species of the organism does occur. The spatial relationships of individual organisms to one another may take several different forms and it is called dispersion. Dispersion is the spatial distribution of individuals of a population and comes in three general kinds of patterns (Figure 2.8):  Clumped (aggregated) dispersion occurs when individuals clumped together or clustered in groups. A clumped dispersion may be seen in plants that drop their seeds straight to the ground—such as oak trees—or animals that live in groups— schools of fish or herds of cows. Clumped dispersions also happen in patchy habitats, with only some patches that are suitable to live in.  Regular dispersion occurs when individuals are of the same distance from one another. One example of regular dispersion comes from plants that secrete toxins to inhibit the growth of nearby individuals—a phenomenon called allelopathy. We can also find regular dispersion in animal species where individuals stake out and defend territories.  Random dispersion occurs when the habitat of the organism is relatively uniform so individuals are neither repelled nor attracted to one another. In random dispersion, individuals are distributed randomly, without a predictable pattern. An example of random dispersion comes from dandelions and other plants that have wind-dispersed seeds. The seeds spread widely and sprout where they happen to fall, as long as the environment is favorable—has enough soil, water, nutrients, and light. | 26 Clumped dispersion Regular dispersion Random dispersion Figure 2.8. Patterns of Distribution Source: https://www.unbc.cal/sites/default/files/sections/cheelkin /biol410lecture2publish.pdf B. Population Density Population Density is the number of individuals per unit area or unit volume. It describes the degree of the crowdedness of a population in a given area. Population Size pertains to the number of individuals in a population. Examples of these are the number of people in the Philippines, the number of cats, acacia tree, and even the number of milkfish. These are the four primary factors that determine population size:  Natality is the addition of organisms to the population through reproduction. Many organisms reproduce fast and some may not, this is the reason why some organisms are more than the others. Natality increase population density.  Mortality is losing a member of the population due to death. It can decrease population density.  Immigration is the addition of organisms because of the movement of an organism from one place to another. It has the same effect as natality.  Emigration is the loss of individuals that move out of the population and has same effect as mortality. C. Population Growth Growth is an important feature of the population since the increase or decrease of population size determines the interaction with other populations in the community and its impact on the environment. | 27 III. Carrying Capacity defined as the capacity of the environment or an ecosystem to support and sustain a level of the population under an ideal set of conditions. The carrying capacity of the Earth is calculated to be 8-15 billion, that when it is surpassed, there will be consequences such as food shortage and shelter shortage. To sustain a certain environment, organisms that should only be the one that would live in that particular place. IV. Limiting Factor are somewhat tied to carrying capacity. For instance, animals increase rapidly and may temporarily exceed the carrying capacity of their habitat so as a result, organisms may experience anxiety, hunger, sickness, poor reproductive success, and damage to the habitat. For example, multiplying grasshoppers can very quickly eat all the vegetation in a farm but with the vegetation gone, food becomes the limiting factor and the grasshoppers may starve or move to another area, thus the farm has a reduced carrying capacity relative to the grasshoppers. V. Community Ecology There are several populations in an area. In a grassland, one would find populations of grasshoppers, frogs, snakes, grasses, herbs and shrubs, and many others. Together, all these populations would form an ecological or biotic community. In other words, Community Ecology is the study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat. VI. Community Interactions Interspecific interactions affect the survival and reproduction of the species that engage in them. As shown in Table 3, these interactions can be grouped into three broad categories: competition, exploitation, and positive interactions. | 28 Table 3. Interspecific interaction Interaction Description Competition (-/-) Two or more species compete for a resource that is in short supply. Example: Rice and weeds competing for light and nutrients found in soil. Exploitation (+/-) One species benefits by feeding upon the other species, which is harmed. Exploitation includes the following: Predation One species, the predator, kills and eats the other, the prey. Example: A snake (predator) eating a bird (prey). Herbivore An herbivore eats part of a plant or alga. Example: A cow (herbivore) eating grass. Parasitism The parasite derives its nourishment from a second organism, its host, which is harmed. Example: A leech is found feeding on a frog's blood Positive interactions (+/+ or 0/+) One species benefits while the other species benefits or are not harmed. Positive interactions include the following: Mutualism (+/+) Both species benefit from the interaction. Example: A clownfish live within the protective tentacles of the sea anemone. In return, the sea anemone receives cleaning and protection. Commensalism (+/0) One species benefits, while the other is not affected. Example: The cattle egrets eat the insects that is stirred up by cattle when they are grazing. The cattle are unaffected, while the birds gain food. | 29 VII. Species Diversity Species Diversity of a community is the variety of different kinds of organisms that make up the community. It has two components: the species richness and relative abundance. Species richness is the number of different species in the community. The relative abundance of the different species is the total number of individuals of a species with relation to the total number of individuals of all species in a given area or community. Imagine two small forest communities, each with 100 individuals distributed among four tree species (A, B, C, and D) as follows: Community 1: 25A, 25B, 25C, 25D Community 2: 80A, 5B, 5C, 10D The species richness is the same for both communities because they both contain four species of trees, but the relative abundance is very different. Relative abundance= Total # of individuals of a species Total # of individual of all species In community 1, the relative abundance of species A is 0.25 Relative abundance=25/100=0.25 In community 2, the relative abundance of species A is 0.8 Relative abundance= 80/100= 0.8 Ecologists use many tools to compare the diversity of communities across time and space. They often calculate indexes of diversity based on species richness and relative abundance. One widely used index is Shannon diversity (H): H = -(pA ln pA + pB ln pB + pC ln pC + c) where A, B, C... are the species in the community, p is the relative abundance of each species, and In is the natural logarithm; the ln of each value of p can be determined using the “ln” key on a scientific calculator. A higher value of H indicates a more diverse community. Let’s use this equation to calculate the Shannon diversity index of the two communities For community 1, p = 0.25 for each species, so H = -4(0.25 ln 0.25) = 1.39. For community 2, H = -[0.8 ln 0.8 + 2(0.05 ln 0.05) + 0.1 ln 0.1] = 0.71. These calculations confirm our intuitive description of community 1 as more diverse. | 30 Elaborate Compute the index of diversity 1. Grassland 1 has 100 individuals distributed among four species: 20A, 25B, 25C, and 30D. Grassland 2 has 100 individuals distributed among three species: 80A, 15B, and 5C. Calculate the Shannon diversity (H) for each grassland. Which is more diverse? | 31 Evaluate Name: Date: Program and Section: Score: I. Multiple Choice Direction: Choose the letter of the correct answer and write it on the space provided before each number. ___1. The group of similar species living in a certain place at the same time. A. Community C. Organism B. Population D. Biosphere ___2. Both species benefit from the interaction. A. Commensalism C. Mutualism B. Predation D. Herbivore ___3. It occurs when individuals clumped together or clustered in groups. A. Random distribution C. Regular distribution B. Clumped distribution D. Irregular distribution ___4. It is the variety of different kinds of organisms that make up the community. A. Species richness C. Relative abundance B. Species diversity D. all of the above ___5. Addition of organisms to the population through reproduction A. Mortality C. Natality B. Immigration D. Emigration ___6.A leech is found feeding on a frog's blood. What type of interaction is this? A. Mutualism C. Herbivore B. Parasitism D. Predation ___7. It is the study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat. A. Community Ecology C. Community B. Population Ecology D. Population | 32  ___8. It is the number of different species in the community. C. Species richness C. Relative abundance D. Species diversity D. all of the above ___9. The cow is eating grass. What type of interaction? A. Mutualism C. Herbivore B. Parasitism D. Predation ___10. Ants are an example of a community or population? A. Community C. Organism B. Population D. Biosphere Supplementary Notes The following are suggested video links for further learning: https://www.youtube.com/watch?v=s4Ty2Oo7MnI https://www.youtube.com/watch?v=D1aRSeT-mQE | 33 References Campbell, N. A., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P.V., and Reece, J.B. (2018) Biology A Global Approach 11th Edition. Pearson Education Limited. New York. 1270-1293 pp Guido, R. M. D., Garcia, R. E., Meneses, J. L., Quilang, A. B.,and Binag, N. D. (2015). Fundamentals of Environmental Science. Books Atbp. Publishing Corp. 179 pp Lee, S.J. and Anes, M.L. (2010). Lecture Notes in Environmental Science. The Economy of Nature and Ecology of Man. 2dn Ed. C& E. Publishing, Inc. 257 pp Miller, G. T. Jr. and Spoolman, S.E. (2009).Essentials of Ecology. Brooks/Cole. Cengage Learning. USA.. 274 pp Miller, G. T. Jr. (2006). Environmental Science, Working with the Earth. 11th Ed. Brooks/Cole. Thomson Learning. USA.436 Tayo, G. T., Gascon, C. N., Maglambayan, V. B., Novicio, L. P. and Viril, V. M. 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