Republic of the Philippines Department of Science and Technology PHILIPPINE SCIENCE HIGH SCHOOL-CENTRAL VISAYAS CAMPUS Talaytay, Argao, Cebu; Office Telephone Number: (032) 36-77-422 E-mail Address: cvisc1@yahoo.com

Module for Integrated Science 1First Quarter

An output of the

INTENSIVE TRAINING WORKSHOP for TEACHERS

Prepared by:

LUCAS E. OMBOYSST-1

ECOLOGY

Ecology (from Greek: οίκος, oikos, "household"; and λόγος, logos, "word") is the scientific study of the distribution and abundance of life and the interactions between organisms and their environment. The environment of an organism includes physical properties, which can be described as the sum of local abiotic factors such as insolation (sunlight), climate, and geology, and biotic factors, which are other organisms that share its habitat.

The term ecology or oekologie was coined by the German biologist Ernst Haeckel in 1866, when he defined it as "the comprehensive science of the relationship of the organism to the environment." [1] Haeckel did not elaborate on the concept, and the first significant textbook on the subject (together with the first university course) was written by the Danish botanist, Eugenius Warming. For this early work, Warming is often identified as the founder of ecology.

1. Living Things and the Environment

Course Overview

he course introduces students to the interconnections among the living and non-living things in an environment. Students explore the connections that occur within the

biosphere, ecosystem, communities, and population. Students gain understanding of the interactions and relationships among living things as they coexist in our world.

T

Objectives:

Define the terms: organism, population, community and ecosystem. Give qualitative and quantitative observation about the environment. Define and differentiate biosphere and ecosphere. Define and differentiate food chains from food webs. Differentiate food chains from ecological pyramid Identify the different types of ecological pyramid

References:www. Wikipedia.comwww. Tutorvista.comSOLOMON, et. Al, “Biology” 6th Ed., 2002

1.1 Scope of Ecology

is usually considered a branch of biology, the general science that studies living organisms. Organisms can be studied at many different Ecology

levels, from proteins and nucleic acids, to cells, to individuals and at the level of populations, communities and ecosystems to the biosphere as a whole.

Ecology is a broad discipline comprising many sub-disciplines namely; Ecophysiology – examines how the physiological functions of organisms influence

the way they interact with the environment, both biotic and abiotic. Behavioral ecology – examines the roles of behavior in enabling an animal to

adapt to its environment. Population ecology – studies the dynamics of populations of single species. Community ecology(or synecology) focuses on the interactions between species

within an ecological community Ecosystem ecology studies the flows of energy and matter through the abiotic

and biotic components of ecosystems. Systems ecology is an interdisciplinary field focusing on the study, development,

and organization of ecological systems from a holistic perspective. Landscape ecology examines processes and relationships across multiple

ecosystems or a very large geographic areas. Evolutionary ecology studies ecology in a way that explicitly considers the

evolutionary histories of species and their interactions. Political ecology connects politics and economy to problems of environmental

control and ecological change. In order to understand how complex our world is, ecologists often speak layers of ecological levels or organization.

Biosphere – the part of the earth that supports life, which includes the top portion of the Earth’s crust (troposphere), all the bodies of water (hydrosphere), and the surrounding atmosphere.

Ecosystem – the area in which living things interact with one another and with their environment. Ecosystems may be large, such as ocean, wetland, or forest. Or, they may be small like a pond, a single tree, or a rotting log.

Community – Different species of organisms that interact with each other in a given area form a community. A species is a group of organisms that share the same general physical characteristics and are able to interbreed and produce fertile offspring. The organisms may share or depend on each other for food, shelter, or other needs. For example, a rainforest may include frogs, monkeys, insects, and birds, all interacting with one another. A community is made up of all populations of plants, animals, and microorganisms living and interacting in a given habitat.

Population - A group organisms of the same species that live in a define area form a population. A community may have many different populations. For example, in a pond community, there may be a population of small fishes, grasses growing along the edge of the pond, of water insects, such as water striders that feed on other insects, or of water lilies living in the pond.

Organism – the living thing present in the environment. The actual place or type of environment in which an organism lives is called its habitat. Fro example, the habitat of cultured milkfish (bangus) is a fish pen as a frog to a pond. A habitat may include food, shelter, and the other sources the organisms need to survive. The role an organism has in its habitat is called its niche. For example, a frog lives in a pond habitat. Its niche is feeding on insects that live around the edge of the pond. Several different kinds of organisms usually share the same habitat. But it is rare that more than one kind of organism fills a particular niche.

Exercise1:1. Why is it important to study ecology?2. In your own words, differentiate community and population.3. Create a drawing or any representation that would relate each ecological

organization.4. What is your niche in PSHS?

1.2 STRUCTURE AND FUNCTION OF AN ECOSYSTEM

An ecosystem can also be defined as 'a structural and functional unit of biosphere or segment of nature consisting of community of living beings and the physical environment, both interacting and exchanging materials between them'.

Besides a mechanical system or a living body, the ecosystem usually has a boundary within which the component parts function together as one unit.

An ecosystem may be natural (like forest, lake, ocean etc) or man-made (such as an aquarium, a crop field etc), temporary (like a rainfed pond) or permanent (like a lake, forest, etc), aquatic (such as pond, ocean etc) or terrestrial (like grassland, forest, etc).

Classification of Ecosystem

An ecosystem may be as small as a drop of pond water and as large as an ocean. Ecosystems can be recognised as self - regulating and self - sustaining units.

Components of an Ecosystem

An ecosystem comprises of two basic components

i) Abiotic components and ii) Biotic components

The relationship between the biotic components and abiotic components of an ecosystem is called 'holocoenosis'.

Abiotic Components

These include the non-living, physico - chemical factors such as air, water, soil and the basic elements and compounds of the environment. Abiotic factors are broadly classified under three categories.

Climatic factors which include the climatic regime and physical factors of the environment like light, humidity, atmospheric temperature, wind, etc.

Edaphic factors which are related to the structure and composition of soil including its physical and chemical properties, like soil and its types, soil profile, minerals, organic matter, soil water, soil organisms.

Inorganic substances like water, carbon, sulphur, nitrogen, phosphorus and so on. Organic substances like proteins, lipids, carbohydrates, humic substances etc.

Biotic ComponentsIt comprises the living part of the environment, which includes the association of a

number of interrelated populations belonging to different species in a common environment.The populations are that of animal community, plant community and microbial community. Biotic community is distinguished into autotrophs, heterotrophs and saprotrophs.

Autotrophs (Gr: auto - self, trophos - feeder) are also called producers, convertors or transducers. These are photosynthetic plants, generally chlorophyll bearing, which synthesize high-energy complex organic compounds (food) from inorganic raw materials with the help of sunlight, and the process is referred as photosynthesis. Autotophs form the basis of any biotic system. In terrestrial ecosystems, the autotrophs are mainly the rooted plants. In aquatic ecosystems, floating plants called phytoplankton and shallow water rooted plants called macrophytes are the dominant producers.

Heterotrophs (Gr: heteros - other; trophs - feeder) are called consumers, which are generally animals feeding on other organisms. Consumer's also referred as phagotrophs (phago - to ingest or swallow) or macroconsumers are mainly herbivores and carnivores. Herbivores are referred as First order consumers or primary consumers, as they feed directly on plants. For example; Terrestrial ecosystem consumers like cattle, deer, rabbit, grass hopper, etc.

Aquatic ecosystem consumers like protozoans, crustaceans, etc.Carnivores are animals, which feed or prey upon other animals. Primary carnivores or Second order consumers include the animals which feed on the herbivorous animals. For example; fox, frog, predatory birds, smaller fishes, snakes, etc. Secondary carnivores or Third order consumers include the animals, which feed on the primary carnivores. For example; wolf, peacock, owl, etc. Secondary carnivores are preyed upon by some larger carnivores. Tertiary carnivores or Quaternary consumers include the animals, which feed on the secondary carnivores. For example; lion, tiger, etc. These are not eaten by any other animals. The larger carnivores, which cannot be preyed upon further are called top carnivores.

Saprotrophs (Gr: sapros - rotten; trophos - feeder) are also called decomposers or reducers. They break down the complex organic compounds of dead matter (of plants and animals).

Decomposers do not ingest their food. Instead they secrete digestive enzymes into the dead and decaying plant and animal remains to digest the organic material. Enzymes act upon the complex organic compounds of the dead matter.

Decomposers absorb a part of the decomposition products for their own nourishment. The remaining substances are added as minerals to the substratum (mineralisation). Released minerals are reused (utilised) as nutrients by the plants (producers).

Exercise 2 :1. What are the important aspects present in an ecosystem?2. Compare and contrast autothrophs, heterotrophs and saprotrophs.

Activity 1Materials:

Short bond paperPencilsColored Pens or Any other coloring material

Procedure:1. Identify any ecosystem found in the campus.2. Draw the identified ecosystem.3. Identify the biotic and abiotic components of your ecosystem.

STRUCTURE and FUNCTION

Released minerals are reused (utilised) as nutrients by the plants (producers). The two main structural features of any ecosystem are its 'species composition' and 'stratification'. An ecosystem can be represented by depicting the producers - consumers relationship in the given ecosystem. This is also called the 'Trophic structure' of an ecosystem, wherein each animal population forms the various trophic levels. The producers (green plants) always form the first trophic level. Herbivores, which feed on producers, are at the second trophic level followed by secondary consumers, tertiary consumers and so on. Trophic structure of an ecosystem can be described in terms of its total amount of nutrients or the amount of living material. The amount of nutrients in the soil at any given time is referred as 'standing state' whereas the amount of living material is referred as 'standing crop'.

FUNCTION

The functional attributes of an ecosystem helps to keep its component parts running together. Few important functional aspects of an ecosystem are: Biological diversity and maintenance of stability

The numerical strength and biomass of organisms affect the functioning of ecosystem.In ecosystems, the biotic communities usually contain a few common species represented by a large number of individuals or by a large biomass and a comparatively large number of individual species occurring in small numbers. Under stress conditions, the number of rare species is usually reduced, and only a few species may survive and their frequency of occurrence may be very high. As a rule, the total number of species in any ecosystem is reduced under conditions of extreme stress, as found in arctic, antarctic and desert region and so on.

A system is considered stable in the ecological sense if its structure and functions remain more or less the same from year to year. A system with high species diversity and low dominance is less productive but stable. On the other hand, a system with a community with low species diversity and high dominance is more productive but unstable.

1.2.1 FOOD ACHAINS AND FOOD WEBS

Exercise 3:1. What are the different trophic structures of an ecosystem?2. Why is a system with high species diversity and low dominance less productive but

more stable?

ood chain is a series of groups of organisms called trophic levels, in which, there is repeated eating and eaten by so as to transfer food energy".F

or"

The series of populations or organisms of an ecosystem through which food and energy contained in it passes with each member becoming the food of the later is called a food chain". For example;

a) Food chain observed in a river:

b) Food chain observed in a grassland:

The transfer of food energy from plant sources through a series of organisms forms a 'food chain'. The base of the food chain is always formed by a plant (producer / autotroph),

which is grazed on by a herbivore, which is predated over by a carnivore, which may be eaten by another carnivore. A food chain, can therefore, be represented as,

Producer Herbivore Carnivore 1 Carnivore 2

Where each link represent a Trophic Level.

Characteristic of a FOOD CHAIN

In a food chain,

a) there is repeated eating in which each group eats the smaller one and is eaten by the larger one. Thus, it involves a nutritive interaction between the biotic components of an ecosystem.

b) the plants and animals which depend successively on one another form the limbs of a food chain.

c) there is unidirectional flow of energy from sun to producers and then to a series of consumers of various types. Thus, a food chain is always straight and proceeds in a progressing straight line.

d) usually 80 to 90% of potential energy is lost as heat at each transfer on the basis of second law of thermodynamics (transformation of energy involves loss of unavailable energy).

e) usually there are 4 or 5 trophic levels. Shorter food chains provide greater available energy and vice - versa.

f) omnivores occupy more than one trophic level and, some organisms occupy different trophic positions in different food chains.

In nature, food chain relationships are not isolated. They are very complex, as one organism may form the food source of many organisms. Thus, instead of a simple linear food chain, there is a web like structure formed by these interlinked food chains. Such interconnected matrix of food chains is called 'food web'.

Food web can be defined as, "a network of food chains which are interconnected at various trophic levels, so as to form a number of feeding connections amongst different organisms of a biotic community". Food webs are indispensable in ecosystems as they allow an organism to obtain its food from more than one type of organism of the lower trophic level.

Generally, a food web operates according to taste and food preferences of the organism, yet availability of food source and other compulsions are equally important.For example, tigers normally do not eat fish or crabs, but Sunderbans tigers are forced to feed on them in the absence of their natural prey.

1.2.2 ECOLOGICAL PYRAMID

Ecological pyramids are also called 'Eltonian pyramids' after C. Elton. Charles Elton (1927) developed the concept of ecological pyramids who noted that "…the animals at the base of a food chain are relatively abundant while those at the end are relatively few in number…" Ecological pyramids can be defined as, "a geographical representation of an ecological parameter like number of individuals or amount of biomass or amount of energy present in various trophic levels of a food chain with producer forming the base and top carnivores at the tip".

Exercise 4:1. Compare and contrast food web from food chain.2. Why do food chains have only 4 to 5 links?3. How are Ecological Pyramids different/similar from food chains?

Graphical representation of the trophic structure is done by drawing ecological pyramids, where the basal, mid and top tiers show the parameter values for producers, herbivores and carnivores in the ecosytsem.

An ecological pyramid may be upright (tapering towards the tip), or inverted (widens towards the tip) or spindle shaped (broader in the middle and narrow above and below).On the basis of the parameters used, ecological pyramids are of three types.

Pyramid of Numbers- is the graphic representation of number of individuals per unit area of various trophic levels stepwise with producers forming the base and top carnivores the tip".

Pyramid of Biomass- is the graphic representation of biomass present per unit area of different trophic levels, with producers at the base and top carnivores at the tip".

Pyramid of Energy- is a graphic representation of the amount of energy trapped per unit time and area in different trophic level of a food chain with producers forming the base and the top carnivores at the tip".

Activity 2Materials:

Magazines, newspapers, pictures, colored pens, markers or pencilsShort bond paper (cartolina or illustration board will do)Paste and others adhesivesRulersPair of scissors

Procedure:1. Create a food web using the materials given. You could draw or make a

collage out of the materials whichever you prefer.2. The Identify the different trophic levels of each organism involved in your

food web.