BIO 202 — Introductory Ecology: Lecture Note

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BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course code: BIO 202 Course title: Introductory Ecology Course credit load: 2 Units Series 1: Concepts and Terminologies of Ecosystem • Part 1.1: Ecology and the Ecosystem Concept o Sub Part 1.1.1: Definition and scope of ecology o Sub Part 1.1.2: Definition and components of an ecosystem o Sub Part 1.1.3: Types of ecosystems • Part 1.2: Abiotic Components of the Ecosystem o Sub Part 1.2.1: Climatic factors o Sub Part 1.2.2: Edaphic (soil) factors o Sub Part 1.2.3: Topographic factors • Part 1.3: Biotic Components of the Ecosystem o Sub Part 1.3.1: Producers (autotrophs) o Sub Part 1.3.2: Consumers (heterotrophs) o Sub Part 1.3.3: Decomposers and detritivores • Part 1.4: Key Ecological Concepts and Terminologies o Sub Part 1.4.1: Habitat, niche, and ecotone o Sub Part 1.4.2: Biome, biosphere, and ecological levels of organisation o Sub Part 1.4.3: Energy flow and productivity

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Ecology is the scientific study of the relationships between living organisms and their environment. It provides the framework for understanding how organisms interact with each other and with the physical world around them. The ecosystem is the fundamental operational unit of ecology, integrating all living organisms in an area with their non-living surroundings. This opening Series introduces the language and conceptual framework of ecology. A firm grasp of ecological definitions and terminology is essential for understanding everything that follows in this course: habitat classification, community ecology, natural cycles, population dynamics, and environmental change. All subsequent Series build directly on the concepts introduced here. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define ecology and explain its scope and relationship to other sciences (Linked to Part 1.1), • SLO 1.2 define an ecosystem, identify its components, and classify the major types of ecosystems (Linked to Part 1.1), • SLO 1.3 describe the major abiotic factors (climatic, edaphic, and topographic) that influence ecosystems (Linked to Part 1.2), • SLO 1.4 describe the biotic components of an ecosystem (producers, consumers, decomposers) and explain their roles (Linked to Part 1.3), • SLO 1.5 define and distinguish between habitat, niche, ecotone, biome, and biosphere (Linked to Part 1.4), and • SLO 1.6 explain the concepts of energy flow and productivity in an ecosystem (Linked to Part 1.4).

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.1 Ecology and the Ecosystem Concept 1.1.1 Definition and scope of ecology Ecology is the scientific study of the interactions between organisms and their environment, including both the living (biotic) and non-living (abiotic) components. The term was coined by Ernst Haeckel in 1866, derived from the Greek oikos (house) and logos (study). Ecology seeks to understand the distribution and abundance of organisms and the processes that determine them. Ecology operates at several levels of organisation: individual ecology (autecology: the response of a single organism or species to its environment); population ecology (the study of groups of the same species in an area); community ecology (synecology: the study of multiple species and their interactions); and ecosystem ecology (the study of the community together with its abiotic environment). Ecology overlaps with physiology, genetics, evolutionary biology, and environmental science. Fill in the blank: Ecology was coined by Ernst ________ in 1866 from the Greek words oikos (house) and logos (study); it is the scientific study of the interactions between organisms and their environment. 1.1.2 Definition and components of an ecosystem An ecosystem is a functional unit consisting of all the living organisms (biotic community) in a defined area, together with all the non-living (abiotic) factors of their environment, interacting as a system. The term was introduced by A.G. Tansley in 1935. An ecosystem has no fixed size: it may be as small as a puddle or a decaying log, or as large as a tropical rainforest or an ocean. An ecosystem has two major components: abiotic (non-living) components, which include climate, soil, water, light, temperature, wind, and mineral nutrients; and biotic (living) components, which include all the organisms: producers (plants and other autotrophs), consumers (animals and other heterotrophs), and decomposers (bacteria and fungi). Energy flows through the ecosystem (from producers to consumers) and matter cycles between biotic and abiotic components.

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: The term "ecosystem" was introduced by A.G. ________ in 1935; it includes all the living organisms (biotic community) and all the non-living (abiotic) factors in a defined area, interacting as a system. Figure 1.1: Diagram of the structure of an ecosystem showing biotic and abiotic components and their interactions 1.1.3 Types of ecosystems Ecosystems are broadly classified as natural or artificial. Natural ecosystems develop without significant human modification; they include terrestrial ecosystems (forests, grasslands, deserts, tundra) and aquatic ecosystems (freshwater: rivers, lakes, ponds, swamps; marine: oceans, coral reefs, estuaries, mangroves). Artificial (man-made) ecosystems are created and maintained by humans; they include agricultural ecosystems (farms, plantations), aquaculture ponds, and urban ecosystems. Ecosystems can also be classified by the level of human input required to maintain them. Self-sustaining ecosystems need only solar energy and basic abiotic inputs; most natural ecosystems

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS are self-sustaining. Subsidised natural ecosystems receive additional energy or nutrient inputs from outside (e.g. estuaries receive nutrients from rivers). Dependent artificial ecosystems require continuous human energy and material inputs to persist (e.g. cropland, which requires ploughing, irrigation, and fertiliser). Nigeria's ecosystems range from mangrove forests in the Niger Delta to Sahel savanna in the far north. Fill in the blank: Ecosystems are broadly classified as ________ (developing without human modification: forests, grasslands, aquatic) or artificial (created by humans: farms, fish ponds, urban areas). Pilot questions 1.1 1. Define ecology and state its four levels of organisation. 2. Define an ecosystem and name its two major components. 3. Classify ecosystems into major types with one Nigerian example of each. 4. Explain what is meant by a self-sustaining ecosystem. 5. State who coined the term "ecology" and who introduced the term "ecosystem". 1.2 Abiotic Components of the Ecosystem 1.2.1 Climatic factors Climatic factors are non-living physical and chemical properties of the atmosphere and climate that influence organisms. Light (solar radiation): the primary energy source for all ecosystems; controls photosynthesis; photoperiod (day length) controls flowering and reproduction in many organisms; light intensity and quality vary with latitude, season, and canopy cover. Temperature: affects metabolic rate, enzyme activity, and distribution of species; determines whether an area supports tropical or temperate life forms. Rainfall (precipitation): the amount, timing, and reliability of rainfall is the most critical determinant of terrestrial ecosystem type in Nigeria; ranges from over 4,000 mm per year in parts of the Niger Delta to under 500 mm in the Sahel. Humidity: the water vapour content of the air;

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS affects transpiration, evaporation, and fungal growth. Wind: disperses seeds, pollen, and spores; increases evaporation and transpiration; affects fire behaviour. Atmospheric gases: CO2 concentration directly affects photosynthesis; O2 levels affect aerobic respiration; N2 is fixed by specialised bacteria. Fill in the blank: ________ (precipitation) is the most critical climatic determinant of terrestrial ecosystem type in Nigeria; it ranges from over 4,000 mm per year in the Niger Delta to under 500 mm in the Sahel. 1.2.2 Edaphic (soil) factors Edaphic factors are properties of the soil that influence the organisms living in and on it. Soil texture: the relative proportions of sand, silt, and clay particles; affects drainage, aeration, and nutrient-holding capacity. Sandy soils drain rapidly and hold few nutrients; clay soils retain water and nutrients but may become waterlogged and anaerobic; loam soils (intermediate texture) are most fertile. Soil structure: the aggregation of particles into clumps (peds); good structure improves aeration and root penetration. Soil pH: the acidity or alkalinity of the soil; most plants grow best at pH 6 to 7; strongly acidic soils (pH below 5) limit nutrient availability and favour acidophilic plants; alkaline soils (pH above 8) limit iron and manganese availability. Soil organic matter (humus): decomposed organic material; improves soil structure, water retention, and nutrient availability; high in forest soils. Soil mineral content: provides essential macronutrients (N, P, K, Ca, Mg) and micronutrients (Fe, Mn, Zn) for plant growth. Soil biota: bacteria, fungi, earthworms, and other organisms cycle nutrients and improve soil structure. Fill in the blank: ________ soils have an intermediate texture of sand, silt, and clay; they have the best combination of drainage, aeration, nutrient retention, and root penetration and are the most agriculturally fertile soils.

BIO la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.2: Diagram of soil profile showing horizons and properties 1.2.3 Topographic factors Topographic (physiographic) factors relate to the physical features of the landscape: slope, altitude,

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