Introduction to Ecology Lecture Notes PDF

Introduction to Ecology  Ecology The word ecology was coined by German zoologist Ernst Haeckel in 1866. The word comes from the Greek oikos, meaning “household,” “home,” or “place to live.” Ology- means “study of.” Thus, ecology refers to an organism and its env...

Introduction to Ecology  Ecology The word ecology was coined by German zoologist Ernst Haeckel in 1866. The word comes from the Greek oikos, meaning “household,” “home,” or “place to live.” Ology- means “study of.” Thus, ecology refers to an organism and its environment.  Ecology The scientific study of the distribution, abundance, and dynamics of organisms, their interaction with other organisms and their physical environment. (British Ecological Society) Components of the Environment  Ecological Terms Species/organism Population Community Ecosystem Biome Biosphere Habitat Niche Interactions  Species/Organism A group of organisms with shared genes, capable of sexual reproduction to produce fertile offspring. -Native Species -Alien Species -Invasive Species  Native Species Naturally occurring Examples: Red-eye tree frog, Giant River otter, Harpy Eagle Alien Species: Introduced by human influence Invasive Species: Alien species which tend to displace natives. Examples: Tilapia, Lionfish, Cane toad, Rock Pigeon  Population A group of individuals of a given species that live in a specific geographic area. It is a quantitative measure Colonies are related- a group of organisms living closely together. -territoriality -a subset of a population  Community Populations of species living in a defined area (habitat/ ecosystem) and interacting in various ways. It may be defined based on taxon (birds), habitat (mudflats) or ecosystem (marine ecosystem).  Ecosystem The term was first coined by A.G.Tansely. A biological community interacting with the abiotic components of its habitat. Note the habitat sets the physical parameters of the system. Types of Ecosystem  Biome A collection of interacting ecosystems defined on broad biophysical characteristics. Examples include: 1. Tundra- Coldest of all biomes. Includes the Arctic and Alpine tundra (Polar Bears, Snowy owl) 2. Rainforest- rain falls all year round (palms, Vines, ferns)  Biome 3. Desserts- the driest (dessert fox) 4. Grasslands- includes Savanna and temperate grassland. Species vary depending on the amount of rainfall (Swift foxes, black-footed ferrets)  Aquatic Biomes The aquatic biome is the largest biome in the world. It covers over 70% of the earth. It is divided into fresh water and marine regions. Freshwater regions have a low salt concentration while the marine regions have a higher salt concentration. Light plays a major factor that influences the communities of organism found in this biome. Aquatic biomes can be broadly placed into five major categories.  Biosphere The collection of all biomes. The zone of life Earth  Habitat The area in an ecosystem defined by physical and chemical characteristics suitable for supporting the life of a species. Micro-habitats are small areas within the habitat. They can be as large as a forest or small like a burrow.  Ecological Niche Each species occupies a niche in the community. A niche is the role the species plays and includes the type of food it eats, where it lives, where it reproduces and its relationship with other species.  Ecological Interactions The range of ways in which individuals (same and different species), colonies and populations interact with each other. These can be categorized into 5 types of relationships: 1. Mutualism 2. Commensalism 3. Parasitism 4. Predation 5. Competition  Mutualism Both organisms benefit Examples - Acacia tree and ants - Sea anemones and clownfish  Commensalism One organism benefits while the other is neither harmed or helped. Examples - Cattle egrets and cattle - Tree frogs and plants  Parasitism One organism benefits while the other is harmed but not usually killed. It can live within or on the host. Examples: tapeworms, bacteria, ticks, fleas. Ring Worm  Predation One organism kills and consumes the other.  Competition Two or more organisms accessing the same limited resource. Intraspecific competition- among the same species Interspecific competition- among different species  Ecology as a systems study Ecology is the study of ecosystems The system consist of two things: - Components- the tangible or physical - Process- how components interact. Systems are defined by boundaries  Eco-System boundaries Ecosystem boundaries are set based on biophysical limits and are not solid/absolute. We may also consider conceptual boundaries within ecosystems. Ecosystem Components Ecosystem Processes  Ecosystem Structure Ecosystem structure is the network of interactions between components (biotic and abiotic) of the system.  Ecosystem Structure: Stratification Vertical distribution of different species occupying different levels.  Ecosystem structure: Organisms Organisms are shaped morphologically, physiologically and behaviorally by their interactions with each other and the physical environment. Ecosystem structure: Population/community Organisms present in a given environment. A collection of niches that the organisms can fit into. Ecosystem structure: Tropic levels  Ecological succession Ecological succession is a gradual process of change and replacement of the types of species in a community. It can take hundreds or thousands of years. Each community makes it harder for the previous community to survive. Primary Succession Secondary Succession  Ecosystem function The fundamental function of an ecosystem is to support life. Biological diversity (Genes-species-ecosystem) Ecological Stability Dependent on diversity Low diversity + high dominance= low stability + high productivity High diversity+ low dominance= high stability + low productivity  Ecosystem Services Regulating: maintenance of essential ecological processes and life support systems. Supporting: providing habitat for wild plant and animal species at local and regional scales Provisioning: provision of natural resources. Cultural: providing life fulfilment opportunities and cognitive development through exposure to life processes and natural systems.