Introduction to Ecology and the Biosphere PDF

An Introduction to Ecology and The Biosphere  Origin of the word…”ecology” Greek origin OIKOS = household LOGOS = study of… Study of the “house/environment” in which we live. Ecology is a branch of biology that studies the relationships between organisms a...

An Introduction to Ecology and The Biosphere  Origin of the word…”ecology” Greek origin OIKOS = household LOGOS = study of… Study of the “house/environment” in which we live. Ecology is a branch of biology that studies the relationships between organisms and their environment. This includes interactions among organisms as well as between organisms and their physical surroundings. Ecology is study of interactions between non-living components in the environment… – light – water – wind – nutrients in soil – heat – solar radiation – atmosphere, etc.  To study Ecology involves… For non-living For living (abiotic) (biotic) – Climatology animal – Hydrology behavior Taxonomy – Oceanography Physiology – Physics mathematics – Chemistry – Geology (population studies) – soil analysis, etc. etc. I. Scope of ecology A. Interactions between organisms and their environment 1. Ecology is the scientific study of the interactions between organisms and their environment. a. Interactions determine distribution and abundance of organisms. b. Two main themes in ecology are: - Where do organisms live? & Why? - How many organisms are present? & Why? c. Ecology was historically an observational science, often descriptive  natural history. d. An organism’s environment has both abiotic and biotic components. - Abiotic components are nonliving chemical and physical factors such as temperature, light, water, and nutrients. - Biotic components are living factors such as other organisms. 2. Ecology and evolutionary biology are closely related sciences a. Events that occur in the framework of ecological time (minutes, days, years) translate into effects over evolutionary time (decades, millennia). Example: Hawks feeding on mice impact mouse population and may eventually lead to selection for mice with fur as camouflage. 3. Ecological research scale ranges from individuals to the biosphere a. Organismal ecology is concerned about the way in which an individual interacts with its environment. b. Population ecology is the study of a group of individuals of the same species. c. Community ecology deals with all interacting species within a particular area. Organismal Ecology Organismal ecology focuses on the morphological, physiological, and behavioral adaptations that enable an organism to survive in its environment. For example, it studies how a specific species of butterfly has adapted to lay its eggs on a particular plant, ensuring the survival of its larvae. Population Ecology Population ecology examines the dynamics of species populations and how these populations interact with their environment. This includes studying factors like birth and death rates, immigration, and emigration. It also looks at how population sizes change over time and the factors that influence these changes. Community Ecology Community ecology explores the interactions between different species within a community and how these interactions shape the structure and function of the community. This includes studying food webs, trophic levels, and the roles different species play within an ecosystem. d. An ecosystem consists of all abiotic factors plus all organisms that exist in a certain area  Ecosystem ecology. Landscape ecology- interactions among ecosystems. e. The biosphere is the global ecosystem. Global climate research is an example of ecology at the biosphere scale. II. Factors affecting the distribution of organisms - Biogeography is the study of past and present distribution of individual species. Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. It examines how species and ecosystems are distributed across different regions and the factors that influence these patterns, such as climate, topography, and historical events like continental drift and glaciation. A. Species dispersal contributes to the distribution of organisms  Dispersal refers to the process of distribution of individuals within geographic population boundaries. Question: Is the distribution of a species limited by dispersal, i.e. by movement of the organisms? Answer can be obtained by transplant experiments. If the transplant is successful, then the organisms just haven’t reached the target area. This suggests that the species’ absence in that area is likely due to dispersal limitations rather than unsuitable environmental conditions.  If the transplant is not successful, then other factors limit the distribution of the organisms, such as competitors, lack of a food source, etc. transplant experiments are a powerful tool used to study how species respond to different environmental conditions. These experiments involve moving organisms from their native habitat to a new location to observe how they adapt and survive.  B. Behavior and habitat selection contribute to the distribution of organisms 1. Organisms may not occupy all potentially suitable habitat. Why? a. Evolution doesn’t lead to perfect organisms. b. Evolution is an ongoing process. Environments change, but it takes a while for organisms to respond. Environments can change faster than organisms can adapt, resulting in a delay before species can fully exploit new or altered habitats. C. Biotic factors affect distribution 1. Organisms required for potential community members to colonize may be lacking. - Pollinators, prey, predators that limit competition D. Abiotic factors affect distribution 1. Abiotic factors of interest include: - Temperature (range from 0 to 45 C) - Water - Sunlight - Wind (increases heat & water loss) - Rocks and soil  Local and seasonal effects on climate. – Bodies of water and topographic features such as mountain ranges can affect local climates. – Ocean currents can influence climate in coastal areas. – Mountains affect rainfall greatly. Fig. 50.14 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings b. Lake stratification and mixing  alters oxygen and nutrient levels. Dependent on temperature changes and effect on water density. SPRING Spring Turnover: As the ice melts and the surface water warms to 4°C, the water becomes denser and sinks, causing the lake to mix completely. This process, known as spring turnover, replenishes oxygen throughout the lake and redistributes nutrients. SUMMER Stratification: The lake stratifies into three layers: 1. Epilimnion: Warm, oxygen-rich surface layer. 2. Metalimnion (Thermocline): Middle layer with a rapid temperature change. 3. Hypolimnion: Cold, oxygen-poor bottom layer. Effects: The hypolimnion can become anoxic (lacking oxygen) due to decomposition, while the epilimnion remains well- oxygenated. FALL Fall Turnover: As the surface water cools and becomes denser, it sinks, causing the lake to mix again. This fall turnover re- oxygenates the deeper layers and redistributes nutrients. WINTER Inverse Stratification: In colder climates, the surface water can freeze, forming an ice layer. The water just below the ice is Aquatic and terrestrial biomes (Biome = major ecosystem type)  A. Aquatic biomes cover about 75% of the earth’s surface -Wetlands: Wetlands are unique ecosystems where water covers the soil or is present near the surface -Lakes -Rivers, streams -Intertidal zones: The intertidal zone is the area where the ocean meets the land between high and low tides. -Oceanic pelagic biome: The oceanic pelagic biome refers to the open ocean waters that are not in direct contact with the shore or the ocean bottom. -Coral reefs: Coral reefs are vibrant underwater ecosystems formed by colonies of coral polyps held together by calcium carbonate. They are often referred to as the “rainforests of the sea” due to their incredible biodiversity. -Benthos: Benthos refers to the community of organisms that live on, in, or near the bottom of bodies of water, such as seas, rivers, lakes, and streams12. These organisms inhabit the benthic zone, which is the lowest layer of a water body Oligotrophic Lake: Nutrient poor, water is clear, oxygen rich; little productivity by algae, relatively deep with little surface area. Eutrophic lake: nutrient rich, lots of algal productivity so it’s oxygen poor at times, water is murkier  often a result of input of agricultural fertilizers Rivers and Streams: Organisms need adaptations so that they are not swept away by moving water; heavily affected by man changing the course of flow (E.g. dams and channel-straightening) and by using rivers to dispose of waste. Wetlands: includes marshes, bogs, swamps, seasonal ponds. Among richest biomes with respect to biodiversity and productivity. Very few now exist as they are thought of often as wastelands. Estuary: Place where freshwater stream or river merges with the ocean. Highly productive biome; important for fisheries and feeding places for water fowl. Often heavily polluted from river input so many fisheries are now lost. Marine environment with zonation. Intertidal Zone: Alternately submerged and exposed by daily cycle of tides. Often polluted by oil that decreases biodiversity. Coral Reefs: occur in neritic zones of warm, tropical water, dominated by cnidarians (corals); very productive, protect land from storms; most are now dying from rise in global temperatures Deep-sea vent: Occurs in benthic zone; diverse, unusual organisms; energy comes not from light but from chemicals released from the magma. B. Terrestrial biomes - Tropical forest - Savanna - Desert - Chaparral - Temperate grassland - Temperate deciduous forest - Coniferous forest - Tundra Tropical Forest: Vertical stratification with trees in canopy blocking light to bottom strata. Many trees covered by epiphytes (plants that grow on other plants). Example of Tropical, Dry Forest Desert: Sparse rainfall (< 30 cm per year), plants and animals adapted for water storage and conservation. Can be either very, very hot, or very cold (e.g. Antarctica) Chaparral: Dense, spiny, evergreen shrubs, mild rainy winters; long, hot, dry summers. Periodic fires, some plants require fire for seeds to germinate. Temperate Grassland: Marked by seasonal drought and fires, and grazing by large animals. Rich habitat for agriculture, very little prairie exists in US today. Temperate Deciduous Forest: Mid-latitudes with moderate amounts of moisture, distinct vertical strata: trees, understory shrubs, herbaceous sub-stratum. Loss of leaves in cold, many animals hibernate or migrate then. Original forests lost from North America by logging and clearing. Coniferous forest: Largest terrestial biome on earth, old growth forests rapidly disappearing, usually receives lots of moisture as rain or snow. Tundra: Permafrost (Permanent frozen ground), bitter cold, high winds and thus no trees. Has 20% of land surface on earth.