Transcript Ecology
Ecology Ecology - the study of the interaction between living things and their environment What is the Biosphere? • The portion of the earth in which all living things exist • Only about 20Km of total diameter of earth • From 11km below oceans surface (hydrosphere) to about 8Km above earth’s surface (atmosphere) Consists of two types of factors • Biotic and Abiotic • What’s the difference? • What are some examples of each? Biotic Factors • • • • • Plants Animals Fungi Protists Bacteria Abiotic Factors • Habitat • Lakes, Oceans, Rivers • Desert • Mountains • Shade, sun • Rocks • Climate • Precipitation, • Temperature Oxygen Cycle • three reservoirs: atmosphere (air), biosphere (the global sum of all ecosystems), lithosphere (Earth's crust). • Water can have areas of hypoxia (insufficient oxygen) • The main driving factor of the oxygen cycle is photosynthesis, which is responsible for the modern Earth's atmosphere and life. Oxygen • Most free oxygen is in the atmosphere (O2) • BUT…most of oxygen mass is found in the rocks! (It is bound to other things) • Most atmospheric oxygen comes from photosynthesis Oxygen Loss • Most free oxygen loss is due to – Respiration and Decay – Oxygen is taken in and released as CO2 (note the water in usually = the water out) Also depicted by Energy pyramids 100J 1,000J 10,000J 100,000J Niches • Eubacteria/Archaebacteria – Found in all environments – Recycle carbon, nitrogen and sulfur – Decomposers, Pathogens, Nitrogen fixation, Sulfur cycle, Carbon cycle (methanogens) • Protists – Found in all environments – Help to make soil, PS (make O2) – Parasites, diseases Niches • Fungi – All environments, decomposers – Weathering rocks, soil production • Plantae – Photosynthesis, production of O2 – Store food and water • Animalia – Make nests, protect offspring, produce detritus, storage of food and water, nutrient cycling Biosphere • Where all living things are found Organized into a hierarchy: • Population: all individuals of a certain species within a certain area • Community: all the populations of different species within a specific area Many subcategories • Ecosystem: includes a community and its physical environment –Includes both biotic and abiotic Many subcategories • Biome: includes all the ecosystems in a particular climate –Examples: Individuals have a habitat and a niche • Habitat: where an individual organism lives; its home – where is yours? • Niche: the role that organism plays in its ecosystem –What is yours? Relationships between organisms • Competition: if two individuals occupy the same niche they will compete –Limited resources like? –Only one will win Relationships between organisms • Symbiosis: two organisms living in close association –Three types: mutualism, commensalism and parasitism Relationships between organisms Mutualism: both species benefit Example? Why? Relationships between organisms Commensalism: one benefits; the other is neither hurt nor helped Relationships between organisms Parasitism: one species benefits at the other’s expense Predator-Prey Relationship • Predator: organism that eats another organism; Receives energy • Prey: organism that is eaten; donates energy • An organism can be both! To examine ecosystems and biomes we must add in some abiotic components All organisms require Energy • As one organism eats another energy moves through ecosystem • Forms food chain • Many food chains make food web Food Chain Food Web Energy Pyramid Energy Pyramid • Producers/Autotrophs: make food from sunlight or other inorganic molecules – examples: plants, algae and bacteria Energy Pyramid • Primary consumers: eat producers –Herbivores –Examples: rabbits, plankton Energy Pyramid • Secondary consumers: eat primary consumers – Omnivores Energy Pyramid • Tertiary (High order) consumers: eat secondary consumers – carnivores –Larger animals –Top, or Apex, consumers are not eaten by anyone Where does the energy go then? • Decomposers: bacteria; break down dead organisms and return nutrients (nitrogen) back to the soil for producers to use • After the decomposers are done, all the energy absorbed by the original producers has been released as heat! Additionally we need materials to make up living things • Biogeochemical cycles! • Carbon, Nitrogen, Oxygen, Phosphorous, Water • All these recycle in unique ways Biomes of the World Succession • the changes an ecosystem goes through over time –A kind of “evolution” (simple complex!) Primary Succession • Begins with rocks • Pioneer species: Moss and Lichens Primary Succession • Primary succession begins in barren areas, such as the bare rock exposed by a retreating glacier. • First inhabitants are PIONEER SPECIES – lichens or mosses – grown on bare rock – convert the rock into soil that can support simple plants such as grasses. • GRASSES : further modify the soil, which is then colonized by other types of plants. – Each successive stage modifies the habitat by altering the amount of shade and soil composition. • CLIMAX COMMUNITY: Stable final stage that can endure for hundreds of years.. Secondary Succession • Occurs after a disturbance Secondary Succession • After a major disturbance, – fire or flood. – Farmland that has been plowed • Secondary succession is similar to primary succession – one important difference: primary succession always begins on a barren surface, – secondary succession begins in an area that already has soil. –Climax community is the goal, but is rarely reached –Disturbances can set the ecosystem back • Fires, logging, flood,etc. Climax community Limits to an Ecosystem Thomas Malthus • Plants and animals produce far more offspring than can survive, • Man too is capable of overproducing if left unchecked. Unless family size was regulated, man's misery of famine would become globally epidemic and eventually consume Man. Carrying Capacity • An ecosystem has only enough resources to support a certain number of organisms –This number is the ecosystem’s Carrying Capacity – Non-renewable resources – Renewable resources CC controlled by • • • • competition immigration emigration catastrophic events seasonal fluctuations in food, water (available resources) • hiding places, and nesting sites (shelter and “family homes • Population Densities Stable or Not? STABLE! • There will always be “fluctuations” around the average What happens as we approach the carrying capacity? Competition • Survival of the fittest – Numbers cannot go higher because there are limited resources. – If an invasive species is present, could result in extinction or severe lowering in the numbers of other species due to lack of predators for the invasive species! Don’t forget the Human Impact slides!