* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Populations, Communities, Ecosystems
Survey
Document related concepts
Soundscape ecology wikipedia , lookup
Ecological resilience wikipedia , lookup
Biological Dynamics of Forest Fragments Project wikipedia , lookup
Source–sink dynamics wikipedia , lookup
Storage effect wikipedia , lookup
Habitat conservation wikipedia , lookup
Human population planning wikipedia , lookup
Pleistocene Park wikipedia , lookup
Reconciliation ecology wikipedia , lookup
Ecological fitting wikipedia , lookup
Renewable resource wikipedia , lookup
Maximum sustainable yield wikipedia , lookup
Restoration ecology wikipedia , lookup
Ecological succession wikipedia , lookup
Molecular ecology wikipedia , lookup
Transcript
Populations, Communities and Ecosystems Chap 19-20 1. Ecology is the study of interactions between organisms and their environment. 2. A Hierarchy of interactions: cells tissues organs organism population community ecosystem. Organismal Ecology – evolutionary adaptations; Population Ecology – concerns mainly with population density and growth; Community Ecology – populations of different species, deals with interactions like predation, competition, symbiosis; Ecosystem Ecology – interactions between biotic and abiotic components, concerns with energy flow and chemical cycling. 3. A population is an interaction between individuals of same species at a place. 4. A community is an interaction between individuals of different species at a place. A Habitat is the place where the community lives. 5. An ecosystem is an interaction between living = biotic factors = community and nonliving = abiotic factors at a place. 6. Ecology and environmentalism: Rachel Carson’s book ‘Silent Spring’ highlighted the bad role of use of insecticide DDT. It showed decline in populations of Pelicans and Bald eagles was due to DDT. America banned use of DDT and related insecticides and saved the endangered birds. 7. Abiotic factors of the environment include sunlight, Temperature, wind, soil, rock, water (precipitation = rain, snowfall, dew, hailstorm). The local conditions of abiotic factors vary and form patchiness of environment to form Habitat = natural surroundings of a species. Different species can live in same habitat. 8. Disturbances in environment like fires, hurricanes, tornadoes, earthquakes and volcanic eruptions damage the community at a place. Most of the times community can recolonize and can grow to earlier stage. This capacity to resist change is Stability of the community. The disturbance leads to succession of communities called Ecological Succession. 9. Organisms respond to disturbance or change in environment by Physiological response – like long term response Acclimation, for example living at high altitude organism starts producing more blood cells; Anatomical response – by undergoing structural change and behavioral response – some animals can migrate to suitable conditions. 10. Population ecology: Population density is the number of organisms living per unit area (square mile). Patterns of dispersion can be clumped, uniform or random. 11. Logistic Growth Model – It is S-shaped. It includes fast growth in the middle part but becomes constant on reaching Carrying Capacity (k) = maximum number of individuals the Habitat at a place can support. It is called Equilibrial Population. For example Polar bears. 12. Exponential Growth Model – It continues to grow very fast at maximum reproduction rate (r) even beyond carrying capacity. Soon population faces population crash when the resources are exhausted. It is J- shaped. It is called Boom and Bust population. It is found in Opportunistic Populations. For example in wild flowers. 13. Regulation of population growth is done using Density-dependent factors that change birth and death rates; and Density-independent factors that affect same % of individuals in all densities – these populations face boom and bust conditions. 14. Human population Growth – In most of developed world population is either slowly growing (USA) or decreasing (Italy) but increasing very fast in most of the developing world (Afganistan). The age structure figures help us understand population growth. When it is a fast growing population the base is broad and narrows to a point = Pyramid shaped (Afganistan). A steady population has base and middle part equal; and declining population has narrow base than middle. 15. Life span climate Growth curve Reproduction Death rate Body size Opportunistic life history short unpredictable Exponential = J-shaped, boom-bust High rate High, more in early life Small, many wild flowers Equilibrial life history Long Relatively predictable Logistic = S-shaped, stable at carrying capacity Low rate Low and in late life Big, polar bear Communities have different food chains linked by predation. Each level is called a trophic level. These always start with Autotrophs = producers that use the sunlight to make their food. Top Carnivore = tertiary consumer, lion 4th trophic level Carnivore = Secondary consumer, human, cheetah, tiger 3rd trophic level Herbivore = primary consumer, deer, hare, zebra, antelope 2nd trophic lelvel Producers = autotrophs, grass, plants 1st trophic level 1. Diversity of community means the different species living in it. 2. Prevalent forms of plants in a community mainly determine the type of animals living in that community. 3. The dead bodies of each level are degraded into simple chemicals by Decomposers = Detrivores 4. Some animals like earthworms, millipedes and many larvae are Detrivores because these feed on dead matter. 5. Bacteria, slime molds and fungi are important decomposers 6. The different organisms like grass or plants, deer or antelope, cheetah or tiger present on same trophic level do not eat each other and are called Competitors. 7. The organisms feeding on different trophic levels like humans are called Omnivores. Humans feed directly on plants and animals. 8. Food Chain is linear and joined by predation. Grass Deer Lion 9. Omnivore feeds at more than one trophic levels – bears, humans 10. Detrivores feed on detritus, a partially decomposed plant or animal part. 11. Food Web has many interconnected food chains. Only food webs exist in nature 12. Interspecific interactions (between organisms of different species) in a community include Competition, Predation, and Symbiosis. Refer chapter review. 13. Disturbance of Communities, when moderate in severity and occurrence leads to increase in diversity of species in the community. Disturbance usually leads to Ecological Succession. 14. Ecological Succession is Primary when it starts on bare rock with no soil. It takes hundreds of years to reach climax community. Disturbances like hurricanes, fires eliminate the community but leave the soil intact – The Succession is called Secondary, it takes lesser time to reach climax community. Chapter 20 Ecosystems: 1. Ecosystem Dynamics: Trophic relationships in an ecosystem determine the routes of energy flow and chemical cycling. Refer review. 2. Energy flow: is unidirectional in the ecosystem. All the time energy must come from Sun producers carnivores decomposers. All these lose energy as heat in the environment. The heat ultimately is lost from the biosphere to the space. 3. Most energy is lost in various activities at each trophic level. Only 5-20% (average 10%) energy is transferred to the next trophic level. 4. Chemical cycling: Plants take CO2 from air and minerals from soil and form Bio-mass. Herbivores feed on bio-mass of plants and C and minerals transfer to them. Carnivores get them on feeding on herbivores. Producers and consumers release CO2 into air. Decomposers or Detrivores break the dead bodies of producers, herbivores and carnivores and release the minerals back to the soil. Burning also releases back the CO2 into air. 5. Producers: can fix only 1% of light energy falling on them 6. 5 – 20% (10% average) of energy / bio-mass is passed from one trophic level to the next trophic level. 7. Weather shapes ecosystems 8. Latitude and Elevation: Rays of sun fall straight closer to equator (tropics) and distribute heat in lesser area. In areas closer to poles rays fall oblique and heat up larger area. Temperature falls from 0⁰ to 90⁰ latitude. Elevation from sea level to mountain top also has a similar effect. 9. Circulation of Air: Sunlight heats the air and makes it lighter. It rises and gets colder and falls back to earth. It creates 3 great pairs of cycles from equator to poles. 10. Rain Shadow Effect: Moist air from pacific rises on west side of mountain range and gets colder. Lower temperature decrease water holding capacity of air and rain or snow (precipitation) falls. 11. On the eastern side of mountain range air descends and gets warmer. Rise in temperature increases the water holding capacity of wind. No rain occurs. 12. Biomes: are very large ecosystems easily recognized on earth. For example, desert, tropical forest, conifer = evergreen forests, grassland, tundra etc. Tropical forests lie around equator and have high temperature and high rain. Deciduous forests lie midway between equator and poles and have high temperature and moderate rain. Evergreen forests or Taiga lie closer to poles and have moderate rain and cold temperature. Tundra is very cold circumpolar desert. Deserts mostly lie around 30⁰ N or 30⁰ S and have very low rain and high temperatures. Grasslands represent conditions of low rain and moderate temperature. 13. Aquatic Biomes: usually have upper Photic Zone with sufficient light for photosynthesis and deeper dark Benthic Zone. Open Sea = Pelagic Zone is rich in Phytoplanktons (microscopic autotrophs like diatoms and other unicellular algae) in the photic zone. These, along with the sea weeds, are the producers in the ocean.