Transcript organism
Lecture 4 Ecosystems & Living Organisms Lecture 5 Ecosystems & Living Organisms Ecosystems & Living Organisms There are 3 main interactions among organisms: 1. Predation 2. Symbiosis 3. Competition Predation - relationship where one organism consumes another - includes both animals eating other animals and animals eating plants. Predator - depends totally or in part on killing another organism for its food Prey - organism killed and eaten by a predator Predator Strategies Predator strategies include: 1. Pursuit (chase) 2. Ambush (lie in wait) 3. Special hunting traits e.g., speed, agility, claws 4. Traps 5. Hunting in packs Prey Strategies Plant Defense Strategies include: - spines or thorns - leathery or waxy leaves - produce bitter or poisonous chemicals Prey Strategies Animal Defense Strategies include: - fleeing - camouflage - mechanical defenses, e.g., horns, quills - group living - warning coloration Symbiosis - a close relationship between 2 or more unrelated species The 3 main types of symbiotic relationships: 1. Mutualism 2. Commensalism 3. Parasitism MUTUALISM – Clownfish and Sea anemone - symbiotic Mutualism shark relationship where both organisms benefit from each other - symbiotic relationship where both organisms benefit from each other remora Commensalism - symbiotic relationship where one organism benefits while the other is unaffected COMMENSALISM - Barnacles encrusted on surface of whale Parasitism - symbiotic relationship where one organism (HOST) is adversely affected by another which benefits (PARASITE) - well-adapted parasites do not kill their host - e.g., tick on dog, tapeworm in human gut PARASITISM – Tapeworm in human Hooks and suckers on head for attachment to body organs PARASITISM − Tomato Hornworm covered with cocoon of braconid wasps Ecological Niche Niche - the sum total of all the requirements and activities of a species - an organism’s unique role - an organism’s “profession” - reduces competition between species Fundamental vs. Realized Niche Fundamental Niche - full potential range of physical, chemical & biological factors a species could use if there were no competition from other species Fundamental vs. Realized Niche Realized Niche - the portion of the fundamental niche that a species actually occupies - species with a narrow realized niche (specialist species) are more susceptible to extinction Habitat - the physical & biological resources required by an organism - an organism’s “address” Competition - if 2 different species require a common resource they are said to be in competition for it Competitive Exclusion Principle - also called Gause’s Principle - 2 species cannot live in the same identical niche & if they try 1 will be excluded Evolution & Succession Evolution & Succession Evolution - change in the genetic material of a population of organisms from one generation to the next. - involve processes which introduce new variations / characteristics (mutations or interbreeding) and processes that make new variants either increasingly rare or common. - does not necessarily mean speciation Natural Selection - a theory advanced by Charles Darwin (1809 – 1882) to explain how evolutionary change occurs - if certain individuals are better able to survive & leave more offspring because of their genetic traits, then frequency of the genes will change over subsequent generations Succession • Succession is a process of community development that involves a changing sequence of species. Succession • The pioneer community is the first community to colonise or re-colonise an area. • Primary succession is community development in an area that has not been previously inhabited e.g. on bare rock, sand, hardened lava flow from volcano, area left by a retreating glacier. • Secondary succession is community development in an environment that has been previously inhabited but was destroyed by some process e.g. fire, flood, harvesting etc. Primary Succession on a lava field on the Rangitoto Island near New Zealand. http://en.wikipedia.org/wiki/File:Rangitotolavapath.jpg Usually takes thousands of years to reach climax community Secondary Succession on an uncultivated field http://en.wikipedia.org/wiki/File:Secondary_succesion_cm01.jpg Secondary Succession Usually takes hundreds of years to reach climax community Biomes & Biodiversity Biomes - large relatively distinct terrestrial regions - characterized by similar climate, soil, plants and animals regardless of where they occur in the world Biomes cont’d The 9 major biomes are: • tropical rain forest • savannah • desert • chaparral • temperate grassland • temperate deciduous forest • temperate rain forest • taiga • tundra Biomes cont’d - precipitation and temperature are the most important factors determining the type of desert, grassland, or forest - climate and vegetation both vary with latitude and altitude Weather & Climate Weather - short-term changes in temperature, pressure, precipitation and other conditions in the atmosphere at a given place & time Weather & Climate cont’d Climate - average weather of an area - taken over a period of at least 30 years - temperature & precipitation are the 2 most important factors that determine climate Biomes BIOMES OF THE WORLD BIOMES OF THE WORLD http://www.marietta.edu/~biol/biomes/biom e.jpg TUNDRA http://en.wikipedia.org/wiki/File:800px-Map-Tundra.png Tundra - also called arctic tundra - just south of the arctic polar ice cap - covered with ice & snow - bitterly cold - permafrost TUNDRA TUNDRA http://en.wikipedia.org/wiki/File:Greenland_scoresbysydkapp2_hg.jpg http://en.wikipedia.org/wiki/File:Kerguelen_RallierDuBatty.JPG TUNDRA TAIGA http://en.wikipedia.org/wiki/File:Distribution_Taiga.png Taiga - also called swamp forest or boreal forest - south of the arctic tundra - long, cold, dry winters with 6-8 hrs sunlight - dominated by few species of coniferous evergreens TAIGA TAIGA http://en.wikipedia.org/wiki/File:Picea_glauca_taiga.j pg TROPICAL RAIN FORESTS www.marietta.edu/~biol/biomes/ Tropical Rain Forest - found near equator warm temperature high precipitation thin, nutrient-poor soil high biological diversity being lost to slash-andburn cultivation and for collection of lumber. SUBTROPICAL DESERTS http://www.marietta.edu/~biol/biomes/images/desert/desert_500.jpg Deserts - precipitation <10 inches per year - widely-spaced low vegetation - slow plant growth rate - low species diversity http://test.scoilnet.ie/res/crosswords/desert.jpg DESERT DESERT