Ecology- The scientific study of interaction between organism and their environments. ◦ Environments: Biotic factors –all the living organism that inhabit an environment Abiotic factors – the nonliving parts of the environment Ex: air currents, temperature, moisture, light, and soil Population – is a group of organisms of one species that interbreed and live in the same place at the same time ◦ Organisms compete for food, water, mates. Determines how large each population can become EcosystemThe interacting system of a biological community and its nonliving environment. Community – is a collection of interacting populations ◦ A change in one population in a community will cause changes in the other populations Habitat- Place where an organism lives; ◦ Even in the same ecosystem, different organisms differ in their habitats. Producer- Organisms that produce their own food are called autotrophs. Ex: Plants all of the species of the ecosystem depend on autotrophs for nutrients and energy. Consumer- They obtain food by eating other organisms. All the organisms that cannot make their own food (and need autotrophs) are called heterotrophs. ◦ There are different levels of consumers: Those that feed directly from producers, i.e. organisms that eat plant or plant products are called primary consumers. Niche_= a role that an organism has in the environment (based on what they EAT!) 1. Herbivores- consumer that eats only plants ◦ Ex: grasshoppers, mice, rabbits, deer, beavers, moose, cows, sheep 2. Carnivores- consumer that eats only other animals. ◦ Ex: Foxes, frogs, snakes, hawks, and spiders. 3. Scavengers – consumer that eats the remains of dead animals. ◦ Ex: vultures, buzzards, crows, ants, beetles 4. Omnivores- eats both plants (acting as primary consumers) and meat (acting as secondary or tertiary consumers). ◦ Ex: Bears --They eat insects, fish, moose, elk, deer, sheep as well as honey, grass 5. Decomposers- organisms that break down the remains of other organisms. ◦ Found at the bottom of the food web. ◦ Ex: Bacteria, yeast, fungi, worms and many insects Symbiosis – permanent, close association between two or more organisms of different species 1. Commensalism – one species benefits and the other species is neither harmed nor helped ◦ Ex: an orchid growing on the branch of a larger plant 2. Mutualism – relationship that is beneficial to both species ◦ Ex: acacia trees (provides food/shelter for ants) and ants (protect tree by attacking any herbivore) 3. Parasitism – one species benefits at the expense of the other species ◦ Ex: ticks, tapeworms live on or in the organism Food Chain- Show one preypredator relationship and how each living thing gets its food. ◦ Some animals eat plants and some animals eat other animals. ◦ Ex: Trees/shrubs giraffes lions Each link in this chain is food for the next link. Always starts with plant life and ends with an animal. Trophic levels-link represented by each organism in a food chain; ◦ Represents a feeding step in the transfer of energy and matter in an ecosystem. All energy in an ecosystem originates with the sun. ◦ Plants transform solar energy into chemical energy (food) via photosynthesis ◦ This is consumed by plant-eating animals, which are in turn consumed as food. The total energy transfer from one trophic level to the next is only about 10 %, the other 90% is lost as heat Heat is lost by: 1) Organisms fail to capture and eat ALL food available at the trophic level below them 2) Not all food that is captured and eaten gets digested 3) Digested food is used by the organism as a source of energy. Food web- model used to express feeding relationship among the members of a community. ◦ A group of interlinked food chains Illustrates: 1. Who eats who? 2. Arrow = Energy flow through the community 3. Functional feeding groups 4. Important ecological interactions 1) Food chains ONLY show one prey-predator relationship. The source of food is also often seasonal with many animals adapting to changes in the season by eating different types of food. 2) Food webs show a better picture of interrelationships between plants and animals. Biomagnification = The process of increasing a chemical concentration through the food chain (Examples: DDT and PCB) ◦ Animals that eat other animals have HIGHER levels of contaminants than animals that eat plants. ◦ Some contaminants are persistent once they are in the animal's body, they stay there for a long time. So when smaller animals are eaten by bigger animals, all the contaminants stored in their tissues are then passed on to the bigger animal. The result of biomagnification is that animals at the "top" of their food chain have higher contaminant levels than animals at the "bottom". The top predators at the end of a long food chain may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low. ◦ The concentration of some chemicals in the fatty tissues of top predators can be millions of times higher than the concentration in the open water. Ex: Mercury, DDT, PCB’s, arsenic 1. Water cycles between the oceans, atmosphere and land. A. Water enters the atmosphere as water vapor, a gas, when water evaporates from the ocean or other bodies of water. ◦ Evaporation—the process by which water changes from a liquid to a gas. B. Water can also enter the atmosphere by evaporating from the leaves of plants—Transpiration. C. Precipitation--rain, snow, sleet, or hail ◦ The sun heats the atmosphere. ◦ Warm, moist air rises and cools. ◦ Eventually, the water vapor condenses into tiny droplets that form clouds. ◦ When the droplets become large enough, the water return to Earth’s surface. D. Run-off—Precipitation runs along the surface of the ground until it enters a river or a stream that carries the run-off back to an ocean or lake. E. Seepage—Rain also seeps into the soil, some of it deeply enough to become ground water. Water in the soil enters plants through the roots, and the water cycle begins anew. Condensation Condensation Precipitation Precipitation Transpiration Seepage Ground Water Evaporation Surface Run-off 1. Every organic molecule contains the element carbon. A. Carbon and oxygen form carbon dioxide gas (CO2), an important component of the atmosphere. B. Carbon dioxide is taken in by plants during photosynthesis and is given off by plants and animals during cellular respiration. ◦ Cellular respiration is a process where cells transform chemical energy (sugar) into a useable form of energy (ATP). 2. Four main types of processes move carbon through its cycle: Biological processes, such as photosynthesis, cellular Geochemical processes, such as erosion and volcanic respiration, and decomposition, take up and release carbon and oxygen. activity, release carbon dioxide into the atmosphere and oceans. Mixed biogeochemical processes, such as the burial Human activities, such as mining, cutting and burning and decomposition of dead organisms and their conversion under pressure into coal and petroleum (fossil fuels), store carbon underground. forests, and burning fossil fuels (car emissions, electricity), release carbon dioxide into the atmosphere. Burning of Fossil Fuels Coal & Petroleum CO2 in atmosphere Cellular Respiration Decomposition of dead organisms Photosynthesis 1. All organisms require nitrogen to make amino acids, which in turn are used to build proteins. A. Nitrogen gas makes up 78% of Earth’s atmosphere. B. Nitrogen containing substances such as ammonia (NH3), nitrites (NO2-), and nitrates (NO3-) are found in the wastes produced by many organisms and in dead and decaying organic matter C. Nitrate is major component of plant fertilizers. 2. Nitrogen gas is the most abundant form but only certain bacteria can use this form. A. Such bacteria live in the soil and on the roots of plants. B. These bacteria convert nitrogen gas into ammonium--nitrogen fixation C. Other bacteria in the soil convert ammonia into nitrites and nitrates. 3. Once the nitrites and nitrates are available, producers (plants) can use them to make proteins. ◦ Consumers then eat the producers and reuse the nitrogen to make their own proteins. 4. When organisms die, decomposers return nitrogen to the soil as ammonia. 5. Other soil bacteria convert nitrates into nitrogen gas--denitrification. This process releases nitrogen into the atmosphere once again. Nitrogen in atmosphere (N2) Denitrification Nitrogen Decomposers return ammonia to soil Nitrates (NO3-) Nitrites (NO2-) Succession = orderly, natural changes that take place in the communities of an ecosystem ◦ The community of organisms inhabiting an area gradually changes. ◦ Difficult to observe since it can take decade or centuries for one type of community to completely succeed another. Figure 1: Succession of plant species on abandoned fields in North Carolina. Pioneer species consist of a variety of annual plants. This successional stage is then followed by communities of perennials and grasses, shrubs, softwood trees and shrubs, and finally hardwood trees and shrubs. This succession takes about 120 years to go from the pioneer stage to the climax community. Primary succession =establishment of a community in an area of exposed rock that does not have any topsoil. ◦ Ex: Lava flowing from a volcano destroys everything in its path, but when it cools it forms new land ◦ Ex: Streams gradually deposit silt along their banks, creating new soil in which plants can take root. ◦ After some time, primary succession slows down, and the community becomes fairly stable. A stable, mature community that undergoes little of NO succession is called a climax community. Secondary succession = the sequence of community changes that takes place when a community is disrupted by natural disasters or human actions Ex: Hurricanes, forest fires, farmers abandoning fields Biomes = a large group of ecosystems that share the same type of climax community Two factors that will determine which biome will be dominant on land: 1. Temperature 2. Precipitation Characteristics: treeless, long cold winters, little winter sun, poor soil, little rain (less than 5 in) Permafrost – permanently frozen ground Location: Canada, Russia, Alaska Vegetation: grasses, moss, lichen Animals: insects, fox, rodents, caribou, reindeer Characteristics: coniferous forest, poor soil, long severe winter Location: Canada, N. Europe, N. Asia Vegetation: pine, fir, hemlock, spruce Animals: rabbits, lynx, caribou, moose, woodpecker Characteristics: deciduous trees, 4 seasons, vegetation exhibits seasonal changes ◦ Deciduous – trees lose leaves in winter Location: East US, Europe Vegetation: Maple, Oak, Birch, Hickory Animals: bear, deer, robin, raccoon Characteristics: warm, wet, humid, most diversity, up to 17 feet of rainfall annually Location: islands, equatorial regions Vegetation: broad lush plants, flowers, vines, palms, fruit trees ◦ lush with many layers in the canopy that support an incredible diversity of life. Animals: monkey, sloth, frogs, snakes, parrots Characteristics: ideal growing season, good soil quality, little precipitation does not support trees, but grasses and herbs are present in great abundance. Location: central regions Types: ◦ Prairie – US ◦ Steppe – Russia ◦ Savanna – Serengeti ◦ Pampas - Argentina Vegetation: grass, grains, crops, wildflowers Animals: bison, prairie dogs, birds, lions, elephants Characteristics: dry & arid, less than 10 in of rainfall Location: SW US, N. Africa, Middle East ◦ Hot- Mojave, Sahara ◦ Cold- Gobi Vegetation: Plant cover is sparse, and characterized by drought tolerant brushes, succulent (cacti, creosote bushes) Animals: rodents(gerbils, jerboas and kangaroo rats), snakes, lizards, scorpions, turtles, hawks All species occur in groups called populations Limiting factors = factors that are biotic or abiotic that keep a population from continuing to increase indefinitely 2 types of Population-Limiting Factors: • density-independent factors • density-dependent factors Density-independent factors = Any factor in the environment that does not depend on the number of members in a population per unit area Usually abiotic (natural phenomena) Ex: Weather events (tornadoes, floods, hurricanes) Fire Human alterations of the landscape Air, land, and water pollution Density-dependent factor = Any factor in the environment that depends on the number of members in a population per unit area Usually biotic Ex: ◦ Predation ◦ Disease- (high population density--> disease quickly spreads) ◦ Parasites ◦ Competition – food, space limitations The population growth rate (PGR) explains how fast a given population grows. Exponential growth occurs when the growth rate is proportional to the size of the population. All populations grow exponentially until some limiting factor slows the population’s growth. The population’s growth slows or stops following exponential growth, at the population’s carrying capacity. A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration. Carrying capacity = The maximum number of individuals in a species that an environment can support for the long term. ◦ limited by the energy, water, oxygen, and nutrients available. ◦ Population exceeds carrying capacitydeaths outnumber births because resources are not available to support all individuals If the major food source of seals declines due to pollution or overfishing, which of the following would likely occur? a) The carrying capacity of seals would decrease, as would the seal population. b) The carrying capacity of seals would decrease, but the seal population would remain the same. c) The number of seal deaths would increase, but the number of births would also increase, so the population size would remain the same. d) The carrying capacity of seals would remain the same, but the population of seals would decrease.