Unit 2 – Ecological Organization Important introductory terminology (Levels of Organization): - - - organism An individual living thing, ex: frog, humans individual Member of a particular biological population population a group of the same species (individuals) that live together in one area at a certain time, ex: number of gophers in Balgonie area, in 2011 community A group of populations (different species) that live together in one area at a certain time, ex: gophers, grasses, hawks in a field north of Balgonie ecosystem includes all organism (living things) in a certain area as well as the non-living things (climate, soil, water, rocks, etc), ex; dugout north of Pilot Butte - - - Biome major regional or global community of organisms, commonly named for the dominant plant life present, ex: grassland biome, rain forest biome Biosphere Anywhere on planet Earth where life can be found, from the highest mountains to the deepest ocean trenches Ecology The study of the interactions among living things, and between living things and their surroundings 1. Questions 1-2, page 400 What are the five different levels of organization studied by ecologists? - organism, population, community, ecosystem, biome 2. - - - Describe the three general methods used by ecologists to study organisms. Observations is the act of watching something over time, such as a population of birds Experimentation can occur in the lab or in the field and involves testing a hypothesis Modeling is a computer-based or math-based method used to predict how changes in one variable may affect another 3. 4. - Questions 3-4, page 400 What ecological research methods would you use to study bird migration? Explain your choices. Observations: band birds capture them at each end of their migratory route to record their movement. Experimentation: devise an experiment to test what triggers migration. Modeling: develop a computer model that includes different variables that might predict the time and path of migration. How might an ecologist use modeling to study a forest fire ecosystem? What might be key variables used to create the model? Ecologist could use models to determine movement of fire, locations where prescribed burns should take place, and areas with the potential for fire outbreaks. Key variables: forest density, types of trees, plant and animal populations, wind patterns, and weather conditions. Question #5, p400 5. - Ernst Haeckel was greatly influenced by the writings of Charles Darwin. How do the principles of ecology relate to the understanding how adaptations occur? Species are adapted to their environments. The concept is directly related to the study of ecology, in which the interactions between organisms and the environment are studied. By understanding the interactions within an ecosystem, scientists can develop an understanding of how populations evolve in response to their environments. Random-Quadrat Analysis Random Quadrat Analysis - Used to sample a stationary population to estimate it’s size Best way to determine a population’s size???? Count them!! But this is commonly not practical and/or possible because: Some individuals move around and are hard to count Some individuals are spread out over a large area Other sampling and population size estimation methods: mark-recapture – used for mobile populations, mark a caught individual and then release it. Capture many individuals, if you recapture the same individuals = small population, if you capture new individuals each time = large population Questions 1-3, page 404 Select an ecosystem that is familiar to you and describe the and abiotic factors that exist there. Answers should show that students understand that biotic factors are living things and abiotic factors are nonliving. 2. How would the removal of a keystone species affect an ecosystem’s biodiversity? - The removal of a keystone species would decrease the ecosystem’s biodiversity. 3. Explain how a change in an abiotic factor such as sunlight would affect biodiversity. Changes in amount of sunlight might affect local temperatures, leading to a change in the numbers and types of species in an ecosystem. New species may now move into the area, taking the place of those that cannot survive. 1. bioti7.527.c Questions 4 & 5, page 404 4. - 5. - Humans are sometimes described as being a keystone species. Does the label fit? Why or why not? Keystone species are those that help to establish and maintain a complex web of life. Humans do not fit this label because human activities often decrease, rather than increase biodiversity. What role might an abiotic factor such as temperature play in the evolution of a species? A long-term temperature change could result in selective pressure that selects individuals better adapted to the temperature, causing populations to evolve. It could alter the types of food available, again creating selective pressure toward individuals that can take an advantage of different food sources. Biotic and Abiotic Factors Biotic factors – living things such as bacteria, fungus, plants and animals Abiotic factors – non-living things such as moisture, temperature, wind, sunlight and soil. Biodiversity – variety of living things in an ecosystem Keystone Species – species that has an unusually large effect on an ecosystem. Energy in Ecosystems Producers : get their energy from non-living sources (make their own food), sometimes called autotrophs Get their energy either by photosynthesis (from light) or chemosynthesis (from chemicals) Consumers: get their energy by consuming/eating another living thing (dead or alive), sometimes called heterotrophs. Questions 1-3, page 407 How does the stability of an ecosystem depend on its producers? 1. - What are the two processes used by producers to obtain energy? 2. - 3. Producers bring energy into an ecosystem Photosynthesis and chemosynthesis Few producers live deep below a lake’s surface. Suggest an explanation for this pattern. - sunlight cannot penetrate the water to a great depth, so photosynthesizing organisms are more common near the surface. Could producers survive without consumers? Explain why or why not? - Producers do not require consumers to fill material needs as a food source. So in that sense, producers do not need consumers to survive. 5. How might chemosynthetic organisms help scientists to understand how life developed on Earth? - Chemosynthetic organisms live in environments that may be similar to those that existed on Earth billions of years ago, when life was beginning to develop. Studying these organisms enables scientists to infer how different life forms may have evolved as Earth changed. 4. Questions 1-2, p411 Why are food chains especially useful for describing the relationships of specialists? 1. - Specialists have specific diets that include only one type of organism, which produces a simple food chain. What happens to energy as it flows through a food web? 2. - Some energy is stored in the organism (10%), but much energy is dissipated into the environment (90%). Only a small percentage of all consumers are specialists. What danger does a specialist faces that a generalist does not? 3. - If a specialist’s food source becomes scarce or disappears, the population may die out. A generalist facing the loss of one of its food sources can shift to a different food source. How might the stability of an ecosystem be affected if all the decomposers were suddenly removed? 4. - The stability of the ecosystem would be negatively affected because without decomposers, vital nutrients would not be returned into the environment. Question 5 5. How might an oil spill in the ocean affect an aquatic food web? What might happen to the food web on land located near the spill? Explain your answers. - The entire food web would be affected by the oil spill. Oily water may kill off phytoplankton. The loss of smaller fish would affect larger fish, which in turn affect tertiary consumers. Plants and animals that live along the coast would also be affected as the oil seeped onto the shore. The overall effect would be a decline in the availability of food sources both within and outside the ocean. Questions 1-3, p416 1. 2. 3. How does the hydrological cycle move water through the environment? Precipitation falls to Earth, and transpiration and evaporation transfer water back into the atmosphere as water vapour. What are four elements that cycle through ecosystems, and why are they important? - oxygen, carbon, nitrogen and phosphorus; they are all necessary for life on Earth. Why might farmers plant legumes such as peas to improve the nitrogen levels in their soil? - Legumes have root nodules, which contain nitrogen-fixing bacteria. Increased levels increase the fertility of the soil. Explain the importance of decomposers to the overall biogeochemical cycle. 4. - 5. Decomposers break down organisms and release various elements, including nitrogen and phosphorus, which other organisms can then use. How might Earth’s biogeochemical cycles help scientists to understand the early history of life on Earth? - Studies of the biogeochemical cycles and how they interact may help scientists reconstruct the sequence of events that led to changes at Earth’s surface that would enable different types of organisms to evolve. Questions 1-3, p419 How does an energy pyramid help to describe energy flow in a food web? 1. - An energy pyramid shows the relative contribution to energy flow made by each trophic level in an ecosystem. What is the difference between a biomass pyramid and a pyramid of numbers? 2. - A biomass pyramid compares the mass of organisms that make up each trophic level in an ecosystem; a pyramid of numbers compares the number of individual organisms that make up each trophic level. How would you draw a pyramid of numbers for a dog with fleas? What shape would it take? 3. - The bottom level would be the dog, and the fleas would be the top level. This would be an inverted pyramid because there are many fleas to just one dog. If each level in a food chain typically loses 90 percent of the energy it takes in, and the producer level uses 1000 kcal of energy, how much energy is left after the third trophic level? 4. - The first trophic level uses 1000 kcal; the second trophic level uses 100 kcal; the third trophic level uses 10 kcal, leaving 1 kcal Question 5, p419 5. - Why is a herbivorous diet more energy efficient than a carnivorous diet? Explain your answer. a herbivorous diet is more energy efficient because it is the closest trophic level to producers, meaning there is more available energy to use. 1. 2. 3. Questions 1-3, page 430 What are the three parts of an organism’s ecological niche? Food type, abiotic conditions, and behavior What does the principle of competitive exclusion say will happen when two species compete for the same resource? One species will be better suited to the niche and the other species will either be pushed into another niche or become extinct. If a group of mantella frogs were transported to the ecosystem of the poison dart frogs, what might happen to the two species’ populations? As ecological equivalents, they share a similar niche. The population better suited to the niche might deprive the other of resources, causing the other to die off. Or one population might respond to limited resources by altering its niche. Questions 4 & 5, page 430 4. 5. - A bison and an elk live in the same habitat and feed on the same grasses. Does this mean that the competitive exclusion principle does not apply? Explain. The competitive exclusion principle only applies if the two species occupy the same niche and habitat. These two species use the same use the same food resource but occupy different niches. Exotic Species – Considering the competitive exclusion principle, why may it be harmful to transport a species, such as a rabbit, to another habitat where it currently does not exist? If the new species is introduced to an area, it may occupy a similar niche as a native species and be better adapted for the niche or have no natural predators. This could drive native species to extinction. Questions 1-3, page 434 1. 2. 3. During the fall spawning of salmon, grizzly bears fight over space on the banks of a river. What type of competition is this? The bears are fighting among themselves, so it is considered intraspecific competition. Describe and give examples of the three types of symbiosis. Mutualism: bee and flower, Commensalism: remora and shark, parasitism: tick and human How are predation and parasitism similar? How do they differ? They are both relationships in which one organism benefits while the other is harmed. In predation, the predator needs to kills its prey in order to benefit. In parasitism, the parasite benefits by keeping the host alive. 4. 5. Questions 4 & 5 After a lion has made a kill, birds will sometimes arrive to pick at the leftover carcass. Which are the predators: the birds, the lion, or both? Why? The term predator is restricted to an organism that finds and eats another living organism. The lion is the predator, the birds are scavengers. Animal Behavior - You have probably heard the saying “There is safety in numbers.” Why might traveling in a large group be beneficial to prey species? A predator may become overwhelmed when facing a large number of prey. Although a predator may have the speed to chase down and kill a single prey animal., it may switch from chasing one individual to another when faced with a large group of prey and tire before it is successful. 1. 2. 3. Page 439, questions 1-3 A shoreline mussel species has a population density of one organism per square meter. Will all mussels be found one meter apart? Explain. No, population density simply describes the number of individuals per unit of area, not the dispersion pattern Draw and label a diagram showing the three population dispersion patterns. Student diagrams should include three dispersion patterns: clumped, uniform and random. Like illustration on page 437! How do survivorship curves show three types of reproductive strategies? If the curve shows a low level of infant mortality, the parents probably care for their young. If the curve shows a very high infant mortality rate, the organisms probably have a high birth rate and provide little or no parental care. Question 4 & 5, page 439 4. 5. What might be the advantages of having a clumped dispersal pattern? Individuals do not have to move very much to find mates, organisms have better protection from predators, and there is more access to food resources from other population members. An organism has ten offspring. Two of these offspring die each year over a five-year period. Is the organism more likely to be a bird or an insect? Explain. The organism is a bird because the mortality pattern described is closest to type II. Insect tend to be type III, with many offspring and high mortality in the early life stages. Question 6 Abiotic Factors - On the African savannah, what types of abiotic factors may lead to high population density and clumped dispersion patterns? 6. - Answers may include limited water supplies, high temperatures, and little or no precipitation. Question 1-3, page 444 1. 2. 3. What four factors determine the growth rate of a population? immigration, births, deaths, emigration How does carrying capacity affect the size of a population? Carrying capacity limits the size of a population What is the main difference between a density-dependent limiting factor and a density-independent limiting factor? Give examples of each. A density-dependent limiting factor is affected by the number of individuals in a given area, but a density-independent limiting factor in not affected by population size. Examples of density-dependent limiting factor includes predation, competition and disease. Examples of density-independent limiting factors include weather, natural disasters and human activities. Questions 4-6, p444 4. 5. - What might cause exponential growth to occur only for a short period when a new species is introduced to a resource-filled environment? Eventually, the growing population will consume all available resources, and the species may experience a population crash. Synthesize - How might density dependent limiting factors be affected by a flood or some other natural disaster? Answers might include effects such as a flood or other natural disaster destroying resources, predators, or prey in a area, which are density-dependent factors. Question 6 6. - Symbiosis - Give an example of how a symbiotic relationship could cause a population crash. If a parasite or disease spreads in a dense population, it could cause a population to decline dramatically over a short period of time. Questions 1-2, p447 1. How is primary succession different from secondary succession? - Primary succession begins with bare rock, worn down and colonized by pioneer species. 2. - Why are pioneer species so important for primary succession? Pioneer species, such as mosses and lichens, can break down rock into smaller pieces. When they die, their remains mix with tiny pieces of rock to form a thin layer of soil. They change the ecosystem in ways that enable the support of more diverse species. 3. 4. 5. Questions 3-5 Infer - Does the process of primary succession take longer in tropical or arctic areas? Explain. Primary succession takes longer in arctic areas because rock is covered with snow part of the year, the growing season is shorter, and cold temperatures slow growth and decomposition. Soil takes much longer to form. Predict - During succession, what might become the limiting factor for sun-loving mosses as taller plants begin to grow? the amount of sunlight that reaches them. Niche - At what point during primary succession does an ecosystem provide the fewest habitats for organisms? Explain your reasoning. There are no habitable areas in the earliest stages of succession because there is no soil to support producers. Land becomes habitable once rock has weathered enough to support mosses and lichens. Over time, the mosses and lichens will provide the resources needed to support other organisms.