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DYNAMIC ECOSYSTEMS Ecology • Ecology • The study of the interactions of organisms with each other and their environment. Ecology • Environment • The surroundings or conditions in which a person, animal, or plant lives. Ecology • Who studies ecology? • Ecologists are scientists who study small areas of Earth called ecosystems • Ecosystems • Biological community of interacting organisms and their physical environment Levels of Organization • Species • Group of organisms whose members have similar characteristics and can interbreed with one another, but not with members of other such groups • Individual • One single living organism Levels of Organization • Population • A group or organisms of the same species • Each population has a place where it lives called its habitat Levels of Organization • Community • The group of interacting populations of different species that occur together in an ecosystem Levels of Organization • Ecosystem • All the living and non-living things that interact with one another in a given area Ecosystems • An ecosystem is made up of 2 groups of things: • Biotic (living) • Living organisms • Plants, animals, fungi, bacteria • Abiotic (non-living) • Physical environment • Water, sunlight, oxygen, soil, nutrients, temperature, wind Levels of Organization • Biome • A collection of regions of Earth that have a certain climate and certain types of living things; usually plants. Levels of Organization • Biosphere • Consists of all living organisms on Earth plus the environments in which they live More Definitions! • Niche • An organism’s particular role in an ecosystem, or how it makes its living (what it eats, when it eats, etc.) • ex. The flightless dung beetle occupies a niche exploiting animal droppings as a food source ENERGY FLOW • All living things need energy to live • What is the source of that energy? The Sun! Photosynthesis • Producers (plants) use the sun’s energy to make food • This process is called photosynthesis • Energy from light is absorbed by proteins in leaves that contain green chlorophyll pigments • Convert light energy into sugars • Animals must eat other organisms to get energy • Breaking down glucose to release energy is called cellular respiration • An organism has to transform the chemical energy into a form that can be used • Organisms that make their own food are called Autotrophs • “Auto”=self “Troph”=feed Plants Moss Some Bacteria Algae • Organisms that use cellular respiration to get energy are called Heterotrophs. • “Hetero”=other “Troph”=feed Some Bacteria Animals Fungi • Herbivores eat only plants • Carnivores- eat mainly meat • ex. • Omnivores- eat both plants and meat • ex. • Decomposers consume and break down dead organisms or waste matter into simple substances • Send nutrients back into the soil • ex. https://www.youtube.com/watch?v=bW7PlTaawfQ • Food chains show the relationship of feeding and energy transfer in organisms of an ecosystem Food Chains • Producers get their energy from the sun • Primary consumers (herbivores) feed directly on producers • Secondary consumers feed on primary consumers • Tertiary consumers feed on secondary consumers • Many food chains become connected in a complex relationships called a food web • Each step in a food chain is known as a trophic level Energy moves up the trophic levels • Scavengers are carnivores that feed on dead animals • ex. vultures, hyenas, seagulls, ravens • Pyramid of biomass shows the total amount (mass) of living material at each trophic level • Only 10% of the energy received from food is stored in the body; 90% is used to run your organs 0 100 • Pyramid of energy shows the total amount of energy at each trophic level • Plants capture light energy and use that energy to make glucose (sugars) • Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into glucose • Oxygen is also released in this reaction Why is it important to us? • We cannot make our own food (glucose, energy), we must get our food from plants. • Plants are the first step in the food chain. • The oxygen released during photosynthesis is necessary for all living things. Cellular Respiration • The release of chemical energy for use by cells. • The breakdown of glucose molecules to release energy • Once the energy that was in sunlight is changed into chemical energy by photosynthesis, an organism has to transform the chemical energy into a form that can be used by the organism. Energy Pyramid • Species in the highest trophic levels have less energy available to them than species near the bottom • This often results on their populations being much smaller than species lower in the food chain (number of predators<herbivores) 0 100 • Each step in a food chain is known as a trophic level Energy moves up the trophic levels Population Control • IF conditions are ideal (excess food, water, shelter, few predators) populations will grow rapidly! “Exponential” growth cannot continue forever! Ideal Population Growth • Conditions are never ideal • A population cannot grow forever The environment sets limits on population growth Real Population Growth • Carrying capacity: maximum population of a species supported by the environment • Ex. How many people can fit on a lifeboat • What factors might affect carrying capacity? • Food availability, • Water, • Environmental conditions • Space • Births • Deaths • Closed populations • Only births or deaths change the population • eg. An island Population Growth= (births) – (deaths) • Open populations • Births/deaths and moving in/out change the population • eg. Manitoba • Immigration: moving into a population • Emigration: moving out of a population Population Growth= (births+immigration) – (deaths+emigration) Factors that limit population growth • Many environmental factors limit population growth • Density-dependent factors affect large and crowded populations • Disease- disease spreads faster in dense areas • Predation- more opportunity for predators • Competition- forced to compete for resources • Stress- overcrowding leads to early deaths • Density-independent factors affect a population regardless of its size/density • Natural factors- without human intervention • eg. Bad weather, natural disasters (floods, fire, drought) • Human activity- because of human intervention • eg. Pollution, deforestation • Populations are restricted by natural ecosystems • If too dense, density-dependent factors act to limit the populations of that species • Density-independent factors limit population regardless of size • Populations usually regulated around the carrying capacity • Why do we care if the number of organisms in an area is growing or shrinking? • Populations that are growing or shrinking can tell us if there are potential problems happening in the environment Exponential Growth Curve • IF conditions are ideal (excess food, water, shelter, few predators) populations will grow rapidly! “Exponential” growth cannot continue forever! Ideal Population Growth • Conditions are never ideal • A population cannot grow forever The environment sets limits on population growth Real Population Growth Logistic Growth Curve • Also known as an “S” Curve • Resources (food, water, space) become more scarce • Rate of population increase begins to slow Carrying Capacity • The largest population of a species that a particular environment can support • Affected by factors such as resource availability and weather • The population of a species will grow rapidly at first. • Once the population has reached the level that the ecosystem can support, the population varies UP and DOWN around the CARRYING CAPACITY. • Point A = lag phase • There are very few organisms in the beginning so the reproduction rate is low. The population grows very slowly. • Point B = acceleration phase • As the young grow up and begin to reproduce, the population enters the acceleration phase • Point C = exponential phase • The population begins to grow very quickly in the exponential phase • Point F = density independent limiting factors cause a sudden crash or decline in population. Scots Pine J-Curve • Point D = deceleration phase • Population growth slows down • Point E = equilibrium • Number of births equals the number of deaths. May not last long due to changes in birth and death rates • Point G = the population fluctuates around the carrying capacity • Limiting factors that produce the S-curve are density dependent • competition, predation, disease • An S-curve results when a population’s density is somehow controlled so that it can become somewhat stable. Predator-Prey Relationships • The prey population increases when there are few predators and lots of food • Now the predator has lots of food, so its population will increase Predator-Prey Relationships • As the predator population increases, there is more predation and competition, so the prey population decreases • Now the predators have less food, so their population decreases • Notice that: • The two population curves follow the same shape • The peaks and valleys of the predator curve trail the peaks and valleys of the prey curve. • The density of each population is dependent on the density of the other. • The predator’s population curve occurs a little behind the population curve of the prey. • The number of different species in an ecosystem is called the biodiversity. • Reducing biodiversity can cause a “domino effect” • can lead to a collapse of an entire food web. Food Web Stability • In some food webs, the populations in the web can survive if one species is removed. Other populations can fill in as prey or predator species. • A food web with more biodiversity is… • less likely to collapse due to the removal of one species. • There is an estimated 5 million to 30 million species living on earth • Why is the estimated range so large? • Most living species are microorganisms and tiny invertebrates • Species are constantly evolving and going extinct Quiz 1. A group of interacting populations of different species that 2. 3. 4. 5. 6. 7. 8. occur together at the same place and time is known as a _______________. An organism’s particular role in an ecosystem is known as it’s _______________. What process do producers use to make food? What are heterotrophs? Give an example of a simple food chain. Identify the producer, primary consumer, secondary consumer, and tertiary consumer. True or False: Each step in the food chain is a trophic level. What is “carrying capacity”? True or False: Population Growth= (births+emigration) – (deaths+immigration) Quiz 1. A group of interacting populations of different species that occur together at the same place and time is known as a _community___. 2. An organism’s particular role in an ecosystem is known as it’s ___niche_____. 3. What process do producers use to make food? Photosynthesis 4. What are heterotrophs? Organisms that feed on other organisms to get energy. Quiz 5. Give an example of a simple food chain. Identify the producer, primary consumer, secondary consumer, and tertiary consumer. Corn, grasshopper, lizard, snake 6. True or False: Each step in the food chain is a trophic level. 7. What is “carrying capacity”? the maximum population of a species supported by the environment 8. True or False: Population Growth= (births+emigration) – (deaths+immigration) Population Growth= (births+immigration) – (deaths+emigration) Scots Pine J-Curve • Limiting factors that produce the S-curve are density dependent • competition, predation, disease • An S-curve results when a population’s density is somehow controlled so that it can become somewhat stable. • Point D = deceleration phase • Population growth slows down • Point E = equilibrium • Number of births equals the number of deaths. May not last long due to changes in birth and death rates • Point G = the population fluctuates around the carrying capacity Frog S-Curve • Predators and prey will often have a relationship described as delayed density dependence. • The density of each population is dependent on the density of the other. • The predator’s population curve occurs a little behind the population curve of the prey. • This happens because the number of predators that survive and reproduces depends on the number of prey available for consumption • As the population of prey increase, the population of predators also increases. • But, this causes a decrease in the population of prey and then a decrease in the population of predators. Predator-Prey Relationship What are some factors that have caused the human population to skyrocket in the past 200 years? Better technology Modern medicine Public health Population Histograms • Population distribution according to age • Useful to show how many organisms there are of a certain age within a population • Can tell us how the population will likely change in the future Compare males vs. females in a population Compare different age groups in a population We can use age-structure diagrams to compare populations of different countries. Population Histograms • Populations along the horizontal axis • Age along the vertical axis • Graph is drawn with horizontal bars • Each bar represents the number of organisms of a certain age group. There are as many bars as age groups. • There is one side for males and one side for females. Population Histograms • An age-population histogram shows a snapshot of organisms, both male and female, that fall into categories of age. While the data represented is for only a particular instant in time, the shape of the distribution allows us to predict if the population is increasing, decreasing or steady. Increasing Population Histogram • Shaped like a pyramid with a wide base. • Wide base=lots of young organisms to replace the older ones who die off. • The population increases since there are fewer older organisms and many more being born Decreasing Population Histogram • Widest part in the middle section. • Few young organisms to replace the older organisms as they die off. • In later years, there will be fewer organisms to reproduce and supply offspring needed to replace those which are now young. • The population decreases. Steady Population Histogram • Reproducing organisms are simply replacing themselves. • Since there are as many organisms being born as are dying, the population remains steady. Let’s review... 1. What is the most populated age group in this population? 2. Predict what age group will be the most populated in 15 years. 3. About how many children in this population are under the age of 5? How many are female? Let’s review... 1. What is the most populated age group in this population? The most populated age group is those between 20 and 24 years in age. Let’s review... 2. Predict what age group will be the most populated in 15 years. Assuming that there is not a major growth period in this population in the next 15 years, the group that is currently 20-24 years old will be in the 35-39 age group. Let’s review... How many of them are female? Looking on the left side in the 0-4 age bracket, about 6% of those under age 5 are female. 3. About how many children in this population are under the age of 5? Approximately 12.5% of the population is 0-4 years old. Canada Age Structure • In 2030, do you think the population will be growing or shrinking? Why? • In 2030, do you think the population will be growing or shrinking? Why? Shrinking. The population is aging and there are less young people to reproduce. • What are some issues that Canada faces in the future? • What are some issues that Canada faces in the future? • Will need to provide more health care for aging population $$$ • http://ed.ted.com/lessons/population-pyramids-powerful- predictors-of-the-future-kim-preshoff Population Growth of Canada P o p u l a t i o n Year