Ecology Populations & How they interact with each other Chapters 15 & 17 Levels of Organization Organism Population Community Ecosystem Biosphere Biome Group of the same type of organism in a given area. (one species) A group of populations in a given area. The community interacting with the nonliving parts of the environment A group of ecosystems that share a common climate and area in the earth. All of the biomes together make up the biosphere, a.k.a. The Earth! Tropical Rain Forest Desert Tundra Biosphere Biome Ecosystem Community Population Organism What is a population? All of the individuals of a species (group of the same type of organism) that live in one place at one time. What are some example populations that live in or around our school? Example Populations 3 Key Features to Populations 1. Size How many individuals the population has Ex: there are 2 turtles in the pond 2 is the population size 2. Density How many individuals of the population per square foot or per liter Ex: There are 10 mud wasps per square yard of garden. 3. Dispersion The way that the individuals of the population are arranged Population Size How what is the population size of each of the following pictures? Changing Population Size There are four main factors that affect population size: Birth Death Immigration individuals moving in Emigration individuals moving out What are some other things that can affect how big a population can get? Resources, waste build up, natural disasters, disease Population Density Which half of the country is more densely populated? Why do you think so? Which population is more densely populated (picture A or B)? Why do you think so? Picture A Picture B Population Dispersion There are three basic patterns of dispersion in organisms. The clumped pattern is the most commonly found. Why do you think this is? Clumped Random Uniform How Populations Grow There are two models of population growth: 1.Exponential Growth 2.Growth with Carrying Capacity Questions! What are the four main ways that a population can change size? Answer: Birth, Death, Immigration, & Emigration Which of the following is an example of immigration? A.Baby being born B.A family moving out of town C.A family moving into town D.A family moving across the street (in the same town) Exponential Growth The rate of population growth is constant. There are no limits placed on the growth the population has more than what it needs to live. Can this type of growth go on forever? Why or why not? Growth with Carrying Capacity Rate of growth starts out fast, but slows as the population reaches its limits. Limits, like resources, are imposed on the population. Carrying Capacity the # of individuals that an ecosystem can support indefinitely. Oh Deer! Listen quietly for directions. Question! What does the red line represent? What would happen to the red line if the deer ate almost all of the food in their ecosystem? Density Dependent FactorsDensity Independent Factors In order for these to affect a population, there has to be a large number of individuals packed into a relatively small area. Examples: Disease Waste Food Supply These factors affect a population no matter how many individuals are packed into a given area. Examples: Tornadoes Earthquakes Forest fires Hurricanes Blizzards Drought Limiting Population Growth What happens to a population that is new? What happens if you introduce a new (invasive) species to an area? What happens if you reintroduce a predator to an area? Zebra Mussel Timber wolf Question! In 1987, wolves were brought back to Yellowstone National Park. What effect do you think that this had on the rabbit population? A.Rabbit population stayed the same B.Rabbit population decreased C.Rabbit population increased D.The wolf population decreased Think about this! What is happening in this graph? How are the wolves and rabbits related? POPULATIONS INTERACTING THE COMMUNITY Chapter 17 Community What is a community? Group of populations in a given area Populations in a community affect each other: Examples: When a population of deer become faster (on average); the wolf population will change so that they can still catch the deer How could they change? When a population of humans develops medicine to kill parasites, what do the parasites do? Communities are Communities are biotic. What does biotic mean? The opposite of biotic is abiotic. What does abiotic mean? What are some examples of abiotic and biotic things? Question! Which of the following is abiotic? A.Rocks B.Mouse C.Tree D.Cat Plant Defenses Example How do plants prevent themselves from getting eaten by herbivores? Poison, bad taste, spines, fuzz, sticky sap, make chemicals that burn, etc. How do herbivores get around a plants defenses? They have ways of neutralizing the poison in their body, they are adjusted to a bad taste, they find ways to pick the leaves out between the spines, etc. Ways Populations Can Interact Predation Competition Symbiosis living together in a close long term relationship Mutualism Parasitism Commensalism Predation One population kills and eats the individuals of another population + for predator, - for prey (what gets eaten) + = benefits the population, - = hurts the population Examples: Lynx eat Snow Shoe Hare Bats eat Insects Cats eat Mice Bears eat Salmon Question! In the relationship below, which animal is the predator? A.Cat B.Mouse C.Both cat and mouse D.Neither Competition Members of two populations fight for the same resources, or share resources even though there may not be enough for both. Question! What effect does competition have on the populations that are competing? Answer: Both populations are negatively affected because they cannot get access to the resources that they need as well as they could if they did not have to compete. (-, -) Most of the time competing populations will share resources by dividing up the resources as much as possible. Sometimes a new competitor will take all of the resources and cause the original population to die. Question! The population of Canada Geese living on the Chain of Lakes has increased to more than 10 times the size it was 20 years ago. If Canada Geese and Mallard Ducks eat the same types of things, then what affect would this situation have on the Mallard Ducks? A.There would be more Mallards B.There would be fewer Mallards C.There would be no effect on the Mallards D.There would be more Canada Geese Mutualism Individuals in both populations benefit or help each other out (+, +) Lichen This is actually a fungus and an algae Pollinators exhibit mutualism. Question! Honey bees pollinate apple trees. Scientists have noticed that the population of honey bees has been decreasing in the last ten years. What affect would this situation have on apples this fall? A.There would be more apples than last year B.There would be fewer apples than last year C.There would be no effect on the apples D.There would be more honey bees Parasitism One population lives on/in individuals from another population (+, -) The parasite feeds on/in another individual The host is what is fed off of. Dog fleas 1.Parasite Round worms; Host Pig 2.Parasite Indian Pipe; Host Tree 3.Parasite Protozoan; Host People 4.Parasite Mistletoe; Host - Tree Commensalism Individuals of one population benefit, but the individuals of the other population are neither harmed nor helped. (+, 0) Ex: Birds Nesting in Trees Diversity Communities are diverse. Diverse = large number of different species. What happens to a community that has lost species to become less diverse? Why is diversity important?