Populations and Communities Chapter 22 Populations and Communities

22-1: Living Things and the Environment  Ecosystem- all living and nonliving things that interact in a particular area Look at the picture below, and list all the living and non-living things you see on the side of your notes:

Habitat- the place where an organism lives and that provides the things an organism needs.   In other words: a habitat is SPECIFICALLY the place in the ecosystem where an organism obtains food, water, shelter, and other things it needs to live, grow, and reproduce from its surroundings Question: What is the ladybug’s habitat in the picture above? Answer: The ferns that grow along side the pond. Organisms interact with both the living and the non-living portions of the ecosystem. Ecosystems are divided into two main parts: Biotic Factors and Abiotic Factors.

  Biotic Factors: living parts of an ecosystem    Abiotic Factors: nonliving parts of ecosystem that affects the living things in an ecosystem Look at the example below. List the Biotic and Abiotic factors on the side of your notes.  

Biotic Factors: Don’t forget about the living things that may be underground such as worms, fungi, and bacteria…..Q: Why are these biotic factors important to the ecosystem? A: These organisms keep the soil rich in nutrients as they break down the remains of other living things. Abiotic Factors: Water- All living things require water to carry out processes. Sunlight- necessary for photosynthesis Oxygen- required for life processes: land- get it from air, water- get it directly from the water Temperature- determines what type of organisms can live there. Some animals can alter their environments to overcome temperature challenges. Soil- influences what type of plants can grow there and what type of animals can use the soil for a home.

Levels of Organization Review: Organisms- build populations which build communities which build ecosystems Organism - one individual Example: _________ Population- all the members of a species in a particular area. Example: ___________________________________ The area in which a population lives can be as small as a blade of grass or as large as the whole planet. However, scientists studying populations usually limit it to a defined area. Some populations do not stay in a contained area.

Community- different populations that live together in an area Community- different populations that live together in an area. Example:______________________________________________________________________________________ To be considered a community, different populations must live close enough to one another to interact. Ways populations interact within a community: 1- Using the same resources like food or shelter or competing for them 2- Predator- prey relationships 3- Symbiotic relationships

Ecosystem- different communities living together along with the non-living factors. Example: ______________________ ______________________________________ For the next pictures: guess which level it is showing! Word bank: Species Population Community Ecosystem

What level of organization? Community

What level of organization? Organism

What level of Organization? Ecosystem

What level of Organization? Population

They also study how organisms react to changes in their environment.  Ecology- study of how living things interact with one another and with their environment Ecologists look at how the biotic and abiotic factors in an ecosystem are related. They also study how organisms react to changes in their environment. Sometimes reactions are fast- like sending out a warning of a predator. Sometimes the reactions are slower- like returning to “normal” after a natural disaster.

Observing- What kind? How many? Ecological Methods Observing- What kind? How many? Experimenting- In artificial environments or out in the natural world. Modeling- Over long periods of time, mathematical formulas based on data, form predictions.

Why would it be difficult at times to study ecology? Very large-scale studies Over long periods of time Organisms change Organisms move Environments change Natural disasters occur Involves a lot of travel Diversity of life is endless!!!

22-2: Studying Populations Population Density- number of individuals in a specific area   Formula: population density = number of individuals unit area Before we practice using this formula, remember that the unit of area can vary greatly depending on what population we are studying. Using the metric system: Q: What would be a good unit of area for studying whales? A: Kilometers Q: What would be a good unit of area for studying bacteria? A: Centimeters or Millimeters

Practice Population Density Problems: If there are 25 butterflies in a 20 ft2 area, what is the population density? 2) If there are 8 lions in a 2 mile2 area what is the population density?

3) If there are 3,000 bacteria in a 4 inch2 area, how many would be in a 12 x 12 area? 4) You have a garden that is 15 x 9 feet. In two a square foot area, you count 4 dandelions, how many are there in the whole garden?

Try on your Own! 5) There is a pond in the woods that is approximately 45 ft. x 30 ft. In one square foot there is 250 unicellular algae. How many could there be in the whole pond?

Determining Population Size  There are four ways of determining population size. 1. Direct Observation- count, one by one, all of its members 2. Indirect Observation –when organisms are small or hard to find, observe their tracks or other signs rather than the organisms themselves 3.Sampling- when a population is very large or spread over a wide area, estimate based on reasonable assumptions 4. Mark-and-Recapture Studies- an estimating method in which some animals are first captured, marked, and released. Then another group of animals is captured and using a mathematical formula, the scientists can estimate the total population.

Changes in Population Size   Populations can change in size when new members enter the population or when members leave the population. How can this happen? 1- Births   birth rate- number of births in a population in a certain amount of time 2- Deaths death rate- number of deaths in a population in a certain amount of time ***The Population Statement: a. if birth rate > death rate, population size increases b. if death rate > birth rate, population size decreases

3- Immigration - moving into a population 4- Emigration- leaving a population *can occur when part of a population gets cut off from the rest of the population Graphing Changes in Population *in figure 8, vertical axis shows the numbers of rabbits in the population, while the horizontal axis shows time

Limiting Factors   limiting factor - is an environmental factor that prevents a population from increasing carrying capacity- largest population that an environment can support (based on limiting factors) There are three main limiting factors: 1- Food- if food is scarce, it becomes a limiting factor 2- Space- space is often a limiting factor for plants  because it can determine how much sunlight, water, and other necessities the plant can obtain. 3-Weather- temperature and rainfall can limit population growth and a single severe weather event can dramatically change the size of a population by killing organisms

22-3: Interactions Among Living Things Adapting to the Environment Natural Selection Review (From Chapter 5) 1- Individuals in populations have different characteristics 2- The individuals whose characteristics are better suited for their environment will survive and produce offspring. 3- Offspring that inherit the favored characteristic will also survive to reproduce. 4- Over many generations individuals with that characteristic will continue to reproduce. 5- Individuals without the characteristic will die off from the population over time. Adaptation- physical characteristics or behaviors that allow organisms to live successfully in an environment.

Every organism has a variety of adaptations that are suited to its specific living conditions. Examples- a cactus can store water, a woodpecker has a long beak to feed off of the cactus without getting hurt. Adaptations create unique roles for organisms in an ecosystem.

Niche- An organism’s particular role in an ecosystem, or how it makes a living. Think of it as an organism’s “job description.” Comparison to a human: If the ecosystem is the varsity baseball field, what are some niches within that ecosystem? ________________________________________________________________________________________________________________________________________________________________________

Niche can include: Type of food it eats How it obtains food What eats it? When it reproduces How it reproduces Physical conditions needed to survive How it interacts with other organisms There are three main ways organisms interact with one another: 1) Competition 2) Predation 3) Symbiosis

NO TWO ORGANISMS CAN SHARE THE SAME NICHE!!! They can share habitat, food requirements, and maybe one or two other things, but never the same EXACT niche. Why? Because that would create direct competition and one species would win (survive) and one would lose (die off). Example: Warblers

Competition- the struggle for an organism to survive in a habitat with limited resources. An ecosystem cannot satisfy the needs of all living things in a particular habitat. There is a limited amount of food, water, and shelter. Q: So what survives? A: The organisms with the best adaptations to reduce competition. The warblers all “specialize” to eat from a particular area of a spruce tree, thus avoiding competition.

Predation- Interaction in which one organism hunts and kills another for food. Predator- Organism that does the killing. Prey- Organism that gets caught and killed. Predator Adaptations Help them catch and kill pray Examples: cheetah’s speed, jellyfish’s tentacles, wolf’s sharp teeth Prey Adaptations Help them avoid being caught as prey Examples: Camouflage, protective covering, mimicry, coloring

Read pg. 708- 2nd paragraph to interpret graph. The Effect of Predation on Population Size Size of population is a cycle of birthrate and deathrate. If predators are effective at hunting prey, the prey population is reduced. However, a decrease in prey can leave the predators without enough food. Read pg. 708- 2nd paragraph to interpret graph.

Symbiosis- A close relationship between two organisms in which at least one benefits. There are three types of symbiosis: 1- Mutualism 2- Commensalism 3- Parasitism Mutualism- A symbiotic relationship in which both organisms benefit. (WIN-WIN) Example- Bacteria and human (intestines)

Commensalism- A symbiotic relationship in which one species benefits and the other is neither helped nor harmed. (WIN-DRAW) Example- A barnacle and a whale Parasitism- A symbiotic relationship in which one organism lives inside or on another and causes harm. (WIN-LOSE) Parasite- The organism that benefits Host- The organism that the parasite lives in or on- usually harmed. Example- A flea and a dog