Presentation on theme: "MRS. HAWLEY 2008-2009 Ecosystems and Populations."— Presentation transcript:
MRS. HAWLEY Ecosystems and Populations
PART ONE Ecosystems
Ecosystem All living and nonliving things interact in a certain area. Examples: Prairie dogs dig their burrows, search for food and hide from predators, they interact with and respond to their environment. They interact with living things such as grass and the predators, and with nonliving things such as the soil.
Habitat The place where an animal lives. This place also gives the animal things it needs such as shelter, food, etc. A single ecosystem is likely to have many habitats within it because each living thing requires different things to make it survive. Example: a dog has different needs than a penguin or a dolphin. They all require food and shelter but not from the same environment.
Biotic Factors Living parts of the ecosystem. Examples: trees, grass, bacteria, animals, etc.
Abiotic Factors Nonliving parts of the ecosystem. Examples: Water Soil (yes, parts of it came from living things but the majority of soil is made from nutrients, air and water so it is considered abiotic) Sunlight Oxygen Temperature
Population All members of the same species in a particular area. Example: if you say “the penguin population in Antarctica is decreasing”, you would be wrong. The term “penguin” is general as there are many species of penguins. However, if you say “the emperor penguin population in Antarctica is decreasing”, you would be correct because you specified which type of penguins.
Society Closely related population of animals that work together for the benefit of the whole group. Example: In a group of meerkats, the female leader is the only one allowed to reproduce. When she gives birth to pups, other meerkats in the group take turns babysitting and even feeding the pups. The survival of pups is important for the survival of the group so they have numbers on their side in case of a fight between meerkat families and so they have more eyes to watch out for predators.
Community All the different populations that live together in an area. Examples: meerkats, owls, hawks, gophers, etc. living together in the Kalahari Desert in Africa.
Levels of Organization Organism (smallest) Population Community Ecosystem (largest)
Ecology The study of how living things interact with each other and their environment. Part of the study includes how organisms respond to changes in their environment.
Review 1. Give 3 examples of biotic factors. 2. Give 3 examples of abiotic factors. 3. List the following levels of organization in order from smallest to largest levels: community, ecosystem, organism, population. 4. Would all the insects in a forest be considered a population? Why or why not?
PART TWO Studying Populations
Population Density The number of individuals in a certain area. Calculated like this: Number of individuals Unit area Example: Suppose you counted 50 macaroni penguins on a beach measuring 10 square meters. What would the population density be? 50 / 10 = 5 macaroni penguins per square meter
Determining Population Size Direct observation – count one by one Indirect observation – counting number of nests, tracks, burrow holes, etc. Sampling – making an approximation of a whole area based on the number counted from a small section. Mark and Recapture studies – some animals are captured, marked and then released back into their environment.
Changes in Population Size Birth rate – number of births in an area within a certain amount of time Death rate – number of deaths in an area within a certain amount of time Immigration – moving into a population Emmigration – leaving a population
Graphing Population Changes # of Animals Year of study
Limiting Factors An environmental factor that prevents a population from increasing.
Types of Limiting Factors Food – all organisms need food to survive Space – cramped quarters (shelter) can create a difficult living environment for organisms Weather – too warm or too cold conditions can cause health problems which could cause death among organisms Predators Disease Water
Review 1. List 4 ways of determining population size. 2. How is birth rate related to population size? 3. List 3 limiting factors for populations. Choose one and explain how this factor can limit population growth. 4. Why would an ecologist need to know the size of a population? 5. A field measures 50 by 90 meters. In one square meter, you count 3 grasshoppers. Estimate the total population of grasshoppers in the field. What method did you us to make your estimate?