Topic 4 Measuring Populations Sampling populations of different

Topic 4 Measuring Populations Sampling populations of different species using different methods

Topic 4 Measuring Populations Key Concepts • Why do we sample populations? • What are the ways in which we measure a non-mobile population? • What are the ways in which we measure a mobile population? • What are benefits & drawbacks to these methods? Vocab • • Sampling Quadrat Mark & capture Mobile/Nonmobile

Measuring Population Size • The most direct method of determining population size would be to count every individual • Why isn’t this possible? Because: 1. populations are always changing 2. It can take a long time! Scientists use the process of sampling instead of counting each individual.

WHAT IS SAMPLING & WHY DO WE USE IT? • POPULATION SAMPLING: is the process of taking a smaller group (or subset) that is representative of the entire population • Why? • Sampling allows scientists to estimate population size by counting a smaller number of individuals in a given area. In short: Scientists use this information to: – It saves money – It saves time Take action Make decisions on environment Manage To conserve (protect) population or habitat Plan Predict future issues or concerns

Quadrat Sampling • Quadrat sampling can be used to estimate populations by counting the individuals within a grid system • Can be used to determine: population size, density, and distribution. *Works best with: non-moving organisms Ex. plants or animals that stay in one place (ex. barnacles)*