Populations

• What is the focus of the video discussed?

  Populations and communities
• What defines a population in ecology?

  A group of the same species in an area
• What is a species?

  Individuals that can interbreed to produce fertile offspring
• Why do we estimate population size instead of counting?

  Counting is impossible for large populations
• What is a random sample in population studies?

  Every member has an equal chance of selection
• How can you create a random sample in a large field?

  Divide the field into grids and select randomly
• What is sampling error?

  The difference between true and estimated values
• How does sample size affect sampling error?

  Larger samples reduce sampling error
• What is a quadrat used for?

  Random sampling of sessile organisms
• What is a sessile organism?

  An organism that does not move around
• How do you use a quadrat for sampling?

  Count individuals within a fixed frame
• What is standard deviation used for in sampling?

  To calculate variability in data
• Why does quadrat sampling not work well for motile organisms?

  Motile organisms move, making counting difficult
• What is the Lincoln index used for?

  Estimating population size of motile organisms
• What is the first step in using the Lincoln index?

  Capture and mark individuals
• What does the Lincoln index formula involve?

  Marked individuals multiplied by recaptured individuals
• What assumptions does the Lincoln index make?

  No migration, births, or deaths occur
• What is carrying capacity?

  The maximum population size an environment can support
• What factors limit carrying capacity?

  Limited resources like food and water
• What is negative feedback control in populations?

  Factors that stabilize population size over time
• How do density-independent factors affect populations?

  They impact populations regardless of size
• What are density-dependent factors?

  Factors that have a greater effect as population grows
• How does population growth occur when births exceed deaths?

  Population increases towards carrying capacity
• What happens when a population exceeds its carrying capacity?

  Density-dependent factors increase mortality
• What is exponential growth in populations?

  Rapid increase when resources are abundant
• What is the sigmoidal curve in population growth?

  A graph showing exponential growth followed by stabilization
• How can you simulate carrying capacity in a model?

  Create a small environment with limited resources
• What are the strengths of using models to study populations?

  Isolate variables and conduct multiple trials
• Why is interdependence important in population studies?

  All factors affect carrying capacity and population size