What are some environmental factors which control population in nature? Think, Write, Share...
Density Dependent (size of population matters) Density Independent (size of population doesn’t matter)
Try this... In cooler climates, aphids go through a huge population increase during the summer months. In autumn, the population ‘crashes’ to much lower numbers. Name a density dependant and a density-independent factor regulating the population Density dependant:______________ Density independant:_____________
Competition Occurs when members of different species try to utilize a resource (light, space, or nutrients) that is in limited supply.
Competitive Exclusion Principle No two species can occupy the same ecological niche at the same time The division of feeding niches =________________________ Chthamalus Species 1: Chthamalus sp Species 2: Balanus Balanus Area of competition
Predation Occurs when one organism, the predator, feeds on another, the prey Predators include: ______________________________ Predators usually limit the prey population, although in extreme cases they can_____________________.
What are the reasons why predators rarely kill and eat all of the prey? Prey species often: - - Often the predator will _________as the prey species becomes lower in numbers.
Turn to a partner... How can predation help maintain species diversity? (think top predator)
Cycling The predator population ______________________________and then the predator population declines in number The prey population ________________________ and suffers the crash, and the predator population follows suit Less predators to worry about means________________
Parasitism and Disease Parasites can also limit the growth of a population (by ______________prey) Range in size from microscopic disease- causing bacteria to tapeworms 30 cm in length
Try this... Type of curve=______________________ a) b) c) d) e)
Describe what might be happening to the population at: b) e)
Exponential population growth or Logistic growth? 1. A lack of food prevents a certain population from growing any further ____ 2. In a steady state, the average growth rate is zero _____ 3. The larger a population of bacteria gets, the faster it grows _____ 4. A particular environment is limited to a certain number of rabbits that it can support _____
Density Dependant (DD) or Density Independant (DI)? 1. Freezing weather _____ 2. Has a greater effect on a larger population_____ 3. A volcanic eruption_____ 4. Predation _____ 5. Floods ______ 6. May limit the population before it even gets close to carrying capacity _____
7. Disease or parasites _____ 8. Fire ____ 9. Storms _____ 10. Intensity of effect no greater for larger population, no less for smaller population _____ 11. Tends to be biotic ______ 12. Tends to be abiotic ______