Can the human population grow infinitely large? Why or why not? Turn in your graphic homework.

3 Factors Affect Population Size Number of births Number of deaths Number of individuals who enter or leave the population (immigration & emigration)

Exponential Growth This kind of growth happens when individuals reproduce at a constant rate. Under ideal conditions a population will grow exponentially. Larger population, faster growth!

Checkpoint What types of organisms would be most likely to experience exponential growth? Why?

But can exponential growth go on forever??? Carrying capacity – the number of organisms of one species that an environment can support. How many individuals can be supported by this environment?

Why does logistic growth seem more realistic? When a population reaches carrying capacity, it no longer shows exponential growth, but logistic growth Why does logistic growth seem more realistic?

What is the carrying capacity of deer on WallaWalla Island?

Do you think humans have reached our carrying capacity Do you think humans have reached our carrying capacity?? What do you think might happen in the future?

Limiting Factors Density dependent factors Factors that happen because of a dense population. (disease, predators, competition, parasites, food availability) Density independent factors Factors that have nothing to do with how dense the population is. (mostly abiotic factors like temperature, storms, floods, etc.)

Human Population Growth The scientific study of human populations is called demograpics. Some countries have very high growth rates while others have very low growth rates. Where do you think the highest growth is happening? Why?

Age Structure Diagrams

What is happening in these populations? Are any growing? Shrinking? Stable?

Exit Ticket Compare and contrast logistic and exponential growth. Why is logistic growth more likely to occur in real populations?