Understanding Population Growth Ch 52 No more for you mrs. Willie!! Understanding Population Growth

Organism

POPULATION POPULATION

Community

Ecosystem

Population Ecology Deals with #’s of indiv. in a species How and why their numbers are the way they are

A better way to describe size of a pop. Manhattan, New York City Population Density # of indiv. of a species unit of area A better way to describe size of a pop. Manhattan, New York City 70,595 people per sq. mile

Dhaka, Bangladesh: 7 million in 59 mi2

Lack of Natural Resources Crowded Much?!? Competition Spread of Disease Lack of Natural Resources Lack of Jobs

Populations Change in Size… Births, deaths, immigrants, and emigrants

Question: How can you get the growth rate of a population to slow down Question: How can you get the growth rate of a population to slow down? Give reasonable solutions! Make a list with your partner 

Reproductive Strategies

Exponential Growth= r-selected AKA J Curve

Occurs when Pops Doubling OverTime

Practice: With a 2 % growth rate, the world population will double…. Doubling Time Time for a pop. w/ a stable growth rate to double in size Doubling Time = td = 70 r (%) Practice: With a 2 % growth rate, the world population will double….

R-selected Species Many small offspring Little/no care of offspring Most offspring die before reaching reproductive age High population growth rate Generalists

Logistic Growth: K-selected AKA S Curve

Carrying Capacity K = carrying capacity (Max. pop. of a particular species that a habitat can support over a given time period.

Carrying Capacity Seasons Changes in environment (fire, storm, etc.) May vary by: Seasons Changes in environment (fire, storm, etc.)

K-selected Species Fewer, larger offspring High parental care Most offspring reach reproductive age Lower population growth rate Specialists

Density-Dependent Factors Increasing pop size leads to less available resources  limiting pop growth DD factors: competition, predation, disease, poisoning…all increase when pops grow w/in limited space.

Density-Independent Factors Limits placed on pop growth (not due to space issues) Ex: Natural disasters or Severe weather

Survivorship Proportion of a pop. to survive to breeding age Type I= Late loss: K-strategists. Type II = Constant loss: intermediate reproductive strategists Type III = Early loss: R-strategists