When the population is reaching carrying capacity the change in population over

When the population is reaching carrying capacity the

This preview shows page 7 - 9 out of 12 pages.

plentiful resources. When the population is reaching carrying capacity thechange in population over time is 0, it will stay constant. When it exceeds carrying capacity, the population change will become negative and the population will decline.oWhen there are plentiful resources the population will grow at the rate ofr. So, when N is close to 0, the population growth = r. The growth rate drops to 0 when the population reaches carrying capacity. Best fit line is expectation. The logistic growth model predicts that the population growth is density dependent.EX. Water fleas – as density increases the growth rate declines.oExponential growth is a straight line, it always grows at the rate of r. Its constant. This is density independent population growth. The population growth does not depend on density. oThe logistic growth model is built on the exponential growth model. Similar assumptions: k is constant, r is constant, linear density dependence, closed system (ignoring I & E), no predation, no interspecificcompetition.Life History TraitsoEX. Polar bear w/ cub & spider w/ baby spiders – they share the care for their young. They have adopted the same investment in parental care.oEX. Pink sleeved flower – long lived, produce 1 flower, have 2-3 seeds, slow development, low reproduction.
Image of page 7
EX. Arabidopsis – simple plant. Can go from seed to flowering in 25 days. Fast reproduction. Produces mass quantity of seeds. These 2 plants are so different but they both thrive. o r-k selection theory explains life-history patterns. Organisms that are driven by r or organisms that are driven by k. r selection. Plentiful resources in the environment. Natural selection will favor the species that leave the most offspring. Since species A has a higher r, it produces more offspring. Species B will become so rare that it is referred to as a relative extinction (don’t disappear, just become less common). Circumstances: Environments that have plentiful resources (collared dove). Population crash (black noddies – grew afer the wipe out of cats). Disturbance (scotch pine – grew following recession of ice). EX. Weeds are all about maximizing reproduction. Or maximizing r. k selection. EX. Bobcats & lynx. 2 species may compete for resources. Resources are limited. Growth is logistic. It doesn’t really matter how quickly you get to the carrying capacity, it matters how large your carrying capacity is. If lynx has a higher carrying capacity and the 2 are ecologically equivalent, the lynx are more efficient at using resources. Adding lynx to meet their carrying capacity will cause the bobcats population growth to become negative since their carrying capacity is over. Therefore, it will decline, while the lynx increases. The bobcats will decline to extinction (0), and the lynx will win since it has the higher k. o American robin (r-selected) & Wilson’s storm petrel (k-selected) – look similar but they have different traits. o Goldenrods are considered a weed, but they are good competitors, they fall somewhere in-between. Salmon are considered all traits for k-select except reproduction. List of Terms: Ecology:
Image of page 8
Image of page 9

You've reached the end of your free preview.

Want to read all 12 pages?

  • Summer '08
  • Brown,D

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture