Creating & making graphs

Pie Chart Show comparisons Compares parts of whole with 6 or fewer categories DO NOT show changes over time

Line graph Track changes over time Better than bar graph for smaller changes over time Can you used to measure changes over time in more than one group

Are all individuals in a population the same age? Do you think different species die at the same age?

Survivorship Curves shows the number of individuals surviving at each age for a given species or group Type I: Less deaths at early ages & mortality highest at old age Type II: Chance of death does not change throughout life; linear Type III: Most deaths at early ages & mortality lowest at old age

Type I

Survivorship curves

Exponential growth

Charles Darwin “There is no exception to the rule that every organic being naturally increase at so high a rate that if not destroyed, the earth would soon be covered by the progeny of a single pair.... The Elephant is reckoned to be the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase: it will be under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pairs of young in this interval; if this be so, at the end of the fifth century there would be alive fifteen million elephants, descended from the first pair.” - (Darwin, 1859 p.64)

What causes change in population size? 3 factors: birth rates, death rates, immigration/migration Immigration- movement of individuals into a population Emigration- movement of individuals out of a population

What conditions might cause exponential growth?

Factors that result in exponential growth: Available in food & resources Unavailable resources Few or no predators DOES NOT APPLY TO MOST POPULATION!!!

Limiting factors any factor that restricts or limits the size of a population. All populations limited by their environment

Logistic growth occurs when the population growth increases initially & then stops or remains constant Death rates = Birth rates; Immigration = Emigration. Populations DO NOT grow indefinetely!!!

Logistic growth

Carrying capacity number of individuals an environment can support

Carrying capacity

Comparing characteristics

Carrying capacity & strategists K strategists have steady population size near carrying capacity Grow & reproduce more slowly Can outcompete other organisms r strategists r strategists populations before carrying capacity Die quickly Grow & reproduce before can be eaten by predators or outcompeted