The x axis is time in days, and the y axis is the population. Environmental resistance may limit the growth rate. List some possible factors that might cause this leveling in growth rate. The population of the USA in 1800 was 5.3 million. The purpose of this portion of the laboratory exercise is to investigate Shelford's Law of Tolerance by studying the optimum temperature for the growth of the wild type fruit fly, Drosophila melanogaster .
Populations can follow one of many growth patterns.
One pattern culminates in a stable population, homeostatic within the carrying capacity of the physical, chemical and biological environment. Another pattern is an irruptive one, in which a sudden boom in population is followed with a devastating bust . When examining the log phase, or exponential phase of these growth patterns, it is useful to see if the growth is at the maximum possible rate, or if some environmental or cultural factor is keeping the growth at some value below the maximum. The rate of growth and maximum population density of an organism may depend on some physical or chemical variable in the environment. Shelford's Law of Tolerance can be summarized that the success of a population depends on a complex of conditions, and too little or too much of any physical or chemical factor may exceed the limits of tolerance for existence for the organism and thus be limiting the growth.