Question

Population group discussion Draw and consider the three types of survivorship curves (be sure to label the axes). Discuss and pick and organism for each type of curve, explaining what about the natural history of the species makes it fit that pattern. With an organism of your group's choice, consider a species with changing abundance patterns in multiple sites that you monitor: one year low, the next medium, the next high, the next year none, then low, medium, high, again. The cycling pattern is different in each of the sites you monitor. What are the factors that drive the cyclic patterns at a given site? How might metapopulation biology influence the diverse patterns at the various sites in a given year, and over time?

Answer 1

Three types of survivorship curves-

♡ 1000 Type I or convey survivors (log scale Type I Type II or concave number of age in relative units

when the data from column lx (survivorship) are plotted against the age(x) column the resulting curve thus formed is called a survivorship curve.this curve is convenient for use as a visual aid to detect changes in survivorship (and mortality)by period of life.

survivorship curves is to use a log scale (y axis)for the number of individuals or survivors and x axis denotes the age in relative units or time.

• Organisms for each type of curve and explanning the natural history of species that they fit to pattern-

The three survivorship curves are called Types I ,II, and III .or better known as convex,diagonal and concave.

The convex or type I curve indicates high survivorship or very low mortality among younger individuals up to a perticular age,after which most of the population dies.this situation is charecteristics of some human population ,many species of large animals and dall mountain sheep.such a situation would happen if environmental factors were uninportant and most of the organisms lived out their full physiological logetivity.the abrupt drop in survivorship would depend on how variable the population was in genetic factors affecting length of life.K selection species are generally under this type of curve.

A highly concave or type III curve results when mortality is high during the young stages.this pattern is typical in the case of oak trees ,marine invertebrates (oysters),many fishes and some human population .mortality is extremely high during the free swimming larval stage or acorn seedling stage.this results from such factors like inexperience in foraging and avoiding predators and lack of immunity to disease.like human population after a spread of virus ,mortality rate sudden increase.once an individual is well established on a favourable substrate,life expectancy improves considerably.r selection species are generally under this type curve.

A diagonal or Type II curve indicates a constant probablity of dying.it can be othewise stated that a constant percentage of the population is lost in each time period.probably no population in the natural world has a constant age-specific survival rate throughout its whole life span,however a sightly concave curve ,approaching a diagonal straight line on a semilog plot is charecteristics of many birds,mice ,rabbit,deer.in this case ,the mortality rate is high in young but low and more nearly constant in the adults( year or older).