Organisms And Populations

Answer (d) Ramdeo Mishra

Population growth curve are the mathematical expression of the growth of a population, which are used to predict the growth rate of population from its beginning till its climax stage i.e., stability. These growth curve may be -shaped or sigmoid shape or -shaped. The later -shaped curve is shown by small population and contain two phases e.g., lag phase and exponential phase and is represented by following exponential equation Where, denote intrinsic rate of natural increases and is size of population, while is rate of change in population size. The integral form of the above reaction can be derived as where, population density after time population density at time = the base of natural logarithm intrinsic rate of natural increase.

Natality and immigration lead to increase inpopulation size whereas mortality and emigration result in population decline.

Population growth under the Verhulst-Pearl logistic equation is sigmoidal ( -shaped), reaching an upper limit termed the carrying capacity, .
Population initiated at densities above K decline exponentially untill they reach , which represents the only stable equilibrium.

Birth, i.e., production of new offspring is an attribute of an individual whereas birth rate i.e., production of new individuals per unit population per unit time is an attribute of population. A sigmoid growth curve is depiction of logistic growth, a more realistic growth model where individuals compete for limited resources and the fittest individual survives and reproduces. In an exponential growth curve (J-shape curve) the asymptote, is beyond carrying capacity as resources are unlimited. V is intrinsic rate of natural increase.

An adaptive trait is an aspect of the developmental pattern of the organism, which enables or enhances the probability of that organism survival and reproduction.