(a) Compare , giving reasons , the J- shaped and S- shaped models of population growth of a species.
(b) Explain " fitness of a species " as mentioned by Darwin.

Explanation

(a) J- shaped - When the responses are not limiting the growth plot is exponential. Darwin showed how even a slow growing animals like elephant could reach enormous numbers in the absence of checks.
dN/dt =rN
The above equation describes the exponential or geometric growth pattern of a population and results in J- shaped curve.
`dN//dt=rN((K-N)/(K))` where, N= population density at time t.
r= intrinsic rate of natural increase.
K= carrying capacity.
(b) When Darwin spoke of the struggle for existence and survival of the fittest in nature . He was cominced convinced that interspecific competition occurs when closely related species compete for same resource that are limiting but this is entively not true.
(1) Unrelated species could also compete for the same . For example . in some shallow South American lakes visiting flamingoes and resident fishes compete for their common food, the zooplankton in the lake.
(2) Resources need not to be limiting for competition to occur in interference.