Read the passage and answer the following questions:
Organisms evolve in their respective habitats to maximise their reproductive fitness, also known as Darwinian fitness, which is often measured by a high "r" value. They adapt to the specific selection pressures present in their environment by developing the most efficient reproductive strategies. This includes variations in breeding frequency and the number and size of offspring produced. Some organisms, such as Pacific salmon fish and bamboo, exhibit a strategy known as semelparity, where they breed only once in their lifetime. In contrast, most birds and mammals follow an iteroparous strategy, breeding multiple times throughout their lives. Additionally, some species, like oysters and pelagic fishes, produce a large number of small-sized offspring, while others, such as birds and mammals, produce a small number of large-sized offspring. The desirable reproductive strategy for maximising fitness depends on the specific conditions and selection pressures within the habitat. Ecologists emphasise that the evolution of life history traits is influenced by the constraints imposed by the abiotic and biotic components of the environment. Factors such as resource availability, competition, predation, and other ecological interactions shape the evolution of these traits. Thus, populations evolve to maximise reproductive fitness in their habitats, and the specific reproductive strategies and traits they adopt depend on the selection pressures and constraints present in their environment. Ecologists investigate these relationships to uncover the mechanisms behind the evolution of life history traits and their ecological significance.
In 1981, the intrinsic rate of natural increase (r) for the human population in India was:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0.0205
In the growth equation dN/dt = rN, r is the intrinsic rate of natural increase, found as per capita birth rate minus per capita death rate (r = b – d). The book gives three sample values to show its size: 0.015 for the Norway rat, 0.12 for the flour beetle, and 0.0205 for the human population of India in 1981.
NCERT Extract:
Population Growth – “… The r in this equation is called the ‘intrinsic rate of natural increase’ and is a very important parameter chosen for assessing impacts of any biotic or abiotic factor on population growth. To give you some idea about the magnitude of r values, for the Norway rat the r is 0.015, and for the flour beetle it is 0.12. In 1981, the r value for human population in India was 0.0205.”