Read the following passage carefully and answer the given questions.
Theory of Evolution
The evolution of life is a gradual process through which simple organisms are transformed into complex life forms over billions of years. It involves genetic changes, adaptation to the environment, and the emergence of diversity in species. Fossil records provide evidence of extinct life forms and transitional stages. Evolution is influenced by factors such as mutation, genetic recombination, and environmental pressure, shaping the biodiversity we see today. Charles Darwin and Alfred Russel Wallace were pioneering naturalists who developed the theory of evolution by natural selection.
According to Darwin, the term 'Fitness' in the context of natural selection refers to:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → The reproductive success of an individual or population
Option (1) Physical strength of an organism — Incorrect. A strong organism that leaves no offspring passes nothing on, so strength alone is not fitness.
Option (2) The ability of an organism to adapt to any environment — Incorrect. Adaptation helps an organism survive in its own environment, not in any environment; and survival counts only if it leads to offspring.
Option (3) The reproductive success of an individual or population — Correct. For Darwin, fitness means reproductive fitness: those better fitted to the environment leave more progeny, and so their traits spread. This is natural selection.
Option (4) Survival without reproduction — Incorrect. Survival without reproduction is the opposite of fitness in Darwin’s sense.
NCERT Extract:
Evolution of Life Forms – a Theory – “… would outbreed others that are less-endowed to survive under such natural conditions. Another word used is fitness of the individual or population. The fitness, according to Darwin, refers ultimately and only to reproductive fitness. Hence, those who are better fit in an environment, leave more progeny than others.”