Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution5 Marks
Question
Show that Darwin’s natural selection is based on natural observation, with an example for each.
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Answer
The resources of the nature are limited, so the size of population of a species is limited.
The size of the population is fixed, except for some seasonal fluctuations.
Each and every member of a population shows variation for every character.
It is found in microbial or bacterial population growing in a culture that if everybody in a population reproduces to its maximum capacity, the population will grow exponentially.
The population size in an ecosystem is limited–due to competition among individuals for limited resources and only those fit individuals utilise the resources at the cost of other to reproduce. Darwin suggested that nature creates some pressure on the population which eliminates some individuals and some better adapted ones survive. This natural pressure at each and every generation creates some small variation in a population, accumulation of which for many generations leads to origin of new species.
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