Read the passage carefully and give the answers to the next five questions:
Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is more than 1.5 million.
The following are the various hypotheses proposed in explaining the greatest biological diversity in tropics except :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Tropical environments have more humidity/moisture which helps the diversity to flourish.
Option (1) Temperate regions are subjected to glaciations, but tropical latitudes have remained relatively undisturbed. — A hypothesis proposed for the greater diversity in the tropics. Speciation is a function of time. Undisturbed for millions of years, the tropics have had a long time for new species to form.
Option (2) Tropical environments have more humidity/moisture which helps the diversity to flourish. — Not one of the hypotheses proposed. The three hypotheses are about time, a constant environment and solar energy. Humidity or moisture is not one of them.
Option (3) Tropical environments are less seasonal and more constant. — A hypothesis proposed for the greater diversity in the tropics. A constant and predictable environment promotes niche specialisation, so more species can live side by side.
Option (4) There is more solar energy available in the tropics which contributes to higher productivity and hence biodiversity. — A hypothesis proposed for the greater diversity in the tropics. More sunlight means higher productivity, which may support more species.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Patterns of Biodiversity – “… Ecologists and evolutionary biologists have proposed various hypotheses; some important ones are (a) Speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification, (b) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and lead to a greater species diversity and (c) There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.”