There is greater biodiversity in tropical/subtropical regions than in temperate region. Explain.
The tropical/subtropical region exhibit maximum biological diversity because these region remain undisturbed due to less variable climatic conditions. So, tropics had a longer evolutionary time for species diversification. The temperate environment are more seasonal, less constant and unpredictable, therefore less niche specialisation and lesser species diversity are observed.
Why are the conventional methods not suitable for the assessment of biodiversity of bacteria?
Many bacteria cannot be cultured under normal conditions in vitro, which creates a problem in studying their morphological and biochemical characteristics.
Morphology and biochemistry along with some other characteristics are used for the assessment of biodiversity of bacteria. Thus, conventional methods are not suitable for the assessment of biodiversity of bacteria.
What criteria should one use in categorising a species as threatened?
The criteria that should be used in categorising a species as threatened are
(i) Number of the members of the species are declining at an alarming rate.
(ii) Their habitat is being modified or destroyed.
(iii) Predator or poacher activities are increasing.
What could be the possible explanation for greater vulnerability of amphibians to extinction as compared to other animal groups?
Amphibians are more vulnerable to extinction
(i) Habitat Modification or Destruction Amphibians generally need aquatic and terrestrial habitats to survive; threats to either habitat can affect populations. Hence, amphibians may be more vulnerable to habitat modification than organisms that require only one habitat type.
(ii) Habitat Fragmentation This means isolation of a few areas by habitat modification. Small populations that survive within such fragments are often susceptible to inbreeding, genetic drift or extinction due to small fluctuations in the environment.
(iii) Large Scale Climate Changes These changes can further modify aquatic habitats, preventing amphibians from spawning.
How do scientists extrapolate the total number of species on earth ?
There are two methods to estimate and extrapolate the number of species on earth
(i) The primary method used by the scientists to extrapolate the number of species on earth is the estimation rate of discovery of new species.
(ii) Total number of species can also be extrapolated by the statistical comparison of the tropical and temperate species richness of exhaustively studied groups of insects. The ratio is then extrapolated with existing species of plants and animals to predict the gross estimate of the number of species on earth.