but, the bushes stat suffering from a plant disease. The amount of
leaf material for the beetles is reduces so that average weight of
adult beetles is reduced. The average weight of adult beetles
decreases because of scarcity of food. After a few years, when
bushes once again become healthy due to the absence of disease,
then the average weight of beetles should once again increase, due
to adequate availability of food.
16.3 SPECIATION :
- Speciation is Origin of New Species : A species
comprises of several populations. Interbreeding is very frequent
among the individuals of a population and is occasional among the
populations of a species whereas inter breeding is absent among the
individuals of different species. There is a free gene flow within the
members of a population and a free gene flow could be maintained
among the members of different population of a species, provide an
opportunity to interbreed. But free gene flow between two species
does not occur on account of marked difference in their genotype, it
means new species arise by the establishment of reproductive
isolation (intrinsic barrier to interbreeding of natural population)
