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Diversification

An organism in the mainland experiences two competitions namely inter and  intraspecific.Hence due to the pressure on the organism it has to evolve more differently from its parents tosurvive if it doesn't it will have to go through a tough time but still certain organisms in the mainland donot evolve much as they have evolved a stable charecter which its competitors have not and hence doesn't need a variation but most organisms in mainland need it and hence migrate to escape dangers or to find food  hence if they adapt  they survive if not they perish.Fowardation means  to evolve under two  of  the above pressures but one might guess  that diversification can be faster  in the mainland  but it is not  due to the interspecific competition which hampers diversification but helps in fowaration.

Also as the population is large one may expect more variation which is again hampered by interspecific competition.In the above image the right reresents an organism in Island with the same in mainland after 't' years the fowardation of the mainland species is 'h'[the black vertical line on the left]  and the fowardation of island species is 'x'[the black vertical line on the right]. Hence the Difference of fowardation between mainland species and  fowardation of island species is h-x which is always positive.The Red lines represent diversification.The smaller lines indicate extinct species [extinct due to pressure and competition].We can see that  more red lines are seen in the right due to lack of interspecific competition.The red lines in the right represent Diversification[B] and diversification[A] to the left.

An easy example to prove  Diversification[B] is faster than [a] is to take say 1000 bacteriaA in a medium   When we introduce another species of bacteria  the bacteriaA are reduced to 500.It is a well known fact that in a small population only small amount of variation is possible and hence when there is no interspecific competition they diversify more.  In the above graph Itake the no.of species in the X axis and the land area the species cover divided by no.of species .From the graph it is visible that lemurs have better diversified and tarsiers are the poorest as they are primitive and live in the mainland.