How important is biotic pollination and dispersal to the success of the angiosperms?

Abstract

The rise to dominance of the angiosperms has frequently been hypothesized to be due to reproductive innovations, especially those involving coevolution with biotic gene dispersers. Wind pollination is considered inefficient in comparison with insect pollination. The scope for speciation is considered to be greater when biotic gene dispersers are involved. The biogeographical restriction of extant conifers to stressful environments is also considered to be due to the inefficiency of wind pollination in species-rich environments. We consider both fossil and contem porary evidence and conclude that biotic gene dispersal has not been as im portant as have innovations affecting growth rates in explaining the rise of angiosperms. We conclude that differences in growth rates, especially in the regeneration phase, can explain the rise of the angiosperms and the extant biogeography of gymnosperms.