Question

Once pollen lands on the stigma of a flower, the pollen germinates, creating a pollen tube that grows down the ovule. The sperm cell moves through the tube to fertilize the egg. Based on the evidence from the experiment above explain how natural selection might have led to directional selection toward higher aperture number.

Answer 1

In plants most pollen grains are tricolpates, that is to say, they have three apertures, what's more there are a great number of different pollen shapes and apertures, this is quite dependent, on the species and pollen stigma dynamics.

Nonetheless, in the present case we have that those pollen grains with more aperture germinate faster, assuming that all repetitions belong to the same species we would be looking at a directional selection towards a higher aperture number, this could be due to a faster interaction of stigma secretions with pollen tube grow, pollen tube could take less time to nourish, interact and grow in the stigma. or could be a mutation in those pollen grains with three apertures that makes them less viable not so much is about germination speed maybe this with pollen with three apertures could be unfertile so the low percentage is not because of time but infertility. Another situation is that those pollen grains with three apertures have differences in pollen kit and receptors so there is no proper recognition stigma pollen, and so germination is slower or inhibited.