Hi all, first time poster. I have a degree in Biomedical Sciences FWI, but not actively engaged in the pursuit of evolutionary biology. I had an interesting thought about the mechanisms behind flower evolution. Basically, could it be that there has been selective pressure towards the evolution of flowers not only due to the most obvious reason of plant reproduction, but also because by offering insects a source of food, the plant kingdom actually modifies the entire selective pressures on insect evolution away from insects eating plants?
So, there is always an arms race between plant and herbivorous insects (pesticides vs resistance), but the evolution of a free food source removes some of the selective pressure on insects to win the arms race and allows plant pesticides to be more effective over a longer period of evolutionary time. Therefore in terms of prospects for survival, the reproductive function of flowers is perhaps not as important as it seems and may even be secondary to the effect they have on altering the course of insect evolution away from every insect species needing to eat plants.
I know it’s not an either/or situation, but I don’t think I’ve heard it mentioned before that the evolution of flowers was driven by their effect on curtailing the tendency towards the evolution of pesticide resistance in insects, rather than primarily a mechanism for improved sexual reproduction. In effect, this may have actually been the primary driver of the evolution of flowers. In the same way that the evolution of fruit is on the one hand a seed dispersal tool but on the other hand a potent way of providing a way for animals to break out of the cycle of needing to eat you to survive.
It’s a bit like tackling internet piracy by giving away freebies such as spotify…once people try spotify they get locked into it and the number of music pirates is reduced. This allows you to be more successful at tackling piracy. The other effect of Spotify being free is obviously that it proliferates users (eg, plant reproduction).