How did flowers come about?

Question

How could they have developed by pollenation by insects and what did the insects eat before flowers came along

Answer 1

It's obvious! The insects ate dung before they ate flowers - the dung came from mammals who ate grasses and other non-flowering plants (plants that multiply using spores.  when God created the first flower, the insects rejoiced and feasted on the new heavenly foodstuff

Answer 2

There are many competing theories each with a smattering of evidence so far. There is even the thought that more than one evolutionary event came to produce the different flowering plant lineages. But the first flowers were pollinated by wind.

The reason for flowers came with the competition between land plants to specialize in spreading their seed into new habitats farther from water. Seeds that have endosperm and a coat to prevent dehydration plus grow in an ovary at the base of the flower are well adapted to survive drier habitats away from very moist areas. The rest of the petals, sepals, and showy pistils or stamens came later after much specialized selection with pollination partners.

Flowers that self fertilize tend to be small, inconspicuous & unscented. They are white or green with little pollen and no nectar since they are not offering any as a reward. They keep their anthers very close to their stigmas so the pollen transfers easily. Wind pollinated plants make much more pollen, just as the conifers do, to ensure fetilization.

Paleoherb or 'sneaky herb' hypothesis suggests smaller herbs or even grasses started it all with separate s*x (dioecious) flowers. These have the oldest known fossils as evidence for being the first flowering plant. A 120 million year old member of the pepper family, a Piperaceae, is the oldest fossil of a flowering plant. The theory suggests that they were weedy, fast growing colonizers looking for disturbed soil, an area that had no established mature plants.  Then chance produced a mutation that prevented self fertilization.  Plants came to some recently opened habitat then and had to find each other over ever longer distances to mate. Since they did not self fertilize the pollen was all wind borne. Some plants made more protein rich pollen than others. So those plants that happened to make lots of pollen could suffer insects eating some of the pollen if they happened to spread it  to female flowers also.  However the first of these flowers were still wind pollinated. Opportune mutations allowed them to use more specific habitats. Habitat drove the shift and flowers came after to ensure sexual reproduction.  

However another of the theories, supported by some molecular studies, is the Woody Magnoliid or the Euanthial theory that says magnolia-like plants with cone-like flowers are the common ancestors and these plants still depend on beetles as pollinators. This would make beetles the first pollination partners with flowers.

Here it is suggested the exposed gamete of the wind pollinated conifer’s cone was gradually enfolded by a protective structure. The structure became the plant's ovary eventually. The female gamete is exposed only once the cone’s scales open at maturity. If the cone developed a cupped shape around the female gametophyte they were more protected but pollen is not blocked from entering with the wind. The more the insects became involved in the pollen delivery process the more the enclosed of the female gamete could become. Because beetles bearing the pollen could crawl into where the female gamete was when wind failed to push the male gamete in.

These were shrubby under story plants with broad leaves. The key feature they developed to push them to the forefront of evolution was their vegetative habitat strategy that needed flowers to ensure reproduction.

Beetles are still important pollinator partners with very ancient types of plants. The flowers they visit are large and strongly scented like magnolias or spice bush with spicy scents and pale colors. Beetles can detect color but scent is more important.

http://www.fs.fed.us/wildflowers/pollina...

http://www.answers.com/topic/coleoptera-...