Most plants use pollen to perform sexual reproduction and cross pollination acts as a way of defense in a population, since it avoids consanguinity and all the dangers of such. Although the wind and other abiotic factors were the simplest ways to achieve that goal, it required an extreme amount of energy spent on reproduction, making it impossible for plants to develop further. Then, so that plants could focus their energy on other areas of their development, new adaptations started to appear. Characteristics such as presence of nectar or attractive patterns on the flowers, made some animals (insects, small birds and some bats) interested in the flowers. Those were the first biotic pollinators. Biotic pollinators are a more effective way to perform cross pollination, since it needs the production of less pollen by the plants, leaving the possibility for further development in other areas, with the small price of keeping the pollinators happy (production of nectar, release of attractive aroma, presentation of attractive colors). Still, the percentage of pollen effectively used to fecund the other flowers is very small, since the pollinators go through several species of plants and the pollen needs to find a suitable match so that reproduction may, actually, happen. It his travels, Darwin found a plant that had that problem easily resolved. The Madagascar star orchid (Angraecum sesquipedale) has an overdeveloped nectary (with a maximum of 30 cm) that, at the light of co-evolution could only mean one thing: this plant had a pollinator partner. In 1877, by analyzing the nectary of the orchid, Darwin and his supporter Wallace predicted that there would be an insect with a proboscis as big as the nectary. It was only in 1903, that the insect was found. The Morgan’s sphinx moth (Xanthopan morgani predicta) had, indeed, a proboscis that could easily access the nectar produced by the orchid. Therefore, the hypothesis that the moth and the orchid had developed in a mutualist way was easy to accept. But it took another century, for Ennos to propose an hypothesis that could also explain the phenomenon. The hypothesis proposed was based also on co-evolution, but on a competitive type one. Ennos proposed that there were several populations of moths. He stated that the evolution of the proboscis were due to the competition between two populations of moths fighting for the same niche. Only the population with the bigger proboscis would be able to retrieve the nectar from the orchids, prevailing over the other population. This way, according to the Gause's law of competitive exclusion, only this would survive. This controversy has been popular in the last years, having the scientific community not reached an agreement yet.
