Figs and fig wasps

Figs are tropical plants that show an amazing relationship with wasps for their pollination as well as for the wasps' reproduction. The two groups totally depend on each other so that one cannot survive without the other. Thus both groups are highly adapted and specialized to maintain the interaction. fig flower is a syconium where the tiny flowers are enclosed in. The cavity of the syconium opens through the ostiole.

Structure of a syconium (http://flower-tales.blogspot.com/2011_11_01_archive.html)

In the world, there are two types of figs.

1. Monoecious figs

 These figs have only one type of trees and their syconium have both male and female flowers.

 
2. Dioecious figs

These figs have two types of trees as male(heterophroditic) and female(hermaphroditic). In female trees all the syconia contains only female flowers with a long style. In male trees syconia have both male and female flowers where female flowers have short styles.

Female flowers in different syconia (http://waynesword.palomar.edu/arbimg10.htm)

For each fig species there is a particular species of fig wasp for its pollination. Fig wasps are adapted for pollination of figs while ovipositing. Female fig wasp carrying pollen enters into a syconium through the ostiole. after its entrance the ostiole gets closed so that the entrance of a second is blocked. the female who enters into the cavity of the syconium is called the foundress and it lays eggs in the female flowers while purposely pollinating them. She has a long oviopositor  which can reach the ovary of the female flower. The egg is laid in the ovary of the fig flower. the developing larvae feeds on developing fig seeds. That is why the female wasp pollinates the female flowers in which she lays eggs purposely. This ensures the development of a fig seed which is food for her developing baby- the larvae.

After her task is completed the foundress wasp dies inside the syconium. After some time the second generation emerges from the fig seeds. Here the males with strong mandibles emerge first. They cut a hole in the wall of the ovary and comes out. Then they cut a hole on ovary walls where female wasps are developing. While the female is inside the ovary they mate. Then the male wasp cuts the stamens of mature male flowers. After that they cut holes on the syconium wall and emerge through it. The male wasps are so soft bodied that they die soon after they emerge out.
On the other hand, the females that emerge from the ovaries of the flowers are hard bodied. They have well developed wings to fly. They collect pollen from the stamen that are cut down by the males. Then they emerge out from the suconium through the holes cut by the males. These females fly in search of receptive syconium of another fig tree of the same species.

Life cycle of a fig wasp (Encyclopedia Britannica)

In this process both the fig and the fig wasp show adaptations to ensure their reproduction as well as maintaining their population.
Fig trees when monoecious have long and short styles int heir female flowers. There the ovipositor of the female wasp cannot reach the ovary of the flower thus they lay the egg halfway of the style. These eggs do not develop into a larvae but the flower is pollinated so that a fig seed will be developed. In short styled flowers, the female ovipositor can reach the ovary and thus the wasp will develop in it. In that way both the wasp and fig population is maintained.
In dioecious figs, all the female syconia have female flowers with long styles and thus, no larvae will develop but only fig seeds will be produced. In male trees all the female flowers have short styles and thus almost all of them produce wasps not seeds. In that way the fig population and the wasp population is balanced.

Maintaining the wasp and fig population (http://www.ces.iisc.ernet.in/biodiversity/sahyadri_enews/newsletter/issue9/index.htm)