The Secret Lives of Fig Trees

1. Chetan Vaity July 2007 The Secret Lives of Fig Trees

2. Pollination • Transfer of pollens to ovules • Seeds/Fruits will not develop if ovules are not fertilized • Agents in cross-pollination: wind, water, bees, birds, bats • In fruit farming, sometimes pollinators are introduced artificially

3. Fig fruits? • These are not fruits – but orchards containing flowers! • Ovules (short and long) and male flowers • How does pollination take place?

4. Fig wasps • Very small insects – about the size of a mosquito • They are the pollinating agents for figs

5. Action inside the fig • Female wasp enters the ostiole - loses her antennae and wings • Inside the fig, the wasp lays eggs in "short" ovules using the long ovipositor • The pollen is transfered to the "long" ovules - thus fertilizing them • Female wasp dies soon after – inside the fig

6. The ovipositor is just long enough to reach the ovules on short “flowers” Female wasp laying eggs • The fertilized ovules in the “long” flowers becomes seeds

7. Male wasps hatch and mate with females which are still unborn In some species, males fight for females and kill each other - all within the fig After the mating, the males make a hole in the fig - and die soon after Some weeks later, the male wasps...

8. The female wasps hatch out - already fertilized The male flowers also are ready with pollen The female wasps escape from the hole in the fig – taking up pollen in the process The female wasps

9. The females fly to another fig tree of the same species The figs produce chemicals which attracts the female wasp The cycle starts again...

10. The fig trees get effective pollination out of the deal The wasps are nurtured/fed inside the fig An unpollinated fig (no wasp entered it) is aborted by the tree Fig and wasp species are usually locked together Fig trees “flower” with lack of synchrony – all year round – thus forming food source for many small animals Mutual dependence

11. Once the wasps leave, the fig ripens Small animals, monkeys, birds eat the figs Seed passes through the digestive system and gets deposited along with dung Seed dispersal

12. Strangler Figs (along with hostel mates)

13. Young tree shoots off roots/branches through the air trying to reach the ground Branches and stem of the host tree are enveloped and strangled The girth growth of the stem of the host is restricted Sunlight competition - the fig grabs most of the light and leaves the host tree in shade Stranglers are murderers... • The fig eventually envelopes the entire main stem and host may die and rot away • The fig is left with a hollow trunk where small animals can live

14. These wasps can lay eggs from outside the fig! They are of no benefit and indeed cause harm to the fig tree Non-pollinating wasps

15. The bodhi sapling was planted in SriLanka after Buddha's death The Bodhi tree (also a fig) • The bodhi tree at Gaya

16. Wikipedia FigWeb (http://www.figweb.com/) http://home.planters.net/~thegivans/figsex.html Wayne's World (http://waynesword.palomar.edu/ww0701.htm) Climbing Mount Improbable – Richard Dawkins References