Hot Jungle Romance!
The lighting is moody and atmospheric. The fragrance of exotic flowers fills the air. The temperature is balmy, and birds sing out of sheer avian exuberance. There is even chocolate nearby! Am I talking about a romantic getaway on Valentine’s Day? Not exactly…
With the return of our Tropical Odyssey exhibit, I’ve been thinking a lot about how pollination happens in tropical rainforests. You see, pollination is a superb example of mutualism, that lovey-dovey interaction in which both parties, in this case a plant and an animal, benefit. Pollination merely means that an animal transports pollen from one flower to another, allowing the plant to reproduce, and often gaining a reward in the process.
Now, pollination isn’t the only way plants and animals can cooperate; in many cases, plants and animals exchange food for protection or for mobility. But pollination not only benefits the plant and animal, but often us as well. After all, almost a third of all the food we eat wouldn’t be possible without the help of animal pollinators!
But just like romance, pollination is not a one-size-fits-all proposition. Some relationships are extremely exclusive. The relationship between the Anagraecum sesquipedale orchid and its sphinx moth pollinator is an example of extreme specialization—not just any old pollinator will do. This orchid from Madagascar has a nectar spur that reaches up to a foot in length. Charles Darwin, upon learning about the plant, predicted that a pollinator had to exist with a similarly long tongue. Many years later, a sphinx moth (Xanthopan morganii praedicta) was found with a foot-long tongue, pollinating the orchid. The benefit, of course, is that little pollen is wasted with this degree of specialization. However, if one species disappears, it means the extinction of the other species.
Other relationships offer surprising rewards. Many flowers offer a simple sugar reward for the animal pollinator’s help. However, in the case of euglossine bees and orchids in the New World tropics, no nectar is exchanged. Instead, the male bee visits the flower to collect rich fragrances. The bees store the fragrances in specialized leg patches and display themselves in rowdy groups. The fragrance, collected together in all that boy-bee glory, attracts female euglossine bees. In this exchange, the plant finds the right plant, and the bee finds the right bee. How romantic is that?
Of course, other relationships are a bit on the dysfunctional side. Occasionally, a pollinator will drink the nectar and eat the pollen without transporting any pollen to other plants. Or what about Ophrys orchids, which mimic the female of certain ants, bees and wasps? The size, shape, color and even smell of the flower provide attractive cues for juvenile male insects. These naive males attempt to mate with the orchid and get bonked on the head with the pollinia. The mimicry is good enough that the young males are deceived more than once. Well, Shakespeare did say that the course of true love never did run smooth!
Over time, these mutualisms lead to more diversity. Just think of all the different types of flowers, the different types of bees and other insects! According to some scientists, this plethora of relationships may be one reason the rainforest has so many different plants and animals. The adaptations required to keep these romances lively create new niches and new relationships. Before you know it, the rainforest is full of thousands of plants and pollinators, dancing their complicated dances.
This amazing diversity of tropical rainforests is one quality that makes these habitats special and worth protecting. Of course, all the products we rely on, such as chocolate, provide other reasons to conserve these wondrous parts of the world. For example, changes to the rainforest in Central America can affect cocoa production. Without mud and leaf litter in the forest environment, cocoa’s pollinators, tiny flies called midges, lose their breeding areas. With the removal of rainforest plants, midge populations plummet, and cacao flowers go unpollinated. And that means less chocolate to give to your sweetie on Valentine’s!
Choices we make can help protect the remaining tropical rainforests. If we want to show our love for the tropical rainforests in the world, we can act like mutualists, and try to do what benefits plant, pollinator and people alike. If you’d like to learn more about rainforests and how to conserve them, visit our Tropical Odyssey exhibit, which reopened this month.
Posted by Amy Yarger, Butterfly Pavilion Horticulturist
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