Let’s focus on the good ones
I think we can all agree that not all partnerships are the same. The worst are probably those, in which both of the coalition are suffering. However, equally unpleasant are unions, in which one of the partners is benefitting, while the other endures hardship often to the extent of a deterioration of health. Such one-sided relationships are, of course, the hallmark of parasites attacking their hosts. The best partnerships are undoubtedly those, in which both members benefit and although it can sometimes be difficult to decide whether partners support or exploit each other, there are some natural partnerships that leave no doubt as to whether there are winners or losers: in fact both are winners.
The seed-bearing, flowering plants rely on honey bees and other nectar-seeking insects for pollination and this is something we already learn at elementary school. Both are winners: the insects get their ‘fuel’ to fly around and the plants get their immobile pollen carried from one flower’s stamens to another flower’s carpel, which is generally a far better arrangement than having to rely on the wind. That in the fig a tiny wasp acts as the pollinator and in the yucca plant the same task can only be performed by a particular species of moth are less well known examples of such mutually beneficial associations, known as ‘symbioses’.
But insects are not the only pollinators: in the tropics large nectar-producing flowers often open upside down so that they cannot be flooded by the frequent tropical showers of the region and they rely on the services of hovering hummingbirds, which often have specifically adapted bills to fit into the calyx of the flower. There are tropical flowers, which are visited and pollinated by mammals too: bats come to mind and in New Zealand a bat even crawls around on the forest floor like a mouse in order to find the flowers it fancies. A Costa Rican plant by the name of Melastomacea blakea opens its lowly placed tiny greenish flowers only at night for a nectar-seeking rodent, which carries pollen from inflorescence to inflorescence and in Australia and in South Africa the lily Massonia depressa is pollinated by at least four rodent species, including two gerbils that carry pollen on the whiskers of their snouts. In Australia a number of tiny marsupials climb over the bottle-brush flowers of various Callistemon and Banksia species and in this way pick up and disperse massive amounts of pollen in their furs.
Needless to say that seed distribution and dispersal also largely depend on transport by birds and mammals. Some fruits are eaten and viable seeds (freed from their protective coats by the digestive enzymes of the consumer) are later expelled at various locations; others cling to the feet, feathers and fur (yes, and clothes as well) and may cover considerable distances in this way. But the strangest plant-animal partnership is probably found in the lowlands of the Amazon River, where for more than half a year specially-adapted trees and other flowering plants may be flooded by 3-5 m high water. Some 200 species of plants in that area have associations not with insects, birds, or mammals, but with fishes. Without the specialized species of these seed-eating fish, the unique Amazonian lowland forest would be in real danger – a danger, which increases with every new cattle ranch that reduces the habitat of the seed-loving and seed-distributing fish in that region.
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2016.
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