LIFE SERVING LIFE
by
Chris Maser

In a world exploding in the fire of ethnic and religious hatreds, I see fear and its grisly gang of distrust, divisiveness, separation, slander, reprisal, greed, fraud, distortion, and duplicity slithering through the dark halls of governments in each of the four hemispheres. It matters not which hemisphere you choose; each has its despots with fingers on the trigger as they suck the life energy from the people in a bid for the power of control. In their anxiety about life's uncertainties and the irrational fear of the future it spawns, their sense of security depends on this control to suppress the imagined portents of personal annihilation.

In such a world, it is difficult to remain consciously aware of the miraculous beauty of form and function that surrounds us. I am particularly blessed in that I have been privileged to travel in many lands, near and afar, from ocean strand to lofty mountain, from parching desert to steaming jungle, and in each have I found beauty unsurpassed: it may have been the odor of jasmine along the Nile, the smile of a Nubian child, the soft touch of a Chilean fern, the iridescence of a Nepalese sunbird, the fuzzy face of an Austrian edelweiss, the intricate structure of a Japanese Shinto shrine, the alert stance of a tiger beetle on a jungle trail in Malaysia, or the leap of a flying fish in the middle of the Atlantic Ocean. Each experience is a snapshot, a touchstone along the continuum of evolution through which the eternal mystery of life unfolds.

Part of our inability to grasp the eternal mystery with our intellect is that no two things in the universe have ever been—or ever will be—exactly the same. Therefore, no two things can ever be equal—only different and complementary in their service to planet Earth. Moreover, all life is composed of physical relationships in ever-changing patterns and rhythms that both affect life and are, in turn, affected by life. In this sense, life not only is pattern seeking and pattern sensitive but also is guided by the eternal rhythms of the universe. As well, every life form is a microcosm of the whole—from the most simple to the most complex.

Everything in the universe is thus connected to everything else in a cosmic web of interactive feedback loops, all entrained in self-reinforcing relationships that continually create novel, never-ending stories of cause and effect, stories that began with the eternal mystery of the original story, the original cause. Everything, from a microbe to a galaxy, is defined by its ever-shifting relationship to every other component of the cosmos. Therefore, "freedom" (perceived in the classical sense as the lack of constraints) is merely a continuum of fluid relativity. Hence, every change (no matter how minute or how grand) constitutes a systemic modification that produces novel outcomes. But, not all feedback loops are competitive; many, although hidden from casual observation, comprises reciprocal relationships in which life serves life, such as that of figs and their wasps.

OF FIGS AND WASPS

Fig trees and their pollinating wasps, which are principally groups of tropical organisms, are obligatory mutualists, a form of symbiosis wherein the survival of one partner requires the survival of both. The fig-wasp feedback loop works as follows:

Fig wasps began to pollinate and co-evolve with figs 90 million years ago, even before continental drift separated what we today think of as the Old World and New World groups of figs, of which there are over 750 recognized species. As for the fig wasps, they form a complex of cryptic species that evolved separately for more than 1.5 million years. A cryptic-species complex is a group of species that satisfies the biological definition of species—that is, they are reproductively isolated from each other but are virtually indistinguishable on a morphological basis. The only way to tell them apart is through DNA sequencing.

Some cryptic species of fig wasps are actually sibling species, which means they not only shared the same ancestor but also probably evolved within a single species of host fig or very closely related species. However, genetically identical wasps may also be found in fig hosts of two different species, a finding that suggests new associations are formed now and then.

Each species of fig has one or more species of small wasp, the female of which pushes her way into the fig while it's still green and hard. As she squeezes herself inside, her wings are torn off. Once within the fig, she is confronted with three kinds of flowers: male, short female, and long female.

To fulfill her life's purpose, she must make her way past the immature male flowers, which, as yet, have no pollen. She then moves further down into the hollow, where she dusts the female flowers with the pollen she brought from the fig in which she grew up. A female wasp can only reach the ovaries of the short female flowers with her ovipositors, in which she lays her eggs and dies soon after. Meanwhile, the long flowers become the fig's seeds.

The eggs laid, the fig tree chemically detects their presence and surrounds them with plant tissue. The eggs hatch and the fig provides the rapidly developing larvae with enough food to grow and restart the cycle. While the larvae grow inside the fig, the male flowers mature.

The male wasps are born first, but look nothing like a wasp because they have neither eyes nor wings; yet they soon detect the baby females and mate with them. Before their brief lives are forfeited, the males perform one other duty: they enlarge the original entrance, which allows the females to exit with their wings intact.

For their part, the female wasps are dusted with pollen as they squeeze past the male flowers to exit the fig. Once outside, they carry the pollen to another green fig, which they, in turn, will pollinate on their way to laying their eggs. After the wasps have left or died, the figs become bright in color, soft, and succulent as they ripen.

In return for providing a home and nourishment for the wasps, fig trees get their flowers pollinated. Without their tiny symbiotic wasps, the figs would not ripen, and the tree would eventually become extinct. Nevertheless, the population of wasps can be maintained only if figs are produced year-round, and because individual fig trees flower synchronously, the wasps that pollinate them have to locate a new individual host tree at each generation.1 Next, consider the whistling-thorn acacia and its contingent of ants.

WHISTLING-THORN

Unlike many acacias, the whistling-thorn does not deter herbivores through the production of toxic compounds. Instead, it recruits colonies of ants as bodyguards against hungry herbivores eager to chomp its leaves, such as giraffes and elephants. At the slightest movement of a branch the ants, which live only in these acacias, swarm out and deliver painful stings to munching giraffes, elephants, or other browsers.

The whistling-thorn acacia is a fair employer, however. In addition to having regular thorns, it also has modified pairs of thorns, which are joined at the base by a hollow, bulbous swelling (called a domatia) that is up to a little more than an inch in diameter. These thorns provide excellent nesting sites for the ants. In addition, special glands at the tips of their leaves produce a sweet secretion for the ants to eat.

Savage competition for the whistling-thorn exists among the four species of ants that attend to it. When the branches of one tree form a bridge to another, the ants invade their neighbors and battle violently until one colony wins control of the tree, after which the colony may grow to be one hundred thousand strong. The black-headed ant, which is the least warlike, comes out very badly in these battles, losing more of its population than any of the other three species.

To defend their trees against invasion, black-headed ants actively chew off all horizontal shoots, which causes the trees to grow tall and skinny and thereby avoid contact with trees that host enemy colonies. Pruning also causes the tree to allocate more energy to new shoots, healthier leaves, and larger nectaries, but unfortunately the ants also prune off all flower buds so the tree is effectively sterilized. Perhaps the tree trades reproduction for increased vigor and protection from browsing animals. As it turns out, however, the black-headed ant's relationship with its acacia is more parasitic than mutually beneficial.

In comparison, the mimosa ant is not only the most antagonistic but also the most cooperative partner with its acacia. These ants rely heavily on the swollen domatia for shelter and are formidable protectors in return. But with no herbivores around to browse on the leaves, the ant's services are not required, and the partnership begins to sour at both ends. The tree begins to evict the ants by shrinking its pro-ant services—namely, reducing the output of its nectaries. With less food and smaller homes, the ants are twice as likely to farm sap-sucking scale insects, whose waste fluid is a sugary liquid called honeydew, which the ants drink, but to make it, the scale insects must suck the juices of the tree. Consequently, the ants are less likely to marshal a defense against such marauding browsers as giraffes and elephants.

Conversely, Sjöstedt's ants actually seem to benefit from a tree's reduced investment in maintaining the aggressive mimosa ants. Less common than mimosa ants, Sjöstedt's ants take a more relaxed attitude toward the partnership, one that could even be viewed as parasitic because it defends the tree less aggressively and ignores the swollen domatia. Instead, it occupies boreholes excavated by beetle larvae.

Because Sjöstedt's ants are dependent on these beetle-created holes, they facilitate the beetle's ability to feed on the trees. The ants don't get upset with the suffering of their competitor, however. When the acacias reduce their provisions, Sjöstedt's ants simply more than double the members of their colony.

Penzig's ant, which is the only species that does not eat the nectar produced by its host acacia, actively destroys the nectar glands in order to make a tree less appealing to the other species. Consequently, the mutualistic feedback loops between whistling-thorn acacias and resident ants break down in various ways in the absence of large herbivores, and the acacias become less healthy as a result. Large herbivores are therefore critical components in the never-ending stories of these dynamic systems. For want of a giraffe or elephant to munch on the trees, the protective ants diminish and leave the whistling-thorn acacia in dire straits.2 Life also serves life beneath the waves, as the following example illustrates.

THE DUSKY FARMERFISH

The Dusky farmerfish around the Japanese islands of Ryukyu, Sesoko, and Okinawa establish and maintain monocultural farms of the red algae (seaweed known as filamentous rhodophytes) by defending them against invading grazers and by weeding out indigestible algae. To control their monocultures, the fish bite off the undesirable species of algae, swim to the edge of their territorial farms, and spit out the unwanted "weeds."3

Because the crops of red algae grow only in fish-tended monocultures, they die out if a farmerfish is removed from its farm. This, in turn, makes the algae's survival dependent on a fish's ability to maintain its farm. Since this is the only algae harvested and eaten by the fish as its staple food, the reciprocal feedback loop is one of obligatory cultivation for mutual benefit.4 In addition to simply maintaining a monocultural algae farm, however, the farmerfish inadvertently create a distinctive habitat that maintains and enhances a multi-species coexistence of foraminifera.5

ENDNOTES

  1. The preceding story of figs and fig wasps is based on:  (1) Marie-Charlotte Anstett, Martine Hossaert-McKey, and Doyle McKey. Modeling the Persistence of Small Populations of Strongly Interdependent Species: Figs and Fig Wasps, Conservation Biology 11 (1997): 204-213; (2)Drude Molbo, Carlos Machado, Jan Sevenster, and others. Cryptic Species of Fig Pollinating Wasps: Implications for the Evolution of the Fig-Wasp Mutualism, Sex Allocation and Precision of Adaptation, Proceedings of the National Academy of Sciences 100 (2004): 5867-5872; and (3) Ian Giddy. Cloudbridge Nature Reserve, Nature Notes, no. 19 (2004), http://cloudbridge.org/fig-wasp.htm (accessed on January 25, 2009).

  2. The preceding story of the whistling-thorn acacia is based on:  (1) Truman P. Young, Cynthia H. Stubblefield, and Lynne A. Isbell. Ants on Swollen-Thorn Acacias: Species Coexistence in a Simple System, Oecologia 109 (1996): 98-107 and (2) Todd Palmer, Maureen L. Stantan, Truman P. Young, and others. Breakdown of an Ant-Plant Mutualism Follows the Loss of Large Herbivores from an African Savanna, Science 319 (2008): 192-195.

  3. (1) Hiroki Hata and Makoto Kato. A Novel Obligate Cultivation Mutualism Between Damselfish And Polysiphonia Algae. Biology Letters, 2 (2006):593-596; (2) Hiroki Hata and Makoto Kato. Monoculture and mixed-species algal farms on a coral reef are maintained through intensive and extensive management by damselfishes. Journal of Experimental Marine Biology and Ecology, 313 (2004):285-296; (3) Hiroki Hata and Makoto Kato. Weeding by the herbivorous damselfish Stegastes nigricans in monocultural algae farms. Marine Ecology Progress Series, 237 (2002):227-231; and (4) Hiroki Hata and Makoto Kato. Demise of monocultural algal farms by exclusion of territorial damselfish. Marine Ecology Progress Series, 263 (2003):159-167.

  4. Ibid.

  5. (1) Hiroki Hata, Moritaka Nishihira, and S. Kamura. Effects of habitat-conditioning by the damselfish Stegastes nigricans on community structure of benthic algae. Journal of Experimental Marine Biology and Ecology, 280 (2002):95-116 and (2) Hiroki Hata and Moritaka Nishihira. Territorial damselfish enhances multi-species co-existence of foraminifera mediated by biotic habitat structuring. Journal of Experimental Marine Biology and Ecology, 270 (2002):215-240.



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