Eight Little Piggies Read Online Free PDF

finest biologists of land snails took up the study of Partula in the next generation, building explicitly on Crampton’s work—Bryan Clarke of the University of Nottingham, Jim Murray of the University of Virginia, and Mike Johnson of the University of Western Australia. They have published numerous papers, in varying combinations of authorship, from the mid-1960s to the present day. Working primarily on everyone’s favorite island of Moorea, they have made important revisions to Crampton’s conclusions and have added great sophistication in mathematical procedures (now computerized) and genetical methods not available to Crampton. In 1980, Murray and Clarke ended an important paper, “The genus Partula on Moorea: Speciation in progress,” with these words:
    Although we cannot yet reconstruct exactly the evolutionary history of the Moorean taxa, they have already revealed in exceptional detail the pattern of interactions between incipient species, and have presented some fascinating paradoxes. They offer both a museum and a laboratory of speciation.
    Add snails to Burns’ litany about the best laid plans of mice and men. Great expectations die quickly on the bonfires of human vanity. We are only a decade from these brave words of 1980, but Moorea is no longer a laboratory for studying active speciation in Partula . It has become a mausoleum.
    Think of all the metaphors you know for little things made worse by attempted solutions that cascade to even greater problems, for you need this apparatus to grasp the extirpation of Partula on Moorea. Think of Pandora’s box. Think of the old woman who swallowed a fly in the folk song. (She then swallowed a spider to catch the fly, a bird to catch the spider, a cat to catch the bird…and up the size range of the animal kingdom. Each successive verse gets longer as singers run through the full range of ingestions, but the last is stunningly brief: “There was an old lady who swallowed a horse. She died, of course.”)
    Partula eats fungi growing upon dead vegetation and poses no threat whatever to agriculture. Its only, and slight, impact upon the native economy is entirely positive, as women string the shells together to make leis for the tourist trade. But animals introduced onto isolated islands often play havoc both with native organisms and with agriculture, witness the rabbits of Australia and, to cite the most dangerous creature of all, the humans who wiped out so many species of moas on New Zealand. An introduced snail began the sad chain of destruction on Moorea.
    In sharp contrast with the benign Partula , African tree snails of the genus Achatina are, in almost all cases, unmitigated disasters. First of all, they are gigantic (as snails go); second, they are voracious herbivores of living plants, including many agriculturally important species. With their clear record of destruction on island after island, I am amazed that people still introduce them purposefully. (They are brought in for food, for I’m told that they are succulent, and you do get a lot of meat per creature.) Achatina was first imported to the Indo-Pacific realm in 1803 by the governor of Réunion who brought them from Madagascar so that a lady friend could continue to enjoy snail soup. They escaped from his garden and devastated the island. By 1847, they had reached India. In the 1930s, they began to spread into South Pacific islands, usually by purposeful introduction for food.
    Achatina fulica reached Tahiti in 1967 and soon spread to neighboring islands. By the mid-1970s, the infestation had become particularly serious on Moorea. The snails even invaded human dwellings; one report tells of a farmer who removed two wheelbarrow-loads of Achatina from the walls of his house. Admittedly, something had to be done. But que faire , as they say in this very French land?
    The attempted solution, like the horse ingested to catch the fly, created greater havoc than the original problem. Biological control