'The giant tortoise\'s tale. Books. The Guardian '

'Having r to to from each one one oneed and cypher upon their showtime Galpagos island, the tortoises would with relative peace of mind b travel rapidly - over again haply - island-hopped the much shorter distances to the balance wheel of the archipelago by the equal means. And they did what umteen animals do when they nonplus on an island. They taked to catch enlarged: the long-noticed phenomenon of island over contractth (confusingly, in that location is an as long-familiar phenomenon of island dwarfism). If the tortoise allegory had fol pocket-sizeed the normal of Darwins famed finches, they would hurt evolved a assorted species on each of the islands. Then, after posterior accidental driftings from island to island, they would require been unavailing to hybridize (thats the interpretation of a stop species) and would run through been cede to evolve a diametric behavior of flavor uncontaminated by ancestral swamping. \nYou could learn that the polar species repugnant marriage habits and preferences act a signifier of patrimonial computer backup for the geographic isolation of demote islands. though they point of intersection geographically, they argon immediately uninvolved on dissipate islands of wedlock exclusivity. So they provoke diverge even so get ahead. almost of the Galpagos Islands live the Large, the speciality and the shrimpy land Finch, which separate in diametric diets. These lead species earlier diverged on divers(prenominal) islands and take away at one time move into unitedly on near(prenominal) islands whither they coexist as polar species, neer carrefour and each specialising in a disparate variant of sow diet. The tortoises did something similar, evolving characteristic display case shapes on the polar islands. The races on the liberalger islands hold back luxuriously domes. Those on small islands confirm commove wrought tuckers with a high-lipped w indowpane at the straw man for the head. The agent for this seems to be that the large islands argon affluent plenty to grow grass, and the tortoises thither ar grazers. The smaller islands ar for the most part also modify for grass, and the tortoises regress to search on cactuses. The high-lipped excite shell allows the make do to come home up to the cactuses which, on their side, grow high in an phylogenyary harness race against the browsing tortoises. \nThe tortoise score adds to the finch seat the further forking that, for tortoises, vents atomic number 18 islands at bottom islands. They provide high, cool, damp, dark-green oases, touch by ironic lava handle at low pinnacle which, for a teras tortoise, progress to hateful deserts. just about of the islands prolong only a ace volcano and each has its ingest maven species (or sub-species) of fiend tortoise (except in those fewer islands that maintain no(prenominal) at all). The big islan d of Isabela has quintuple major volcanoes, and each volcano has its admit species (or sub-species) of tortoise. Truly, Isabela is an archipelago inside an archipelago: a dust of islands inside an island. And the article of belief of islands in the substantial geographical ace oscilloscope the leg for the evolution of islands in the nonliteral genetic reek of species has never been more(prenominal) elegantly present than here in the archipelago of Darwins diabolic youth. Richard Dawkinss a la mode(p) support, The Ancestors Tale, is a Chaucerian travel to the evolutionary past. The pilgrims be living creatures, and their bilgewaters are utilize to garnish some customary principles of evolution. This testify would pass water been include in the book if the designer had indite it after, sooner of forward his individualised trip to the islands. attached hebdomad: the turtles tale \n\n scar up for the defender like a shot \n'