Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom
Sean B. Carroll, Jamie W. Carroll, Josh P. Klaiss
Format: PDF / Kindle (mobi) / ePub
Author note: Jamie W. Carroll (Illustrator), Josh P. Klaiss (Illustrator)
Publish Year note: First published April 11th 2005
“A beautiful and very important book.”— Lewis Wolpert, American Scientist
Throughout much of the animal and even plant kingdoms, almost the same ancient genes code for almost the same proteins. And further, to everyone's astonishment, the genes involved in making the complex eyes of fruit flies are close matches to those involved in making the very different eyes of octopuses and people. So what leads to the nature's "endless forms most beautiful"?
The key to this mystery is being unravelled by "Evo Devo" or the new science of evolutionary development biology. By looking at how a single-celled egg gives rise to a complex, multi-billion celled animal, Evo Devo is illuminating exactly how new species – butterflies and zebras, trilobites and dinosaurs, apes and humans – are made and evolved. The key, it turns out, is all about location and timing... For anyone who has ever pondered where did I come from?, Endless Forms Most Beautiful explores our history, both the journey we have all made from egg to adult, and the long trek from the origin of life to the very recent origin of our species.
Literacy Genius (Cambridge, Mass.: Zoland, 1999). The most comprehensive analysis of butterfly wing patterns is H. Frederik Nijhout, The Development and Evolution of Butterfly Wing Patterns (Washington, D.C.: Smithsonian Institution Press, 1991), which explains much of the background I cover on the structure and diversity of wing patterns. The tool kit gene associated with the development of scales is reported in R. Galant et al., Current Biology 8 (1998): 807–13. The discovery of Distal-less
5.3 Integration of longitude and latitude determines positions of small clusters of cells that will become limbs. DRAWING BY JOSH KLAISS The physical integrity of switches is very important to normal development. If a switch is disrupted or broken by mutation, then the proper inputs are not integrated. Many of the spectacular mutants we’ve seen—flies with legs coming out of their head or humans with six fingers or toes—are due to broken switches that turn on tool kit genes in the wrong positions
representatives of major groups, but a parade of variations on basic body types. The Burgess Shale alone contains about 140 species of animals representing more than ten phyla. Other sites have yielded additional bounty; in particular, the Chengjiang fauna found in the Yunnan province of China is notable for spectacularly preserved specimens and, perhaps even more important, it is about 15 million years older than the Burgess Shale. The Chengjiang fauna helps push back the earliest known
largely one of increasing segment and limb type diversity. Trilobites possessed three main body regions—head, trunk, and pygidium—and in each of them, most or all of the segments and appendages appeared very similar to one another, differing generally only in size. In the living groups of arthropods, representatives of which had all appeared before or within the first 150 million years after the end of the Cambrian, the range of appendage types is much greater, to as many as a dozen or more.
evolve. FIG. 8.5 Predator damage on a butterfly. This Bicyclus anynana butterfly has been attacked, but because the damage is localized to the edge of the wing, it can still fly and reproduce. PHOTO (TAKEN IN KENYA) COURTESY OF PAUL BRAKEFIELD, UNIVERSITY OF LEIDEN Making Eyespots: Teaching Old Genes New Tricks The adult wing patterns we see are the realization of a process that begins in the caterpillar. Each wing forms from a flat disc of cells that grows enormously during the many