![]() ![]() The researchers found that egg shape was a continuum - with many species overlapping. Mahadevan/Museum of Vertebrate Zoology, Berkeley) The researchers began by plotting the shape - as defined by the pole-to-pole asymmetry and the ellipticity - of some 50,000 eggs, representing 14 percent of species in 35 orders, including two extinct orders.Īverage egg shapes for each of 1400 species (black dots), illustrating variation in asymmetry and ellipticity. Mahadevan is also a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard University. “We showed that egg shapes vary smoothly across species, that it is determined by the membrane properties rather than the shell, and finally that there is a strong correlation linking birds that have eggs that are elliptical and asymmetric with a strong flight ability, the last a real surprise.” Paulson School of Engineering and Applied Sciences (SEAS), Professor of Organismic and Evolutionary Biology, and of Physics at Harvard. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at the John A. ![]() “Our study took a unified approach to understanding egg shape by asking three questions: how to quantify egg shape and provide a basis for comparison of shapes across species, what are the biophysical mechanisms that determine egg shape, and what are the implications of egg shape in an evolutionary and ecological setting,” said senior author, L. Using an evolutionary framework, the researchers found that the shape of an egg correlates with flight ability, suggesting that adaptations for flight may have been critical drivers of egg-shape variation in birds. Using methods and ideas from mathematics, physics and biology, they characterized the shape of eggs from about 1,400 species of birds and developed a model that explains how an egg’s membrane determines its shape. The answer to that question may help explain how birds evolved and solve an old mystery in natural history.Īn international team of scientists led by researchers at Harvard and Princeton universities, with colleagues in the UK, Israel and Singapore, took a quantitative approach to this question. The question is, how and why did this diversity in shape evolve? Now, 360 million years later, bird eggs come in all shapes and sizes, from the almost perfectly spherical eggs of brown hawk- owls to the tear-drop shape of sandpipers’ eggs. The evolution of the amniotic egg - complete with membrane and shell - was key to vertebrates leaving the oceans and colonizing the land and air.
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