exciting field of evolutionary development
Many women scientists have made discoveries that reinforce the Theory of Evolution through the fields of biology, anthropology, molecular biology, evolutionary psychology. Here are a few of the most prominent women evolutionary scientists who made contributions to the Modern Synthesis of the Theory of Evolution are Rosalind Franklin, Mary Leakey, Jane Goodall, Mary Anning and Barbara McClintock.
1 of 6: Hox genes
2 of 6: what is evolutionary developmental biology?
3 of 6: Tim Blais's parody
4 of 6: blast from the past :: Thomas hunt morgan's fruit fly
5 of 6: Genes control body segmentation
6 of 6: Current research in evo-devo
Image source :: Mark, M., Rijli, F. & Chambon, P. Homeobox Genes in Embryogenesis and Pathogenesis. Pediatr Res 42, 421–429 (1997). https://doi.org/10.1203/00006450-199710000-00001
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"Endless forms most beautiful" is a direct quote from Charles Darwin's poem. Yes, you heard me right, he produced a lyrical crescendo in the last paragraph of On the Origin of Species.
'Thus, from the war of nature, from famine and death,the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.' The first and still perhaps the most stunning discovery of Evo Devo is the ancient origin of the genes for building all sorts of animals. The fact that such different forms of animals are shaped by very similar sets of tool kit proteins was entirely unanticipated.Tthe discovery that organs and structures that were long viewed as independent analogous inventions of different animals, such as eyes, hearts, and limbs, have common genetic ingredients controlling their formation has forced a complete change in our picture of how complex structures arise. Rather than being invented repeatedly from scratch, each eye, limb, or heart has evolved by modification of some ancient regulatory networks under the command of the same master gene or genes. Parts of these networks trace back to the last common ancestor of bilaterians (Urbilateria), and earlier forms. Hox genes help lay out the basic body forms of many animals, including humans, flies, and worms. They set up the head-to-tail organization. You can think of them as directing instructions as an embryo develops: "Put the head here! Legs go over there!". The Hox gene family was first discovered in fruit flies in the lab of Thomas Hunt Morgan in 1915: Scientists in Morgan's lab were working with a large collection of fruit fly mutaants when they noticed that some had duplication of the thorax such that the flies had two sets of wings. Morgan's researchers late found that this mutation was caused by gene that they named "bithorax". (this gene is the first known Hox gene). Around the same time William Bateson observed homeotic transformations in other organisms (crayfish with extra oviducts, bees with lengs in place of antennae and polydactyly (extra fingers and toes) and extra ribs in humans. What they had done is, they had triggered the changes by damaging the fly's DNA.
How: Within each cell of the developing embryo is a chain called DNA. Experiments showed that DNA was somehow causing the embryo to divide into segments. They began to understand that the DNA itself was made up of segments called genes. Now, the question was so, how genes shape the body? One researcher Ed Lewis of Caltech studied this question for 30 years, his work led him to a controversial (but simple) idea. He proposed, that each segment of the fly was being directed to grow by a single gene. And a small set of genes (a kind of genetic toolkit) appeared to be laying out the entire body. Nobody thought that a single genecan control something as complex as the structure of the body. ~ Few interesting books ~
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