sábado, 29 de noviembre de 2008

Selección del Complexity Digest - Noviembre

Elysia chlorotica, the solar-powered sea slug, is about 3 cm long (Image: PNAS)

Solar-Powered Sea Slug Harnesses Stolen Plant Genes, New Scientist


Young E. chlorotica fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in earlier work.

But a mystery remained. Chloroplasts only contain enough DNA to encode about 10% of the proteins needed to keep themselves running. The other necessary genes are found in the algae's nuclear DNA. "So the question has always been, how do they continue to function in an animal cell missing all of these proteins," says Rumpho.

Darwin 200: The Needs Of The Many, Nature

Excerpts: Yet group selection - the idea that evolution can choose between groups, not just the individuals that make them up - has a higher profile today than at any time since its apparent banishment from mainstream evolutionary theory. And it gets better press, too. This is in part owing to the efforts of David Sloan Wilson, of Binghamton University in New York, who argues that the dismissal of group selection was a major historical error that needs to be rectified. And it does not hurt that he has been joined by Edward O. Wilson, the great naturalist and authority on social insects.

Darwin 200: Beneath The Surface, Nature

Excerpts: You might think that once evolution has found one way to get something done, it will stick with it. But similar physical forms can hide radically different wiring, (...).

Tunicates - also known as sea squirts - are humans' closest invertebrate cousins. They have tadpole-like larvae that closely resemble miniature vertebrate embryos and so were expected to build their bodies in the same way. But they don't. (..) It's as if you had found a car in which components of the engine were scattered all over the back seat - but the car still worked.

Genetics: Quick Change, Nature

Excerpts: By mutating just two genes, researchers in Belgium have turned a slender annual plant (...) into a bushy, woody perennial (...).

Variation In Evolutionary Patterns Across The Geographic Range Of A Fossil Bivalve, Science

Excerpts: Within a fossil bivalve genus, evolution tended to occur as a random walk at the highest latitudes and to be in stasis mode in deep marine environments.

The fossil record is the only direct source of data for studying modes (patterns) and rates of morphological change over long periods of time. Determining modes and rates is important for understanding macroevolutionary processes, but just how modes and rates vary within a taxon, and why, remain largely unaddressed. We examined patterns of morphological change in the shell of the Mesozoic marine bivalve genus Buchia over its geographic and temporal range.

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