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Lamarkian evolution (of a sort) returns as a helper

#1
C C Offline
https://www.sciencemag.org/news/2018/11/...-evolution

EXCERPT: . . . The toads display phenotypic plasticity, the ability to change how they look and act, and how their tissues function, in response to their environment. [...] Recently, [David] Pfennig and his team have come upon something even more remarkable than that dramatic behavioral plasticity. In one species of spadefoot toad, they found, the carnivorous tadpole stage has become entrenched—there's no need for a dietary trigger. A flexible response to the environment somehow became fixed.

To some, such findings evoke the spirit of the French naturalist Jean-Baptiste Lamarck. Decades before Charles Darwin laid out his evolutionary theory in On the Origin of Species, Lamarck and other biologists proposed their own mechanisms for evolutionary change. Among his ideas, Lamarck famously asserted in the early 1800s that organisms can acquire a new trait in their lifetime—longer necks for giraffes reaching for food; webbed feet for water birds—and pass it on to their offspring. Later, biologists cast aside Lamarckism, as the classic view of evolution emerged: that organisms evolve as a result of natural selection acting on random genetic changes.

Now, however, evolutionary biologists have shown in multiple organisms, including lizards, roundworms, and yeast, that a plastic response can pave the way for permanent adaptations. The new evidence, much of it reported at the Second Joint Congress on Evolutionary Biology here this summer, shows the connection between plasticity and evolution "is a real thing," says Carl Schlichting, an evolutionary biologist at the University of Connecticut in Storrs. "If you look for it, you are going to find it."

On the surface, the findings vindicate Lamarck: Acquired traits can be inherited. But biologists are quick to stress that what these organisms show is not true Lamarckian evolution. Application of Lamarck's idea to modern findings "has led to a lot of confusion and debate," says Cameron Ghalambor, an evolutionary ecologist at Colorado State University in Fort Collins.

As biologists explore the underpinnings of plasticity and how it can lead to permanent change, they've uncovered a process that extends traditional evolutionary mechanisms rather than challenging them. The plasticity those changeable tadpoles display is built into their genetic code. And when an "acquired" trait does become permanent, it is because of mutations that "fixed" the plastic trait—a process biologists call genetic assimilation.

Although some researchers bristle at giving any credence to Lamarckian thinking, "The way plasticity can influence evolution really fits very comfortably in the general framework of how we think evolution works," Pfennig says....

MORE: https://www.sciencemag.org/news/2018/11/...-evolution
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#2
Syne Offline
There's not much "sort of" about it.
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