A better understanding of the natural history of model organisms will increase their value as model systems and also keep them at the forefront of research. DOI: 10.7554/eLife.06956.001 JANE ALFRED* AND IAN T BALDWIN*

The UV to soft X-rays of luminous AGNs dominate their bolometric luminosity, driven by an accretion-powered dynamo at the center. These photons ionize the surrounding gas, thereby providing clues to fueling and exhaust. Two sets of important relationships – neither of them understood – link the continuum and gas properties. (i) Boroson & Green’s ‘eigenvector 1’ relationships: Steeper soft X-ray...

The Baldwin EEect, rst proposed in the late nineteenth century, suggests that the course of evolutionary change can be innuenced by individually learned behavior. The existence of this eeect is still a hotly debated topic. In this paper clear evidence is presented that learning-based plasticity at the phe-notypic level can and does produce directed changes at the genotypic level. This research ...

The puzzle of the persistent question marks (a phrase coined by Harvey in 1993) refers to the occurrence of residual learnable alleles in simulations of the Baldwin effect, which concerns interactions between learning and evolution. Explanations of the puzzle have focused on the role of fitness proportional selection pressures and of drift. We replicated the original 1987 model by Hinton and No...