Friday, August 26, 2011
"Since Darwin we know that we must explain the elephant not only in mechanistic terms (of mutation, selection and adaptation on the population level) but also in historical terms, as 'descent with modification', evolution in phylogeny. Molecular changes hundreds of millions of years ago constrain the possibility of change here and now. Not everything is possible, and evolutionary history is as much a story of constraint as functionality. Leonardo's 'flying machines' didn't just fail because bodies of a human size and weight fall under physical scaling laws limiting how big muscles could become. The evolutionary history that led to our present body size also stops us acquiring wings, either now or any time soon." Full article @ Nature
"In microbial “quorum sensing” (QS) communication systems, microbes produce and respond to a signaling molecule, enabling a cooperative response at high cell densities. Many species of bacteria show fast, intraspecific, evolutionary divergence of their QS pathway specificity—signaling molecules activate cognate receptors in the same strain but fail to activate, and sometimes inhibit, those of other strains. Despite many molecular studies, it has remained unclear how a signaling molecule and receptor can coevolve, what maintains diversity, and what drives the evolution of cross-inhibition." Full article: Social conflict drives the evolutionary divergence of quorum sensing @ PNAS.