Siderophore cooperation of the bacterium Pseudomonas fluorescens in soil

While social interactions play an important role for the evolution of bacterial siderophore production in vitro , the extent to which siderophore production is a social trait in natural populations is less clear. Here, we demonstrate that siderophores act as public goods in a natural physical environment of Pseudomonas fluorescens : soil-based compost. We show that monocultures of siderophore producers grow better than non-producers in soil, but non-producers can exploit others' siderophores, as shown by non-producers' ability to invade populations of producers when rare. Despite this rare advantage, non-producers were unable to outcompete producers, suggesting that producers and non-producers may stably coexist in soil. Such coexistence is predicted to arise from the spatial structure associated with soil, and this is supported by increased fitness of non-producers when grown in a shaken soil–water mix. Our results suggest that both producers and non-producers should be observed in soil, as has been observed in marine environments and in clinical populations.

Studies in Turkish History and Folk-Legend

The Karaosmanoglou dynasty, which during the eighteenth century and part of the nineteenth ruled the province of Saroukhan (Magnesia) in Asia Minor, stands almost alone in Turkish history as an example of a family which not only won and retained a wide local supremacy, but was conspicuous for family solidarity and wise administration throughout its tenure of power. Of the numerous pretenders to independence who disputed the Sultans' sway during the centuries in question few were able to make their claims hereditary and none could justly boast as could the Karaosmanoglou that their administration had raised their dominions from poverty and disorder to a degree of prosperity unknown probably since the Roman empire.The history, real and mythical, of this great Turkish family affords an interesting illustration of the growth of folk-tradition and its relation to historical fact, since we have here the rare advantage of being able to compare and contrast fact and fiction, and even to trace the growth of the myth. Less than a hundred and fifty years from the rise of the family, which is not extinct at the present day, its real origin is completely obscured; its actual history is supplanted by a purely legendary set of incidents and associations by which the family gains in prestige no less than in antiquity.