Tight Genetic Linkage of Prezygotic Barrier Loci Creates a Multifunctional Speciation Island in Petunia

Most flowering plants depend on animal vectors for pollination and seed dispersal. Differential pollinator preferences lead to premating isolation and thus reduced gene flow between interbreeding plant populations [1, 2, 3 and 4]. Sets of floral traits, adapted to attract specific pollinator guilds, are called pollination syndromes [5]. Shifts in pollination syndromes have occurred surprisingly frequently [6], considering that they must involve coordinated changes in multiple genes affecting multiple floral traits. Although the identification of individual genes specifying single pollination syndrome traits is in progress in many species, little is known about the genetic architecture of coadapted pollination syndrome traits and how they are embedded within the genome [7]. Here we describe the tight genetic linkage of loci specifying five major pollination syndrome traits in the genus Petunia: visible color, UV absorption, floral scent production, pistil length, and stamen length. Comparison with other Solanaceae indicates that, in P. exserta and P. axillaris, loci specifying these floral traits have specifically become clustered into a multifunctional “speciation island” [ 8 and 9]. Such an arrangement promotes linkage disequilibrium and avoids the dissolution of pollination syndromes by recombination. We suggest that tight genetic linkage provides a mechanism for rapid switches between distinct pollination syndromes in response to changes in pollinator availabilities.

A bHLH Complex Controls Embryonic Vascular Tissue Establishment and Indeterminate Growth in Arabidopsis

Plants have a remarkable potential for sustained (indeterminate) postembryonic growth. Following their specification in the early embryo, tissue-specific precursor cells first establish tissues and later maintain them postembryonically. The mechanisms underlying these processes are largely unknown. Here we define local control of oriented, periclinal cell division as the mechanism underlying both the establishment and maintenance of vascular tissue. We identify an auxin-regulated basic helix-loop-helix (bHLH) transcription factor dimer as a critical regulator of vascular development. Due to a loss of periclinal divisions, vascular tissue gradually disappears in bHLH-deficient mutants; conversely, ectopic expression is sufficient for triggering periclinal divisions. We show that this dimer operates independently of tissue identity but is restricted to a small vascular domain by integrating overlapping transcription patterns of the interacting bHLH proteins. Our work reveals a common mechanism for tissue establishment and indeterminate vascular development and provides a conceptual framework for developmental control of local cell divisions.

Thinking Time : a multidisiplinary perspective on time

"Time" has been much less widely studied in psychology and related disciplines than has "space". This book offers theoretical and empirical insights into the study of time-related perception, memory, identity, learning, and reasoning. With carefully selected chapters by a truly international and interdisciplinary team of authors, this book provides an unterstanding of time and mind that goes beyond psychophysiology and experimental psychology to encompass wider phenomena, both social and eduational. By providing a philosophical basis for understanding how the mind "graps" the concept of time and the timing of behavior in a cultural context, this unique book should help promote a cross-fertilization of research on this important dimension, which ist so often neglected in cognitive and sociocultural research.

Unnatural Narration beyond Postmodernist Alterities

Postmodernism has frequently employed unnatural narration with the aim to disturb and subvert conventionalized reading practices. Postmodernist discourses thus widely associate the unnatural with alterity, marginality and the suppressed. In this paper, I caution against such a perspective, which threatens to unduly limit our understanding of the broad variety of relations between natural and unnatural narrative on the one hand, and of the multiple possible functions of unnatural narratives on the other. Taking my cue from the use of unnatural narration in a number of recent novels, like Mark Z. Danielewski’s House of Leaves (2000), Michael Chabon’s Amazing Adventures of Kavalier & Clay (2000), or Yann Martel’s Life of Pi (2001), I will argue that a postmodernist approach which foregrounds ontological and epistemological questions and emphasizes alterity and subversion remains blind to some of the pragmatic implications that are the main concern of the unnatural narratives under consideration. This not only begs the question whether and in how far such a shift from ontological and epistemological towards pragmatic concerns constitutes a move beyond postmodernism, but also calls for a reconsideration of some of our widely established theories and assumptions about unnatural narratives.

The Serious Business of Play

Most managers see strategy development as serious business. It is ironic, then, that some of the most remarkable strategic breakthroughs in organizations emerge not from well-ordered processes but from messy, ambiguous and sometimes irrational activities - pursuits that can best be described as play. Referring to research in the fields of developmental psychology and anthropology, the authors argue that play can stimulate the development of cognitive, interpretive skills and engender an emotional sense of fulfillment. It can help establish a safe environment for introducing new ideas about market opportunities, generating debate about important strategic issues, challenging old assumptions and building a sense of common purpose. The authors draw on their own experiences working with managers at the Imagination Lab Foundation and Templeton College, Oxford University, and they make sure to point out that play is no substitute for rational, conventional strategy development. Indeed, after the creative sessions are over, plenty of hard work remains to translate the ideas and insights into processes and actions.