Diverse bilaterian clades emerged apparently within a few million years during the early Cambrian, and various environmental, developmental, and ecological causes have been proposed to explain this abrupt appearance. A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record, demonstrating a macroevolutionary lag between the establishment of their developmental toolkits during the Cryogenian [(850 to 635 million years ago (Ma)], and the later ecological success of metazoans during the Ediacaran (635 to 541 Ma) and Cambrian (541 to 488 Ma) periods. We argue that this diversification involved new forms of developmental regulation, as well as innovations in networks of ecological interaction within the context of permissive environmental circumstances.

https://science.sciencemag.org/content/sci/334/6059/1091.full.pdf

The Cambrian conundrum: Early divergence and later ecological success in the early history of animals

Scientific activities take place within the structured sets of ideas and assumptions that define a field and its practices. The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation. Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. We review some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the 'extended evolutionary synthesis' (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism-environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2015.1019

The extended evolutionary synthesis: its structure, assumptions and predictions.

The HIV envelope (Env) protein gp120 is protected from antibody recognition by a dense glycan shield. However, several of the recently identified PGT broadly neutralizing antibodies appear to interact directly with the HIV glycan coat. Crystal structures of antigen-binding fragments (Fabs) PGT 127 and 128 with Man9 at 1.65 and 1.29 angstrom resolution, respectively, and glycan binding data delineate a specific high mannose-binding site. Fab PGT 128 complexed with a fully glycosylated gp120 outer domain at 3.25 angstroms reveals that the antibody penetrates the glycan shield and recognizes two conserved glycans as well as a short β-strand segment of the gp120 V3 loop, accounting for its high binding affinity and broad specificify. Furthermore, our data suggest that the high neutralization potency of PGT 127 and 128 immunoglobulin Gs may be mediated by cross-linking Env trimers on the viral surface.

/pdf/a-potent-and-broad-neutralizing-antibody-recognizes-and-3dqvjtxj1b.pdf

A Potent and Broad Neutralizing Antibody Recognizes and Penetrates the HIV Glycan Shield

New developments in goblet cell mucus secretion and function

https://www.cell.com/current-biology/pdf/S0960-9822(15)01177-X.pdf

Uncertainty in the Timing of Origin of Animals and the Limits of Precision in Molecular Timescales.

In 1909 Charles Walcott discovered the remarkable soft-bodied animal fauna of the Middle Cambrian age Burgess Shale in British Columbia. These fossils have become the iconic representation of the astonishing expansion of animal diversity during the Cambrian, including the first appearance in the fossil record of essentially all living phyla, known as the “Cambrian explosion.” Although the Burgess Shale biota is the public face of the Cambrian explosion, even appearing on a 1995 cover of Time, it is only a small part of the story (and somewhat late in the tale). Most readers will be familiar with the Cambrian explosion through Stephen Jay Gould’s 1989 book Wonderful Life (1989) or perhaps Martin Brasier’s more recent Darwin’s Lost World (2009). Both of these books were written to reach a general audience. What has been lacking to date is a more technical book, aimed at students and professionals, which summarizes and introduces the tremendous amount of research that this episode of earth history has received in the last 25 years. The Cambrian Explosion: The Construction of Animal Biodiversity by Douglas H Erwin and James W Valentine more than fills this need. It will become required reading for anyone who wants to understand the multiple lines of evidence, from geology, geochemistry, paleontology, genetics, phylogenetics, comparative morphology, and ecology, that have to be integrated to understand one of the most important episodes in the history of life. The authors, both paleontologists, are deeply respected authorities on evolution and the Cambrian fossil record, with a welldeserved reputation for innovative approaches. This book necessarily covers a tremendous amount of ground; the forty-two pages of references demonstrate the depth and breadth of scholarship that the authors summarize. The first section covers the geological context of the explosion, stretching back to the Snowball Earth episodes of the Cryogenian. This includes summaries of the current status of the absolute and relative time scales for this period and what geochemical proxies reveal about ocean chemistry, including oxygenation states and changes in the carbon cycle. The latter is unfortunately the weakest part of the book; there is very poor integration between figures (which come from external sources) and text; the figure captions and labels are inadequate. The book hits its stride in the next section. It begins with a brief review of phylogenetics and of living metazoan morphology and relationships, a subject Valentine explored in more depth in his comprehensive earlier book, On the Origin of Phyla (2004). This is followed

The Cambrian Explosion: The Construction of Animal Biodiversity

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The Cambrian Explosion: The Construction of Animal Biodiversity