How The Spider Spun Its Web: ‘Missing Link' In Spider Evolution Discovered, ScienceDaily
Excerpts: New interpretations of fossils have revealed an ancient missing link between today's spiders and their long-extinct ancestors. The research (...) may help explain how spiders came to weave webs. The research focuses on fossil animals called Attercopus fimbriunguis. While modern spiders make silk threads with modified appendages called spinnerets, the fossil animals wove broad sheets of silk from spigots on plates attached to the underside of their bodies. Unlike spiders, they had long tails. (...) caused the paleontologists to reinterpret their original findings. (...)
- Source: How The Spider Spun Its Web: ‘Missing Link?In Spider Evolution Discovered, ScienceDaily & University of
- Contributed by Atin Das - dasatin
yahoo.co.in
Historical and Philosophical Perspectives on Contemporary Biology, PLoS Biol
Excerpt: The work of historians and philosophers of science has long benefited from conversations with practicing scientists, but to many scientific researchers, perhaps especially to those engaged in laboratory work, the value that such dialogue might have for their own endeavor is not nearly so obvious. There are of course exceptions, evolutionary biology, for one. Over the last several decades, a tradition of active engagement between historians and philosophers on the one hand, and evolutionary biologists on the other, has become well established (...)
- Source: Historical and Philosophical Perspectives on Contemporary Biology, Evelyn Fox Keller, DOI: 10.1371/journal.pbio.0060321, PLoS Biol 6(12): e321, 2008/12/23
Where Bacteria and Languages Concur, Science
Excerpt: Two articles in this issue mark a substantial advance in our understanding of human population history in the Pacific area. On page 479, Gray et al. (1) report a computational linguistic analysis that offers a detailed and precise scenario for the dispersal and development of the Austronesian languages, and by implication of human populations among the Pacific islands. The authors come down decisively in favor of one of the two major models for the peopling of the Pacific. On page 527, Moodley et al. (2) come to the same conclusion as Gray et al. about the source and trajectory of spread of the human populations in question, based on results from a seemingly unrelated field: the archaeogenetics of human gastric bacterial parasites.
- Source: Where Bacteria and Languages Concur, Colin Renfrew, DOI: 10.1126/science.1168953, Science, 2009/01/23
Is Genetic Evolution Predictable?, Science
Abstract: Ever since the integration of Mendelian genetics into evolutionary biology in the early 20th century, evolutionary geneticists have for the most part treated genes and mutations as generic entities. However, recent observations indicate that all genes are not equal in the eyes of evolution. Evolutionarily relevant mutations tend to accumulate in hotspot genes and at specific positions within genes. Genetic evolution is constrained by gene function, the structure of genetic networks, and population biology. The genetic basis of evolution may be predictable to some extent, and further understanding of this predictability requires incorporation of the specific functions and characteristics of genes into evolutionary theory.
- Source: Is Genetic Evolution Predictable?, David L. Stern and Virginie Orgogozo, DOI: 10.1126/science.1158997, Science Vol. 323. no. 5915, pp. 746 - 751, 2009/02/06
The evolution and distribution of species body size, arXiv
Abstract: The distribution of species body size within taxonomic groups exhibits a heavy right-tail extending over many orders of magnitude, where most species are significantly larger than the smallest species. We provide a simple model of cladogenetic diffusion over evolutionary time that omits explicit mechanisms for inter-specific competition and other microevolutionary processes yet fully explains the shape of this distribution. We estimate the model's parameters from fossil data and find that it robustly reproduces the distribution of 4002 mammal species from the late Quaternary. The observed fit suggests that the asymmetric distribution arises from a fundamental tradeoff between the short-term selective advantages (Cope's rule) and long-term selective risks of increased species body size, in the presence of a taxon-specific lower limit on body size.
- Source: The evolution and distribution of species body size, Aaron Clauset and Douglas H. Erwin, DOI: 0901.0251, arXiv [Science 321, 399 - 401 (2008)], 2008/01/02
A Neandertal Primer, Science
Excerpt: The rough draft of the Neandertal nuclear genome may usher in a brave new world of research on these extinct humans, but after 150 years of study, we already know a few things about them.
- Source: A Neandertal Primer, Michael Balter, DOI: 10.1126/science.323.5916.870, Science Vol. 323. no. 5916, p. 870, 2009/02/13
No hay comentarios:
Publicar un comentario