{"id":98287,"date":"2008-08-07T11:41:00","date_gmt":"2008-08-07T11:41:00","guid":{"rendered":"http:\/\/weblogs.madrimasd.org\/\/universo\/archive\/2008\/08\/07\/98287.aspx"},"modified":"2010-01-22T03:48:35","modified_gmt":"2010-01-22T02:48:35","slug":"evolucion-de-las-redes-ecologicas-y-cadenas-troficas-desde-el-cambrico-hasta-la-actualidad","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2008\/08\/07\/98287","title":{"rendered":"Evoluci\u00f3n de las Redes Ecol\u00f3gicas y Cadenas Tr\u00f3ficas desde el C\u00e1mbrico hasta la Actualidad"},"content":{"rendered":"

Se supon\u00eda que la complejidad de las redes ecol\u00f3gicas en general<\/SPAN><\/B> (por ejemplo, las cadenas tr\u00f3ficas) hab\u00eda aumentado conforme avanzaba la evoluci\u00f3n desde el origen de la vida<\/SPAN><\/B>. La doctrina est\u00e1ndar sosten\u00eda que tal hecho, como tambi\u00e9n que tal proceso hab\u00eda  <\/SPAN>sido acompa\u00f1ado por un incremento de la biodiversidad<\/SPAN><\/B>. En muy pocas semanas parece ser que todo este entramado te\u00f3rico se ha venido abajo<\/SPAN><\/B>. Desde hace m\u00e1s de 500 millones de a\u00f1os, tanto la topolog\u00eda de les mencionadas redes de interacci\u00f3n como el n\u00famero de especies no parecen haber sufrido modificaciones relevantes<\/SPAN><\/B>. El trabajo sobre la topolog\u00eda de las redes tr\u00f3ficas del C\u00e1mbrico ha sido recientemente publicado<\/SPAN><\/B> por PloS Bioloy<\/SPAN><\/B> en acceso abierto, por lo que os pod\u00e9is bajar el material pinchando el<\/SPAN><\/B> siguiente enlace<\/FONT><\/A> (al final del post os incluimos el resumen). <\/o:p><\/SPAN><\/P>

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Redes ecol\u00f3gicas del presente y pasado<\/o:p><\/SPAN><\/P>

Fuente: Dune et al. (2008) Plos One. Enlace en el texto<\/o:p><\/SPAN><\/P><\/p>\n

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El estudio fue realizado haciendo uso del material paleontol\u00f3gico preservado en dos yacimientos excepcionales <\/span><\/b>y de modelos de computaci\u00f3n. No entrar\u00e9 en detalles, por cuanto lo que interesa a los j\u00f3venes es tal regularidad, mientras que los profesionales disponen del art\u00edculo, as\u00ed como de los dos res\u00famenes que incluyo al final de este post. <\/o:p><\/span><\/p>\n

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Propiedades de las Redes ecol\u00f3gicas del presente y pasado<\/o:p><\/span><\/p>\n

Fuente: Dunne et al. (2008) Plos One. Enlace en el texto.<\/o:p><\/span><\/p>\n

Leyenda al final de la \u00faltima figura<\/o:p><\/span><\/p>\n

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 <\/o:p><\/span>Ya hemos venido hablando en varios post de que las redes de los sistemas complejos<\/span><\/b> (ya sean biol\u00f3gicas, sociales o mentales) y artefactos tecnol\u00f3gicos, se encuentran sujetos a una serie de leyes que condicionan su estructura y din\u00e1mica<\/span><\/b>. Lo que pudiera sorprender a primera vista deviene de que tales estructuras se alcanzaran relativamente pronto a lo largo de la historia de la vida<\/span><\/b> (al menos desde la aparici\u00f3n de los animales marinos, hace aproximadamente 500 millones de a\u00f1os). Sin embargo, tal descubrimiento no nos deber\u00eda deparar asombro alguno. Hemos venido mostrando<\/span><\/b> y demostrando que tales arquitecturas emergen espont\u00e1neamente en los m\u00e1s disparatados \u00e1mbitos<\/span><\/b>, por ser consecuencia de<\/span><\/b> la autoorganizaci\u00f3n de los elementos de los sistemas abiertos a los flujos de energ\u00eda, materia e informaci\u00f3n. Si las redes sociales en Internet se han autoorganizado en pocos a\u00f1os, no resulta ins\u00f3lito que en los ecosistemas naturales se alcanzaran las mismas regularidades en millones de a\u00f1os<\/span><\/b>.<\/o:p><\/span><\/p>\n

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 <\/o:p><\/span>Propiedades de las Redes ecol\u00f3gicas del presente y pasado<\/o:p><\/span><\/p>\n

Fuente: Dunne et al. (2008) Plos One. Enlace en el texto.<\/o:p><\/span><\/p>\n

Leyenda al final de la \u00faltima figura<\/o:p><\/span><\/p>\n

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Uno debe tener cuidado al generalizar las repercusiones de tales hallazgos por cuanto los patrones detectados no refutan que la vida haya ido ganando en complejidad<\/span><\/b>, como lo demuestra la emergencia de animales cada vez m\u00e1s complejos y sofisticados<\/span><\/b>. La lecci\u00f3n e extraer resultar\u00eda ser que la estructura invariante de las redes complejas emerge r\u00e1pidamente debido a <\/span><\/b>las leyes de la f\u00edsica de los sistemas complejos.  <\/span>\u00bfPorqu\u00e9 hemos tardado tanto tiempo en percatarnos?<\/span><\/b> De los textos incluidos m\u00e1s abajo se infiere r\u00e1pidamente que la raz\u00f3n estriba en la carencia de las bases de datos adecuadas<\/span><\/b>. No nos cansaremos de repetir que obtener buenos inventarios es una de las bases fundamentales para extraer conclusiones acertadas<\/span><\/b> en casi todos los \u00e1mbitos de las ciencias de la tierra y de la Vida. Sin embargo, en la ciencia moderna se desprecia tal actividad<\/span><\/b> en aras de investigaciones m\u00e1s sofisticadas. \u00a1Error de bulto!<\/span><\/b>. Por mucha instrumentaci\u00f3n y modelizaci\u00f3n que apliquemos, todo el edificio se viene abajo si no se dispone de buenas bases de datos (trabajo muy arduo, ingrato y despreciado<\/span><\/b>). Los pilares del conocimiento deben hundir sus ra\u00edces en los inventarios. Una vez disponiendo de buenos productos todo lo dem\u00e1s viene por a\u00f1adidura<\/span><\/b>.  <\/span><\/o:p><\/span><\/p>\n

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Propiedades de las Redes ecol\u00f3gicas del presente y pasado<\/o:p><\/span><\/p>\n

Fuente: Dunne et al. (2008) Plos One. Enlace en el texto.<\/o:p><\/span><\/p>\n

Leyenda al final de la \u00faltima figura<\/o:p><\/span><\/p>\n

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En cualquier caso, nuestro conocimiento del pasado es muy limitado quedando mucho por estudiar. Lo que lo que hoy nos ofrece la ciencia bien pudiera ser refutado en poco tiempo.      <\/span> <\/span><\/o:p><\/span><\/p>\n

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Juan Jos\u00e9 Ib\u00e1\u00f1ez<\/o:p><\/span><\/p>\n

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Otros post Previos Relacionados con el Tema<\/o:p><\/span><\/p>\n

Redes Complejas: Redes Sociales y Redes Ecol\u00f3gicas (Los Mundos Peque\u00f1os)<\/font><\/a> <\/o:p><\/span><\/p>\n

Conectividad, Redes Sociales y Redes Ecol\u00f3gicas<\/font><\/a> <\/o:p><\/span><\/p>\n

Especies Clave y Nodos Clave: Redes Ecol\u00f3gicas, Redes Sociales<\/font><\/a><\/o:p><\/span><\/p>\n

Evoluci\u00f3n de la Biodiversidad a lo largo de la Historia de la Tierra<\/font><\/a><\/o:p><\/span><\/p>\n

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Continuar\u00e1<\/span><\/b>\u2026\u2026\u2026\u2026<\/span><\/b><\/o:p><\/span><\/b><\/p>\n

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Juan Jos\u00e9 Ib\u00e1\u00f1ez<\/o:p><\/span><\/p>\n

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Find \u00abterradaily \u00abfood webs\u00bb\u00bb on Tribe.net<\/font><\/span><\/a><\/span><\/o:p><\/span><\/p>\n

by Staff Writers; <\/span>Washington<\/span><\/st1:city> <\/span>DC<\/span><\/st1:state><\/st1:place> (SPX) May 01, 2008 <\/o:p><\/span><\/p>\n


Similarities between half-billion-year-old and recent food webs point to deep principles underpinning the structure of ecological relationships, as shown by researchers from<\/span><\/b> the Santa Fe Institute, Microsoft Research Cambridge and elsewhere It was an Anomalocaris-eat-trilobite world, filled with species like nothing on today’s Earth. But the ecology of Cambrian communities was remarkably modern, say researchers behind the first study to reconstruct detailed food webs for ancient ecosystems<\/span><\/b>.  <\/span>Their paper, published this week in the open-access journal PLoS Biology<\/span><\/b>, suggests that networks of feeding relationships among marine species that lived hundreds of millions of years ago are remarkably similar to those of today<\/span><\/b>. <\/o:p><\/span><\/p>\n


Food webs depict the feeding interactions among species within habitats–like food chains, only more complex and realistic. The discovery of strong and enduring regularities in how such webs are organized will help us understand the history and evolution of life, and<\/span><\/b> could provide insights for modern ecology–such as how ecosystems will respond to biological extinctions and invasions.<\/o:p><\/span><\/p>\n


A multidisciplinary group of scientists led by ecologist Jennifer Dunne of the Santa Fe Institute in Santa Fe, New Mexico <\/span><\/b>and the Pacific Ecoinformatics and Computational Ecology Lab in Berkeley, California, studied the food webs of sea creatures preserved in rocks from the Cambrian, when there was an explosion of diversity of multicellular organisms–including early precursors to today’s species as well as many strange animals that were evolutionary dead ends. <\/p>\n

Report co-author Richard Williams of Microsoft Research in <\/span>Cambridge<\/span><\/st1:place><\/st1:city>, <\/span>UK<\/span><\/st1:place><\/st1:country-region>, developed the cutting edge \u00abNetwork3D\u00bb software that was used for analysis and visualization of the food webs<\/span><\/b>. The researchers compiled data from the 505 million-year-old Burgess Shale in British Columbia, Canada and<\/span><\/b> the even earlier Chengjiang Shale of eastern Yunnan Province, China, dating from<\/span><\/b> 520 million years ago<\/span><\/b>. Both fossil-rich assemblages are unusual because they have exquisitely preserved soft-body parts for a wide range of species. They determined who was eating whom by piecing together a variety of clues.<\/o:p><\/span><\/p>\n


There was the occasional smoking gun, such as fossilized gut contents in the carnivorous, cannibalistic priapulid worm Ottoia prolifica. However, in most cases, feeding interactions were inferred from where species lived and what body parts they had. For example, grasping claws, swimming lobes, big eyes, and toothy mouthparts suggest that Anomalocaris canadensis, a large, unusual organism with no modern descendents, was a formidable predator of trilobites and other arthropods, consistent with bite marks found on some fossils.<\/o:p><\/span><\/p>\n


To compare the organization of Cambrian and recent ecosystems, the team used methods for studying network structure, including new approaches for analyzing uncertainty in the fossil data. \u00abPaleontologists have long known that food webs were important but we have lacked a rigorous method for studying them in deep time<\/span><\/b>,\u00bb comments co-author and paleontologist Doug Erwin of the Santa Fe Institute and the Smithsonian Institution.<\/o:p><\/span><\/p>\n

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\u00abWe have shown that we can reconstruct ancient food webs and compare them to modern webs, opening up new avenues of paleoecology. We were surprised to see that most aspects of the basic structure of food webs seem to have become established during the initial explosion of animal life<\/span><\/b>.\u00bb The Cambrian food webs share many similarities with modern webs, such as <\/span><\/b>how many species are expected to be omnivores or cannibals, and the distribution of how many types of prey each species has. Such regularities, and any differences, become apparent only when variation in the number of species and links among webs is accounted for. <\/o:p><\/span><\/p>\n


\u00abThere are a few intriguing differences with modern webs<\/span><\/b>, particularly in the earlier Chengjiang Shale web. However, in general, it doesn’t seem to matter what species, or environment, or evolutionary history you’ve got, you see many of the same sorts of food-web patterns<\/span><\/b>,\u00bb explains Dunne. \u00abWhat we don’t know,\u00bb Dunne adds, \u00abis why food webs from different habitats and across deep time share so many regularities<\/span><\/b>. It could be that species-level evolution leads to stable community-level patterns, for example<\/span><\/b> by limiting the number of species with many predators through selective pressures that result in extinctions or development of predator defences. Or, patterns may reflect dynamically persistent configurations of many interacting species, or fundamental physical constraints on how resources flow through ecological networks<\/span><\/b>.\u00bb <\/o:p><\/span><\/p>\n


Answering such questions will break new ground at the intersection of ecology, evolution and physics<\/span><\/b>. And it may provide valuable insights into present-day ecology. As Williams points out, \u00abThis research is an excellent example of how computational methods can be used as part of an inter-disciplinary study to help produce novel results. By getting a better idea of how ecosystems behaved in the past, we may better comprehend and mitigate what is happening to ecosystems today and in the future.\u00bb<\/o:p><\/span><\/p>\n

www.terradaily.com\/reports\/<\/font><\/a><\/o:p><\/span><\/p>\n

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 <\/o:p><\/span> <\/o:p><\/span><\/p>\n

Compilation and Network Analyses of Cambrian Food Webs<\/o:p><\/span><\/b><\/p>\n

Jennifer A. Dunne1<\/font><\/a>,3<\/font><\/a>*<\/font><\/a>, Richard J. Williams2<\/font><\/a>,3<\/font><\/a>, Neo D. Martinez3<\/font><\/a>,4<\/font><\/a>, Rachel A. Wood5<\/font><\/a>,6<\/font><\/a>, Douglas H. Erwin1<\/font><\/a>,7<\/font><\/a> <\/o:p><\/span><\/p>\n

<\/a>1 Santa Fe Institute, Santa Fe, New Mexico, United States of America, <\/a>2 Microsoft Research Limited, Cambridge, United Kingdom, <\/a>3 Pacific Ecoinformatics and Computational Ecology Lab, Berkeley, California, United States of America, <\/a>4 National Center for Ecological Analysis and Synthesis, Santa Barbara, California, United States of America, <\/a>5 Grant Institute, School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom, <\/a>6 Edinburgh Collaborative of Subsurface Science and Engineering, University of Edinburgh, Edinburgh, United Kingdom, <\/a>7 Department of Paleobiology, National Museum of Natural History, Washington, D.C., United States of America <\/o:p><\/span><\/p>\n

<\/a> <\/o:p><\/span><\/p>\n

A rich body of empirically grounded theory has developed about food webs\u2014the networks of feeding relationships among species within habitats. However, detailed food-web data and analyses are lacking for ancient ecosystems, largely because of the low resolution of taxa coupled with uncertain and incomplete information about feeding interactions<\/span><\/b>. These impediments appear insurmountable for most fossil assemblages; however, a few assemblages with excellent soft-body preservation across trophic levels are candidates for food-web data compilation and topological analysis<\/span><\/b>. Here we present plausible, detailed food webs for the Chengjiang and Burgess Shale assemblages from the Cambrian Period<\/span><\/b>. Analyses of degree distributions and other structural network properties, including sensitivity analyses of the effects of uncertainty associated with<\/span><\/b> Cambrian diet designations, suggest that these early Paleozoic communities share remarkably similar topology with modern food webs. Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web<\/span><\/b>. Most aspects of Cambrian food-web structure are well-characterized by a simple \u201cniche model,\u201d which was developed for modern food webs and takes into account this scale dependence<\/span><\/b>. However, a few aspects of topology differ between the ancient and recent webs: longer path lengths between species and more species in feeding loops in the earlier Chengjiang web, and higher variability in the number of links per species for both Cambrian webs<\/span><\/b>. Our results are relatively insensitive to the exclusion of low-certainty or random links. The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions<\/span><\/b> among metazoan species. The few differences could reflect a transition to more strongly integrated and constrained trophic organization within ecosystems following the rapid diversification of species, body plans, and trophic roles during the Cambrian radiation<\/span><\/b>. More research is needed to explore the generality of food-web structure through deep time and across habitats, especially to investigate potential mechanisms that could give rise to similar structure, as well as any differences<\/span><\/b>.<\/o:p><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Se supon\u00eda que la complejidad de las redes ecol\u00f3gicas en general (por ejemplo, las cadenas tr\u00f3ficas) hab\u00eda aumentado conforme avanzaba la evoluci\u00f3n desde el origen de la vida. La doctrina est\u00e1ndar sosten\u00eda que tal hecho, como tambi\u00e9n que tal proceso hab\u00eda  sido acompa\u00f1ado por un incremento de la biodiversidad. En muy pocas semanas parece ser que todo este entramado te\u00f3rico se ha venido abajo. Desde hace m\u00e1s de 500 millones de a\u00f1os, tanto la topolog\u00eda de les mencionadas redes de interacci\u00f3n como el n\u00famero de especies no parecen haber sufrido modificaciones relevantes. El trabajo sobre la topolog\u00eda de las redes\u2026<\/p>\n","protected":false},"author":26,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[586,607,616],"tags":[],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":4}},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/98287"}],"collection":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/comments?post=98287"}],"version-history":[{"count":2,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/98287\/revisions"}],"predecessor-version":[{"id":134720,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/98287\/revisions\/134720"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=98287"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=98287"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=98287"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}