Seminario científico en el Real Jardín Botánico, CSIC, el día 20 de enero de 2010 Tuesday, 19 de January de 2010 | Unidad de Cultura Científica

Título: Hot Spring ecosystems through time: homes for endemic specialists or widespread generalists?
Fecha y hora: 20 de Enero de 2010, 13.00
Lugar: Salón de seminarios, RJB.

Resumen: Hot spring sinter deposits are a rare but extremely important feature of the rock record. They are prized by palaeontologists because they provide anatomical evidence of entombed organisms and even near-intact ecosystems that are preserved in situ as silica laden hot spring waters permeate and encrust tissues and cells. The 400 million year old (Lower Devonian) Rhynie Chert of Aberdeenshire, Scotland is arguably the finest example of such a deposit. At Rhynie the discharge of silica-rich geothermal fluids from hot springs preserved a diverse early land plant flora, including, the earliest well-documented plant of lycophyte affinity (Asteroxylon), rhyniophytes (e.g., Rhynia) and those of less certain relationships (e.g., Horneophyton, Aglaophyton). Other elements of the local ecosystem include bacteria, algae, fungi, lichens, and diverse arthropods including crustaceans, arachnids and insects. The Rhynie assemblage provides our best insight into early terrestrial ecosystems. It underpins many inferences of the paleo-ecophysiology of the plants and of their taxonomic affinities, plus the broader evolutionary patterns. Just how typical the Rhynie biota is of “normal”  Devonian dry-land ecosystems is however conjectural. Most of the biota is recorded solely from the Rhynie deposit, giving the impression of a highly endemic and specialized ecosystem. This talk will use examples of active analogue hot spring systems and other, younger, fossil hot spring deposits to illustrate that the fossil record of hot spring ecosystems is strongly biased towards aquatic (or flooding tolerant) organisms which are alkaliphilic and salinity tolerant. The vast majority of plants and animals preserved in situ around hot springs through the Phanerozoic are thus typical of wetlands and ephemeral water bodies.
Whilst endemics are a feature of hot spring ecosystems the vast majority of preserved organisms have very broad specific and generic geographical ranges and are widespread generalists. Most are pre-adapted to life in hot spring environments through life in more widespread but stressed environments such as saline and alkaline seeps and salt marshes.

Alan Channing. School of Earth and Ocean Sciences, Cardiff University, CF10 3YE, Wales, UK.
(E-mail: channinga@cardiff.ac.uk)

Real Jardín Botánico
Real Jardín Botánico, CSIC. Plaza de Murillo, 2. Madrid E-28014 (ESPAÑA). Tel. +34 91 4203017. FAX: +34 91 4200157
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