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Bioécologie

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Richard Lenski: Experimental Evolution

3 Février 2017,

Publié par Bioécologie

The main focus of my lab is on experimental evolution. Evolution is usually investigated using the comparative method or by studying fossils. Our approach is to watch evolution as it happens, in the context of experiments that are replicated and performed under controlled conditions. The idea of watching evolution in action is not new. In fact, Charles Darwin, in the first edition of On the Origin of Species (1859, p. 187), said "In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors ; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form."

In order to study evolution as it happens requires either a time machine (which we don't have) or else organisms that replicate, mutate, and evolve very fast, so that we can detect changes on a reasonable time scale. In our research, we are now performing experiments with two different fast-evolving systems:

In both systems, we are investigating the dynamics of evolution, including genomic as well as phenotypic changes. We aim to integrate our understanding of these genomic and phenotypic changes by identifying and manipulating the genetic and ecological determinants of organismal performance and fitness. The approaches we use to draw these connections span a wide range, from finding specific mutations of interest to analyzing arrays that summarize the relationship between the entire genome and all the phenotypes that it encodes. By using two very different systems, we seek commonalities that may indicate more general features of evolving systems. Of equal interest, major differences between these systems may lead us to further experiments that explore the reasons for particular outcomes.

 

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Global Soil Biodiversity Initiative

17 Juin 2016,

Publié par Bioécologie

The Global Soil Biodiversity Initiative was launched in September 2011 and is open to all those interested in developing a coherent platform for promoting the translation of expert knowledge on soil biodiversity into environmental policy and sustainable land management for the protection and enhancement of ecosystem services.

Global Soil Biodiversity Initiative

Publié depuis Overblog et Facebook

3 Mai 2016,

Publié par Bioécologie

Las superbacterias que viven en Chernóbil

21 Avril 2016,

Publié par Bioécologie

Un equipo científico halla unos microbios resistentes a la radioactividad, lo que puede tener implicaciones en la lucha contra el cáncer

Kristin Suleng (Valencia, 24 mars 2016):

Aunque su nombre recuerda a una de las mayores catástrofes medioambientales de la historia, Chernóbil no es sinónimo de ausencia absoluta de vida. En el escenario inhóspito que dejó el accidente nuclear hay poco rastro de presencia humana, pero algunas especies de vegetales, insectos y aves son capaces de resistir la radiactividad 30 años después del desastre. ¿El hecho de vivir en ambientes radiactivos podría generar una resistencia a la radiactividad? Esa es la pregunta fundamental que plantea un reciente estudio publicado en la revista Scientific Reports, el primero en confirmar la resistencia de ciertas bacterias a dosis intermedias de radiactividad, fruto de un trabajo liderado por el biólogo español Mario Xavier Ruiz-González.

Las bacterias pueden sobrevivir en el lugar más insospechado del planeta. También en los entornos radiactivos. Esa es la hipótesis inicial de esta investigación pionera que considera la radiactividad como una condición de estrés, al igual que las temperaturas extremas, a las que se adaptan los animales y las plantas como motor de los procesos evolutivos.

Aunque descubrir los efectos negativos de la radiactividad sobre los microorganismos no es una novedad, en cambio, lo es demostrar la adaptación de las bacterias a ambientes radiactivos. Investigaciones previas han caracterizado la vida en Chernóbil a partir de la detección de mutaciones y aberraciones en plantas, insectos, hongos y bacterias, o de la evaluación del impacto de la radiactividad sobre la biodiversidad. Pero el estudio de este investigador valenciano es el primero en analizar la resistencia de las bacterias tras el desastre nuclear.

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Chernobyl Nuclear Power Plant's reactor 4

Chernobyl Nuclear Power Plant's reactor 4

Meet the Bird Brainiacs: American Crow

22 Mars 2016,

Publié par Bioécologie

PET scan of a crow's brain: Courtesy of Robert Miyaoka/Dept. of Radiology/University of Washington

PET scan of a crow's brain: Courtesy of Robert Miyaoka/Dept. of Radiology/University of Washington

Corvid expert John Marzluff scans crows’ brains to crack the mystery of what makes these smart birds so successful.

Editor's Note: Members of the crow family, known as the corvids, are among the smartest birds in the world. Some are capable of using tools, playing tricks, teaching each other new things, even holding “funerals.” And yet there’s still much we don’t know about these fascinating, sometimes confounding creatures. What’s going on inside the mind of a corvid? Three leading scientists are finding answers.

The crows in your neighborhood know your block better than you do. They know the garbage truck routes. They know which kids drop animal crackers and which ones throw rocks. They know the pet dogs, and they might even play with the friendly ones. If you feed them, they probably not only recognize you but your car as well, and they might just leave you trinkets in return. These birds live their lives intertwined with ours, carefully observing us even as most of us barely take note of them. That’s how they survive, and they’re good at it: In recent decades the American Crow has taken over our suburbs, and even moved into the hearts of our big cities. As we’ve reshaped the landscape, we’ve created an ideal environment for an animal that is canny and perceptive enough to exploit our riches.

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The “Trimates,” The Founding Mothers of Primatology

8 Mars 2016,

Publié par Bioécologie

Birute Galdikas (orangutans), Jane Goodall (chimpanzees) and Dian Fossey (gorillas in particular mountain gorillas) (Read more here)

The Jane Goodall Institute, the Karisoke Research Center (founded by Fossey), and the Orangutan Foundation International (founded by Galdikas) are part of the remarkable legacy of these tireless women, whose work in understanding and protecting humanity’s closest living relatives will never be finished.

The “Trimates,” The Founding Mothers of Primatology

The aquatic-terrestrial model ecosystem – a possibility to integrate riparian food webs in stream mesocosm testing

27 Février 2016,

Publié par JMB

In this post, Matthias Wieczorek informs about their recent paper on the use of an aquatic-terrestrial model ecosystem to study cross-ecosystem effects of contaminants.

The scientific background

Emerging aquatic insects provide an important food source for predatory species in riparian food webs. If these aquatic insects are exposed to contaminants during their aquatic life stage, they may transport contaminants to riparian ecosystems during their emergence. Therefore, riparian food webs may be at risk from either an aquatic-terrestrial transfer of contaminants or from contaminant-driven reductions of emerging aquatic biomass. The objective of the present study was to develop an aquatic-terrestrial model ecosystem enabling the possibility to investigate such cross-ecosystem effects on a mesocosm scale under controlled conditions.

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The stream mesocosm facility at the Campus Landau (photo by M. Wieczorek)

The stream mesocosm facility at the Campus Landau (photo by M. Wieczorek)

Neurodevelopmental Disorders and Prenatal Residential Proximity to Agricultural Pesticides: The CHARGE Study

3 Février 2016,

Publié par Bioécologie

By Janie F. Shelton, Estella M. Geraghty, Daniel J. Tancredi, Lora D. Delwiche, Rebecca J. Schmidt, Beate Ritz, Robin L. Hansen, and Irva Hertz-Picciotto. June 2014.

  • Background: Gestational exposure to several common agricultural pesticides can induce developmental neurotoxicity in humans, and has been associated with developmental delay and autism.

    Objectives: We evaluated whether residential proximity to agricultural pesticides during pregnancy is associated with autism spectrum disorders (ASD) or developmental delay (DD) in the Childhood Autism Risks from Genetics and Environment (CHARGE) study.

    Methods: The CHARGE study is a population-based case–control study of ASD, DD, and typical development. For 970 participants, commercial pesticide application data from the California Pesticide Use Report (1997–2008) were linked to the addresses during pregnancy. Pounds of active ingredient applied for organophophates, organochlorines, pyrethroids, and carbamates were aggregated within 1.25-km, 1.5-km, and 1.75-km buffer distances from the home. Multinomial logistic regression was used to estimate the odds ratio (OR) of exposure comparing confirmed cases of ASD (n = 486) or DD (n = 168) with typically developing referents (n = 316).

    Results: Approximately one-third of CHARGE study mothers lived, during pregnancy, within 1.5 km (just under 1 mile) of an agricultural pesticide application. Proximity to organophosphates at some point during gestation was associated with a 60% increased risk for ASD, higher for third-trimester exposures (OR = 2.0; 95% CI: 1.1, 3.6), and second-trimester chlorpyrifos applications (OR = 3.3; 95% CI: 1.5, 7.4). Children of mothers residing near pyrethroid insecticide applications just before conception or during third trimester were at greater risk for both ASD and DD, with ORs ranging from 1.7 to 2.3. Risk for DD was increased in those near carbamate applications, but no specific vulnerable period was identified.

    Conclusions: This study of ASD strengthens the evidence linking neurodevelopmental disorders with gestational pesticide exposures, particularly organophosphates, and provides novel results of ASD and DD associations with, respectively, pyrethroids and carbamates.

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