martes, 26 de diciembre de 2017

viernes, 22 de diciembre de 2017

miércoles, 20 de diciembre de 2017

Domestication of tomato has reduced the attraction of herbivore natural enemies to pest-damaged plants 

Xiaohong Li, Michael Garvey, Ian Kaplan, Baoping Li, Juli Carrillo

  1. Plant domestication can alter species interactions and influence novel associations among crops and insects. We performed a series of preference and performance experiments to test predator and herbivore attraction to domesticated and wild plants and to evaluate the efficacy of herbivore-induced plant volatiles (HIPVs) across a domestication gradient in tomato, including wild relatives, landraces and domesticated commercial cultivars.
  2. We employed a tri-trophic system consisting of the specialist lepidopteran herbivore Manduca sexta and two of its natural enemies: an egg predator, the stilt bug Jalysus wickhami, and a larval parasitoid, the wasp Cotesia congregata.
  3. In olfactometer trials, natural enemies consistently preferred HIPVs of wild tomatoes over domesticated cultivars, with landraces in between. Plant-domestication effects were also apparent in terms of decision speed: predators were slower to orient towards damaged crops than to damaged wild relatives.
  4. By contrast, M. sexta moths were more likely to oviposit on domesticated than on wild or landrace tomatoes, indicating that insect responses to plant odours vary with trophic level. Field trials confirmed olfactory preference tests: caterpillars recovered from wild tomato relatives were more likely to be parasitized than those recovered from landraces or domesticated tomatoes.
  5. The results of the present study suggest that tomato domestication has reduced the efficacy of HIPVs in attracting predators compared with wild relatives and also that this decreased attraction leads to lower attack rates by enemies in the field. This outcome has implications for understanding the specificity of tri-trophic plant defences and the compatibility of natural enemies for biocontrol in agro-ecosystems.


martes, 19 de diciembre de 2017

In these days it may be good to remember some historical facts about ideologies and science.

Lysenkoism (1920s -1960s) was an ideology-based approach to agriculture in the USSR, supported by Stalin (and developed by Trofim Lysenko) that assumed the heritability of acquired characteristics (explicitly denying Mendelian genetics).  Because of it, many scientists were sent to prison (e.g., Nikolai Vavilov) or executed. Finally, it produced declined yields and famine.

Not a good idea to denied fact-base science.

GHG emissions from agriculture by continent

sábado, 9 de diciembre de 2017

In the very earliest time
When both people and animals lived on earth
A person could become an animal if he wanted to
and an animal could become a human being.
Sometimes they were people
and sometimes animals
and there was no difference.
All spoke the same language
That was the time when words were like magic.
The human mind had mysterious powers.
A word spoken by chance might have strange consequences.
It would suddenly come alive
and what people wanted to happen could happen--
all you had to do was say it.
Nobody could explain this:
That's the way it was.
-- Nalungiaq, Inuit woman interviewed by ethnologist Knud Rasmussen in the early twentieth century.

"...A few years ago, I was entering a restaurant very near my home and noticed a sign in front that said "Native Grass Garden-Do Not Disturb." My first response, naturally, was to trample over to the sign to see what the fuss was about. I knelt down and admired the soft, variegated green foliage, the tiny pointed leaves and small yellow and orange flowers. Suddenly it occurred to me that these were exactly the same plants that I had been mowing down on my John Deere sit-down mower the day before...but I had been thinking of them as "weeds"! This was a lesson in the power of labels, of the trances induced by the word-worlds that are enacted every time someone categorizes in speech or thought. 

Is this a question of "mere semantics" as some might argue? The plants remained "the same" regardless of any label I might apply in this view. But the effect in the real world was as tangible as in Nalungiaq's story where what people said came to be. Having labeled the plants in my yard "weeds," I mowed them down. The "native grasses" at the neighboring restaurant remained untouched because a conservation-minded gardener had, by contrast, elevated them to a place of respect with his label. 

Among indigenous peoples, the concept of "weed" does not exist. Every plant has a purpose or it would not be here. The entire field of ethnobotany consists of attempts to articulate in western terms the web of life as it is perceived through native eyes and the categories of native languages. Comparative ethnobotany reminds us that the Linnaean system of categorization is but one of an infinite number of possible taxonomies available to humankind. The categories we use in our everyday speech and thinking, like the formal categories of Linnaeaus for plants, are inherited as part of socialization and constitute in large measure a collective sense of "reality." In the view being advanced here, language always mediates experience in some measure. Yet the path of least resistance is to accept the habitual categories in lieu of the complexities of experience. Language creates reality rather than merely describes it as the First Peoples still remember..."

miércoles, 6 de diciembre de 2017

DNA metabarcoding data unveils invisible pollination networks      

André Pornon, Christophe Andalo, Monique Burrus & Nathalie Escaravage

Animal pollination, essential for both ecological services and ecosystem functioning, is threatened by ongoing global changes. New methodologies to decipher their effects on pollinator composition to ecosystem health are urgently required. We compare the main structural parameters of pollination networks based on DNA metabarcoding data with networks based on direct observations of insect visits to plants at three resolution levels. By detecting numerous additional hidden interactions, metabarcoding data largely alters the properties of the pollination networks compared to visit surveys. Molecular data shows that pollinators are much more generalist than expected from visit surveys. However, pollinator species were composed of relatively specialized individuals and formed functional groups highly specialized upon floral morphs. We discuss pros and cons of metabarcoding data relative to data obtained from traditional methods and their potential contribution to both current and future research. This molecular method seems a very promising avenue to address many outstanding scientific issues at a resolution level which remains unattained to date; especially for those studies requiring pollinator and plant community investigations over macro-ecological scales.

Bipartite pollination networks built from visit surveys (Nobs, right panels) and metabarcoding (Nseq, left panels) data. (a,b) Plant-pollinator groups; (c,d) plant-pollinator species; (e,f) individual pollinator-plant species (Empis leptempis pandellei as an example of pollinator species). Line thickness highlights the proportion of interactions. Apis: Apis mellifera; Bomb.: Bombus sp.; W.bee: wild bees; O.Hym.: other Hymenoptera; O.Dipt.: Other Diptera; Emp.: Empididae; Syrph.: Syrphidae; Col.: Coleoptera; Lep.: Lepidoptera; Musc.: Muscidae.


sábado, 2 de diciembre de 2017

Spatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective. 

Hatt S, Boeraeve F, Artru S, Dufrêne M, Francis F. 

Spatial diversification of crop and non-crop habitats in farming systems is promising for enhancing natural regulation of insect pests. Nevertheless, results from recent syntheses show variable effects. One explanation is that the abundance and diversity of pests and natural enemies are affected by the composition, design and management of crop and non-crop habitats. Moreover, interactions between both local and landscape elements and practices carried out at different spatial scales may affect the regulation of insect pests. Hence, research is being conducted to understand these interdependencies. However, insects are not the only pests and pests are not the only elements to regulate in agroecosystems. Broadening the scope could allow addressing multiple issues simultaneously, but also solving them together by enhancing synergies. Indeed, spatial diversification of crop and non-crop habitats can allow addressing the issues of weeds and pathogens, along with being beneficial to several other regulating services like pollination, soil conservation and nutrient cycling. Although calls rise to develop multifunctional landscapes that optimize the delivery of multiple ecosystem services, it still represents a scientific challenge today. Enhancing interdisciplinarity in research institutions and building interrelations between scientists and stakeholders may help reach this goal. Despite obstacles, positive results from research based on such innovative approaches are encouraging for engaging science in this path. Hence, the aim of the present paper is to offer an update on these issues by exploring the most recent findings and discussing these results to highlight needs for future research.

lunes, 20 de noviembre de 2017

"The tree which moves some to tears of joy is in the eyes of others only a green thing that stands in the way. Some see Nature all ridicule and deformity, and some scarce see Nature at all. But to the eyes of the man of imagination, Nature is Imagination itself."

- William Blake, 1799, The Letters


A cropland cartogram of the world, with grid boxes resized based on the amount of cropland they contain.

viernes, 10 de noviembre de 2017

Harassment, a field study
Science, including the fields of ecology and evolution, must advocate a zero-tolerance policy towards harassment and bullying. This means promoting safe workspaces in all contexts, and letting go of the idea that fieldwork entails special circumstances.

Revelations of harassment at the highest levels of Hollywood and the UK government in the past month have led to increased personal and professional reflection across all industries. Social media users have flocked to post #MeToo stories on Facebook and Twitter, revealing the gamut of acts of harassment they have experienced in their lives. Science is no exception to this, and scrutiny reveals particular problems in the fields of ecology and evolution.

The past few years have seen numerous news stories about senior figures in these disciplines who have been accused by some of their colleagues and students of multiple forms of intimidation, bullying and sexual harassment. At the same time, there has been an increased awareness and understanding of how colleagues and students may be exposed to vulnerable contexts through lack of oversight. A recurring theme in this coverage is the challenges of fieldwork.

Social media initiatives such as #PregnantInTheField and science educator Emily Graslie’s call for public discussion of the taboos and challenges surrounding menstruation have raised awareness of the particular trials fieldwork can pose to women. But many challenges imposed by constraints of the field, such as limited privacy, geographic isolation and a dependence on others, can affect everyone. Yet ecology and evolution fields seem to prize these ‘macho’ challenges almost as a badge of honour. Conferences echo with anecdotes of the extremes researchers have gone to in order to retrieve the season’s data: the stressful make-or-break deadlines; the isolation posed by remote field sites; the topsy-turvy situation where work colleagues become living companions for weeks or even months on end; the challenges of temporary field accommodation to maintenance of personal hygiene. But during assertion of these bragging rights, there may be limited awareness of the fact that these constraints all contribute to creating contexts of increased personal vulnerability. Complaints alleged against prominent Antarctic geologist David Marchant by two of his former students, which Marchant denies, illustrate such a context.

And, of course, the field is not the only context of manufactured vulnerability: the ‘field mentality’ easily filters through to the department, the lab, or the conference (which shares many similarities with the challenges of the field) as still more reports reveal. Journalist Michael Balter has repeatedly investigated parallel claims of sexual harassment leading from institution to conference and back again, notably in the case of Brian Richmond, ex-curator of human origins at the American Museum of Natural History, who is alleged to have sexually assaulted a junior colleague in a hotel room while both were attending the European Society for the Study of Human Evolution (ESHE)’s annual meeting in 2014; allegations that Richmond denies. In reporting other claims, Balter has suggested that new iterations of sexual harassment on the part of junior colleagues may derive from exposure to a culture of such behaviour exhibited by senior colleagues.

There is evidence that the issue of harassment in ecology and evolution extends far beyond these specific cases: a 2014 study of 666 field scientists1 found that 64% of survey participants had experienced sexual harassment (defined as inappropriate or sexual remarks), and 20% experienced sexual assault (defined as sexual contact that was unwanted, unconsenting, or where it was unsafe not to consent). Of those who experienced sexual assault, only 23% reported it, and only 19% of those who reported it were satisfied with the outcome of their report. When these acts occurred, the victims were more likely to be women, and either junior colleagues or students. The impact of these attacks may be long-lasting: Kathryn Clancy and co-authors posited that the strain and stress of experiencing harassment and assault may contribute to the ‘leaky pipeline’ phenomenon1, that is, the gradual loss of women from science, technology, engineering and mathematics fields; their 2017 follow-up study2 confirmed this perception among victims of historic harassment.

The 2017 study highlights the difficulty of establishing acceptable behavioural norms in the absence of explicit and enforced policy, as well as the overwhelming importance of such policies in fieldwork contexts: where codes of conduct and expectations were not clearly established, understood and enforced, there was a correlation with higher rates of sexual harassment2. It seems probable, although not tested in that particular study, that a correlation would exist with other forms of bullying and abuse as well. Appropriate information flow emerges as a key criterion in creating safe workspaces—both senior staff and junior participants need to understand and abide by regulations for them to be effective. In order to combat contexts of vulnerability in which harassment and bullying can arise, this information flow should extend from what is acceptable interpersonal behaviour, to what are reasonable expectations for junior and senior fieldworkers alike in constrained circumstances: provision of a rota for meal preparation; discussion of appropriate noise levels at night; and access to sufficient food, water and breaks during strenuous or restrictive activity, for example.

The good news is that codes of conduct for acceptable behaviour, and provision of reporting structures to facilitate resolution of complaints, are on the rise in scientific contexts, although admittedly more so at conferences than for fieldwork. Following calls from researchers, for example ref. 3, many conferences and societies now issue codes of conduct for meetings (see the Ecological Society of America’s policy, for instance). ESHE now provisions ombudspersons to whom incidents (both harassment and other forms of inappropriate behaviour) can be reported. By constituting an independent body outside a university department or conference organizational committee, ombudspersons help to combat the recognized challenge that a victim may be wary to report an incident perpetrated by a senior colleague. It’s to be hoped too that growing awareness of not only historic incidents but also formerly taboo subjects, such as the personal challenges of fieldwork, may empower victims to speak up. The ecology and evolution communities must continue speak out about these issues and these incidents, calling out colleagues when we witness bullying or harassment.

As for combatting the structures that have facilitated harassment and bullying, as Clancy et al. suggest, it’s time to let go of the idea that the field or the meeting entail special circumstances that mitigate inappropriate behaviour1. While it’s true that there are challenges specific to both, this is all the more reason to push for regulation and oversight to preserve safe workspaces for all, regardless of whether this workspace is halfway up a mountain, in a conference centre, or a lab.


sábado, 4 de noviembre de 2017

Searching for Patterns, Hunting for Causes: Robert MacArthur, the Mathematical Naturalist


miércoles, 1 de noviembre de 2017

Life is not easily bounded

 Derek J Skillings

" ...Most of the time the living world appears to us as manageable chunks. Even a toddler can see that. We know if we have one dog or two; at a pinch, we can probably count how many trees are growing in our backyard. Natural history museums started, in part, as embodiments of early scientific approaches to ordering and cataloguing the diversity of life. This is possible only because humans can usually intuitively pick out one organism from the next – that is, because most of the creatures we come across have pretty clear boundaries in space and time...

...How come, then, the meaning of individuality is one of the oldest and most vexing problems in biology? For millennia, naturalists and philosophers have struggled to define the most fundamental units of living systems and to delimit the precise boundaries of the organisms that inhabit our planet. This difficulty is partly a product of the search for a singular theory that can be used to carve up all of the living world at its joints. But my view is that no such unified theory exists; there’s no single answer to the question: ‘What parts of the world are a part of you as a biological individual, and what parts are not?’ Different accounts of individuality pick out different boundaries, like an overlapping Venn diagram drawn on top of a network of biotic interactions. This isn’t because of uncertainty or a lack of information; rather, the living world just exists in such a way that we need more than one account of individuality to understand it...

...When you stop to think about it, the problem of individuality is (ironically enough) actually composed of two problems: identity and individuation. The problem of identity asks: ‘What does it mean for a thing to remain the same thing if it changes over time?’ or ‘What makes two entities the same kind of thing?’ The problem of individuation asks: ‘How do we tell things apart?’ or ‘What are the boundaries of an object?’ Identity is fundamentally about the nature of sameness and continuity; individuation is about differences and breaks...

...These two issues are different sides of the same coin. You can often reframe one in terms of the other to suit your focus. To pick something out in the world you need to know both what makes it one thing, and also what makes it different than other things – identity and individuation, sameness and difference. Each of these aspects of individuality also tends to come in degrees. A bee is better individuated than a swarm; and a swarm is better individuated than an ecosystem. Similarly, you are closer to the person you were yesterday than you are to the one in your baby photos... "

miércoles, 25 de octubre de 2017

Farmer Perceptions and Behaviors Related to Wildlife


Below-ground complementarity effects in a grassland biodiversity experiment are related to deep-rooting species 

Natalie J. Oram, Janneke M. Ravenek, Kathryn E. Barry,Alexandra Weigeltz Hongmei Chen, Arthur Gessler, Annette Gockele, Hans de Kroon, Jan Willem van der Paauw, Michael Scherer-Lorenzen,     Annemiek Smit-Tiekstra, Jasper van Ruijven, Liesje Mommer.

  1. Below-ground resource partitioning is often proposed as the underlying mechanism for the positive relationship between plant species richness and productivity. For example, if species have different root distributions, a mixture of plant species may be able to use the available resources more completely than the individual species in a monoculture. However, there is little experimental evidence for differentiation in vertical root distributions among species and its contribution to biodiversity effects.
  2. We determined species-specific root standing biomass over depth using molecular techniques (real-time qPCR) in a large grassland biodiversity experiment (one to eight plant species mixtures), in 2 years. Species-specific root biomass data were used to disentangle the effects of positive interactions between species (complementarity effects) and effects due to dominance of productive species (selection effects) on root biomass in mixtures. In a next step, these biodiversity effects were linked to the diversity of rooting depths and the averaged rooting depth of the community.
  3. Root biomass increased with species richness. This was mainly due to positive interactions (the complementarity effect), which increased with species richness below-ground. In contrast, the selection effect decreased with species richness. Although there was considerable variation in vertical root distribution between species in monocultures, the diversity of rooting strategies did not explain the complementarity effect. Rather, the abundance of deep-rooting species in mixtures (i.e. high community-weighted mean) was significantly related to the complementarity effect. Comparing the “predicted” root distribution (based on monocultures) to the actual distribution in mixtures, we found that mixtures rooted deeper than expected, but this did not better explain the complementarity effect.
  4. Synthesis. This study demonstrates that vertical root distributions of species provide only subtle evidence for resource partitioning. We found no evidence that functional diversity in vertical rooting patterns was important for the complementarity effect, in contrast to our expectation that the enhancement of productivity was due to resource partitioning. Alternatively, we found significant but weak relationships between the complementarity effect and deep-rooting communities, based on the community-weighted mean root distribution. This suggests that factors other than below-ground resource partitioning alone may drive the biodiversity–productivity relationship.


martes, 24 de octubre de 2017

Geographic mosaics and changing rates of cereal domestication 
Robin G. Allaby, Chris Stevens, Leilani Lucas, Osamu Maeda, Dorian Q. Fuller
Domestication is the process by which plants or animals evolved to fit a human-managed environment, and it is marked by innovations in plant morphology and anatomy that are in turn correlated with new human behaviours and technologies for harvesting, storage and field preparation. Archaeobotanical evidence has revealed that domestication was a protracted process taking thousands of plant generations. Within this protracted process there were changes in the selection pressures for domestication traits as well as variation across a geographic mosaic of wild and cultivated populations. Quantitative data allow us to estimate the changing selection coefficients for the evolution of non-shattering (domestic-type seed dispersal) in Asian rice (Oryza sativa L.), barley (Hordeum vulgare L.), emmer wheat (Triticum dicoccon (Shrank) Schübl.) and einkorn wheat (Triticum monococcum L.). These data indicate that selection coefficients tended to be low, but also that there were inflection points at which selection increased considerably. For rice, selection coefficients of the order of 0.001 prior to 5500 BC shifted to greater than 0.003 between 5000 and 4500 BC, before falling again as the domestication process ended 4000–3500 BC. In barley and the two wheats selection was strongest between 8500 and 7500 BC. The slow start of domestication may indicate that initial selection began in the Pleistocene glacial era.


miércoles, 18 de octubre de 2017

The role of agriculture in destabilizing the Earth system at the planetary scale

Through examining nine planetary boundaries, or “safe limits”: land-system change, freshwater use, biogeochemical flows, biosphere integrity, climate change, ocean acidification, stratospheric ozone depletion, atmospheric aerosol loading, and introduction of novel entities. Two planetary boundaries have been fully transgressed, i.e., are at high risk, biosphere integrity and biogeochemical flows, and agriculture has been the major driver of the transgression. Three are in a zone of uncertainty i.e., at increasing risk, with agriculture the major driver of two of those, land-system change and freshwater use, and a significant contributor to the third, climate change. Agriculture is also a significant or major contributor to change for many of those planetary boundaries still in the safe zone. To reduce the role of agriculture in transgressing planetary boundaries, many interventions will be needed, including those in broader food systems. 



Way too much livestock!!!