Saturday, September 4, 2010
Maybe the best way forward is not more international governmental summits, but rather focusing on small scale, achievable short term goal. Guillaume Chapron started the Biodiversity 100 campaign, hosted by the Guardian (see story here), which seeks out public and professional input into the 100 immediate and achievable projects or ideas that will help protect biodiversity. The idea is to be able to go to governments and international agencies with this list and get them to make specific pledges to carry out these tasks.
There is till time to participate! If you have an idea of an action to protect biodiversity, fill out the web form. There are already a plethora of great suggestions, from protecting specific habitats to stemming population growth. This list is important because it includes the voices of the international public citizenry and that of scientists. More than that though, there will be a concrete list of tasks (ranging from very local to very global) that citizen groups can use to sustain pressure on governments.
Tuesday, July 27, 2010
In this era of species loss and habitat degradation, understanding the link between biodiversity and functioning of species assemblages is a critically important area of research. Two decades of research has shown that communities with more species or functional types results in higher levels of ecosystem functioning, such as nutrient processing rates, carbon sequestration and productivity, among others. This research has typically used controlled experiments that standardize environmental influences and manipulate species diversity. However, a number of people have hypothesized that biodiversity may be even more important for the maintenance of ecosystem functioning during times of environmental stress or change rather than under stable, controlled conditions. It is during these times of environmental change that preserving ecological function is most important, as changes in function can have cascading effects on other trophic levels, compounding environmental stress. Therefore, explicitly testing how biodiversity affects function under environmental stress can help to inform management decisions.
Image from Wikimedia commons
In a recent paper in the Journal of Applied Ecology, Li and colleagues examine how algal biodiversity influences productivity in microcosms with differing cadmium concentrations. Cadmium (Cd) is a heavy metal used in a number of products and industrial processes, but it is toxic and Cd pollution is a concern for human populations and biological systems, especially aquatic communities. This is especially true in nations currently undergoing massive industrial expansion. In response to concerns about Cd pollution effects on aquatic productivity, Li et al. used algal assemblages from single species monocultures to eight species polycultures grown under a Cd-free control and two concentrations of Cd, and measured algal biomass.
Their results revealed that there was only a weak biodiversity-biomass relationship in the Cd-free teatment, which the authors ascribed to negative interactions offsetting positive niche partitioning. In particular, those species that were most productive in their monocultures were the most suppressed in polycultures. However, in microcosms with Cd present there were positive relationships between diversity and biomass. They attribute this to a reduction in the strength of competitive interactions and the opportunity for highly productive species to persist in the communities.
While a plethora of experiments generally find increased ecosystem function with greater diversity, Li et al.’s research indicates that the effect of biodiversity on function may be even more important in polluted systems. If this result can be duplicated in other systems, then this gives added pressure for management strategies to maintain maximal diversity as insurance against an uncertain future.Li, J., Duan, H., Li, S., Kuang, J., Zeng, Y., & Shu, W. (2010). Cadmium pollution triggers a positive biodiversity-productivity relationship: evidence from a laboratory microcosm experiment Journal of Applied Ecology, 47 (4), 890-898 DOI: 10.1111/j.1365-2664.2010.01818.x
Thursday, July 22, 2010
Mayfield and Levine (2010, Ecology Letters), the authors critique the current ecological justification for the competition-relatedness hypothesis, noting that it does not agree with a more current view of the processes driving species coexistence. As established by Chesson (2000, Annual Review of Ecology and Systematics), coexistence can involve both stabilizing forces (niche differences between species), and equalizing forces (fitness differences between species). In a simplistic example, plants using different soil types (niche differences) may coexist, while plants with similar high growth rates may exclude those species with lower growth rates (fitness differences). The final community should reflect the interplay of both these processes.
The implication of this view of species coexistence is that there is no preconceived phylogenetic pattern which should reflect competition: if species with the highest heights are competitively superior and exclude other species (coexistence driven by fitness differences), and height is a phylogenetically conserved trait, the community will appear to be phylogenetically clustered. Traditionally, a clustered pattern would not be considered to indicate the effects of competition. In fact, Mayfield and Levine show that the expected phylogenetic pattern depends entirely on whether niche and/or fitness differences are important and/or related to phylogenetic distance.
This suggest that conclusions in past studies may need to be reinterpreted. It also adds to the list of assumptions about evolutionary relatedness and ecological function which need to be tested: for example, how do niche and fitness differences tend to change through time? Do they tend to be conserved among closely related species? Does one or the other tend to dominate as a driver of coexistence in different systems? If nothing else, we need to be careful about making generalizations which don’t account for the differing evolutionary history, geographical location, and ecological setting that communities experience, when interpreting observed patterns in those communities.
Wednesday, July 7, 2010
While, multiple farming strategies are needed for adequate agricultural production, there are strong arguments for organic farms to be a important part of agricultural practice. These results show that organic farms have cascading effects on pest predators and pathogens and show that enemy evenness, as opposed to richness, has important ecosystem service consequences. To quote myself, evenness is a critical component of biodiversity, and much research has emphasized species richness, maybe at the detriment of studying evenness.
Crowder, D., Northfield, T., Strand, M., & Snyder, W. (2010). Organic agriculture promotes evenness and natural pest control Nature, 466 (7302), 109-112 DOI: 10.1038/nature09183
Tuesday, July 6, 2010
Saturday, June 12, 2010
This week’s issue of Nature features a couple of pieces focusing on biodiversity through a political or economic lens. Although the economic benefits and services provided by species-level diversity has been well illustrated, in “Population diversity and the portfolio effect in an exploited species”, Schindler et al. (Nature, 465, 609-612) new evidence that at even finer divisions than the species, diversity plays an important role. In this case, they find that genetic diversity at the population level is an additional and significant contributor to ecosystem stability. Schindler et al. examine the effects of hundreds of locally-adapted populations of sockeye salmon on the valuable salmon fishery in the Bristol Bay area of Alaska. They suggest that the portfolio effect (or the robustness of biodiversity to variable conditions – like a diverse financial portfolio) can function at the population level as well as the species level. High levels of intra-specific diversity can produce temporal variation among populations in response to environmental variability, resulting in catches that are more stable year-to-year, and making fishery closures less likely, a clear economic benefit.
Populations are declining at an even faster rate than species themselves: the more we understand the importance of conserving diversity at multiple biological scales (ecosystem, species, population, even the individual?), the more complicated and onerous the task of conserving diversity becomes.
In the same issue of Nature is an editorial on the possibility of an IPCC-like panel for biodiversity. At this very moment (give or take a few time zones), government representatives from all over the world are deciding whether or not to create this panel. So far, they have a catchy name for it, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which hopefully hasn’t been written in stone. But they also have a strong recognition of the inextricable links between biodiversity, ecosystem services and human wellbeing – links that are highlighted in the Schindler et al. article. Furthermore, an explicit goal of IPBES is to address the currently tangled state of biodiversity organizations, conventions and programs by forming a unified front of sound biodiversity policy and science. The Convention on Biological Diversity had set a target of halting biodiversity loss by 2010 and we have failed spectacularly. Is IPBES the solution?
Wanted: an IPCC for biodiversity. Nature, 465, 525-525
Schindler, D.E., Hilborn, R., Chasco, B., Boatright, C.P., Quinn, T.P., Rogers, L.A. & Webster, M.S. Population diversity and the portfolio effect in an exploited species. Nature, 465, 609-612
By Nick Mirotchnick and Caroline Tucker
Wednesday, June 9, 2010
This is just the latest symptom of the growing tension between publishing and academia, and is a stark reminder that other publishing models need to actively supported. Perhaps the UC system could invest in open access publishers in lieu of NPGs outrageous costs? Something has to give, and perhaps the UC boycott will remind libraries that they hold the purse strings and could be the greatest driving force for change.
Tuesday, June 1, 2010
They used four species of bacteria: Bacillus pumilus, B. cereus, Frigoribacterium sp. and Serratia marcescens as residents in every possible 1, 2, 3 and 4-species communities and invaded them with a subspecies of S. marcescens. What they found was that the invader density was highly significantly related to phylogenetic distance, so that the invader reached its greatest density when communities contained only distantly-related species.
Though these types of laboratory experiments are simplistic (I too use these systems), they offer insights into particular mechanisms, which may otherwise be difficult to detect in noisier systems.
Jiang, L., Tan, J., & Pu, Z. (2010). An Experimental Test of Darwin’s Naturalization Hypothesis The American Naturalist, 175 (4), 415-423 DOI: 10.1086/650720
Tuesday, May 25, 2010
Two issues have been published and they have been populated by good, entertaining articles. I especially enjoyed the one by Bob O'Hara and Johan Kotze on why you shouldn't log transform count data. As a researcher, I've done this (instead of using a GLM with proper distribution) and as an editor, I've allowed this, but it has always felt wrong somehow, and this shows that it is.
The early success of the journal is not just the product of the good papers it has already published, but also because of the savvy use of electronic communication. They Tweet on Twitter, link fans through Facebook, blog about recent advances in methods from other journals and post podcast and videocast interviews with authors. These casts give readers access to authors' own explanations of how their methods can be used.
I am excited about this new journal and hope it has a great impact on the publication of methodological papers.
Tuesday, May 11, 2010
Thanks Steve for all your hard work and for making these tests available to everyone.
Kembel, S., Cowan, P., Helmus, M., Cornwell, W., Morlon, H., Ackerly, D., Blomberg, S., & Webb, C. (2010). Picante: R tools for integrating phylogenies and ecology Bioinformatics DOI: 10.1093/bioinformatics/btq166