Many different aspects of biodiversity (e.g. taxonomic diversity, genetic diversity) can be monitored in an ecosystem and each of these aspects has the potential to provide a unique answer to environmental change. However most monitoring programs traditionally estimate biodiversity only considering a single taxonomic approach while functional dimensionality is generally neglected. The paper of Vandewalle et al. (2010) shows that the use of functional traits for biodiversity monitoring clearly complements taxonomic indicators, bringing new insights for understanding ecological response to land use change. Another great point is that this paper focuses especially on functional traits of animal groups as biodiversity indicators, which is relatively uncommon. Animal traits have not been often used to access community response as much as plant traits have, and the authors present four case studies across different ecosystems and groups (benthic invertebrates, collembolans, insects and birds) suitably using their traits to access it. So, although I do recognize that this paper does not bring really novel concepts to ecological studies, it does help functional diversity studies to overcome certain barriers which have restrained the development of the field for the past years. The paper shows its applicability to applied studies, such as biodiversity monitoring, and a feasible methodological approach capable to understand diversity patterns.
The study cases presented in the paper focus on the response of biodiversity estimated by three components with simple metrics: species diversity (Simpson index), functional diversity (Rao index, e.g. the range of trait values within the community) and mean traits (calculated for each species trait). Results showed positive relations between functional and species diversity descriptors for different biological groups, but in some cases the functional and taxonomic dimensions responded to different drivers. For example, beetle species diversity was directly correlated with landscape heterogeneity while the functional dimension (both functional diversity and mean traits) was influenced by the shift in landscape composition from forested to open agricultural landscapes. For benthic invertebrates, the results imply that are the community mean trait values (e.g. such as those related to aquatic stages, reproduction and dispersion) that respond to environmental gradients rather than the overall community diversity. So, what makes this paper interesting for me is that it shows that without functional knowledge a biodiversity monitoring program may achieve different conclusions. This feasible and applicable sequence of monitoring indicators allowed the determination of changes in community structure.
Nevertheless I think that some other dimensions could be included as additional indicators of biodiversity. Dominant traits associated to functional diversity express the importance of the community mean traits and its variation, but does not express the convergence or divergence between communities, what could be assessed by beta functional diversity (see de Bello et al 2009). Additionally, I believe that functional diversity, as almost all community properties, should be calculated in different spatial and temporal scales.
References
de Bello, F; Thuiller, W.; Lepsˇ, J; Choler, P.; Clément, J.; Macek, P.; Sebastià, M. & Lavorel, S. 2009. Partitioning of functional diversity reveals the scale and extent of trait convergence and divergence. Journal of Vegetation Science 20:475-486. (http://onlinelibrary.wiley.com/store/10.1111/j.1654-1103.2009.01042.x/asset/j.1654-1103.2009.01042.x.pdf?v=1&t=h8ywv6l0&s=44c302d8cf56592c9a19e9f22d6388430c1c6555)
Great write-up Luciana! If you are interested in this work, I suggest you check out the 2009 Ecology Letters paper by Dan Flynn and others showing how land use intensification drives disproportionate loss in functional diversity relative to loss of species in bird and mammal communities.
Incidentally, the use of functional traits as biological indicators is a really interesting one. In fact, this has been done in fisheries biology for at least a decade by Simon Jennings and others, who have shown body size characteristics (such as mean length or weight) have been steadily decreasing with increasing fishing pressure. David Conover and others have done some great experiments showing directional selection on silversides. It’s funny how two different fields can converge on the same ideas, from totally different perspectives.
Thanks Jon! The paper of Flynn et al (2009) is also one of my favorite, relating species richness of animal communities, functional diversity and land use intensification. I just chose Vandewalle et al (2010) because it was a very important paper to me in the beginning of my PhD, when I was just start thinking about functional traits in arthropods and its applicability. It showed to me in a very modest way that we need to consider the different dimensions of diversity, especially the functional, on the biodiversity monitoring. And we can do that sometimes using complementary simple metrics, as CWM, Rao and Simpson diversity.
It is funny that such basic indicators, as body size, give us so great answers. It seems that fields are converging to the most simple and obvious ideas.
I agree with Jon, great write up Luciana! I too was very inspired by Vandewalle et al. (2010) early on in my phD. Animal functional traits have a long way to go! I’m currently in my 3rd year of my phd looking at functional traits/diversity and beetles across logging/ old-growth forest boundaries in Tasmania (Australia). I’m particularly interested in building a consistent invertebrate trait framework. Kind of along the lines of McGill et al http://www.oeb.harvard.edu/faculty/pringle/jc/McGill_etal_2006_TREE.pdf
In the work I’ve done so far body size seems to be the most sensitive to forest disturbance!
Hey Nick, your work sounds super interesting. Any idea when it will be coming out? Here’s a bit of synchronicity for you: I was just in Tasi working with one of your external supervisors on similar ideas in reef fishes! Small world…
It is a small world!! Very amusing! Did you enjoy Tassie? How is the reef fish stuff going? My functional trait review is still in review at the moment, so we’ll see how that goes. Otherwise we’ve got a Honours student busily measuring morphological traits, whilst I’m formulating a molecular phylogeny of the beetles to enable us to weigh the traits appropriately.
Sounds great! Enjoyed my visit very much (although MONA was a bit…weird). The reef fish stuff is chugging along, trying to balance it and everything else. I’d be interested in chatting some more about your methodology (using phylogeny to weight traits? Interesting idea!). Feel free to drop me a line via email, you can get my address by searching for my name on the VIMS website. Cheers!