Many plants imported to the US for horticultural purposes (landscaping, ornamental gardening etc…) in the past have become invasive. For example, Oriental Bittersweet was introduced to New England from China as an ornamental around 1860. Nowadays, the species is widespread in the US and, if left unchecked, shades out native trees, bushes and shrubs.

The horticultural trade is still prolific and as the global economic situation changes the US is trading with a wealth of new countries. Any of the species that the US is newly importing from these countries have the potential to become the next big invasive problem.

A garden in the Sonoran Desert planted predominantly with drought-tolerant species introduced from the Chihuahuan desert in Mexico

Another factor that needs to be considered is what kind of species US gardeners will want to import in the near future. As climate changes, the US is getting warmer. This means for example that gardeners in New England are starting to plant the kinds of species that previously could only be grown south of the Appalachians. The kinds of places that are being gardened are also changing. The massive influx of people into the southwest has led to a huge demand for garden plants that can survive the hot dry climates. This region has relatively few invasive species compared to the rest of the US, but as its human population grows this is likely to change.

So we wanted to know whether new trade relationships would promote the introduction of plants that are ideally adapted to become problematic invasives.

It turns out that emerging US trade partners  are clustered mainly across tropical regions, the Middle East, and
Eastern Europe – imports have risen by around 70% from these countries in the last 10 years.

We analysed invasive plants already in the US and found that species were likely to escape from gardens and grow wild in parts of the US that have the same kind of climate as the countries they come from. Armed with this information we realised that species imported from many of the emerging trade partners were likely to grow wild in the US because climate change is making US conditions more suitable for them, and these species are suited to the hot, dry conditions of the southwest where they are increasingly being planted.

The good news is that armed with this information we may be able to prevent invasives from arriving. Screening systems in place in Australia that aim to prevent imports of potentially invasive species have proved quite effective. These systems ask whether the climate in the export country is similar to climate in Australia. This kind of measure could be implemented in the US, but with the improvement that the similarity between the export country and future US climate conditions also be assessed. With new trade relationships emerging all over the world, we advise that screening systems used by any country be on the look out for species that have never before been exported outside their home region, as any of these untested species might turn out to be pests.

Bethany A Bradley, Dana M Blumenthal, Regan Early, Edwin D Grosholz, Joshua J Lawler, Luke P Miller, Cascade JB Sorte, Carla M D’Antonio, Jeffrey M Diez, Jeffrey S Dukes, Ines Ibanez, and Julian D Olden. 2011. Global change, global trade, and the next wave of plant invasions. Frontiers in Ecology and the Environment (e-View). Doi:http://dx.doi.org/10.1890/110145

A gap in the climate path of the speckled black salamander traps the species in a delining range in California.

Unexpectedly (we were planning to study something a bit different) we discovered that the unsteady rate of climate change caused species to get stuck part way along their climate paths. Species moved forward while climate warmed, but retreated if climate cooled down for a period – two steps forward, one step back. It turns out that, during these periods when climate change pauses, if species can persist at the point of the climate path they have reached for 10 or 20 years they are ready to move forward when the climate starts to change again. Unless species can do this their progress is continually knocked back, so they end up with very small ranges – to the point of endangerment. Even if species can hang on to the advancing edge of the climate path, it’s not always enough to allow them to reach their future range.

This makes conservation under climate a change a little more tricky than we thought (and no one thought it was easy to start with). But the more we study the range-shift process, the better able we are to predict the challenges that climate change poses to wildlife.

The article is freely available here: http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2011.01681.x/abstract, a press release about the research is here: http://news.brown.edu/pressreleases/2011/09/species. Media coverage can be found at the BBC, Scientific American and Discovery News.

This year, starting with the IBS biennial meeting in January, it’s been obvious to me that the collaborative opportunities and discussion that have arisen through interaction with my peers have been more fruitful than those with more established scientists. This obviously has a lot to do with the fact that my career is moving along, but also reflects what an exciting field biogeography is to be in right now and the remarkable scientific maturity of the PhD students and post-docs around me. To me this reflects the advances the field of biogeography has made in becoming not just a distinct discipline, but one that manages to consider simultaneously processes occurring anywhere from millions of years in the past to every hour of the day. To do this, as Lawrence Heaney pointed out, scientists must examine the paradigm through which they analyse the world. The young scientists I see in my field are perfectly positioned to do just that. There was an emphasis on inter-disciplinary thinking that I haven’t seen at any of other the meetings I’ve attended in the last eight months (since the last IBS meeting in fact!). Even more than that, the presenters were serious about their tools they are using to do integrate their multitudes of perspectives. There were several new techniques presented for uniting data across temporal and spatial scales that seem likely to take biogeography forward.

In particular, Corey Merow presented some really practical work on how a widely used ecological-niche modelling tool can be refined to produce much more realistic results. Nicholas Matzke talked us through new models for reconstructing the ecological niches and distributions of ancestral species. This seems pretty important for investigating speciation and diversification. Juliano Sarmento Cabral demonstrated conceptually how long and short term range dynamics can be united to synthesise the conditions that might have led to the formation of particular communities

There was also a note of confidence in taking on some of the old paradigms in biogeography. Alex Pigot demonstrated that traditional explanations of the ‘boom and bust’ trajectory of range size during a species’ life time are no more supported than a null model. Yael Kisel and Lynsey McInnes showed that there may be a role for speciation and extinction in determining Species Area Curves, over and above environmental drivers.

So to the organizers – more please, and to the colleagues I’ve just met – thanks!

Protected and Threatened Components of Fish Biodiversity in the Mediterranean Sea.

David Mouillot,Camille Albouy, François Guilhaumon, Frida Ben Rais Lasram, Marta Coll, Vincent Devictor, Christine N. Meynard, Daniel Pauly, Jean Antoine Tomasini, Marc Troussellier, Laure Velez, Reg Watson, Emmanuel J.P. Douzery, and Nicolas Mouquet.

The Mediterranean Sea (0.82% of the global oceanic surface) holds 4%–18% of all known marine species (not, vert, similar17,000), with a high proportion of endemism (see a comprehensive review available at PLoS One). This exceptional biodiversity is under severe threats but benefits from a system of 100 marine protected areas (MPAs). Surprisingly, the spatial congruence of fish biodiversity hot spots with this MPA system and the areas of high fishing pressure has not been assessed. Moreover, evolutionary and functional breadth of species assemblages has been largely overlooked in marine systems. Here we adopted a multifaceted approach to biodiversity by considering the species richness of total, endemic, and threatened coastal fish assemblages as well as their functional and phylogenetic diversity. We show that these fish biodiversity components are spatially mismatched. The MPA system covers a small surface of the Mediterranean (0.4%) and is spatially congruent with the hot spots of all taxonomic components of fish diversity. However, it misses hot spots of functional and phylogenetic diversity. In addition, hot spots of endemic species richness and phylogenetic diversity are spatially congruent with hot spots of fishery impact. Our results highlight that future conservation strategies and assessment efficiency of current reserve systems will need to be revisited after deconstructing the different components of biodiversity.

http://www.sciencedirect.com/science/article/pii/S096098221100532X