Part of this blog was written on the flight between Sault Ste Marie and Toronto, sipping complimentary sprite and eating complimentary pretzels. The other part was much more mundanely written from a coffee shop in Vancouver on August 29th.
The TIPS conference turned out to be a mix of policy, management, and scientific presentations. I was expecting more scientific content, but I really enjoyed it this way. I met people I wouldn’t have had the opportunity to meet otherwise; people from various levels of government agencies from Canada, the USA and Mexico, parks and urban managers, scientists in government and academia. I heard about exciting cutting edge research, as well as the adventures of the people on the ground fighting invasives.
The talks that stood out most for me were those on pathogens and biocontrols. This is where invasion biology researchers seem to be closest to the ecological and evolutionary theory.
Biocontrols are all about species interactions. It works on the idea that when you take an organism out of one environment and put it into a new environment, you’ve left behind all the natural “enemies” (diseases, predators, parasites, etc.). By being “released” from the restraining control of these enemies, the invasive species are able to reallocate energy that was previously used for protection (e.g. thorns or chemicals that make their leaves uncomfortable or taste gross) into the growth and reproduction that make them “invasive”. This is called the “enemy release hypothesis”, or the “Evolution of Increased Competitive Ability” (EICA) hypothesis. Alternatively, there may not need to be any reallocation of energy; maybe it was enough to escape the enemies that hold population numbers of the invasive in check. Anyway, the idea of a biocontrol is to find organisms from the native range that selectively prey on the invasive species but on nothing else (or few other things), and reacquaint it with the invasive species. So like I said, research on biocontrols is really about application of ecological (i.e. species interactions and community dynamics keep the population numbers of the species of interest from overrunning local biodiversity in their native range) and evolutionary (i.e. genetic drift followed by selection for increased reproduction/vitality after being released from the selective pressure of an enemy) theory. I could (and probably should) write a whole blog post about this topic.
For pathogens I think it gets most interesting when there are multiple players involved. For example, beech trees are plagued by a fungal pathogen, but the fungus can only attack the tree after infestation by a scale insect. The scale insects bore holes through the bark so that they can feed from the phloem beneath. The pathogen then uses the wounds left by the insect to infect the tree. Not all trees are attached by the scale insect, and not all infested trees become infected with the fungus…
Another neat example (with no insect component =[ ) is the native eastern and western white pine species and their blister rust. Macedonian pine is sold as an ornamental tree, but it is more susceptible to the blight than the two native species are. Furthermore, the Macedonian pine hybridizes with the native species, and all the hybrid offspring show the Macedonian pine’s increased susceptibility! So be careful what you plant in your garden – you might be inadvertently leading to decreased fitness of the white pine species by introducing bad genes (i.e. more susceptible to the blight).
All this cool tree-pathogen work was presented/discussed by John McLaughlin from the Ontario Ministry of Natural Resources.