Friday, February 02, 2007

Square Pegs

This post has been selected to appear in the Open Laboratory 2007 anthology of science blogs!

Since being gifted with a copy of the book Mind Performance Hacks this past holiday, I have become fascinated by all the different memory techniques that have been developed. One of the first hacks is to create a system of numerical "pegs" to hang memories on, and after playing various games memorizing grocery lists and cars on the highway, I decided to put this new hack to good use.

Below is my set of 10 Invasive Species Pegs, along with ten important facts about invasive species that I am now guaranteed to never forget. They're not in order of importance, just in the order that I use to remember them. Mousing over the pegs will display my brain's (sometimes odd) associations with each number.

1=Phragmites, a wetland grass --> both aquatic and terrestrial
A Dividing Line - There are divisions that exist between various disciplines that prevent biologists from working together to tackle invasive species issues: terrestrial|aquatic, freshwater|marine, plant|animal. Most of this has its root in pre-existing organizations that were created to focus on weeds, or aquatic ecosystems, or pathogens and disease. Many of these organizations have found that invasive species now fall under their jurisdiction, and while many have taken steps to partner with each other, there is a lot of room for improvement.
2=mute swan --> charismatic megafauna
Feathers and Fluff - The attention an invasive species gets is frequently determined by how charismatic it is, whether that attention is positive (mute swan) or negative (snakeheads). Anyone want to start a program to adopt snakehead fish? Or gypsy moth caterpillars? Anyone?
3=bee --> Africanized bees, honeybees, hybrid bumblebees
DNA Matters - Invasion isn't just about one species displacing others - it can occur at the subspecies level. The genetic material of invasive organisms can threaten native species by leading to hybridization (between natives and non-natives, or even between two non-natives, leading to more aggressive invaders) and loss of genetic variation (when invaders attract mates or pollinators away from native species).
4=chalice --> The Holy Grail
The Holy Grail - Scientists wish they could predict, with certainty, exactly which species will be invasive, based on biological characters...but they still cannot. Tropical species can invade temperate zones, proliferous breeders don't necessarily succeed while those with low reproductive output sometimes do, and we're still not sure what role biodiversity levels in the native habitat play in the whole mess. What we do know: it is a very, very complex problem to try to tease apart.
5=snake --> snakes on a plane, brown treesnakes sneaking in to Hawaii
Snakes on a Plane - While people care very much about political borders, invasive species, in general, do not. Take a look at the invasive species lists for any state, province or country and compare them to one of their neighbors. First, you'll likely find that you can't match them up completely because one will be lacking mammals, the other lacking pathogens, etc. Second, the species on the list for a particular type of organism will likely differ so much that the mind *boggles.* Take a look at this study I did back in 2003 just for invasive plants in the New England states. Keeping in mind that the data is three years out of date (the Massachusetts and Connecticut lists are now much larger), note the huge differences between these relatively tiny, adjacent land masses [map]. Now think about the fact that New York and Vermont each manage Lake Champlain differently to control the invasive sea lampreys [insert your favorite expletive here].
6=vine --> vines have weedy habits
The vine wants what the vine wants - Some native species exhibit characteristics that are considered invasive. The general public often gets confused by this separation between native and non-native when something is simply a nuisance (You're going to keep the poison ivy and kill that pretty purple loosestrife - wha?). But more importantly, invasive species ecology does not need to stand alone as a science, ecological concepts like succession, r- and k-selected species still have meaning regardless of the origin of a species.
7=flag --> marking a transect next to a bottle of 7Up --> bottleneck
All Bottled Up - Endangered species are often at risk due to genetic bottlenecks, where a massive species loss leads to a lack of genetic variation which theoretically puts the species in danger of extinction. But non-native species introduced to new habitats typically experience these same bottlenecks (very few individuals, low population numbers, little genetic variation)...yet can become invasive. Sometimes those bottlenecks even lead to evolution of novel characters that are thought to make the species better invaders. Interesting...and I plan on looking into this more during my class this semester.
8=belt+two rollers --> construction equipment
What is “Natural”? - Some people say "Let nature take its course" with regard to invasive species. Yet humans are constantly influencing nature in a variety of direct and indirect ways. We dig, we plant, we pollute, we change weather patterns, we alter hydrologic paths. Why is it that we cannot also try to protect native species at the same that we are harming them?
9=cat with nine lives --> 3^2 --> multiples
Multiplicity - Most invasive species have several vectors of introduction. This is one of the few good predictors of invasive success. Also, the ways something gets introduced and the ways it later gets spread around are often entirely different. Though most species are linked with intentional introductions, unintentional spread via natural pathways (wind, flood, migration) makes controlling invaders much more complicated. Which is why prevention is such an attractive concept...
10=0=egg --> unidentified eggs of unknown origin --> egg timer
Time is Short - We don't have enough of it to definitively answer what the impact of every introduced species will be. There aren't enough grad students to do all those studies and there definitely isn't enough funding. That is the main reason why prevention is such an attractive proposition, even if prevention is a brush that paints with broad strokes.

Pegs 1, 2, 3, 6 and 10 are my photos, the rest are from photographers who generously shared their photos under a Creative Commons license. Thanks to LeoL30 (4), Geordie Torr (5), zen (7), D. Bjorn (8) and Salim Virji (9)!


Nuthatch said...

Great post!

budak said...

Very nice breakdown of the issues and questions!

Anonymous said...

I would like some clarification - is poison ivy a non-native? I was told it was brought from England and has naturalized

Also when would it be considered invasive?

Please send reply also to

Jennifer Forman Orth said...

Poison ivy (Toxicodendron radicans) is native to the eastern half of North America. For more info, see here: