Article by Dr. Matthew A. Barnes
Charles Elton opened his 1958 text by explaining, “Nowadays we live in a very explosive world, and while we may not know where or when the next outburst will be, we might hope to find ways of stopping it or at any rate damping down its force.” Given the timing of publication, one might assume that this was an introduction to the growing political crisis that would come to be known as the Cold War. However, Elton, a zoologist at Oxford University, was referring to “ecological explosions,” dramatic increases in biological populations including disease epidemics and outbreaks of agricultural pests and weeds. The book was The Ecology of Invasions by Animals and Plants, and it would go on to be considered a seminal resource in the study of biological invasions.
Even by 1958, Elton recognized that globalization and associated increases in trade and travel were promoting biological invasions, the intentional or accidental movement of organisms out of their native range and introduction someplace new, where they can have negative impacts on the local environment and economy. Infamous invaders include jumping Silver Carp in North American rivers, stinging fire ants in the southern United States, and literal herds of rabbits in Australia, among many others. Today, the cost of biological invasions has become massive. It is estimated that invasions cost over $120 billion each year in the United States alone, and although difficult to express in dollar values, invasive species rank among the top drivers of global species extinctions.
So what can we do about invading armies? Biological invasion is the result of an unfortunate chain of events beginning with organisms accessing transport out of their native range (which can be accidental as in the case of small aquatic organisms being captured in a ship’s ballast tank or intentional as in the case of flowering plants being farmed and transported for garden sales), surviving transport and being released in a new habitat, establishing a self-sustaining population in that new habitat, and causing ecological and economic impacts. Recognizing this process, efforts can target specific links in the chain: preventing organisms from accessing and surviving transport, detecting introductions early so they can be eradicated before negative impacts manifest, and controlling the spread of invaders to minimize further damage. Because it would be logistically difficult and ethically abhorrent, we cannot incite invasions to tailor opportunities to study the ecology and management at each stage in the process. But we can study ongoing invasions (like in the Pieris project!) to gain knowledge that will help manage in the present and prevent future invasions.
Dr. Matthew Barnes is an Assistant Professor in Natural Resources Management at Texas Tech University and an editor of a blog he co-founded about how to combat invasive species by eating them - Invasivore.org. His research focuses on improving our ability to detect and predict the spread of ongoing biological invasions. When he’s not studying or cooking invasive species, he enjoys relaxing at home with his wife and kitty, playing hockey, and tasting new beers.
One of our citizen scientist's Ansel Oomenn raised some cabbage whites this summer and noticed how variable the color of their chrysalis can be. Being a little inquisitive, he did a little experiment to see how the colors in the caterpillars environment might affect the color of their chrysalis. This is something called "phenotypic plasticity" (an organisms phenotype - how it looks and behaves - can be altered by its environment) and has been observed in many other butterflies. He placed different colored tissue paper (green or white) or different materials - cardboard and potted plants - at their pupation site (where they turn from a caterpillar to a chrysalis) and he found... it did influence their color!