During the late 1820s, Rene Lesson visited many times the ornithological collection of François Victor Masséna. Every morning, he crossed the doors of the Parisian palace of the Dukes of Rivoli and immersed himself in the more than 12,000 species they had accumulated there. Some say he fell in love there.
Sometimes, just before immersing himself in work, he would come across a very young woman Anna d’EsslingMasséna’s wife. Lesson, who was well aware of his social situation, never said anything; but in his papers he described Anna as “a woman of exceptional beauty, elegance and education.”
I imagine that, for this reason, when he discovered the amethyst-headed hummingbird among the Duke’s specimens, he thought of her. I imagine that, for this reason, Lesson named it after him. What I can’t imagine is what the French ornithologist would think if we told him that we were “evolving” the hummingbird he gave to Anna until we changed it forever.
But that’s how it is.
The evolution live and direct. I came to this story (and Global Change Biology study which supports it) thanks to a bluit by Carlos Cabido. It is, as the evolutionary ecologist says, “another case of rapid evolution that has generated observable adaptive changes in a very short period.”
The “smoking gun.” But let’s start at the beginning: researchers at the University of California Berkeley analyzed the population expansion and the morphological changes in the beaks of hummingbirds in relation to a very specific device: the feeders that, since the 1930s, have been used on the west coast of the United States.
These are simple sugar water dispensers, but (always according to researchers) they have caused a series of very striking changes.
What changes? On a regional and temporal scale, “the density/use of feeders appears as the best predictor of population expansion”; well above other variables analyzed. This means that the installation of these dispensers is the key to the expansion of hummingbirds.
Linked to that, researchers they observed significant changes in the morphology of the beak: it has become longer (to better access the feeder) and sharper (in a context where territoriality is becoming more important because it is linked to a very concentrated resource).
And all this in a couple of decades. That is, in about ten generations.
Why is it important? Above all, because it is one more example that a cheap, massive and standardized device (if it creates a new food environment) can reconfigure body structures and behavioral repertoires.
And, beyond all that, because it shows that, if environmental change is intense and sustained, natural selection works like a shot.
However, all that glitters is not a hummingbird. In fact, Anna’s hummingbird is almost an exception. As far as we know, countless hummingbird species They are suffering (and big time) the changes linked to the Anthropocene: although the Anna is growing, its first cousins are in clear decline. And yes, it is our fault.
Yeah this study shows that we have great power to change nature, the overview reminds us that “with great power comes great responsibility.”
Image | Robert Bottman
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