We’ve long known that plant seeds can remain viable not only after floating a long time in fresh or salt water, but also when passing through the guts of birds, including waterfowl. In fact, I believe that at least half of the plants that arrive on oceanic islands, later to form new species, come from seeds pooped out by birds—as opposed to having floated across the ocean.
Now, however, there’s a new method of dispersal: instead of plant seeds being transported in bird guts, plants themselves can pass through a gut and remain able to reproduce (at least asexually). This is the first time it’s been shown for any flowering plant (“angiosperm”) in any bird, though there are previous reports of moss fragments and fern spores being able to pass through and remain viable in the guts of waterfowl. The study described here allows plants a new way of dispersal…
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The many conceptual and empirical advances in evolutionary biology during the second half of the twentieth century that I have briefly sketched in part I of this essay naturally led to a broader theoretical turmoil. More and more people felt like the Modern Synthesis (MS) was increasingly becoming too restrictive a view of evolution to keep playing the role of biology’s “standard model.” This group included Carl Schlichting and myself, Mary Jane West-Eberhard (2003), Eva Jablonka, and others. But arguably none made a more concerted, if partial, effort than Stephen Jay Gould in his magnum opus, The Structure of Evolutionary Theory, published in 2002.
Scientific theories are always provisional accounts of how the world works, intrinsically incomplete, and expected to be replaced by better accounts as science progresses. The theory of evolution, colloquially referred to as “Darwinism,” is, of course, no exception. It began in 1858 with joint papers presented to the Linnaean Society by Charles Darwin and Alfred Russell Wallace and was formalized shortly thereafter in On the Origin of Species. The original theory featured two conceptual pillars: the idea of common descent (which was accepted by a number of scholars even before Darwin), and that of natural selection as the chief mechanism of evolution, and the only one capable of generating adaptation.
