Systems of change

“[…] it is often not easy to assign insects to precise categories because there are so many species and their morphological, behavioral, and genetic differences frequently tend to overlap or intergrade. Often the best we can do is estimate degrees of relationship and/or distinctness and assign them to hypothetical groups as information becomes available. As anyone who gardens is well aware, botanists are often found transferring species from one genus to another, changing generic names, or even changing family names, for somewhat obscure reasons. […] it is because the evolutionary relationships of groups of species, genera, and families of plants are obscure and difficult to reconcile. This obscurity arises because organisms, whether plants or animals, are constantly evolving over time and space and are not precisely fixed genetic statues. Every individual organism is prone to variation, which the taxonomist attempts to codify, but the truth is that organisms have no particular regard for those of us who attempt to study them.” ~ Eric Grissell, Bees, Wasps, and Ants: The Indispensable Role of Hymenoptera in Gardens (Timber Press, 2010).

This is such an important point: it’s hard to pin down a moving target. The epic work of codification by the pioneering taxonomists, or systematists, took place before genetics were unraveled. Much of it was even pre-Darwinwallace. The one thing we probably all learned about species, that they are reproductively isolated, that is, they cannot breed with organisms outside their species, turns out to have been pretty simplistic, and not necessarily so. The fluidity of evolution is an amazing thing. Different species can often interbreed, and produce fertile offspring, but usually don’t because of their physical isolation.

There’s only one recognized Homo species now, but there have been, we think, something like half a dozen others historically; yet just as a H. erectus female didn’t given birth one day to a H. sapiens child, some of us now are probably in the process of becoming a new species (or two or three?). (Evidently, some of them are not going to be able to see for shit.)

In bird-land, the pronunciamentos of the authorities (the American Ornithological Union) come down from on high: last year, they split the winter wren (formerly Troglodytes troglodytes) into Pacific (T. pacificus) and Eastern (T. hiemalis) species; while the Eurasian wren remained T. troglodytes. Meanwhile, the subspecies T. t. icelandicus, which I saw on Iceland, is a darker bird, with a longer bill and longer legs, than the mainland Eurasian. Indeed, for this small species, icelandicus looks like a big bruiser. Might it be split someday, too? Probably. Islands, after all, are intense sites of evolution.

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