Wednesday, September 22, 2010

Jeff Lockwood on Speciation

A few thoughts from Jeff on the nature of species my prompted by my "Big Black Nemesis" post. I like "constrained perspectivism". And notice he is a fellow Asia- phile (;-)

Book reviews and some photos coming...

"The photos at “Lauren” are great—I love the eagle booties and the landscape images (I’d swear that Mongolia is Wyoming’s ecological doppelganger, which is why I loved the Asian steppe so much when I was there).

"As for species and the nature of Gyrfalcons and Saker falcons, it just so happens that I’m involved with a reading group that is engaging the philosophical foundations of what species actually are. It’s a lovely mess! I’ve attached a few of the papers that we’ve been working on (some being more readable than others, but all being intriguing at least in terms of the intellectual battles of philosophers for the meaning of species).

"My inclination is to see species as the imposition of discrete categories on a fundamentally continuous process, such that it is not surprising that we sometimes (often?) “catch” life in the process of speciation. I suppose that I’m a kind of pragmatist—not in the pejorative sense but in terms of the great intellectual tradition of American Pragmatism. In fact, a colleague and I have a book out recently from Cambridge University Press: Philosophical Foundations for the Practices of Ecology (I’ll send you a copy if you’ll give me your address, which I’m sure I have somewhere already but won’t find easily). The basic idea is one that we call “constrained perspectivism”—that there is a real world out there, but our access to it is invariably partial and derived from our interests. This gives rise to a kind of pluralism that is neither the absolutism of certainty nor the relativism of hopelessness. So as for species, I’m something of a realist-pluralist. That is, I think that there are multiple ways of carving up the world with regard to species such that some of these approaches fail and others accord with our interests in ways that tell us that these formulations of species are representative of a way that the world actually is.

"All of this is to say that your view that the birds, “imperfectly separated at the end of the Ice Age, may still interbreed, and even more controversially may segregate into distinct types that are named and valued differently by Arab falconers when caught on migration” seems to touch on at least two approaches to species that could be empirically valid depending on whether one’s interests are evolutionary or eco-geo-cultural. In the former case, there is one species for the purposes of scientific explanation (assuming that reproductive isolation is the standard that one selects) and in the latter case, there are two species for the purposes of biogeographic/social purposes (assuming that this formulation “works” for these people in terms of engaging nature in a way that satisfies their interests)".

3 comments:

Matt Mullenix said...

Some serious brainpower in evidence.

smartdogs said...

After reading this I got to thinking about man-caused extinctions today while waiting for an oil change. I wonder if the important issue isn't so much that man causes dramatic changes in the environment but that the changes we bring are disruptively ephemeral when considered on an ecological time scale. With rapid and continuing change, existing species are stressed into extinction but new ones don't have time to evolve to fit a new niche before it disappears.

Mark Churchill said...

I think smartdogs is on to something here, in that anthropogenic change tends to be both rapid and unstable. For example: Viewed on an evolutionary timescale, agriculture itself is a very recent development; in many parts of the world, it essentially just happened.

This ties in to our recent discussion about the passenger pigeon, which may have gone from a "normal" species ecologically similar to the mourning dove, to a sky-darkening "superorganism" to extinction in the geological blink of an eye. White-tailed deer may have benefited from the decline of the passenger pigeon, and certainly have benefited from habitat changes in recent times, after being decimated less than a century ago.

Laurie Garrett, in The Coming Plague, an excellent book on emerging diseases, relates another story of nearly instantaneous ecological change: political instability and revolution leads to a regional change from ranching to farming, the plowing of riparian habitat and the sudden abundance of grain allows a previously uncommon and obscure rodent to flourish and come into close contact with humans, and a virus carried by the mice causes an outbreak of a new hemorrhagic disease.

Any change that can cause a population to rapidly spike might cause another to rapidly plummet, but while upper limits are flexible depending on ecological conditions—millions of whitetails, billions of pigeons, given adequate food resources—the lower limit is inflexible: there's no coming back from zero, and in some cases from near-zero.

As the Grants have demonstrated with Darwin's finches in the Galapagos, evolution is a constantly ongoing process; gyr-saker populations (for example, and to bring this back on-topic) may be converging, or may be separating, based on local/regional ecological conditions. Punctuated equilibrium allows for rapid speciation under some conditions, but in a rapidly-fluctuating environment, an incipient species may not have enough time to develop a foothold or enough genetic variation to adapt to new conditions.

Public policy implications: So while it may be a valid criticism to say that the "timeless" ecosystems environmentalists seek to conserve are in some cases very recent, or even that our recent climate may be an anomaly, that does not make them any less worthy of conservation. The world we have is the only one we can save, and while change is life's only constant, the only way to hang on to as much biodiversity as we can is to slow down the rate of change.