Adventitious knowledge

Joseph Grinnell, eminent ecologist and zoologist of the early 20th century, and founding Director of the Museum of Vertebrate Zoology, where I was a graduate student, wrote some hilarious stuff. Google Scholar lists 376 publications in his name, most of which are actually by him, including foundational papers in niche ecology, bio-geography, museum science, and so forth. He took so many thousands of pages of detailed, elegant, highly legible, informative, rigorous, lyrical, systematic field notes that if I told you how many, I'd have to look it up again, and it is getting late here. And he is rightly revered as a founder and role model in the MVZ. But perhaps my favorite thing of all about Joseph Grinnell is his nearly forgotten, mildly disturbing, profoundly droll paper, "A Striking Case of Adventitious Coloration." I have no memory of how I first encountered this paper, other than that it was in my former life as an ornithologist at the MVZ. I have never come across another paper that cited it, and Google Scholar lists none. It is, at core, a mystery.

The whole story is available here. The first two sentences:

On February 8, 1920, I spent the afternoon with my family at a point in Moraga Valley, Contra Costa County, California, some five miles, airline, northeast of Berkeley. My son Willard undertook to exercise the shotgun for the purpose of securing some specimens of local birds such as happened to be needed at the Museum.

So ornately informal, so precisely vague, so informatively not-to-the-point, I am in love with this opening. No reputable journal would publish it these days, and that is a shame. He's storytelling, and quite well. The story strides on: Willard blasts a mated pair of Oak Titmice, both of whom have bright yellow breasts. Why bright yellow? Oak Titmice are grey, never yellow.  Grinnell rushes the five airline miles back to Berkeley, marches into the botany department with his dead birds, and tells them to figure out what kind of yellow pollen these birds have got on them. Not pollen, say the botanists. Grinnell marches into a mycology lab and tells them to figure out what kind of yellow spores his birds have on their breasts. Maybe slime molds, hard to tell, say the mycologists. Grinnell concludes that possibly bird feathers could be an important means of dispersal in slime molds! He finishes by pointedly mentioning that if anyone is interested, these two birds "and their loads of spores, constitute Nos. 40,391 and 40,392 in the bird collection of the Museum of Vertebrate Zoology." He publishes the whole thing in The Auk, and that is the end of that, for almost a century. A century, by the way, is how long Grinnell said some of the MVZ's specimens might have to wait before they would be put to some as yet un-imagined use. It has been 97 years.

Which brings me to that wonderful word in Grinnell's title, "adventitious." It means something on the order of "acquired by chance" which is how those titmice presumably got their yellow, and how I came to the knowledge that in a drawer in Berkeley two spore laden titmice waited.  What did I intend to do with this knowledge? Keep it in a drawer, until, perhaps after one hundred years, it proved valuable.

Now, I unexpectedly find myself with colleagues interested in spore dispersal ecology, and somebody mentioned spore dispersal via bird feathers. Which started me rummaging around in my dusty rusty musty gusty fusty drawers of ornithology, hunting for memory of birds with spores on them. All I remembered clearly was Willard undertaking to exercise the shotgun, but eventually (this morning) I found first memory, then paper, and shared both. And by afternoon my new mycology colleagues had requested access to Nos. 40,391 and 40,392 from my old ornithology colleagues at the MVZ, so that we can collect some of the long faded yellow dust. A little bit of molecular genetics wizardry (our lab is set up for sequencing DNA from dried fungal museum specimens) and we may finally be able to discover what made Grinnell's birds so yellow. If it is a new species of anything, we must surely name it after Willard.

Malards on my mind

My office here at the institute has a beautiful view of the unter-Warnow, the tidal harbor area just before the Warnow River flows into the Baltic. The city of Rostock and many of its suburbs are arrayed along both banks of the unter-Warnow, and the Institute is right above the banks, allowing marvelous views. There are some drawbacks to this for a person easily distracted by birds, as I am. I frequently find myself watching the gulls chasing each other, the swans terrorizing the mallards, or the rooks, hooded-crows and jackdaws playing in the wind.
The last several days I have noticed that the same two groups of mallards are always in the same two spots. In the river, near the institute there is a consistent group of six males and five females, always floating in about the same spot. In a drowned foundation on the abandoned port-facility just west of here, there are always four male and three female mallards, with one of the males showing the white splotching indicating it has some ancestry among the domestic mallards. These several birds always seem to be in the same two groups, in very similar spots, and I can only assume they have found something good to eat there, as they don't seem to move elsewhere to feed. I wonder if they will stay all winter. I wonder what I should have done in the time I spent censusing mallards.

Benign Decline?

For many decades now intellectuals, policy makers, humanitarian organizations and environmentalists have put time, money and effort into worrying about the negative impacts of humanity's ever-increasing population. It is certainly a problem worth worrying about. Everything from food and water shortages to increased disease transmissibility to habitat destruction and global climate change are made worse by overpopulation. Jared Diamond, in his excruciatingly detailed and example rich tome, Collapse, explores how human societies can fail when their population outgrows the resource base on which they depend. World population projections estimate that we will top out at 9 to 12 billion some time between 2050 and 2075. That is a lot of people for this little planet, and the risks are real and enormous. But I've been thinking about the opposite problem, one we have thought very little about, but is predicted in the same forecasts, declining population.

World population is predicted not to level off and stay at 9 to 12 billion, but to begin declining. There are two main reasons for this. First, the fertility declines that have driven the demographic transitions in rich countries are predicted to eventually reach poorer and then poorest countries as well. There is good evidence that this is already happening, as education of females and availability of information have reached places like Iran and India, fertility rates in those places has dropped very dramatically and without Chinese style coercion. Fertility rates are declining almost everywhere, even if they are still quite high in some places. The countries that undergo this transition latest are expected to still get there eventually. If the whole world had fertility rates like what the Japenese have, world population would eventually decline.

The second reason population is expected to decline dramatically is what is called population momentum. A population that had a lot of babies 20-30 years ago inevitably has a lot of babies now, because of the large number of young women reaching their peak reproductive capacity. Iran is a perfect example of this. Iran is still producing an enormous number of babies, even though per-woman fertility has declined dramatically, because there are just so many reproductive age women who were born when fertility was extremely high 20-30 years ago. Americans are familiar with this effect from the "echo boomers" the large cohort of children born in the 60s and 70s as offspring of the baby boomers. Much of what is currently carrying world population upward is this type of momentum. Much of the world still has a very young (median age in Pakistan is about 16), and therefore reproductive, population. As fertility rates decline and longevity decreases, world population is aging dramatically. Median age in Japan is about 47 and rising fast. By 2050, the UN predicts that median age in Pakistan will be closer to 35 and Japan closer to 55.

Somewhere around there world population will begin to decline, slowly at first, and then more rapidly. That is the prediction anyway. The problem is that all of our models are predicated and tested based on increasing world population. World population has increased every year since before the advent of modern science. And it is not only our demography that is based on the assumption of ever increasing population. Our entire economic system is built around the idea of ever-expanding demand driven by ever expanding population. We know how to add new housing developments, houses, cities, businesses, banks and so forth. We know how to tear down small buildings to make space for bigger, taller ones. We have no system for dealing with declining population. How should a business respond if its potential audience gets smaller every year? How should a city respond if fewer and fewer of its housing units are occupied? How should a family respond if there is no one to take over the family business or farm? How should a government respond if there are too few people to pay its taxes or fill its military?

We do have case studies of this sort of thing. Flint, Michigan is talking about condemning and leveling not just individual homes, not just whole neighborhoods, but major portions of the city that are no longer viable because the population of that city has shrunk so fast. Japan, Germany and much of the former Soviet Block are experience population decline, and adapting to it with various degrees of success. The countries that do well despite population decline seem to be those that base their economies on exports to other regions where population is still increasing. If domestic demand declines but overall demand continues to rise, it may not be such a problem. But what will happen if population is declining almost everywhere? Will people or nations increase fertility in response? Will the general lack of children induce even more people to not have children, driving fertility even further down? Will we develop economic and development structures that thrive on population decline, as our current system requires population growth?

Michigan's population decline is directly attributable to collapse in demand for Michigan's main product. Population declines in Eastern Europe are similarly caused by politial, economic and social decline. The types of population declines Jared Diamond wrote about were caused by collapses of ecologies and socieites. If we manage to get through the population maximum of the 21st century without major collapses, we may be faced with the relatively novel situation of benign decline. That can only happen if we build systems that can function and thrive with declining populations. We don't yet know how to do that.

Wherefore art thou, niche conseratism?

"Niche conservatism is the tendency of species to retain ancestral ecological characteristics." (PDF)

But why do species have this tendency, or more particularly, why do ecological traits not change more rapidly than they do as a lineage evolves? Wiens and Graham state that, "We refer to niche conservatism as a process, although it may be caused by more than one factor at the population level," but don't say what those factors may be, or provide a reference to someone who does.

So what causes niche conservatism:

Two basic mechanisms occur to me. The first is that new traits simply don't arise, and therefore can't be selected for or against. Why don't we have rats that can eat iron? There is lots of elemental iron around these days, and it is very high in energy. Surely a rat that could eat iron and extract all that energy would do very well, and make lots more iron-eating rats. But that trait has not occurred (and is not likely to do so) and as such there is no way for natural selection to favor the iron-eating rats. But for traits like sexual mass dimorphism, this type of constraint seems unlikely. We know that closely related species sometimes have very different mass dimorphisms (compare gorillas to humans). But closely related species usually don't have wildly different mass dimorphisms, so there is conservatism in the trait even though it is pliable.

The second possibility that occurs is that niche conservatism comes about simply because a trait works well with the way a population lives, and the other traits is has, and therefore some form of selection acts to keep the trait where it is. The trait is conserved because it is functional. Even if some other combination of traits would be more advantageous, that combination would require so many modifications that you can't get there from here. The population would have to go to far 'downhill' on the fitness landscape to get to that taller hill across the way. So selection, which tends to push the population 'uphill,' keeps it on the little local peak it is on. By keeping the population where it is, selection causes niche conservatism.

I'll call it a hypothesis. First I need to find out who has already said almost the same thing.