Camels (and alpacas and equids)

There are camels, at least seven of them, in one of the vacant lots adjacent to the Institute. These (the lots, not the camels) are generally dominated by garbage-bespangled weeds and scrubby little trees. Today there is a circus truck, a tent with camel stalls, and a bunch of camels happily chomping the weeds down to the ground. I've seen goats, sheep and even cows used to clear brush, but the camels seem to be eating through the weeds faster than any of these could. The garbage has been removed (hopefully before the camels were let in), and there is a man who looks more like a circus worker than a government worker cutting and hauling away the woody stuff  the camels pass by (actually just throwing it into another one of the vacant lots). It seems like by tomorrow evening they will have to move them to another lot, or bring in fodder. I wonder if the circus is paying for, or being paid for, the use of the lot. Seems like a good deal for both parties.

It is 6C (43F) and sunny, which means that Rostockers think it is summer, and are walking around, admiring the camels. Some college kids have carried their couch onto the waterfront and are setting up a barbeque.  The ice on the harbor has all melted, and the gulls and mallards are looking for handouts.

Given all this, you might rightly ask why I am in the lab on a Sunday, instead of showing my daughter the camels, or walking with my wife, considering that I have excellent student assistants who are doing all of the actual lab work. The answer is that student assistants are not allowed to be in the lab by themselves, regardless of how mature or well trained they might be, or how routine or undangerous the work. So if the animals need to be checked every day, someone has to be here every day to baby-sit whichever student is in that day. This situation has actually gotten somewhat better. For 18 months that someone always had to be me, and I worked 7 days a week unless I was too sick and had to ask a colleague to cover for me. Now I am working with two wonderful post-docs, and only need to be in the lab every third weekend. Soon another graduate student will join us, and it will be every fourth weekend. Of course, the more experiments there are going on, the longer we have to be in the lab each day, and we are at about 6 hours now, and this will increase. So while those 7 day work weeks I was working included two pretty short days, the occasional work weekend will soon mean working almost full time.

This is honestly not so bad, but I’d rather be out watching the camels eat up that vacant lot.

Update: 10 camels, 6 alpacas, 4 miniature ponies, 3 donkeys and 9 horses. Only the camels are out grazing, fodder is being brought in and more tents are being set up in the areas already cleared.

To survive and reproduce in good times and bad

jte asks:

Is there reason to believe, or evidence to support, that the forms of evolution occurring among species during a period of abundant resources is different from the forms of evolution occurring among species during a period of deficient resources?

It seems that a lot of the argument in evolutionary theory is that it takes a lot of energy to grow extra and useless appendages or what have you, so if they really are useless, you'd expect them to evolve away. But if resources are abundant--energy is not a particularly limiting factor--do you then get a scenario in which all kinds of wacky and useless appendages appear and are not attritioned away? Which gives those appendages time to hang around enough to be available when the environment changes and all of a sudden they are useful and confer an advantage?

Or something like that?

I wouldn't go so far as to say the "forms of evolution" are different. In good times and bad evolution acts through natural selection, genetic drift, mutation and all the same basic mechanisms. Rather I would say that selection acts of different traits, or favors different forms of those traits, depending on if times are good or bad. One excellent example of this has been documented by Peter and Rosemary Grant in long term studies of Darwin's Finches on the Galapagos Islands. The climate in the Galapagos is impacted hugely by the El Nino/La Nina climate cycles. In some parts of the cycle, the islands are cool and damp, vegetation grows lush, and there are lots of big seeds to be had. In other parts of the cycle, it is very hot and very dry and only the desert plants with their tiny little seeds are producing. In the good years, the finches with the big bills can eat lots of big seeds, and reproduce like mad. In only a few years the population of one finch species is dominated by big-billed finches. Then when the rains stop, the population starts to crash, and the finches with the little bills good for extracting and opening small seeds are much more likely to survive. After a few years of that, the population of that same species is again dominated by small billed finches. This isn't individuals developing differently depending on the food supply, this is just massive, cyclical natural selection driving the population's genetic make-up around in circles.

On a much larger time scale, generalists are much more likely to survive large extinction events, while specialists often dominate in habitats that have been very stable for millions of years. Consider which of each of these pairs of species is in greater danger of extinction?

German Cockroaches or Lord Howe Island Woodeating Cockroaches
The Black Rat or the Salt-Marsh Harvest Mouse
The Common Pigeon or the Mariana Fruit Dove
The Common Raccoon or the Cozumel Raccoon
Goats or Alpine Ibex
Humans or Sumatran Orangutans

In each case the generalist are doing fine, while their specialized relatives can't cope with change. The fossil record shows multiple examples of large groups going extinct when the coprolites hit the fan, but one or two very generalized species in those groups making it through and giving rise to many new species. The amazing thing is that over and over most of those new species are specialists, evolving to be increasingly good at dominating increasingly narrow sets of resources. Give Rattus rattus a few tens of millions of years and no other mammals on the planet, and they would evolve into many thousands of separate species, filling a vast array of niches, and most of those species would be specialists. If another great collapse came, the ones most likely to make it through would again be the super generalized rat.

As far as the "useless appendages" argument goes, remember that even when resources are abundant, there is still the race to see who can convert those resources into the most offspring the fastest. Plus, the ideal situation rarely lasts very long. Usually within a few generations the population of predators has increased, the food supply has diminished, or population density has gotten so high that pathogens are spread easily. Exponential growth is not to be underestimated. So with the possible exception of humans over the last couple of hundred years, it is almost never the case that a population goes on growing for many generations without selection knocking back those who spend their energy recklessly.

That said, there are traits that are advantageous in bad time and costly in good times, or the opposite. Sometimes species evolve plasticity, such as the ability to grow a thicker coat when the winter is colder, but not waste the protein in mild winters. And sometimes, like Darwin's finches, they just evolve back and forth. The camel's hump is probably something of a hindrance when water and food are plentiful, but it bears that cost because more often than not things will get dry again, and that hump will save its life. If camels lived in an environment where it didn't get dry for some thousands of years, they might end up sans hump, looking more like big llamas. Or they might just die out, vanquished by cows and goats. Camels, after all, are specialists.