Via io9: BIOL 103, “Biology in Science Fiction”, at Kenyon College. Sure, the lesson on tribbles is probably just about density-dependent population growth. But it’s a lesson on tribbles.
Monthly Archives: October 2009
Endless forms: Oral sex by fruit bats
One of those scientific papers that seems to have been written with the blogosphere in mind: biologists have just published records of fellatio by the fruit bat Cynopterus sphinx. Apparently C. sphinx females are pretty flexible — they lick their mate’s penis during copulation, which evidently induces him to stay in longer (see the graph below, with drawing). The authors offer a handful of non-mutually-exclusive hypotheses for the adaptive benefit of the behavior, ranging from lubrication to increased fertilization efficiency. The full text is available for free at PLoS ONE, if you’re up for some hot-and-heavy behavioral observations.
Graph from Tan et al. (2009), Figure 3.
Update: In a more in-depth post over at Boing-Boing, Maggie Koerth-Baker wonders why there needs to be an adaptive purpose for a pleasurable behavior (there doesn’t, as far as I’m concerned), and points out that there’s also a video in the supporting information. Which video has some totally unscientific background music.
Tan, M., Jones, G., Zhu, G., Ye, J., Hong, T., Zhou, S., Zhang, S., & Zhang, L. (2009). Fellatio by fruit bats prolongs copulation time PLoS ONE, 4 (10) DOI: 10.1371/journal.pone.0007595
How to synchronize flowering without really trying
One way plants can gain an advantage in their dealings with pollinators, seed dispersers, or herbivores is to act collectively. For instance, when oak trees husband their resources for an extra-big crop of acorns every few years instead of spreading them out, acorn-eating rodents are overwhelmed by the bumper crop, and more likely to miss some, or even forget some of the nuts they cache. These benefits of synchronized mass seed production, or “masting,” are straightforward, but how it happens is less clear. A paper in the latest issue of Ecology Letters has an answer — synchronization happens accidentally [$-a].
Bumper acorn crops ensure that squirrels miss a few. Photo by douglas.earl.
When Dan Janzen first described masting as an adaptation in plants’ coevolution with seed predators, he proposed that “an internal physiological system” [$-a] acted as a timer between masting events, with masting ultimately triggered by weather conditions. However, mathematical models have suggested a different possibility, the “resource-budget hypothesis:” that masting synchronization arises through an interaction of resource and pollen limitation [$-a].
Resource limitation works in concert with pollen limitation by catching plants at two stages of the seed-production process. First, if the resources required for seed production are more than can be accumulated in a single year, or if the availability of resources varies from year to year, then some years will be spent building up reserves instead of producing flowers. When reserves are built up, seed production is limited by the availability of pollen to fertilize flowers. Plants that flower when most of the rest of the population doesn’t will fail to set much seed, so they’ll have reserves to make seeds in the next year. This doesn’t require Janzen’s “internal physiological system” for the plants to synchronize, although such a system might evolve to reduce the likelihood of wasting resources by flowering out of synch.
The new paper tests this model in populations of a western U.S. wildflower, Astralagus scaphoides, which flowers at high frequency every alternate year. The authors prevented seed production in the plants by removing their flowers, either in a “press” of three years in a row or in a single “pulse” during one high-flowering year. The plants’ response to these treatments would reveal the role of resource and pollen limitation in synchronizing seed production.
If resource depletion after fruit set prevents reproduction in successive years, we predicted that ‘press’ plants would ﬂower more than control plants every year, as they were never allowed to set fruit. We predicted that ‘pulse’ plants would ﬂower again in 2006, but not set fruit due to density-dependent pollen limitation in a low-ﬂowering year.
The authors also measured the sugars stored in the roots of plants collected before and after flowering in a high-flowering year.
Seed predator in action. Photo by tombream07.
The resource-budget hypothesis worked. Plants prevented from setting seed were forced out of synch with the rest of the population. “Pulse” plants flowered the year after treatment, but because few other plants did, they received little pollen and set little seed. They then had resources to flower yet another year, with the rest of the population this time, and set much more seed, depleting their reserves and bringing them back into synch. “Press” plants continued to flower at high rates each year, as long as they were prevented from setting any seed. Sugar levels built up in the tested roots during non-flowering years, and dropped after high-flowering years.
So masting arises as an emergent result of two limitations acting on plants — the resources needed to make seed, and good access to pollen. A couple of simple rules lead, undirected, to an ordered system that affects entire natural communities.
Crone, E., Miller, E., & Sala, A. (2009). How do plants know when other plants are flowering? Resource depletion, pollen limitation and mast-seeding in a perennial wildflower. Ecology Letters, 12 (11), 1119-26 DOI: 10.1111/j.1461-0248.2009.01365.x
Janzen, D. (1971). Seed predation by animals Ann. Rev. Ecol. Syst., 2 (1), 465-92 DOI: 10.1146/annurev.es.02.110171.002341
Janzen, D. (1976). Why bamboos wait so long to flower Ann. Rev. Ecol. Syst., 7 (1), 347-91 DOI: 10.1146/annurev.es.07.110176.002023
Satake, A., & Iwasa, Y. (2000). Pollen coupling of forest trees: Forming synchronized and periodic reproduction out of chaos. J. Theoretical Biol., 203 (2), 63-84 DOI: 10.1006/jtbi.1999.1066
Someone’s on the ball
The website for Evolution2010 is already online! I really like the logo. The site design looks familiar, and good for the organizers for not wasting time to re-evolve the camera eye, say I. Portland is going to be a great location, I think — my experience is that Evolution meetings are largely remembered by the quality of beer available, which should be hard to get wrong in that town.
Image from Evolution2010.
An important distinction
Here I would remind us, again, of Wendell Berry’s distinction between religion and superstition. Religion, Berry said, is belief in something which cannot be disproved. Superstition, on the other hand, is belief in something that has been disproved. The former can be reasonable, the latter cannot. For all of Bill Maher’s railing against religion as “mere superstition,” it seems he doesn’t understand either of those ideas. His latest anti-vaccine, anti-medicine, anti-science crusade is superstitious nonsense. It’s religulous.
The first church of taking offense
Heard about R. Crumb’s comic-book adaptation of Genesis? The Slog passes this along from the Daily Telegraph:
“It is turning the Bible into titillation,” said Mike Judge, of the Christian Institute, a religious think-tank. “It seems wholly inappropriate for what is essentially God’s rescue plan for mankind.
“If you are going to publish your own version of the Bible it must be done with a great deal of sensitivity. The Bible is a very important text to many many people and should be treated with the respect it deserves.”
Thing is, Crumb’s adaptation is an entirely straight-faced illustration of the text. (Check out NPR’s excerpt, if you want to see for yourself.) So, yes, Adam and Eve are naked, and Lot has incestuous (and unwilling) sex with his daughters. But these are straight out of the text! That’s right: a Christian “think-tank” is objecting to the very concept of illustrating the Bible. Slacktivist is right, in spades.
Fearmongering for good?
Medical thriller specialist Robin Cook outlines the plot of a book about the catastrophe resulting from recombinant influenza, in the hope that such a book would spur preparedness efforts:
Governments and individuals will do desperate things, some rational and others not so, like deploying the military to try to close borders or using firearms to keep possibly infected strangers at bay. Hospitals will be overwhelmed at first and later forced to lock their doors. To avoid interpersonal contact, people will hole up in their homes, causing government offices, schools, and businesses to close. Many public officials will be forced to quarantine themselves from a diseased population and retreat to undisclosed locations, which will only fuel the public panic. Riot police in biohazard suits (if there are even enough to go around) will increasingly be called upon to beat back waves of sick, scared, and helpless civilians, desperate for food, water, and medicine.
Tom Clancy seems to inspire a lot of our homeland security policy (though less so under the present Administration) — why shouldn’t Cook have a go at public health planning? Personally, I find the pandemic ‘flu threat more probable than terrorists armed with exploding water bottles.
Social termites team up with non-relatives
In social insects, colonies of hundreds or thousands of workers and soldiers forgo reproduction to support one or a few “reproductives” — drones and a queen. In most cases, this isn’t as selfless as it might seem. Because the workers in a colony are all offspring of the queen, they’re really reproducing through her — because the queen shares genes with the workers, when she reproduces it contributes to their evolutionary fitness.
This is called kin selection, and in many cases it’s a good explanation for the way the interests and behavior of individual workers are overridden by the interests of the colony. There are, however, exceptions — and an open-access paper in the latest issue of PNAS describes what looks like a good case: mergers between unrelated colonies of termites.
Zootermopsis nevadensis, a social insect inclined to negotiated settlements. Photo by BugGuide/ Will Chatfield-Taylor.
The termite Zootermopsis nevadensis lives in small, socially-stratified colonies that tunnel through rotting logs. Each colony has a pair of reproductive individuals, a king and queen, served by sterile workers and soldiers. Multiple unrelated colonies usually nest in a single log, and when they encroach on each other’s territory, something interesting happens — they merge.
In what the authors refer to obliquely as the “interaction” that precedes a merger, the king and queen of one or both colonies may die. Mergers occur in the aftermath, as workers from the two colonies began to work in concert, and one or a few of them become replacement reproductives. This ability of sterile workers to start reproducing in the absence of a king and queen is unique to termites. DNA analysis shows what happened after mergers — new reproductives could arise come from either or both colonies, and that in some cases they interbred.
It’s this possibility to become genetically invested in the newly merged colony, the authors say, that motivates workers from two unrelated colonies to work together. If this is the case, it means that kin selection is not what keeps merged colonies together. Group selection might be a better explanation. Kin selection is often contrasted with group selection, in which unrelated individuals sacrifice their own interests to those of a larger group, so that their colony can better compete against rival colonies. In a classic 1964 Nature paper [$-a], John Maynard Smith discussed the conditions under which kin selection operates well:
By kin selection I mean the evolution of characteristics which favour the survival of close relatives of the affected individual, by processes which do not require any discontinuities in population breeding structure.
And contrasts them to conditions necessary for group selection to work:
[Under group selection] … If all members of a group acquire some characteristic which, although individually diadvantageous, increases the fitness of the group, then that group is more likely to split into two, and in this way bring about an increase in the proportion of individuals in the whole population with the characteristic in question. The unit on which selection is operating is the group and not the individual.
The ecology of Zootermopsis nevadensis may set the stage for group selection to overpower kin selection. With many small colonies competing for a single rotting log, the benefits of possibly contributing to the reproduction of a larger, more competitive colony make mergers worthwhile. Something similar has been documented in ants, which can form supercolonies of unrelated colonies if there is some external threat (another ant species) to force them to band together — you can find discussion of a recent paper on this case over at Primate Diaries.
SMITH, J. (1964). Group selection and kin selection Nature, 201 (4924), 1145-1147 DOI: 10.1038/2011145a0
Johns, P., Howard, K., Breisch, N., Rivera, A., & Thorne, B. (2009). Nonrelatives inherit colony resources in a primitive termite Proc. Nat. Acad. Sci. USA, 106 (41), 17452-6 DOI: 10.1073/pnas.0907961106
The birth of “scientific” management
Read this last weekend, but didn’t get a chance to comment: online at The New Yorker, Jill Lepore reviews Matthew Stewart’s The Management Myth: Why the Experts Keep Getting It Wrong. Lepore digs into the origins of “scientific” management approaches that emerged in the early 20th century, aiming to wring the maximum productivity out of every worker. The field was essentially created out of whole cloth by one Frederick Winslow Taylor, who made up data, trafficked in racist stereotypes, treated industrial workers like livestock to be trained, and charged companies ridiculous fees for the service:
How did Taylor arrive at forty-seven and a half tons [as the amount of iron one man could load in a day] for Bethlehem Steel? He chose twelve “large, powerful Hungarians,” observed them for an hour, and calculated that, at the rate they were working, they were loading twenty-four tons of pig iron per man per day. Then he handpicked ten men and dared them to load sixteen and a half tons as fast as they could. They managed to do it in fourteen minutes; this yields a rate of seventy-one tons per man per ten-hour day. Taylor inexplicably rounded up the number to seventy-five. To get to forty-seven and a half, he reduced seventy-five by about forty per cent, claiming that this represented a work-to-rest ratio of the “law of heavy laboring.” Workers who protested the new standards were fired.
Cheaper by the Dozen first-edition cover. Image from Wikipedia.
The saner practitioners of scientific management turn out to be none other than Frank and Lillian Gilbreth, whose efficiency-oriented family life is chronicled in Cheaper by the Dozen, a book I loved in about sixth grade. What doesn’t come through in the book is that Lillian was a substantial contributor to Frank’s thinking and writing about worker efficiency, and may have ghostwritten one or more of his books. This moment, I think, sounds like the Frank and Lillian Gilbreth I know from the CBTD:
Onstage, Frank was challenged by Emma Goldman. He was pointing to a chart illustrating the hierarchical relationship between the foreman and the worker. “There is nothing in scientific management for the workman,” Goldman shouted. “The only scheme is to have the workman support the loafers on top of him.” Lillian leaned over and whispered something to Frank, who cheerfully turned the chart upside down.
“Management,” as a separate academic discipline has always struck me as basically bunk. But the Gilbreths, at least, seem to have had legitimately good intentions.
Not sure that’s a problem with the website
Via Slog: There have been some glitches in the launch of the new GOP.com (to which I refuse to link).
Among the problems were the posting of administrator passwords, a list of GOP accomplishments that ended in 2004 and a “future leaders” section that was devoid of material. In addition, the site was inaccessible for much of the day.