Traveling scientists, traveling birds, traveling trees

Here are links to some interesting looking articles I heard about today. Maybe Twitter is useful after all.

1. Lee Barrett Russell Garwood argues at Nature that uprooting researchers can drive them out of science.

2. Hung et al. have a new paper in PNAS arguing that extinction of the passenger pigeon (Ectopistes migratorius) was due not only to extreme over-hunting but also possibly to population fluctuations inherent in the species, as driven primarily by acorn supply. But as is so common now, the article title (“Drastic population fluctuations explain the rapid extinction of the passenger pigeon“) does not follow the overall message of the article. The nosedive to extinction was surely a “drastic population fluctuation”, but clearly market hunting was an enormous factor in that, no matter if they have indeed found good evidence for an effect of natural population variation.

When I get the paper I’ll read their full argument, but I note here that it appears to be based on historic population fluctuations inferred from the genomic analysis of just four museum specimens, which is surely a red flag. I note also that although the PNAS article page says that the protein sequences analyzed have been deposited at NCBI, the link given returns a message saying “The requested page does not exist“. I find mainly mitochondrial nucleotide sequences for passenger pigeons there, one of which has been pulled by the original contributors. The supplemental material is available here.

GrrlScientist has an article on the paper at The Guardian, which is how I heard about it, and which includes this terrific watercolor:Ectopistes

3. Dan Kahan, who I find to be a perceptive, non-extreme sort of fellow, has a three part series (starting here) at Cultural Cognition on just what a consensus in science is really all about, and how it relates to what he terms internal and external validity (which roughly correspond to verification and validation in modeling). I haven’t read it yet, but it looks like he’s put a lot of thought into the issue, more than +/- anyone, so I surely will.

4. Lastly there’s this interesting looking study regarding very long distance dispersal of an Acacia species between the Hawaiian and Reunion Islands. But not by floating–the seeds won’t germinate after exposure to salt water–had to be via some other route, mostly likely avian.

3 thoughts on “Traveling scientists, traveling birds, traveling trees

  1. Re Kahan’s piece:
    The 97% consensus on climate change looks more like the 97% vote total claimed by a dictator in a third world country than the 97% belief that the earth revolves around the sun. There really shouldn’t be a 97% consensus about the future trajectory of a partially constrained, nonlinear, feedback-driven system that is not subject to empirical testing!

  2. If you read the Passenger Pigeon paper I’ll be interested if your take, but they sequenced DNA from only 3 museum specimens from 2 museums. so inferring past population bottlenecks seems to require a suspension of disbelief, especially if the specimens were acquired near the end of the species’ life or acquired by the same collector. Also, statements such as according to the surprised Dr Hung “outbreak species are either insects or rodents” doesn’t raise one’s confidence in a careful consideration of alternative hypotheses (nor does being published in PNAS). I can think of several bird species that are known to have periodic population outbreaks (and of course Snowshoe Hares are not rodents, nor are Lynx).
    If you accept the belief that PP required a large minimum population size to breed, then I think that commercial hunting and habitat destruction are sufficient to explain the demise of the Passenger Pigeon. Given they were long-lived, able to wander long distances in search of food, fairly general in their feeding habits, and at least occasionally captive bred, then I suspect there must be some other factor in their extinction, most likely an exotic disease that caused reduced fertility or sterility. That would explain the eventual failure of captive breeding too.

    • “especially if the specimens were acquired near the end of the species’ life”
      Agreed. Or any group with a high degree of inbreeding for whatever reason.

      Appears to be yet another case of the glamour journals putting sensational but tenuous findings above all else in their publication criteria, and hoping nobody will make a fuss about it.

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