Butterfly Surveys Find Design, Not Darwin - Evolution News & Views

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Butterfly Surveys Find Design, Not Darwin

Gatekeeper butterfly

Thousands of laypeople join scientists each year cataloguing butterflies for science. Not only is it a fun way to focus on the winged wonders around us, it is important for long-term tracking of various species. Some recent articles showed what is being learned in surveys in different parts of the world. Unsurprisingly, Darwin usually has little to do with it.

The Scottish edition of the BBC News had a story on September 15 about Scotland's annual "Big Butterfly Count" with more than 34,000 people taking part and 322,000 butterflies and moths recorded. According to the survey, the coldest summer in 18 years was responsible for an overall drop of 11%, with some species faring better than others. The Gatekeeper butterfly (pictured above), a rust-and-brown beauty with two prominent black eyespots, was the most commonly seen. Tortoiseshell butterflies are stabilizing after a severe decline, while red admirals are up 98%. This article did not mention evolution.

Last month, PhysOrg reported the largest distribution atlas of butterflies in Europe, much larger than the previous 2002 edition, with almost three times as much data. 272 volunteers assisted the primary authors by providing the basic data for the publication. The new atlas included "all 441 European butterfly species," the article said; it did not mention evolution either.

Across the globe, a team of scientists has been working on an "intense, 30-year, ongoing biodiversity inventory" of Lepidoptera (butterflies and moths) in northwestern Costa Rica. As a part of the work, they published a report in PLoS ONE on "Reading the complex skipper butterfly fauna of one tropical place."1 Reading? Yes; "There is a living newspaper called 'The Dicot-eating Skipper Butterflies' that covers Hesperiidae in the subfamilies Eudaminae and Pyrginae inhabiting Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica," they said. "Field ecologists... have been reading this daily since 1978, through the spectacles of a field inventory of ACG caterpillars, their parasitoids, and their food plants." What they're reading is the DNA of these butterflies in a process called DNA barcoding. Have they read any Darwin headlines in this living newspaper?

The paper did discuss evolution in a few places, but not in ways very supportive of evolutionary theory. In one paragraph about neighboring species that differ in DNA barcode by less than 1%, they had to backpedal slightly: "Though they are presumably each other's nearest living relatives, we do not mean to imply that they evolutionarily split into separate species within ACG," they said. "The existence of species pairs like this shows how important it is to check thoroughly for possible cryptic species even when the divergence between barcode clusters is slight."

Here's another example of their caution about jumping to evolutionary conclusions:

If many of the similar species on either side of a shallow barcode split have a recent origin, then barcoding large samples might catalyze detailed studies of the ecology of sibling species earlier in their evolutionary histories than is generally the case. However, we are not suggesting that the large complex biota of ACG evolved in situ, or is even in any site-specific way evolving in situ. Rather, we believe that the ACG biota -- though now on an ecological island in the agroscape -- largely comprises somewhat to far more widespread continental species that have "ecologically fit" themselves into the complex mosaic of ACG topography, weather, climate, and biodiversity.
Another pitfall is the selection effect arising from the fact that we're only human:
The seemingly subtle morphological differences that often correlate with each side of an ACG barcode split show that no matter how good our viewing technology, we still see the world from the viewpoint of a large diurnal vision-oriented mammal. This in turn leads us to view morphological differences that we can easily observe as somehow more important in the biology of species discreteness and "older" evolutionarily. While there may be large-scale truth to this, for any specific case the generality may not apply.
The authors provided a few examples of how very morphologically diverse species may not be older than more "conserved" conspecifics in the evolutionary timescale. More problems arise when DNA barcodes are similar, but morphologies are not, or vice versa. Cryptic species and mimics are often hard to tease apart. Where is the split between a variety and a species? What about sexual dimorphism? When you find an anomalous barcode, what does it mean? "Is this seemingly deviant barcode a laboratory error, a pseudogene, a rare polymorph, or a single individual of another species?" they asked.

On top of that, comparing latest surveys with notes from a century ago, or even as recent as 2003, often leaves today's field scientist wishing better data had been kept. "The study of the biogeography of DNA barcode segregates within 'established' morphologically defined Lepidoptera species in the tropics is in its infancy," they sighed. Finding an evolutionary story in the voluminous data, even for one city-sized region in one country, is tedious and confusing. "A mere listing of the legacy species names for a given country tells us far less than we thought it did just a decade ago," they remarked regretfully in conclusion. "The complex skipper fauna needs a longer and deeper reading."

That was it for evolution in this paper, in spite of the fact that the study area should be a veritable Darwinian lab: "Because ACG dry forest, rain forest, and cloud forest intergrade and interdigitate over a relatively short distance, individuals of a volant species that 'occupies' one of these ecosystems can, and probably often do, contact at least the margins of the other two." Butterflies do, after all, fly. But after thirty years of research, these scientists could only offer questionable conclusions about evolution within certain genera of butterflies, hoping that future surveys throughout Central America may reveal more.

In a real sense, they have barely scratched the surface of Darwin's problems with butterflies.

Thumbnail image for metamorphosis-bluray.jpgDNA barcodes and morphology tell nothing about how the genetic instructions for legs, wings and eyes came to be in the first place in these fantastic flyers. The authors, furthermore, did not even dare to address the problem of metamorphosis. For more on problems with evolution and butterflies, and to learn about non-Darwinian explanations, see the film Metamorphosis: The Beauty and Design of Butterflies from Illustra Media. See also the companion e-book, Metamorphosis: The Case for Intelligent Design in a Chrysalis, in which world butterfly taxonomist Bernard d'Abrera discusses (in no uncertain terms) his impatience with lepidopterists trying to force data into a Darwinian mold.

Readers may wish to take part in a butterfly survey, just for the pleasure and value of getting outdoors and witnessing these delicate champions of biological design up close. For many, that will provide sufficient evidence that spectacular engineering does not arise by an unguided process.

Reference Cited

(1) Janzen DH, Hallwachs W, Burns JM, Hajibabaei M, Bertrand C, et al. 2011 "Reading the Complex Skipper Butterfly Fauna of One Tropical Place." PLoS ONE 6(8): e19874. doi:10.1371/journal.pone.0019874