Ants from a Kilometer Up « Myrmecos Blog

7 02 2008

Ants from a Kilometer Up « Myrmecos Blog

This blogger finds photos of ant nests in Arizona and the Amazon online. Ho-hum? How about from within Google Earth?

Harvester ants and Leafcutter ants — Amazing!





standard “emetic units”

6 02 2008

Finished today:

Moth Catcher, by Michael M. Collins

 

The kind of book that you should read if and only if the subtitle “An Evolutionist’s Journey Through Canyon and Pass” sounds like your kind of book — this book doesn’t rise above the expectations set by that title, nor does it fail in the end to meet them, either.

 

For the most part, it’s just the story of the “ordinary” life of a modern scientist — following and illuminating his passion for caterpillars and moths, describing the work of a lifetime in the span of a 150 pages, the bits and pieces of the real contributions Collins has made to science. Not earth-shattering or sky-splitting, but a valuable gleaning of facts contributing to a better understanding of speciation and hybridization.

 

eupackardia calleta

Pasted from <http://photo.net/photodb/photo?photo_id=5784219>

This is a Eupackardia calleta larva. “The gaudy color and pattern suggest warning coloration , as does the blood chemistry.”

 

He describes one experiment in the book that bears repeating (in fact, I’ve already repeated it to my son.) Nestling blue jays were raised

…as naïve predators, feeding them palatable viceroy butterflies, a supposed mimic of the poisonous monarch. The birds eagerly accepted the viceroys and learned to recognize them by their color and pattern When they were then offered monarch, the jays at first could not discriminate them from viceroys. Each time they attacked a monarch they quickly spat it out and retched in response to the cardiac glycosides these butterflies sequester from milkweed during the larval stage. (Revealing his wry humor, Brower [one of the scientists] quantified glycoside levels in standard “emetic units.”) Still reeling from the experiement, the wretched brids subsequently refused to feed on viceroy adults, presumably solely on the basis of their visual resemblance to monarchs. More than a century after Henry Walter Bates proposed the idea of micry, the Browers and their students linked together plant biochemistry and predatoation to explain the evolution of warning coloration in the monarch model and of convergent patterns on the wings of the viceroy mimic.

 

Such is the progress of science — proving or disproving, logic isn’t enough; although one feels a bit of sympathy for those poor jays.

 

Near the end of the book, the tone suddenly shifts from memoir to science article with a closely reasoned and intellectually stimulating description of the debate over the meaning of species — essentially, where you draw the line. It’s clear from reading this, by the way, that humans at this point in time are all one species, although he doesn’t address this question.

 

One question I would pose to him, though. He says “The longer two species evolve along separate lineages, the more genetic differences they accumulate and the less successful their hybrids will be.” But my understanding is that after a “short” separation, crosses are more successful leading to hybrid vigor. (http://en.wikipedia.org/wiki/Hybrid_vigor )

 

Post-script — one interesting fact.

He usually collects his butterflies and moths in traps, baiting the traps with females raised from captured  caterpillars that he hopes will lure the males he is interested in. There goes my vision of chasing around fields with butterfly nets — although that does happen at one point, it’s not the norm. 🙂

 

This book was mentioned in an earlier post: Tracks of Tracks in the Snow