How to make a bat

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fossil_bat.jpg

or•gan•ic | ôr'ganik | adjective. denoting a relation between elements of something such that they fit together harmoniously as necessary parts of a whole; characterized by continuous or natural development.

One of the wonderful things about how development works is that organisms function as wholes, and changes in one property trivially induce concordant changes in other properties. Tug on one element, changing it's orientation or size, and during embryogenesis any adjacent elements make compensatory adjustments, so that the resultant form flows, fits, and looks organic. This isn't that surprising a feature of development, though, unless you have the mistaken idea that the genome encodes a blueprint of morphology. It doesn't; what it contains is a description of interacting agents that work together in a process to produce a complex result. Changes in genes and regulatory elements can essentially produce changes in rules of development, rather than crudely specifying blocks of morphology.

What does this mean for evolution? It means that subtle changes to the rules of development can be caused by small changes to genes (and especially, to regulatory regions of genes), and that the resulting morphological changes may be dramatic, but are still integrated organically into the form of the organism as a whole. Our understanding of how development works is making it clear that large scale macroevolutionary change may be much easier than we had thought.

Here's an example where this insight is clarifying the evolution of an organism: the fossil record of bats shows an abrupt appearance of fairly sophisticated creatures with elongated digits, clearly capable of gliding or powered flight, with no known intermediates. We expect there were less fully flight-ready predecessors, but fossil preservation is not kind to small, delicate boned animals. It's also possible that the transitional period was fairly brief; it looks like turning a paw into a long-fingered membranous wing may be a fairly simple change on a molecular level.

Continue reading "How to make a bat" (on Pharyngula)

9 Comments

…unless you have the mistaken idea that the genome encodes a blueprint of morphology.

I’ve heard it said that a recipe is a better analogy.

Bill Gascoyne:

I’ve heard it said that a recipe is a better analogy.

Certainly stirring can be fun.

Not to mention licking the bowl.

Nice post, PZ!

I did a not-so-technical post on Bmp2 and bat evolution back in November 2004

Cheers, Dave

Not only that, but some bats are cute.

Henry

Re “Certainly stirring can be fun. Not to mention licking the bowl.”

But does it taste like chicken?

Henry

I wonder if someone can tell me if anyone’s done any molecular/genetic ancestry tracing on bats. I’m interested if fruit bats and flying foxes and such are more closely related to other mammals, possibly prosimians, than to other bats.

Why aren’t the ID proponents coming up with stuff like this?

If it were real science, you’d think they’d start publishing stuff that makes people say “Hey! Cool!”

Sanitary Inspector:

The Tree of Life web page has an excellent write-up on bat phylogeny:

http://tolweb.org/Chiroptera

Read the section on bat monophyly. DNA studies support monophyly. Some morphology supports a diphyletic relationship within the Chiroptera. Genetics trumps morphology everytime. ; )

But does it taste like chicken?

Funny you should ask that. A couple of years ago, I was on a project in northeast Australia and the conversation turned to the fruit-bats, which flew over us every evening like pterodactyls from the Land of the Lost.

One of the guys on the crew had been posted on islands up there in WW-II, and when supplies got thin, they ate the bats (which were easy to catch). He described them as surprisingly nasty, foul-smelling and gamey for something that lived on fruit.

So, depending on how the chicken tastes in your part of the world, the answer is probably no.

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This page contains a single entry by PZ Myers published on April 18, 2006 5:01 PM.

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