Not Your Father’s Evolution

SticklebackIt isn’t hyperbole to say that in recent years there has been a revolution in our ability to explore the genome. Though genome sequencing occurred as early as the ’70s, it burst into the national consciousness in 2000 when the Human Genome Project completed its first draft of a complete human genome. Since that time nearly 200 organisms have had their genomes sequenced giving us an ever increasing picture of the diversity of life.

This growing knowledge has also impacted our understanding of how organisms are related. Unlike previous methodologies which relied heavily on interpretations of morphological similarities to determine relationships between organisms (particularly in the fossil record), methods which were fairly subjective and vulnerable to the predispositions of the person studying the organism, genome sequencing is a much more objective methodology which relies on more rigorous analytical comparisons to determine relationships between organisms. It is also modifying our view on how the genome interacts with the environment and how changes actually occur there.

One such recent analysis of a genome has to do with that of the three-spined stickleback, a species (actually, multiple species) which are found throughout the world in both fresh and salt water habitats. The forms actually vary morphologically depending on the sort of environment they are found in, which presents a significant opportunity to study genetic adaptation to different environments as investigator David Stanley of Stanford explains in the Sciencedaily report:

“The cool thing about these fish is that they’ve colonized a whole series of new environments in the last 10,000 to 20,000 years,” says Howard Hughes Medical Institute (HHMI) investigator David Kingsley of Stanford University School of Medicine. As the glaciers melted at the end of the last ice age, marine sticklebacks ventured into fresh water, settling in rivers, lakes, and streams. The fish adapted to their new homes. Compared with their marine relatives, freshwater sticklebacks tend to be smaller and sleeker, with less bony body armor. The challenges of surviving in new habitats also prompted modifications to their teeth, jaws, kidneys, coloration, and numerous other traits. Moreover, this pattern of colonization and adaptation has repeated itself in several areas where sticklebacks live, including the east and west coasts of North America, western Europe, and eastern Asia. “A world-wide collection of lakes and streams became countless natural evolutionary experiments,”

Many might see in such findings substantive evidence for evolution – and on a small scale, having to do with a variety of variations possible in an organism, they would be right. But these findings are actually quite contrary to the sort of evolution often advocated by Darwinian evolutionists. Instead of incidental mutations coding sequences leading to the production of new proteins (and conceivably, novel structures and systems) the researchers found that the changes were primarily to the same sets of regulatory sequences in separate populations of sticklebacks:

For their latest study, Kingsley, scientists from the Broad Institute of MIT and Harvard, and an international team of collaborators started by sequencing the genome of an Alaskan freshwater stickleback to serve as a standard for comparison. That was an achievement in itself, yielding the first complete stickleback genome sequence. Next, the team followed suit with the genomes of twenty additional sticklebacks from around the world, including ten ocean stickleback varieties found around North America, Europe, and Japan, as well as the genomes of ten freshwater relatives from nearby freshwater locations. They then analyzed the sequences to identify DNA regions that changed whenever the fish made the move from salt water to fresh.

The researchers found 147 “reused” regions in the fish’s genome. That suggests that each time the fish left the sea, variants in this same group of genes helped remodel the fish into forms that were better suited to fresh water, Kingsley says.

While the researchers continue to use the term ‘evolutionary change’, the reality is this is nothing like the sort of change described by the modern evolutionary synthesis, a theory which relies on natural selection acting on genetic mutation. The very fact that the researcher describes these as “key genes that control evolutionary change” contradicts the ordinary notion of evolution itself, which is purportedly an unguided process. If natural selection acting on incidental mutations were actually capable of producing the radically different body plans, structures and systems we find throughout the plant and animal kingdoms, then we wouldn’t expect to see the consistent similarity of genetic modifications that we do with regard to the various populations of sticklebacks. The changes wouldn’t be a matter of merely regulating extant genes, but the origination of new genetic capabilities. As it is, the genetic variation in sticklebacks conforms closely to the expectations we would have if there were limits to evolution as proposed by Michael Behe in his book The Edge of Evolution. Genetic sequencing continues to demonstrate that there are limits to biological variation.

Biologist Francois Jacob famously said, “evolution is a tinkerer, not an engineer”; if that is the case then the various populations of stickleback can’t be said to have ‘evolved’ given that the variations they display appear to be the result of well-designed systems engineered to allow organisms to adapt themselves to a variety of environments.

About these ads

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 66 other followers

%d bloggers like this: