It a newly issued study in the PNAS, a species of lizard was transplanted 36 years ago from one island in the Adriatic to another. Tremendous phenotypic changes have occurred, the most dramatic, in my estimation, being the development of ‘cecal valves’ in the digestive tract to be able to digest the plant food that the transplanted species of lizards has taken to eating. Cecal valves occur in only 1% of all lizard populations, yet it developed in only 36 years—along with changes in head size, jaw size, and bite strength (needed to chew the cellulose found in plants)!
There seems to be two ways of looking at this: (1) that NS has brought all of these changes about; or (2) the environment, specifically the proteins/enzymes/chemicals of the plant life on the new Adriatic island has interacted with the genome to quickly bring about these changes. Considering Haldane’s Dilemna–much discussed here at UD–there have been simply too many changes that have occurred to the physiology of these lizards for NS to be invoked as the cause. Additionally, if NS “can” work this fast, then why aren’t we seeing the development of higher taxa of animals and plants right now? The old argument is that NS works too slowly to be seen, and that’s why we don’t see these higher taxa—nor the intermediate forms which would be required—in present day flora and fauna.
What we seem to be seeing isn’t exactly Lamarckism, but a kind of form of it: i.e., the environment produces changes in the phenotype of the lizards which is inheritable, but is doing so via genetic regulatory mechanisms; IOW, epigenetics.
The more we learn, the harder it is for RM+NS to keep up.
Here’s what PhysOrg.com has to say: “Observed changes in head morphology were caused by adaptation to a different food source. According to Irschick, lizards on the barren island of Pod Kopiste were well-suited to catching mobile prey, feasting mainly on insects. Life on Pod Mrcaru, where they had never lived before, offered them an abundant supply of plant foods, including the leaves and stems from native shrubs. Analysis of the stomach contents of lizards on Pod Mrcaru showed that their diet included up to two-thirds plants, depending on the season, a large increase over the population of Pod Kopiste.
“‘As a result, individuals on Pod Mrcaru have heads that are longer, wider and taller than those on Pod Kopiste, which translates into a big increase in bite force,’ says Irschick. ‘Because plants are tough and fibrous, high bite forces allow the lizards to crop smaller pieces from plants, which can help them break down the indigestible cell walls.’. . .
“Cecal valves, which were found in hatchlings, juveniles and adults on Pod Mrcaru, have never been reported for this species, including the source population on Pod Kopiste.
“’These structures actually occur in less than 1 percent of all known species of scaled reptiles,’ says Irschick. ‘Our data shows that evolution of novel structures can occur on extremely short time scales. Cecal valve evolution probably went hand-in-hand with a novel association between the lizards on Pod Mrcaru and microorganisms called nematodes that break down cellulose, which were found in their hindguts.'”
Here’s the link.