Literature

Despite natural selection's central role within the neodarwinian synthesis, there are important limitations to the empirical research that has been undertaken. In particular, "long-term morphological time series with information on the selective regime are exceedingly rare." Drake and Klingenberg have sought to extend the time-span of available data by looking at skeletons of dogs in museums. "Domestic dogs are a unique system for the study of phenotypic evolution, because there not only is a considerable amount of morphological variation, but the history of breeds and the breed standards also provide a documented record of the selection regime that has been applied by breeders". One museum has provided skeletal material for the St Bernard breed spanning 120 years. Their paper documents morphological change over this period and provides an analysis.
Originally, these dogs were working animals and breeding was designed to enhance function. However, in the 1880s, the focus shifted so that the animals were bred as pets and show dogs. Significantly, "the breed standard describes the perfect St Bernard in terms of its appearance, but not its behaviour". Morphological variations are documented in the paper, and it is not surprising to read that "the shape changes [. . .] correspond to the features specified in the breed standard for St Bernards".
There are two interesting findings. First, the changes show intelligent agency at work. "The close agreement between the observed changes and the features described as desirable in the breed standard, and therefore favoured by breeders, suggests that the observed change was brought about by selective breeding." Second, there is no evidence that allometry has been a factor. "Previous research has suggested that morphological diversity in dogs may be due in large part to allometric shape changes. Our data indicate that this is not the case for the historical change in St Bernards." In particular, there was "no consistent trend of skull size in the time period covered by our study."
Since Mendel's pioneering work, there has always been a question mark over the relevance of artificial selection, because breeders are working with innate variation rather than new mutations. Did their study cast any light on this issue? The answer appears to be no:

"Unfortunately, the available data do not allow us to decide whether a sufficient amount of genetic variation still persists from the initial, heterogeneous breeding stock or whether genetic variation is replenished continuously by new mutation".

As the paper stands, it is a useful addition to the literature. However, outside the paper, a spin is being put on the findings that are completely unjustified. This is illustrated by the EurekAlert! headline: "St Bernard study casts doubt on creationism". Also, the last sentence of the news release: "this research once again demonstrates how selection - whether natural or, in this case, artificially influenced by man - is the fundamental driving force behind the evolution of life on the planet." These words are attributed to Dr Klingenberg, one of the co-authors. In order to make this claim, it is necessary to paint creationists and ID advocates as deniers of both natural selection and artificial selection - which is as untrue today as it was in Darwin's day. We do not deny natural selection; we deny that it has the capability to make complex specified information in living things. The changes documented in this paper are trivial:

"The upper jaw and palate have tilted, raising the anterior and lowering the posterior part, which contributes to the shortened and relatively high muzzle. This tilting of the upper jaw and palate, together with the upward shifts of landmarks on the frontal bone, contribute to the pronounced stop, the angle between the muzzle and the forehead, which the breed standard specifies as desirable. [snip]"

"Once again", studies of minor variations in peppered moths, Galapagos finch beaks, beach mice in Florida, etc., are used to claim that natural selection is "the fundamental driving force behind the evolution of life on the planet." Once again, this illustrates the bankruptcy of Darwinism.

The pace of morphological change: historical transformation of skull shape in St Bernard dogs
Abby Grace Drake and Christian Peter Klingenberg
Proceedings of the Royal Society B: Biological Sciences, 275, 7 January 2008, 71-76 | doi:10.1098/rspb.2007.1169 | doi:10.1098/rspb.2007.1169

Abstract: Owing to the great morphological diversity of domestic dogs, the study of historical shape change in dog skulls provides an excellent opportunity for investigating the dynamics of morphological evolution. Breed standards make known which features were selected by breeders. Here we use the methods of geometric morphometrics to study change of skull shape in a series of purebred St Bernard dogs spanning nearly 120 years. A regression of shape on time was highly significant and revealed a consistent trend of shape change that corresponded to the features deemed desirable by the breed standard. Historical shape change in St Bernards involves a broadening of the skull and a tilting of the palate and upper jaw relative to the rest of the skull. This trend appears to be linear throughout the entire period and appears to be continuing. Allometry was ruled out as a contributing factor to this change because there was no consistent trend of historical change in skull size and because neither the patterns of static nor ontogenetic allometry corresponded to the historical shape change. The dramatic modification of the St Bernard skull demonstrates that selection can achieve sustained and substantial change and can completely overcome constraints such as allometry.

See also:
St Bernard study casts doubt on creationism, EurekAlert! 23 October 2007.