Throughout all the history of its development humanity wanted to get information about the main peculiarities of its development. People wanted to know what happened many years ago and how all living beings obtained their modern appearance and traits. That is why, the science of evolution obtained great significance and become very popular. Many scientists devoted their works to investigation of the main peculiarities of this process. Moreover, they created different theories which are connected with the process of development of some certain species. Taking it into account, it is possible to say that the interest to the issue of evolution will remain on the high level and new and new works will appear.
The article The origin and evolution of segmentation by Gregory Davis and Nipam Patel also touches this issue. The authors investigate whether arthropods, annelids and chordates have common ancestor or they are derived from different kinds of animals. To investigate the issue better, the authors suggest three hypothesis which are connected with the issue of evolution of segmentation. The first hypothesis states the fact that the segmentation was obtained in all these three phyla. However, this theory is not so obvious and may introduce some serious debates. The second hypothesis main idea is that segments are homologous within the protostomes, however chordates developed segments independently. Nevertheless, this theory has its own drawbacks and weak points as it predicts some differences and similarities between different species at the same time. The third hypothesis states the fact that segmentation is homologous throughout the Bilateria. It seems to be the most probable among all these three theories as it has the best evidence. Moreover, a great number of different facts and researchers show that this hypothesis can be called the most valuable and important. The authors of the work, however, just not enumerate existing hypothesis, they also investigate them in order to find out which is more credible and reliable. Having analysed the issue very precise, the authors are able to give their own arguments within the framework of each theory. The authors rely on the suggestion that some structures of homologous nature are more likely to employ the same tools of their development than structures which have developed independently. Having made this statement, the authors use it as the basis for their analysis of all these three hypothesis of evolution of fragmentation. Moreover, they use Drosophila melanogaster as the main practical material for their research. Analysing the peculiarities of genes and their development within this kind of animal, the authors confirm or refute above mentioned theories.
Having conducted their research, the authors come to certain conclusion. First of all, they state the fact that the data which is at their disposal at the moment, is not enough to determine which theory is the most plausible and how the process of evolution of segmentation flew. More genes in more species are needed to make some certain conclusion which will be able to answer all existing questions connected with this issue. However, some results obtained by the authors are quite surprising as they show similarities in patterning between distantly related organisms.
Having analysed the article, it possible to state some facts. First of all, this work is very important within the framework of investigation of the issue of evolution of segmentation. Moreover, it can be taken as a credible source which can be used in further investigations of this issue.