| This study evaluated the validity of the recently developed multidisciplinary scheme for gastropod subclass phylogeny. The multidisciplinary scheme appeared to be more suitable than the longstanding, firmly entrenched classical scheme, which is seen currently in textbooks and many journals. In order to ascertain this, I described and analyzed novel molecular and morphological characters as cladograms, which I then compared to the two phylogenetic schemes. I accumulated these characters using two techniques: 18S ribosomal DNA sequencing and three-dimensional magnetic resonance microscopy (MRM). For this study, I sequenced DNA encoding the 18S rRNA subunit of seventeen previously uncharacterized gastropods in order to develop a more complete molecular survey of the Gastropoda. The result was a robust computer analyzed consensus tree. The MRM portion of my thesis dealt with the acquisition of the first 3D non-destructive models of the musculo-skeletal arrangements within the gastropod foot. The eight models generated represent a pan-class selection and were analyzed for and resulted in several morphological and functional trends regarding the tarsos and columellar musculature and their integration with each other. In short, the phylogenetic analysis of these two datasets supported the new multidisciplinary scheme but with modifications. It also shows that the smoothly graded classical prosobranch-opisthobranch-pulmonate scheme is probably artificial. Additionally, both these techniques have been adapted for addition to the toolbox of malacologists and other biologists for uses that extend beyond phylogenetic studies. |
