Abstract
The Naegleria genus encompasses a remarkable amount of diversity such that analyzing the delineation of species within the genus using genomic data is incredibly informative. Naegleria species cannot be completely defined on the basis of morphology or sexual
reproduction, and thus it is necessary to rely on DNA sequence comparisons for observing species boundaries. For several years, sequences from the ribosomal plasmid gene ITS (internal transcribed spacer) have been used to define Naegleria species. Overall, a portion of the mitochondrial gene CO1 (cytochrome c oxidase I) is widely used to define and ‘barcode’ species. The goal of this study was to first determine whether there would be consilience (agreement) between the ITS and CO1 phylogenetic trees in terms of whether the same strains would group with the same species between the different gene trees. Despite the fact that certain species clusters were not always in the same location between the ITS and CO1 trees, consilience was achieved between the ITS and CO1 Maximum Likelihood phylogenetic trees such that the same strains always clustered together to create the same species groupings. This consilience indicates that either DNA sequence provides a useful way to examine Naegleria species. Moreover, in comparing both the within- and between-species sequence variation for both ITS and CO1 gene sequences, the range of sequence variation that existed for each gene was achieved here. In general, greater within-species sequence variation existed with CO1 sequences than with ITS sequences, but there was a greater amount of between-species sequence variation with ITS sequences than with CO1 sequences. Finally, the diversity of species found in a small micro-environment (a birdbath) was examined. Overall, the results of this study indicate that there are many more species in the Naegleria genus than were anticipated a few years ago, but the results also leave open numerous questions about species delineation in molecular species such as Naegleria, especially when considering the worldwide distribution of Naegleria species.