Review on Elaboration and Phylogeny of W. bancrofti

Felix EG Beaudry^*
*Correspondence: Felix EG Beaudry, Department of Ecology and Evolutionary Biology, University of Toronto, Canada, Email:

Letter to Editor

The interest in examining the phylogeny of the filarial nematodes (Animalia Nematoda, Secernentea Spiruria, Spirurida Filarioidea Onchocercidae) is to determine the evolutionary relationship between extant species for the purpose of relative analysis. For illustration, B. malayi is nearly related to Wb and can be dressed in non-human species, whereas Wb and Loa loa are dependent on primate hosts. If we're to influence information collected from lab trials on B. malayi to help us more understand Wb, also it's necessary that we shoulder a detailed analysis of their evolutionary relationship.

Mitochondrial Genome Phylogeny

The most complete mitochondrial genome phylogeny to date included 65 species of nematodes. To use the nonstop publications of mitochondrial data, we searched Gen Bank for published mitochondrial genome sequences of nematode species. We plant complete mitochondrial genomes for 78 species of nematodes, an increase on the most recent mitochondrial phylogeny. A translational alignment of the 78 nematode species produced a data set nucleotides in length. The alignment was generated using only the 12 concatenated protein rendering genes common to all nematodes, since an exploratory data analysis showed no enhancement by including the transfer RNAs or ribosomal RNAs in the analysis.

We constructed a Bayesian phylogenetic tree using the aligned mitochondrial genomes and the program BEAST1.7.5. The following settings in BEAST1.7.5 were plant to yield the loftiest tree liability generalized time reversible model (GTR) with 4 rate orders, lognormal relaxed timepiece, Yule process speciation model, and a UPGMA starting tree. To estimate divergence times, we used the mitochondrial mutation rate of Pristionchus pacificus and the estimated divergence time of 100 million times between Caenorhabditis elegans and C. briggsae. The performing model was run 3 independent times for 50 million generations each.

The connections among taxa were plant to be in broad agreement with preliminarily published datasets exercising smaller samples. Thus, we will antedate discussion of the general topology and rather concentrate on the order Spirurida, which contains the family Onchocercidae (filarial nematodes). As noted in previous publications also exercising the mitochondrial genome, there are some disagreement between the rDNA and mitochondrial topology.

For the filarial worms this concerns the asserted monophyly between the Spirurida, Ascaridida, and Oxyurida. In our phylogeny as well as others there was no support for a common ancestor between the three orders. There was further support for the monophyly between the Spirurida and Oxyurida, with the Ascaridida nested within the Rhabditida. The main result of the nonmonophyletic relationship is also the independent origin of host mammalian and raspberry host preference.

Divergences and Utmost Recent Common Ancestor (MRCA)

Knowledge about when two species most lately participated a common ancestor (MRCA) provides a environment to their evolutionary relationship. Wb and B. malayi are both causative agents of LF and share parallels in morphology, host choice, and geographic distribution. Grounded on the mitochondrial genome, Wb and B. malayi are fairly youthful species with MRCA as recent as 12.5 (2.5 – 30) million generations ago (mga). Given estimates of generation time for Wb (8 months) and B. malayi (2 – 3 months), this was likely 4 – 6 million times agone (mya). Given this fairly recent divergence, it's possible that by studying B. malayi, we can gain sapience into the life history of Wb. Other interpretations of this divergence time are enterprise, but unborn studies may want to examine the possibility that Wb and B. malayi began to diverge at the same time as the common ancestors of mortal and chimpanzees. The geographic distribution of Wb and substantiation from the mitochondrial genomes of Africa and PNG, give limited substantiation to this end.

While the mitochondria handed robust support for topology, the divergence time estimates have large believable intervals. Counting solely on estimates of mitochondrial mutation rates lead us to underrate divergence time between C. elegans and C. brigades. The distinction is probably due to rate variation among the lineages as well as 3rd position mutational achromatism of the mitochondrial genome. It's likely that the parasitic nematodes change faster than free-living nematodes due to host vulnerable pressure and free-radical exposure in vivo. We considered rate variation when estimating divergence times and are more confident in our estimates for youngish species dyads than we are for deeper divergences. A result would be to use multiple independent genes, since the mitochondria have only a single history, and further than a single estimation time. This is delicate on two accounts. First, given the species diversity in the nematodes it would be delicate to test genes unevenly across the taxa. Second, given the soft bodies of the nematodes, little fossil substantiation exists for secondary estimation.