One of these things is not like the other……

...okay none of these things are very similar (courtsey wikipedia articles for: jon snow, nematodes and parrots)
While we know that bacteria are pretty scandalous with their DNA, not minding horizontal gene transfer (HGT) and such (which can be pretty confounding when trying to discuss species concepts), and although it’s clear that this kind of genetic material sharing is also important in eukaryotes, examples can be relatively more rare. Sometimes, however, some really cool and interesting cases come along….
In nature, webs of complex relationships are essential across all types of ecosystems, and, as the study points out, more and more evidence has been highlighting the role of closely associated relationships (such as that between a host and parasite) in the transfer of genetic material.
Figure 1, Suh et al., 2016
A nifty recent study published in Nature Communications from Uppsala University has published findings of fascinating transposable elements that turn up in tropical bird genomes that have only been identified in parasitic nematodes and also mammals. The group used their findings to make conclusions about the biogeography and point of occurrence of ancient host-parasite interactions. Ultimately they developed insight into the prehistoric evolutionary origins of a few human diseases, specifically lymphatic filariasis (aka elephantiasis) and loiasis, spread by mosquitoes (ugh, of course) and flies, respectively.
Figure 2, Suh et al., 2016
The transposon they identified, AviRTE, is related to a diverse group of retrotransposon-like elements (RTEs)….ah HA the acronym makes sense! This set includes a bunch of fun animals that are aquatic or reptilian. This is an interesting finding, especially given the fact that some human diseases originate from animal hosts (think about avain flu). So basically, the study found that these parasitic nematodes used to be bird parasites around 25-17 million years ago….so a LONG LONG time ago (but still in our galaxy).
Figure 3., Suh et al., 2016
One of the reasons genomic comparison studies are sooo interesting is because they can be informative in a variety of different model systems. From bacteria and archaea, to birds, nematoes, and humans…genomes can reveal interesting evolutionary histories. In the study by Suh and colleagues, it turns out that they found a pretty cool example of a parasitic animal jumping from birds to mammals.
Suh, A., Witt, C. C., Menger, J., Sadanandan, K. R., Podsiadlowski, L., Gerth, M., Weigert, A., McGuire, J. A., Mudge, J., Edwards, S. V., Rheindt, F. E. 2016. Ancient horizontal transfers of retrotransposons between birds and ancestors of human pathogenic nematodes. Nature Communications 7: 11396.

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