Tuesday, June 8, 2021

My magnum opus? A new paper published on Indo-West Pacific trematodes of the family Gorgocephalidae

All the hoops which need to be jumped through to get a piece of research published often leaves me feeling rather over the project once they actually appear nicely formatted in a journal somewhere. I just find it difficult to get excited about seeing my papers in print after I have already read them over and over again writing, editing, proofing, revising etc. However, I am still finding myself rather chuffed over one of my most recent papers:

2021. Huston, D.C., Cutmore, S.C., Miller, T.L., Sasal, P., Smit, N.J. and Cribb, T.H. Gorgocephalidae (Digenea: Lepocreadioidea) in the Indo-West Pacific: new species, life-cycle data and perspectives on species delineation over geographic range. Zoological Journal of the Linnean Society, doi: https://doi.org/10.1093/zoolinnean/zlab002.

This paper is the final result of something I started at the beginning of my PhD in 2015, and represents over 5 years of effort – collecting specimens, sequencing specimens, studying the morphology of specimens, banging my head against the keyboard as I searched for real morphometric differences, learning how to operate a scanning electron microscope, writing grants to travel and collect more specimens, on and on. It was a really great undertaking, and I think it is easily my best piece of work to date.

All that effort was really worth it. I collected specimens of the family Gorgocephalidae from all around Australia, and from the eastern and western extremes of the Indo-West Pacific marine region (French Polynesia and South Africa, respectively). As far as I am aware, this is the very first paper on marine digeneans to include data from specimens collected from the breadth of the Indo-West Pacific. Perhaps the most important thing I found was that it appears one species of the genus (Gorgocephalus yaaji) spans the entire range of the Indo-West Pacific! This has important implications, because the within-species genetic variation we observed could easily be misinterpreted as between-species genetic variation if other aspects (morphology and hosts) were ignored.

It is possible that the trematode taxonomy community (and that includes me) might be going a bit overboard with the proposal of cryptic species. Don’t get me wrong, I 100% accept the existence of true cryptic species, but we need to be more careful in proposing them. Cryptic species are easy to detect if they are occurring in sympatry. However, if you find a trematode at locality A that is morphologically indistinguishable from a trematode at locality B, but has some molecular differences, how do you know that the molecular difference is sufficient to consider them different, and not representative of natural intraspecific variation? I see a lot of molecular ‘cutoffs’ being thrown around, especially in terms of percent difference, but I never really see strong evidence presented for why 5% or 10% difference in cox1 or ITS or whatever is sufficient to consider one population species A and another species B. Sure, 5% might be a comfortable species-level difference for some trematode lineages, but that does not mean that 5% is going to apply to all trematode lineages. We need more reference datasets before we can have real confidence in such methods – and those reference datasets need to have specimens incorporated from wide geographic ranges!

No comments:

Post a Comment

New paper on a new species of acanthocephalan

I’ve got another recent paper out, another collaboration with the eminent Emeritus Professor Lesley Warner (she publishes under Lesley Smale...