Taxacom: Minimalist revision of Mesochorus

[Neal Evenhuis]

Although I am an ICZN Commissioner, I am speaking here as a taxonomist who has described more than 700 new species of flies, all based on morphological characters (although I have used molecular ones to test hypothetical species groups to tell me I was either spot on or whacko in my hypotheses). To me, molecular characters are just another character set and not the end unto themselves. As has been pointed out, barcodes do not always = unique species and to use them without resort to morphological characters is, in my opinion, sloppy taxonomy.

I was trained in taxonomy in an age where we were curious biologists and wanted to know not only the manifest of Spaceship Earth (yes, I’m from the Bucky Fuller era), but how things worked. We went into the field; hand-collected specimens, and watched our taxa live their lives and how they nourished, parasitized, predated, courted, mated, etc. When I describe species impaled on pins or floating in ETOH (thankfully I do not have to prepare them on slides – except genitalia), I am always asking myself how those species recognize each other in order to mate and have F1 generations. If Sharkey et al. are on the right path, then maybe they have sensory devices we have not found yet that can discern barcode sequences and those little wasps can confidently say with a wink after they have found one of their kind and the opposite sex -- “Whoowhee, baby! How YOU doin’ ACCGTCTAAGGT?” I doubt it. Insects have other sensory devices to discern their own species. I do not think males of Mesochorus in Guanacaste fly around humping everything that looks similar in hopes of a successful mating (maybe they do – do we know? That would be a step backward evolutionarily as wasteful energy epxediture). Instead I’d wager they discern their own species either visually or semiochemically. The former requires that each species is visually different somehow. The latter may require other techniques that include molecular - in hopes that what is used codes for those different semiochemicals. Barcodes do not. Nor do they always account for normal variation in a population of the same species.

My hunch (having done taxonomy on tropical flies over the last 40+ years  - in habitats similar to the dry-but-tropical Guanacaste) is they use visual characters. I am finding that some of the tropical flies I work with have unique Wing Interference Patterns (WIPs) that are used in species recognition. Males and females all have to rest and when they do and the sunlight hits their wings, they show a distinct pattern that is receptive to like-kind species. They sometimes vary geographically in the same species, but in restricted geographical populations where many occur sympatrically, they work well in differentiating otherwise cryptic species. There are other hard-to-see morphological characters to differentiate (some internally), but the WIPs cinch my hypotheses that the specimens are the same taxon and I hypothesize THAT is the way they find each other. Do Mesochorus use WIPs for species recognition? I don’t think Sharkey et al. ever tested that. And maybe WIPs won’t work and are indeed too variable. Apparently they are in other Hymenoptera like Figitidae. But rather than look for WIPs or other morphological sets of characters that may solve that problem, Sharkey et al. resorted to an expedient way of running sequences and putting names on BINs and letting future workers sort out the mess. I’m not a fan of that as a way to “solve” the taxonomic impediment – it just creates another impediment for future workers.

We all want to solve the taxonomic impediment by finding expedient ways of naming all the undescribed species that are still out there (some of us are doing it, others are armchair pundits only but rally others toward that goal). But I would suggest not to fall back on the “easy way out” with the routine of “barcode first and ask questions later” -- but instead ask yourself -- if I were a [put taxon name here] how would I find a mate? and look for other morphological character sets -- and use barcodes as just another character set and not THE only one. I still am curious about biology and taxa and how things work in real life. Unfortunately, DNA sequences do not tell me that. Maybe we have lost the luxury of time to learn more about our taxa and have lost sight of that while keeping our eyes on the prize of describing as many things as fast as we can. I hope we taxonomists do not devolve into pipette jockeys and number crunchers and lose the curiosity of how things work in real life.

Neal

Neal L. Evenhuis
Senior Curator of Entomology
Bishop Museum
Honolulu, Hawaii  96817-2704, USA

On Stardate 8/30/23, 9:49 AM, "Taxacom" <taxacom-bounces at lists.ku.edu> wrote:

I think one thing that seems to be missed in the discussion is that, despite lacking a morphological diagnosis in words, the species presented in the Mesochorus paper do provide a substantial amount of biological information (identity of host parasitoid, caterpillar host of primary host parasitoid, host plant, plant community in which it is found) plus multiple photos showing the morphology, in addition to the barcodes and collection data. It could be argued that this combination of information is actually more extensive than the earlier descriptions in the group, and more useful to ecologists and other biologists. This is not to say it is the perfect solution, nor is it the way I typically work, but it is not quite so minimalist as it may be portrayed as being.

Jim  Sent from my iPhone
_______________________________________________
Taxacom Mailing List

Send Taxacom mailing list submissions to: taxacom at lists.ku.edu
For list information; to subscribe or unsubscribe, visit: https://lists.ku.edu/listinfo/taxacom
You can reach the person managing the list at: taxacom-owner at lists.ku.edu
The Taxacom email archive back to 1992 can be searched at: https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftaxacom.markmail.org%2F&data=05%7C01%7Ctaxacom%40lists.ku.edu%7C90173fb975e848a9619808dba999d46a%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638290250391234275%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=O1%2BNW9Z1Il7W2HKfu86sZKzrL6%2BfJknZhFSmAyEHtkg%3D&reserved=0

Nurturing nuance while assailing ambiguity and admiring alliteration for about 36 years, 1987-2023.