You are true but to my knowledge we have at best national legislations definying designable units such as ESU's and so on. On the other hand, IUCN Red List, for example, deals mostly with species and subspecies. So global definitions are lacking at the moment.

Yea.. you are right

Hi.

Sometimes, clearly different subspecies, which may be recognized as full species in the near future, are not considered so important like other taxa from the conservationist point of view. There are some clear examples of this in the Macaronesian or Mid-Atlantic islands (.e.g. the Canaries).

Best regards.

yes Rubén and it is a pity that most researchers believe that species and subspecies belong to two separate 'classes' and therefore take care of only the most important one (species). Yet designable units are often not recognised by a formal Latin name (although possibly they had one historically), so their existence is still more 'questionable' and their fate less 'accountable' from a biodiversity conservation perspective.

Hi again.

Thanks for your response, Spartaco. One example from the Canary Islands of great increment of the interest about an endemic taxon is the Gran Canaria Blue Chaffinch (Firngilla polatzeki). When this bird was a "mere" subspecies (F. teydea polatzeki) it was considered relevant, but after its recent split from F. teydea, the species has gained attention and now many birders want to see it in its natural habitat and a lot of people is interested in its conservation and protection.

I Agree with Spartaco Gippoliti

Since Gote Turesson conceived of the concept of "ecotypes" nearly 100 years ago, we still have not invented a language or taxonomic method to describe and start discussing the reality that exists there.

When we are concerned about the extinction of "Species" we forget that the range of genetics across each plant and animals range is enormous. We still do not wrap our minds around that spatial extinction of the various ecotypes of plants and animals, may be even more important because it took millennia for each of those ecotypes to be created and formed.

you utilised two interesting terms; taxonomic method and millenia. At least as Vertebrate biologists and ecologists are concerned, ecotype is utilised for 'something' that have no history (and thus no future). I do not agree with this vision and think that 'ecotypes' should have a taxonomic rank accorded and are very important in speciation process.

There is unlikely ever to be consensus about units of conservation significance, just as there has never been agreement about species concepts. The scholars responsible for the codes of nomenclature wisely recognized long ago that you cannot legislate circumscriptions of taxa. Rather than trying to impose a "one size fits all" definition or circumscription of species or ESUs, or whatever, around the world, each taxon of conservation concern should be evaluated by the criteria - biogeography, population structure and stability, ecological linkages, and other factors - that are unique to it.

Hi Andrew,

being an anarchic taxonomist myself (as depicted in a 2018 Nature paper) I fully agree with taxonomic freedom. But you certainly know that several influential papers in recent years have expressed concern about the growing number of specie recognised among mammals and birds "for conservation reasons". Therefore, I suppose that if many researchers share this view, even conservation of ESU's, MU's and the like is today saw as an impediment (see the issue of so-called genetic rescue). Here my recent view on the issue Article Everything mammal conservation biologists always wanted to k...

Hi Spartaco,

We have included a sidebar in the new edition of our textbook about your African ungulate debate! In general, my view is that as long as there is empirical evidence that populations are historically distinct, they should be viewed as separate taxa. Of course, as you well know, that all depends on what is considered "evidence" and how "significant" that evidence might be, if one cares about confidence intervals.

However, in my own group of organisms (Heliconius butterflies), the empirically recognizable "separate taxa" are subspecies or geographical races that hybridize. Evolution is not tidy, and there is no good place to draw the line - historically, in Heliconius, it has been interbreeding, but even that is now questioned by prominent researchers in the field who believe that the species boundary in Heliconius is a continuum and tinterpret their genomic data to infer that there is massive introgressive gene flow throughout the genus - so, how many species? 400? 20? The checklists say about 45.

From a conservation perspective, by the time people are moving organisms around to replenish gene pools and that sort of thing, "nature" is a distant memory, and what is being managed is essentially a wildlife park.

Anyway, I think we basically agree on the principles.

Anyway, we have two sensible options: either

a) we wish to base conservation decisions on scientific (biological) knowledge, and then must use the terms like "species" or "subspecies" according to their biological definitions; or

b) we consider conservation as independent of biological knowledge, and then - to avoid confusion - should not use these terms at all, perhaps creating an alternative "consertaxonomy" with "consertaxa" like "conservon", "subconservon", "superconservon" &c.

Anyway, falsifying scientific knowledge to suit conservation (or agriculture, or tourism, or anything else) is the worst solution!

Hi Andrew,

which textbook?

Your Heliconius case is paradigmatic of what we believed with BSC. Regrettably it seems things are not so simple and the differences among species and subspecies blurred. Personally I found ESC a little bit more objective and, if this led to an increase of species number, we can rely to transparent prioritization processes so that we do not need falsifying any scientific knowledge.

Since you ask, "Biological Systematics: principles and applications (3rd edn.)" by myself and R. T. Schuh, due out in 2021 (Cornell University Press). We are checking the proofs now.

I'm a PSC (Wheeler and Nixon version) guy (except for Heliconius!).

The problem we have in plants in California, is that the ecotypes are genetically fixed...so when you grow them in a common garden setting, they physically look so different that you would consider them different species, like the famous Stanford experiments in the 1940s by Clausen, Keck and Hiesey. The books written were Experimental Studies on the Nature of Species. I. Effect of Varied Environments on Western North American Plants published in 1940 and Experimental Studies on the Nature of Species. III. Environmental Responses of Climatic Races of Achillea in 1948. Clausen produced one additional book about his work based on the Messenger Lectures he gave at Cornell which was published in 1951 as Stages in the Evolution of Plant Species. These guys dove deep into the ecotype pool!

Or as Edwin Lee Greene named 112 different "species" of California poppy in Revision of Eschscholtzia. PITTONIA 5: 205-293, because the concept of "ecotype" was still a few decades into the future, so there was no way in science to talk about these variations, other than sort them out into different species.

The best method so far is "subspecies"... but that still relies on the old physical taxonomic method of splitting based on plant physical traits. That may work with ecotypes, but when plants, like 100 out of the 300 California native grasses undergo polyploidy and change their chromosome numbers, but look identical by are separate species because they can no longer breed with each other, that throws yet another wild card into the taxonomic stew pot.

Plus, with the ecotypes... you can see evolution in real time, with the environment forcing the "budding off" of new species when they are isolated at the extreme fringes of the main population, image attached from my study listed below.

Basically, taxonomy in 2020 is currently stuck, at least in regards to plants, about 1870... before the concept of ecotypes was created in the 1920s-1930s, and before the advent of DNA fingerprinting in the 1980s-1990s. You can read my ecotype experiments and 100+ year bibliography at https://www.ecoseeds.com/juicy.gossip.three.html

Thanks Andrew! Your bibliography is really interesting especially because much literature before the advent of the Modern Synthesis was simply forgotten later!

Ciao Spartaco

Stepping in a bit late, but I would rather like to go back directly to your question. It seems that I have more questions to ask than really answers to give to your own question, sorry... Although we may come up with answers after that!

You mentioned the use (and abuse) of alternative designable units in conservation and legislation. Since you used the term "abuse", is that your observation that these units are abundant nowadays? I had the feeling that, at least in the case of mammalian carnivores, there were rather very few species for which ESU's and MU's have been described so far.

Secondly, you mentioned that such terms are "maintained". Does that mean you may think there should not be maintained, and as such these units are not legitimate and/or useful? What is your take on this?

To extend on this, would "maintaining" those be a strategy by conservationists and/or politicians so that things go "incognito" (sort of "nessuna eruptione del Vesuvio", hahaha) in case populations making these units go extinct? I would rather think that - at least conservationists - would much prefer for such populations never to go extinct and for this to be known if this happens, no? (I may think that most politicians - unless these are natural scientists who decided to be involved in politics - do not care about conservation issues).

In general, I had the feeling that it is so difficult to reach a consensus as to what a species/subspecies really is (hence the numerous recent published opinions on the topic), that having ESU's, MU's or ecotypes was the only way to conserve entities (since taxa might not apply here) that are unique/isolated enough, but may not qualify to be regarded as species/subspecies following a specific set of criteria - whatever these are.

A presto

Emmanuel

Caro Emmanuel,

you have interpreted me correctly.

As probably you, I was highly positive about the development of alternative designable units (ADUs) mainly through molecular data. At first, my concern was about the relative indipendence one observe between classical taxonomy and molecular identification of ADUs, a separation that is biologicaly unexplicable. But later I 'discovered' that ADUs are strongly connected to national legislations, but, as such, they 'escape' international systems such as the IUCN Red List (a 'presumed' barometer of biodiversity status). This is much more commoner in some countries and in some taxonomic groups (I think of one deer genus in particular but possibly also cetaceans).

I think that genus taxonomic revisions are a better choice but in some countries it is not pursued because taxonomy has a bad reputation among scientists. Therefore there is apparently a collaboration between politicians and scientists, that is not positive for biodiversity in the end. But the too much later response to Covid outbreack in most Western democracies - fueled by economic concern - shows us how is hard fighting economic forces that degrade the environment even in the richest countries.

Finally, we are all aware of definition problems of taxonomic ranks, yet if we consider the genetic evidence of most ADUs (including ecotypes) I wonder if taxonomy should still be the easier way to guarantee transparency in conservation work.

Here a new paper on caribou that confirm my thesis https://jem-online.org/index.php/jem/article/view/599