Recognizing hybrids as a unique taxon?

[Chuck]

Does anyone know the rules for recognizing a hybrid taxon as a species?

It seems that for a long time doing so was avoided- and still is. The first known (or confirmed) example I can think of is some bird that was shown to be a recombinant hybrid with a self-sustaining population.

The best known example to most of us is probably Papilio appalachiensis, which is a recombinant hybrid. Still though, I hear grumbling that it should not have been recognized.

Now I read of all sorts of things- plants, snakes, other butterflies, etc. that are recombinant hybrids with self-sustaining populations. It apparently isn't as unusual as was thought. So what shall be done?

[eurytides]

Recombination hybridization is a well recognized pathway for speciation over long time scales. Whether or not a particular population of hybrid origin gets to be a species though, according to humans, is probably subjective and contingent upon what’s “fashionable” at the time. I wonder if Adam can shed some light on this in terms of whether the ICZN has an official stance on the matter.

[eurytides]

https://meridian.allenpress.com/pbsw/ar ... m=fulltext

[adamcotton]

I wonder if Adam can shed some light on this in terms of whether the ICZN has an official stance on the matter.

Here are the relevant ICZN Code articles:

1.3. Exclusions. Excluded from the provisions of the Code are names proposed
1.3.3. for hybrid specimens as such (for taxa which are of hybrid origin see Article 17.2);

Article 17. Names found to denote more than one taxon, or taxa of hybrid origin, or
based on parts or stages of animals or on unusual specimens. The availability of a name is not
affected even if
17.2. it is applied to a taxon known, or later found, to be of hybrid origin (see also Article 23.8);

23.8. Application to species-group names established on hybrids. A species-group name
established for an animal later found to be a hybrid [Art. 17] must not be used as the valid name for
either of the parental species, even if it is older than all other available names for them. Such a
name may enter into homonymy. For names based on taxa which are of hybrid origin see Article
17.2.

So basically, names for hybrids are not recognised by the ICZN Code, but names for species of hybrid origin are.

Adam.

[eurytides]

And that makes sense. We have plenty of examples where a species arose from hybridization in the past. It makes sense that a single individual that’s a hybrid has no name, but hybrid population stable over time and space can be named.

[Chuck]

Thanks guys.

Some cases are cut and dry- the hybrid bird which is now very geographically isolated, for example.

But what of those recombinant hybrids that are arguably still in evolution? Those that have some overlap and interbreeding with the parent population(s)?

[Chuck]

https://meridian.allenpress.com/pbsw/ar ... m=fulltext

I don't have access, so can only read the abstract. Can you email it to me? Thanks.

[eurytides]

Unfortunately, I don’t have access either! But I thought the abstract was telling enough. There is no issue naming hybrid populations. There doesn’t seem to be clear criteria for when a hybrid population “should” get named. I think people just do it, present the evidence, and the rest of the community reaches a consensus about whether they accept that evidence as sufficient or not.

[adamcotton]

1.3. Exclusions. Excluded from the provisions of the Code are names proposed
1.3.3. for hybrid specimens as such (for taxa which are of hybrid origin see Article 17.2);

If I understand correctly this article basically refers to man-made hybrids, excluding them from being recognised names under the ICZN Code.

Article 17.2 applies to natural hybrids collected in the wild and named as species but subsequently understood to be hybrids between two species. Article 28.3 then applies in the case that the natural hybrid was actually named before one or both of the parent true species.

Adam.