Proposal (359) to South American Classification Committee

Eliminar la categoría "Incertae Sedis" de la "Main SACC List"

El avance de los análisis moleculares ha permitido resolver muchos problemas taxonómicos y sobre la secuencia linear de órdenes, familias, géneros y especies. Sin embargo, yo pienso que el SACC Committee ha exagerado la importancia de dichos análisis, a tal punto que los trabajos taxonómicos llevados a cabo por ornitólogos tradicionales: Hellmayr, Zimmer, Peters, y tantos otros, parecen tener poca importancia en la actualidad. Por lo que se observa en la Main List, algunos de los problemas que no pueden resolver los análisis moleculares se los deriva a "Incertae Sedis" (que tampoco resuelve nada), en vez de mantener la taxonomía tradicional, hasta tanto los análisis moleculares demuestren "definitivamente" cuál es la verdadera relación taxonómica. Hay un gran número de taxas que todavía necesitan estudios más profundos para determinar su verdadera relación, que podrían también pasar a la categoría de "Incertae Sedis", pero no parece la solución.

Por ejemplo, la Familia Cathartidae ha sido tradicionalmente incluida en Falconiformes y también se ha dicho que podría estar relacionados con los Ciconiiformes. Los análisis moleculares (Cracraft et al. 2004, Ericson et al. 2006, Gibb et al. 2007, Slack et al. 2007) refutan la relación Cathartidae/Ciconiiformes. Su relación con otros Falconiformes los análisis moleculares son controvérsicos. Ericson et al. (2006) y Gibbs et al. (2007), no encuentran relación entre Cathartidae y Accipitridae, mientras que Slack et al. (2007) incluyen Cathartidae en Falconiformes. En la "Main SACC List" se deriva la familia a "Incertae Sedis", siendo que para mí lo lógico sería mantenerla dentro de Falconiformes, como ha sido tradicionalmente hecho, hasta que se demuestre lo contrario.

Otro caso es el de Phibalura flavirostris, Piprites chloris, Piprites pileata y Calyptura cristata. Aunque hay varios análisis moleculares, los resultados no son coincidentes en la relación con Cotingidae/Pipridae/Tyrannidae, por lo que se evidencia también que los análisis moleculares no son infalibles. Para mi habría que dejar Phibalura flavirostris y Calyptura cristata dentro de Cotingidae y Piprites chloris y Piprites pileata en Pipridae, como fue hecho por un especialista en ambas familias: David Snow en el HBW, hasta que se demuestre lo contrario.

A Donacobius atricapillus yo la pondría en Donacobiidae como propuesto por Aleixo & Pacheco (2006), con la aclaración "SACC proposal pending to recognize Donacobiidae". Si la votación decide lo contrario (ya hay cinco votos a favor y ninguno en contra), le aclararía "Proposal needed" para ubicar a esta especie en alguna de las familias existentes.

El otro grupo es: Chlorospingus, Mitrospingus, Rhodinocichla, Coereba, Tiaris, Certhidea, Platyspiza, Camarhynchus, Geospiza, Saltator, Saltatricula y Parkerthraustes. Yo pondría a Chlorospingus en Emberizidae, como sugerido por Yuri y Mindell (2002) y Klicka et al. (2007) y el resto (Mitrospingus y Rhodinocichla, Coereba, Tiaris, Platyspiza, Camarhynchus y Geospiza) en Thraupidae (Burns et al 2002, 2003, Klicka et al. 2007).

Como me parece que pasar taxas a "Incertae Sedis" es algo artificial y si se quiere poco científico, yo voto SI a esta propuesta.

Manuel Nores, May 2008

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Comments from Remsen: "NO. I recognize that this category is unpopular with most on SACC. Here's my defense of it. Taxa above the species level must be monophyletic to have any scientific value in terms of phylogeny. Therefore, inclusion of taxa within a higher-level taxon implies a level of certainty that is part of our responsibility to evaluate in terms of recent research. Therefore, Incertae Sedis allows us the necessary option to indicate a reasonable level of uncertainty. It further provides the useful educational function of alerting everyone to the need for further research and that much research is still needed to make certain that higher-level taxa represent monophyletic groups."

Comments from Cadena: "NO. I generally don't like incertae sedis and like other committee members, I feel we often tend to use it too much. However, I think this is useful for cases in which we simply do not know where different taxa should go. To use Manuel's words, I'd argue it is more unscientific and more artificial to leave taxa in groups where we know they do not belong. For example, many "tanagers" were unplaced for a while because we knew they were outside Thraupidae but could not assign them to any other family with certainty, a situation that we are now finally being able to solve. That said, I'd reemphasize that there are many cases in which we are not absolutely clueless (e.g. Donacobius) and in those, we should go with the best available information. In sum, avoid incertae sedis whenever we can, but let it be."

Comments from Nores: "YES, por las razones dadas en la propuesta."

Comments from Zimmer: "NO. Having it allows us to move when we know something doesn't belong where the current taxonomy places it, even though we are not sure where it should go. Without the category, we are stuck with either making no move until everything is settled, or having to just make our best guess about where to move a misplaced taxon."

Comments from Schulenberg: "NO. Most if not all members of the committee do not much like the category "incertae sedis," and we probably use it too often. So, I can sympathize with the arguments that Manuel makes for us to eliminate this category. But as Daniel points out, there are rare situations for which we still need to invoke "incertae sedis." If we have strong evidence that a taxon is classified incorrectly, but at the same time are left with little or no evidence of the true relationships of this taxon, then I don't see that we have any choice other than to place it in "incertae sedis." Leaving said taxon in the traditional classification perhaps is more convenient, but we could so only be ignoring strong evidence that this classification is incorrect; and I don't think that we should make a habit of ignoring strong evidence."

Comments from Stotz: "NO I don't like Incertae sedis, just like most of the rest of the committee. But especially with molecular work telling us that the status quo is wrong is a particular case, but not clearly providing a new "truth" we will have situations where we can stick with something we know to be wrong, or place something somewhere new that we can't really justify (or create a new taxon; not often a good choice).  Incertae sedis provides a temporary holding pen for these problems, and also points out clearly problems that require more work."

Comments from Jaramillo: "YES - Count this as a protest vote, given that I doubt that the category will be eliminated given the voting thus far. The protest is that I think we should avoid it at all costs. The Donacobius is a good example of where it is to be used. However, in the shifts and re-arrangements of groups where information may as yet be incomplete, I suggest we leave species misplaced in the status quo, until new information comes along. They were misplaced all along, so why not keep that going for a few more years, until the data is all in? No need to shift them out to Incertae Sedis just to be an increment close to an incomplete solution."

Additional comment from Remsen: "Responding to Alvaro's point above on 'why not leave them misplaced,' the rationale is as follows. Say someone wants to use a classification to define taxonomic groups for an analysis of some sort. By continuing to include taxa in that group that we know do not belong in the group, that analysis becomes flawed. If these problem taxa are excised and deported to holding areas, namely Incertae Sedis, then no one will include them in any of their groups, which they hope are monophyletic."