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| SPOROPHITIC VS. GAMETOPHITIC | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The relative value of sporophytic versus gametophytic characters as indicators of phylogenetic relatedness is a fundamentally important question in moss systematics and nowhere is the issue more relevant than in the Hookeriales. We have done a first evaluation of this issue in the Hookeriales through a comparison of two classifications of this order by Crosby (1974) and Buck (1987, 1988) with a modern classification based on molecular evidence by Buck et. al. (2005). Crosby's classification is based exclusively in sporophitic characters while Buck's one is mainly based on gametophitic features. We compare here both classifications with a more objective one proposed by Buck et. al. (2005) after the phylogeny of the order based on molecular data from four genes (26S, NAD5, rps4 and trnL).Comparison of Crosby (1974) and Buck et al. (2005) classifications:
This comparison shows that using only sporophytic characters to create the taxonomic groups in the Hookeriales leads to a completely artificial classification. Comparison of Buck (1987, 1988) and Buck et al. (2005) classifications:
As this comparison shows Buck’s classification (1987, 1988), based mainly in gametophytic characters, was closer to represent the phylogeny of the group than Crosby’s one. However, he failed in the circumscription of the family Hookeriaceae, that was made on the basis of the presence of a multistratose calyptrae. In general gametophytic characters are more useful inferring relationships in Hookeriales than sporophytic ones. Nevertheless, every morphological character should be assessed under a phylogeny based on molecular data. After this example it seems that the problem is not sporophytic vs. gametophytic characters, but FEW CHARACTERS VS. MANY CHARACTERS.
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| SENSU BUCK ET AL. (2005): | |||
| ________ | Daltoniacea | ||
| ________ | Hookeriacea | ||
| ________ | Hypoterygiacea | ||
| ________ | Leucomiacea | ||
| ________ | Pilotrichacea | ||
| ________ | Saulomatacea | ||
| ________ | Schymperobryacea | ||
