Plant variation in nutrient concentrations encompasses two major axes. The first is connected to nitrogen (N) and phosphorus (P), reflects growth rate and has been designated as the leaf economics spectrum (LES) while the second follows the gradient in calcium (Ca) and magnesium (Mg) and mirrors cell structural differences. Here, we tested in grasslands whether the sum Ca + Mg concentrations is a better indicator of digestibility than LES constituents. Structural equation modelling revealed that the total effect size of N (0.30) on digestibility was much lower than that of Ca + Mg (0.58). The N effect originated predominantly from sampling date (biomass ageing), while the Ca + Mg effect largely from phylogenetic composition (proportion of monocots). Thus, plant variation in partially substitutable divalent cations seems to play a significant role in biomass digestion by ruminants. This finding contests, together with litter decomposition studies, the prominent role of the LES for understanding both fundamental ecological processes.

• Klíčová slova
• asterids, biomass, dicots, leaf dry matter content, leaf economics spectrum, monocots, nitrogen, phosphorus, rosids, rumen liquor,
• MeSH
• dusík MeSH
• fosfor MeSH
• fylogeneze MeSH
• fyziologie rostlin MeSH
• hořčík * MeSH
• listy rostlin MeSH
• rostliny MeSH
• vápník * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dusík MeSH
• fosfor MeSH
• hořčík * MeSH
• vápník * MeSH

A phylogeny of blue butterflies of the genus Maculinea and related genera (Lycaenidae) is proposed, based on 91 morphological and ecological characters. The resulting tree shows that: (1) Phengaris is a derived group nested within Maculinea; (2) the Maculinea-Phengaris clade is probably nested within Glaucopsyche; (3) there are three well supported groups within the Maculinea-Phengaris clade: (alcon group ((teleius group) (arion-Phengaris group))). Some species (M. alcon, M. arionides) appear to be non-monophyletic and require reclassification. The two alternative strategies of parasitic myrmecophily in the Maculinea-Phengaris clade, viz., "predatory" and "cuckoo", seem to be derived characters of the alcon group, and of the teleius and arion-Phengaris groups, respectively. The common ancestor of Maculinea used dorsal nectary organ secretions for ant attraction, while this trait was reduced in the ancestor of the alcon group and in M. nausithous (of the teleius group). The three recent Maculinea lineages utilize taxonomically diverse host plants, the asterid families Gentianaceae (alcon and arion-Phengaris groups), Lamiaceae (arion-Phengaris group), Campanulaceae (arion-Phengaris group), and the rosid family Rosaceae (teleius group).

• Publikační typ
• časopisecké články MeSH