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We studied the habitat preferences of various bryophytes on a landscape in which calcareous and granitic rocks interdigitate. On both substrates, plots were placed in sunny dry locations, shady dry locations, and along streams in wet locations. In other words, six habitat types were studied in a factorial design involving edaphics × moisture. Wet granitic habitat had the highest species richness, whereas wet calcareous habitat had the lowest species richness. In dry sites, shady plots had higher richness than sunny plots, regardless of edaphics. Particular species varied widely in their preferences with at least one species being an indicator for each of the six habitats, e.g.: "fan-form tubers Bryaceae" was specialized on granitic wet habitat; Grimmia lisae was specialized on granitic shady habitat; Grimmia montana was specialized on granitic sunny habitat; Didymodon tophaceous was specialized on calcareous wet habitat; Orthotrichum cupulatum + hallii was specialized on calcareous shady habitat; Grimmia anodon was specialized on calcareous sunny habitat. The composition of the bryophyte assemblages was very strongly affected by the interaction of calcareous-versus-granitic × dry-versus-wet; the wet calcareous assemblage was the most distinctive. To the extent possible, we classified the various species into guilds (e.g., the calcicolous rheophyte guild) taking into account generalization versus specialization. In summary, we found remarkable interactions between edaphics and wetness. [ABSTRACT FROM AUTHOR]

Recent hypotheses argue that phylogenetic relatedness should predict both the niche differences that stabilise coexistence and the average fitness differences that drive competitive dominance. These still largely untested predictions complicate Darwin's hypothesis that more closely related species less easily coexist, and challenge the use of community phylogenetic patterns to infer competition. We field parameterised models of competitor dynamics with pairs of 18 California annual plant species, and then related species' niche and fitness differences to their phylogenetic distance. Stabilising niche differences were unrelated to phylogenetic distance, while species' average fitness showed phylogenetic structure. This meant that more distant relatives had greater competitive asymmetry, which should favour the coexistence of close relatives. Nonetheless, coexistence proved unrelated to phylogeny, due in part to increasing variance in fitness differences with phylogenetic distance, a previously overlooked property of such relationships. Together, these findings question the expectation that distant relatives should more readily coexist., (© 2014 John Wiley & Sons Ltd/CNRS.)