4 research outputs found

    Distribution ecology of pollen tubes: fine-grained, labile spatial mosaics in southern Spanish Lamiaceae

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    • Patterns of intraspecific variation in the number of pollen tubes per style in naturally pollinated plants are poorly known, yet that information is essential for assessing the frequency of occurrence and evolutionary implications of microgametophyte com- petition in the wild. • This paper analyses intraspecific variation in the number of pollen tubes per style for six species of southern Spanish insect-pollinated Lamiaceae (Ballota hirsuta, Lavandula latifolia, Marrubium supinum, Phlomis lychnitis, Rosmarinus officinalis and Teucrium rotundifolium) differing in growth form, phenology, flower size and pollinators. • Number of pollen tubes exceeded number of fertilizable ovules in 26 – 87% of styles, and mean number per pollen tube of other pollen tubes in the same style varied between five and 12. Within-plant variation in pollen tube number was extensive in all species, accounting for 68–92% of total population-level variance. In L. latifolia mean pollen tube number per style differed between populations and between plants within populations, but such differences were not consistent among years. • It is concluded that opportunities for microgametophyte competition and selec- tion on competitive ability are considerable in all species studied, although extreme spatial fine-graininess and marked stochasticity in the variation of pollen tube numbers, including temporal inconstancy of individual differences, will greatly reduce the opportunity for selection on sporophytic characters influencing degree of microgametophyte competition.Peer reviewe

    Contrasting responses to mycorrhizal inoculation and phosphorus availability in seedlings of two tropical rainforest tree species

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    This work aimed at understanding the role of mycorrhizal status in phosphorus efficiency of tree seedlings in the tropical rainforest of French Guyana. * Mycorrhizal colonization, growth, phosphorus content, net photosynthesis and root respiration were determined on three occasions during a 9-month growth period for seedlings of two co-occurring species (Dicorynia guianensis and Eperua falcata) grown at three soil phosphorus concentrations, with or without inoculation with arbuscular mycorrhizas. * Seedlings of both species were unable to absorb phosphorus in the absence of mycorrhizal association. Mycorrhizal seedlings exhibited coils that are specific of Paris-type mycorrhizae. Both species benefited from the mycorrhizal symbiosis in terms of phosphorus acquisition but the growth of E. falcata seedlings was unresponsive to this mycorrhizal improvement of phosphorus status, probably because of the combination of high seed mass and P reserves, with low growth rate. * The two species belong to two different functional groups regarding phosphorus acquisition, D. guianensis being an obligate mycotrophic species

    Distribution ecology of pollen tubes: fine-grained, labile spatial mosaics in southern Spanish Lamiaceae

    No full text
    • Patterns of intraspecific variation in the number of pollen tubes per style in naturally pollinated plants are poorly known, yet that information is essential for assessing the frequency of occurrence and evolutionary implications of microgametophyte com- petition in the wild. • This paper analyses intraspecific variation in the number of pollen tubes per style for six species of southern Spanish insect-pollinated Lamiaceae (Ballota hirsuta, Lavandula latifolia, Marrubium supinum, Phlomis lychnitis, Rosmarinus officinalis and Teucrium rotundifolium) differing in growth form, phenology, flower size and pollinators. • Number of pollen tubes exceeded number of fertilizable ovules in 26 – 87% of styles, and mean number per pollen tube of other pollen tubes in the same style varied between five and 12. Within-plant variation in pollen tube number was extensive in all species, accounting for 68–92% of total population-level variance. In L. latifolia mean pollen tube number per style differed between populations and between plants within populations, but such differences were not consistent among years. • It is concluded that opportunities for microgametophyte competition and selec- tion on competitive ability are considerable in all species studied, although extreme spatial fine-graininess and marked stochasticity in the variation of pollen tube numbers, including temporal inconstancy of individual differences, will greatly reduce the opportunity for selection on sporophytic characters influencing degree of microgametophyte competition.Peer reviewe
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