Autocompatibilidad y selección mediada por polinizadores sobre el despliegue floral en una población de Psychotria carthagenensis (Rubiaceae)

ANALÍA BENAVIDEZ; MARIANO ORDANO; MARIANA VALOY

Lilloa

Fundación Miguel Lillo

Lugar: San Miguel de Tucumán; Año: 2013 vol. 50 p. 10 - 19

0075-9481

The reproductive system of Psychotria carthagenensis varies among populations. Studies carried out in Brazil indicate that this species shows floral polymorphism with a heterostylic system, and is self-compatible. In this work, we studied a population of Yungas in the Tucumán province, Argentina. Our goals were (1) to determine if plants produce fruits by spontaneous autogamy, (2) to evaluate the role of pollinators in fruit production and as selection agents on floral display. The individuals of the studied population are self-compatible and apparently monomorphic. In 23 plants, the proportion of fruits produced by spontaneous autogamy (inflorescences closed to pollinators) varied between 0,06 and 0,74 (mean = 0,36; s.d. = 0,17). In open inflorescences of the same plants, the proportion of produced fruits varied between 0,23 and 0,92 (mean = 0,56; s.d. = 0,22), and differed significantly from spontaneous autogamy. This suggests that pollinators play an important role in fruit production. Selection analyses indicate that the number of inflorescences ( β = 0,379; s.e. = 0,091; p < 0,001) and the number of flower per inflorescence might be targets of pollinator-mediated selection ( β = 0,515; s.e. = 0,091; p < 0,001). Altogether, the self-compatibility and the role of pollinators suggest that P. carthagenensis keeps a mixed reproductive system. It is discussed if this condition might be associated with pollinator-mediated and frugivore-mediated selection on floral and fruit display, in relation with the reproductive assurance hypothesis linked to self-fecundation.