Artículos de revistas
Pollinator-mediated selection and experimental manipulation of the flower phenotype in Chloraea bletioides
Fecha
2010-05-20Registro en:
FUNCTIONAL ECOLOGY, Volume: 24, Issue: 6, Pages: 1219-1227, 2010
0269-8463
Autor
Cuartas Domínguez, Marcela
Medel Contreras, Rodrigo
Institución
Resumen
1. While many studies of flower evolution have relied on the assessment of selection coefficients,
these estimates represent correlative evidence of selection. Few studies have combined correlative
with experimental evidence, and hence the mechanisms underlying selection processes are not
well understood.
2. In this study we quantified the magnitude, direction and form of pollinator-mediated selection
acting upon morphological traits in the Chilean endemic orchid Chloraea bletioides. Results
revealed strong selection differentials for plant height and flower number, and absence of total
selection for morphological flower characters. Multivariate analysis of selection revealed a
strong and positive directional selection gradient for flower number.
3. The labellar lobe and flower tube were under negative correlational selection, indicating that
selection promoted alternative combinations of traits. Plants with long floral tubes and small
labellar lobes, and short floral tubes with large labellar lobes were selected for. Interestingly,
selection on flower number increased at a higher rate through the female function than through
the male function, which suggests that size-dependent resource limitation may be more important
than pollinator-mediated selection for fruit set.
4. In addition to estimates of phenotypic selection, we evaluated through phenotype modification
the impact of pollinators on the correlation and potential integration of flower traits coming
from different whorls. We removed the tip of the lateral sepals and the labellar lobe in a 2 · 2
factorial design.
5. Results revealed that phenotypic modification had no effect on male and female fitness. The
absence of effect was consistent with the low and non-significant selection coefficients. Nevertheless,
the observation of significant correlational selection for labellar lobe and flower tube
suggests that experimental studies performed on these characters may be of interest to evaluate
the functional and adaptive integration of flower design in orchids.