Estrategias adaptativas del polen en especies de la Tribu Lycieae (Solanaceae)

AGUILAR R., BERNARDELLO G. & GALETTO L.

San Carlos de Bariloche (Argentina)

Congreso; I Reunión Binacional de Ecología Chilena-Argentino; 2001

Asociacion Argentina de Ecologia y Sociedad de Ecologia de Chile

Pollen volume may be involved in different associations with other floral traits. Particularly, literature indicates that pollen volume can be implicated in a functional relationship with pistil length, and that it may be affected by a trade-off with pollen number due to the subdivision of limited resources. To assess these associations, pollen volume was subjected to correlation analyses with pollen number and pistil length in 20 Argentinean and Chilean taxa of the monophyletic tribe Lycieae. Depending on the mechanisms operating on pollen size and number, the variability of these traits may be different. Therefore, their coefficients of variation were compared. Pistil length and pollen volume showed a strong positive correlation. In contrast, pollen grain size and number were significantly correlated at neither inter- nor intraspecific levels. Results suggest that pollen size and pistil length may co-evolve. The central role of this interaction is discussed. The lack of correlated variation of pollen size and number may be related to the similar constraints experienced by the species and/or because constraints are operating at the plant level and not at the species level. Lower variance in pollen size compared to pollen number denotes that pollen size may be the main trait subjected to natural selection.