Asymmetric pollen transfer and reproductive success of the hawkmothpollinated distylous tree Palicourea tetragona (Rubiaceae) at La Selva, Costa Rica

Silvana Martén-Rodríguez, Paola Muñoz-Gamboa, Ruth Delgado-Dávila, Mauricio Quesada

Research output: Contribution to journalArticlepeer-review

Abstract

Distyly is a floral polymorphism that presumably evolved to facilitate cross-pollination and to prevent sexual interference. However, pollen transfer is often asymmetric,with one floral morph acting as a pollen donor and the other as a pollen recipient. We evaluated the association between floral morphology, pollinator visitation and effectiveness on patterns of pollen transfer in distylous Palicourea tetragona at La Selva Biological Station in Costa Rica. To assess floral variation we measured corolla, pistil and stamen traits from 66 plants. We quantified pollinator visitation and efficiency on 56 individuals and counted pollen loads on stigmas of flowers observed for 1 h.We determined fruit set 2 molater and assessed between-morph variation in pollen transfer and female reproductive success. Floral variation was mostly consistent with a typical distylous system; however, there was overlap in the stigma heights of pin and thrum individuals in the study population. Primary pollinators were two species of hawkmoths that visited both morphs at a frequency of 2 visits per flower h-1. The mean number of pollen grains deposited on stigmas was 89 for pin and 153 for thrum individuals. However, loads of illegitimate pollen were higher on stigmas of thrum individuals, while loads of legitimate pollen were higher on stigmas of pin individuals. Consistently, fruit set was higher in pin (31%) than in thrum individuals (22%). High deposition of illegitimate pollen, in addition to the lower female reproductive success in the thrum morph reveal that distyly in P. tetragona does not always prevent sexual interference. We suggest that in long and narrow tubular flowers, like those of P. tetragona, stigma clogging by deposition of self- or same-morph pollen may reduce legitimate fertilization of ovules causing the observed asymmetric fruit set.

Original languageEnglish
Pages (from-to)501-510
Number of pages10
JournalJournal of Tropical Ecology
Volume29
Issue number6
DOIs
StatePublished - 1 Nov 2013
Externally publishedYes

Bibliographical note

Publisher Copyright:
© Cambridge University Press 2013.

Keywords

  • Asymmetric pollen transfer
  • Costa Rica
  • Distyly
  • Hawkmoth
  • Pollination

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Fingerprint

Dive into the research topics of 'Asymmetric pollen transfer and reproductive success of the hawkmothpollinated distylous tree Palicourea tetragona (Rubiaceae) at La Selva, Costa Rica'. Together they form a unique fingerprint.

Cite this