DOI: 10.5061/dryad.mn6np
title: Data from: Heterostyly promotes disassortative pollination and reduces sexual interference in Darwin’s primroses: evidence from experimental studies

description: Different strategies to reduce selfing and promote outcrossing have
 evolved in hermaphroditic flowers. Heterostyly, a complex floral
 polymorphism that occurs in at least 27 families of angiosperms, is
 hypothesized to achieve both goals by optimizing cross-pollination (via
 disassortative pollen transfer) and restricting gamete wastage to autogamy
 (via the reduction of sexual interference between male and female organs).
 In heterostylous flowers, the reciprocal positioning of sexual organs in
 different morphs and the pollen incompatibility-system within flower or
 between flowers of the same morph are thought to optimize both male and
 female functions, reducing the conflicts inherent to the occurrence of
 both sexual organs in the same reproductive unit. Specific elements of the
 disassortative-pollination and sexual-interference hypotheses have been
 tested individually before. However, despite the long-standing interest in
 heterostyly – ever since Darwin's seminal work on primroses – the
 predictions derived from these two hypotheses have never been
 experimentally and systematically examined in the same system. Using
 distylous primroses (Primula elatior, P. vulgaris) we compare pollen
 transfer (i) between reciprocal and non-reciprocal flowers; (ii) from
 anthers onto different parts of the pollinator's body; (iii) within
 flower and between flowers of the same morph. We further test whether (iv)
 anther-stigma distance correlates with self-pollen transfer; (v) seed-set
 differs after pollinations with compatible, incompatible, and both pollen
 types. Reciprocal herkogamy promotes differential placement of pollen onto
 different parts of the pollinator's body, thus effecting transfer of
 more pollen to reciprocal than non-reciprocal stigmas and realizing the
 key predictions of the disassortative-pollination hypothesis. However,
 short-styled flowers transfer pollen more disassortatively than
 long-styled flowers in both species, whereas long-styled flowers export
 more pollen to non-reciprocal than reciprocal stigmas in P. vulgaris, thus
 compromising male function in this species. Furthermore, larger distance
 between sexual organs lowers self- and intra-morph pollination and the
 pollen incompatibility-system decreases seed production after
 self-pollination, thus diminishing sexual interference. Our results help
 us understand how the morphological and physiological components of
 heterostyly contribute to optimizing pollen transfer and minimizing self-
 and intra-morph pollination, thus promoting more efficient outcrossing in
 species with this floral polymorphism.
description: Raw data from
 experiments performed to investigate the disassortative-pollination
 hypothesis and sexual-interference hypothesis in distylous
 primrosesThe excel file contains
 raw data of number of pollen grains, number of developing seeds, and
 anther-stigma distances from flight-cage and hand-pollination experiments
 performed to investigate the disassortative-pollination hypothesis and
 sexual-interference hypothesis in distylous primroses. Data for each
 experiment are presented in an individual worksheet. Names of column
 headings correspond with terms used in the original
 paper.FE-2013-00720.xlsx