Fruit and seed production in hand-pollination experiments in <i>C. trichotomum</i>.

<p>mean ± SE,</p>**<p>: <i>P</i><0.01.</p><p>Cross:Outcross pollination treatment, Self:Self-pollination treatment.</p><p>The fruit/flower and seed/ovule ratios were analyzed using the Mann-Whitney <i>U</i>-test.</p

Flowering phenology of 19 flowers on three <i>C. trichotomum</i> plants.

<p>The hatched bar indicates the staminate phase and the white bar represents the pistillate phase. Numbers denote individual plants.</p

Contribution of Pollinators to Seed Production as Revealed by Differential Pollinator Exclusion in <em>Clerodendrum trichotomum</em> (Lamiaceae)

<div><p>A diverse assemblage of pollinators, such as bees, beetles, flies, and butterflies, will often visit a single plant species. However, evaluating the effect of several insects on fruit and seed production is difficult in plants visited by a variety of insects. Here, we analyzed the effect of three types of pollinators, <em>Papilio</em> spp., <em>Macroglossum pyrrhosticta</em>, and <em>Xylocopa appendiculata</em> on fruit and seed production in <em>Clerodendrum trichotomum</em> by using a flower visitor barrier experiment with nets of specific mesh sizes. As a result, fruit/flower and seed/ovule ratios were significantly lower under <em>Papilio</em> exclusion than under natural conditions. On the other hand, ratios were not significantly different between <em>Papilio</em> excluded and both <em>Papilio</em> and <em>M. pyrrhosticta</em> excluded treatments. Therefore, <em>Papilio</em> and <em>X. appendiculata</em> are effective pollinators, whereas <em>M. pyrrhosticta</em>, which was the most frequent visitor, of <em>C. trichotomum</em>, is not. From our observations of visiting behaviors, we believe that because <em>M. pyrrhosticta</em> probably promotes self- pollination, this species is a non-effective pollinator. This is the first study to separate and compare the contribution of various visitors to the reproductive success of a plant.</p> </div

Comparison of the fruit/flower and seed/ovule ratios among the three treatments in 2009 and the four treatments in 2010.

<p>Letters indicate differences in the fruit/flower and seed/ovule ratios as determined by AICs depending on GLMMs. “Out” indicates the outcross-pollination treatment, “Con” denotes the control experiment, “100” denotes the flower visitor barrier experiment with a 100-mm mesh, and “25” refers to the flower visitor barrier experiment with a 25-mm mesh.</p

Frequencies of flower visitors in <i>C. trichotomum</i>.

<p>Observations were conducted in a 4 m×4 m plot in 2008 and in 2 m×2 m plots in 2009 and 2010. Total time of observation per year was 27.5 h.</p

The frequency of visits per area for <i>M. pyrrhosticta</i>, <i>X. appendiculata</i>, and <i>Papilio</i> spp. in 2009 and 2010.

<p>Each period represents a total of five observations in one flowering season. Asterisks indicate that no flower visitors were observed.</p

Examples of foraging bouts and pollen movement.

<p>Each circle indicates experimental flowers. Solid arrows indicate foraging movements of swallowtail butterfly (A) and hawkmoth and gray circles are visited flowers. Dashed arrows show pollen movement from donors to recipients.</p

Pollinator-Mediated Selection on Flower Color, Flower Scent and Flower Morphology of <i>Hemerocallis</i>: Evidence from Genotyping Individual Pollen Grains On the Stigma

<div><p>To trace the fate of individual pollen grains through pollination processes, we determined genotypes of single pollen grains deposited on <i>Hemerocallis</i> stigmas in an experimental mixed-species array. <i>Hemerocallis fulva</i>, pollinated by butterflies, has diurnal, reddish and unscented flowers, and <i>H. citrina</i>, pollinated by hawkmoths, has nocturnal, yellowish and sweet scent flowers. We observed pollinator visits to an experimental array of 24 <i>H. fulva</i> and 12 F2 hybrids between the two species (<i>H. fulva</i> and <i>H. citrina</i>) and collected stigmas after every trip bout of swallowtail butterflies or hawkmoths. We then measured selection by swallowtail butterflies or hawkmoths through male and female components of pollination success as determined by single pollen genotyping. As expected, swallowtail butterflies imposed selection on reddish color and weak scent: the number of outcross pollen grains acquired is a quadratic function of flower color with the maximum at reddish color, and the combined pollination success was maximal at weak scent (almost unrecognizable for human). This explains why <i>H. fulva</i>, with reddish flowers and no recognizable scent, is mainly pollinated by swallowtail butterflies. However, we found no evidence of hawkmoths-mediated selection on flower color or scent. Our findings do not support a hypothesis that yellow flower color and strong scent intensity, the distinctive floral characteristics of <i>H. citrina</i>, having evolved in adaptations to hawkmoths. We suggest that the key trait that triggers the evolution of nocturnal flowers is flowering time rather than flower color and scent.</p> </div

Flowers of <i>H. fulva</i> and F2 hybrid.

<p>(A) A swallowtail butterfly <i>Papilio xuthus</i> visiting a <i>H. fulva</i> flower. (B) A hawkmoth <i>Theretra japonica</i> visiting a F2 hybrid flower.</p

Typical reflectance spectra of F2 hybrids (above) and the relationship score, reflectance (below).

<p>(A) Reflectance spectra of the central part of tepals. Three representative F2 hybrids, DG11 (SCC=3), BD3 (SCC=13) and BC12 (SCC=21), are showed. (B) Reflectance spectra of the peripheral part of tepals. (C) The relationship between color chart score and relative reflectance at 525 nm of the central part of tepals. (D) The relationship between color chart score and relative reflectance at 360 nm of the peripheral part of tepals.</p