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Pollination ecology and reproductive success in Jack-in-the Pulpit (Arisaema triphyllum) in Quebec (Canada)
Abstract
Pollination ecology and reproductive success of Jack-in-the-pulpit (Arisaema triphyllum) were studied in two natural populations in Québec, Canada. Individual A. triphyllum plants can be of three types: male, female or bisexual. In both populations studied, the presence of bisexual inflorescences was not negligible (13%), where 'female' and 'male' bisexual plants were categorised according to the relative number of stamens and ovaries. 'Male bisexual' plants produce only pollen and 'female bisexual' plants produce only fruit. Hence, A. triphyllum is a true dioecious plant, as each plant only reproduces through either the male or the female function. 'Female bisexual' plants were equivalent to female plants in terms of visitation rate by insects, fructification rate and production of berries and seeds. Neither agamospermy in female plants nor self-pollination in 'female bisexual' plants was found, thus A. triphyllum relies on insects for cross-pollination. Despite the long flowering cycle, a low visitation rate was documented: only 20-40% of inflorescences were visited, according to gender, by a mean of 1.5 insects. In this study, Mycetophilidae represented the most generically diversified and abundant family, as well as the most efficient insect pollinator, especially the genera Docosia and Mycetophila.
... Arisaema have a pitchertrap pollination system (Barnes, 1935;Vogel and Martens, 2000;Nishizawa et al., 2005). Their pitcherlike inflorescences attract fungus gnats (Mycetophilidae and Sciaridae) (Barnes, 1935;Vogel and Martens, 2000;Barriault et al., 2010) by the odor emitted from the spadix appendage and/or the spathe blade (Barnes, 1935;Vogel and Martens, 2000). The Arisaema in florescence does not usually offer any rewards for their pollinators, except for some species that secrete nectar from extrafloral nectar ies (Murata et al., 1993;Vogel and Martens, 2000). ...
... To examine seasonal transitions in the frequency of insect visita tion (functional flowering phenology), we collected all floral visi tors of the two Arisaema species when we investigated the apparent flowering phenology. The exit hole of the male spathe ( Fig. 1D) was sealed with Teflon tape before the spathe opened to prevent the attracted insects escaping (Barriault et al., 2009(Barriault et al., , 2010Tanaka et al., 2013). All insects in the spathe were collected daily during the flowering season using a handmade aspirator. ...
... This hybridiza tion might be because some families (e.g., Sciaridae, Chironomidae, and Phoridae) of floral visitor assemblages were shared between the lateflowering A. sikokianum and natural A. tosaense (Fig. 6), although they did not seem to be effective pollinators of the two Arisaema species. Furthermore, floral visitor assemblages can fluc tuate regionally, as reported for A. triphyllum (Linnaeus) Schott (Rust, 1980;Barriault et al., 2010;Jones et al., 2013). ...
Premise:
The genus Arisaema (Araceae) has rapidly diversified in Japan, and multiple species often coexist in the field. Although Japanese Arisaema species hybridize from artificial crossing, hybrid individuals are rare in mixed populations; suggesting the presence of effective pre-pollination barriers. We examined the following reproductive barriers between A. sikokianum and A. tosaense: habitat, phenology, and pollinator isolations.
Methods:
Habitat isolation was examined by interspecific comparisons of microhabitat conditions at a mixed site and of altitude at the sampling site of herbarium specimens. Phenological isolation was evaluated by comparing seasonal transition in apparent spathe condition and frequency of insect visitation. Pollinator isolation was examined by comparing floral visitor assemblages between the two Arisaema species. To avoid overestimation of pollinator isolation due to seasonal changes in insect assemblages, we also compared visitor assemblages between natural and late-flowering A. sikokianum, where the latter was experimentally introduced and blooming with a natural A. tosaense population.
Results:
Microhabitat conditions and sampling elevations of herbarium specimens overlapped between the two Arisaema species. At the population level, A. sikokianum and A. tosaense flowered for 39 and 52 days, respectively, with 13 days overlap. Insect visitation in A. sikokianum decreased before the seasonal overlap. Floral visitor assemblages differed between the two Arisaema species, while the difference between natural and late-flowering A. sikokianum was less distinct.
Conclusions:
Phenological and pollinator isolation contribute to reproductive isolation between the two Arisaema species and should enable the two species to coexist in this area.
... It is not known whether Ditassa flowers are deceptive. Representatives of deceptive and pollinator-trapping plant species in other families, such as Aristolochiaceae (Aristolochia; [25][26][27]), Araceae (Arisaema; [28][29][30][31][32]), and orchids (e.g., Pleurothallis [33], Trichosalpinx [34], Lepanthes [35], Pterostylis [36,37]) are likewise known to be visited/pollinated by Phoridae (Megaselia), Sciaridae (Bradysia, Corynoptera, Pseudolycoriella), Chloropidae (Oscinimorpha), and Ceratopogonidae (Forcipomyia). Furthermore, various economically important crops (e.g., Cacao; [38]) depend on the same dipteran families and genera for pollination. ...
... It is not known whether Ditassa flowers are deceptive. Representatives of deceptive and pollinatortrapping plant species in other families, such as Aristolochiaceae (Aristolochia; [25][26][27]), Araceae (Arisaema; [28][29][30][31][32]), and orchids (e.g., Pleurothallis [33], Trichosalpinx [34], Lepanthes [35], Pterostylis [36,37]) are likewise known to be visited/pollinated by Phoridae (Megaselia), Sciaridae (Bradysia, Corynoptera, Pseudolycoriella), Chloropidae (Oscinimorpha), and Ceratopogonidae (Forcipomyia). Furthermore, various economically important crops (e.g., Cacao; [38]) depend on the same dipteran families and genera for pollination. ...
Elaborated kettle trap flowers to temporarily detain pollinators evolved independently in several angiosperm lineages. Intensive research on species of Aristolochia and Ceropegia recently illuminated how these specialized trap flowers attract particular pollinators through chemical deception. Morphologically similar trap flowers evolved in Riocreuxia; however, no data about floral rewards, pollinators, and chemical ecology were available for this plant group. Here we provide data on pollination ecology and floral chemistry of R. torulosa. Specifically, we determined flower visitors and pollinators, assessed pollen transfer efficiency, and analysed floral scent chemistry. R. torulosa flowers are myiophilous and predominantly pollinated by Nematocera. Pollinating Diptera included, in order of decreasing abundance, male and female Sciaridae, Ceratopogonidae, Scatopsidae, Chloropidae, and Phoridae. Approximately 16% of pollen removed from flowers was successfully exported to conspecific stigmas. The flowers emitted mainly ubiquitous terpenoids, most abundantly linalool, furanoid (Z)-linalool oxide, and (E)-β-ocimene—compounds typical of rewarding flowers and fruits. R. torulosa can be considered to use generalized food (and possibly also brood-site) deception to lure small nematocerous Diptera into their flowers. These results suggest that R. torulosa has a less specific pollination system than previously reported for other kettle trap flowers but is nevertheless specialized at the level of Diptera suborder Nematocera.
... Thysanoptera and Coleoptera were also abundant in one population (Barriault et al. 2010). ...
... Hand-pollination experiments could enhance our comprehension of the impact of pollen limitation, weather conditions, and saprophage-related damage on fruit set. In Arisaema triphyllum, a species that also exhibits a low floral visitation rate, hand-pollination experiments resulted in a significant increase in fructification rate from 32% to 80%, suggesting pollen limitation is probably the main reproductive limitation (Barriault et al. 2010). ...
The pollination ecology of Symplocarpus foetidus (L.) W. Salisbury was studied in a seasonally forested flooded bog in Québec (Canada) in 2008 and 2009. The protogynous anthesis duration ranged from 15 to 20 days with, chronologically, a female phase of about 5 days, a bisexual phase of 2 days, and a male phase of 9 days. The spadix temperature differences with ambient air were higher during the female phase (mean: 13.6°C) than during the bisexual and male phases (mean: 4.5°C). The air inside the floral chamber was warmed by the heating spadix, particularly during the female phase (~6°C warmer than ambient air). High temperatures were maintained through nighttime during the female phase, whereas they occurred only during the daytime during the bisexual and male phases. The average natural fruit and seed sets were relatively low (18.2% and 14%), and the fruit set varied between years (13% in 2008 vs. 31% in 2009). Since spontaneous self-pollination is a rare reproductive event, sexual reproduction in Symplocarpus foetidus relies mainly on insect cross-pollination. Pollination is probably generalist considering the large variety of Coleoptera and Diptera families attracted to the plant, such as Chironomidae, Sphaeroceridae, Mycetophilidae, Phoridae, Drosophilidae, Chloropidae, and Anthomyiidae. Since many different insect types visit the inflorescences, it is unclear whether this pollination system is a deceptive interaction (its unpleasant floral scent is typical of other deceptive Araceae), a breeding site mutualism (developing larvae have been observed on the inflorescences), or a combination of the two.
... The genus Arisaema (Araceae) is pollinated by fungus gnats (Vogel and Martens, 2000) and is suitable for the examination of their contribution to reproductive isolation for the following four reasons. First, the quantification of pollinator visits is easy in Arisaema because all visitors can be trapped in the pitcherlike spathe (Fig. 1) by artificial manipulation (Barriault et al., 2009(Barriault et al., , 2010. Second, pollinator isolation caused by selective visitation of fungus gnats (Vogel and Martens, 2000) and contrasting fly pollinators (Kakishima et al., 2019;Matsumoto et al., 2019) has been reported in sympatric Arisaema species. ...
... In contrast, the female spathe has no exit hole, and the captured fungus gnats move around the female spadix, depositing pollen grains on the stigma, and then die. Therefore, all floral visitors of male and female inflorescences can be collected by closing the exit hole of male inflorescence (Barriault et al., 2010). ...
Background and Aims
Interspecific difference in pollinators (pollinator isolation) is important for reproductive isolation in flowering plants. Species-specific pollination by fungus gnats has been discovered in several plant taxa, suggesting that they can contribute to reproductive isolation. Nevertheless, their contribution has not been studied in detail, partly because they are too small for field observations during flower visitation. To quantify their flower visitation, we used the genus Arisaema (Araceae) because the pitcher-like spathe of Arisaema can trap all floral visitors.
Methods
We evaluated floral visitor assemblage in an altitudinal gradient including five Arisaema species. We also examined interspecific differences in altitudinal distribution (geographic isolation) and flowering phenology (phenological isolation). To exclude the effect of interspecific differences in altitudinal distribution on floral visitor assemblage, we established 10 experimental plots including the five Arisaema species on high- and low-altitude areas and collected floral visitors. We also collected floral visitors in three additional sites. Finally, we estimated the strength and contribution of these three reproductive barriers using the unified formula for reproductive isolation.
Key Results
Each Arisaema species selectively attracted different fungus gnats in the altitudinal gradient, experimental plots, and additional sites. Altitudinal distribution and flowering phenology differed among the five Arisaema species, whereas the strength of geographic and phenological isolations were distinctly weaker than those in pollinator isolation. Nevertheless, the absolute contribution of pollinator isolation to total reproductive isolation was weaker than geographic and phenological isolations, because pollinator isolation functions after the two early-acting barriers in plant life history.
Conclusions
Our results suggest that selective pollination by fungus gnats potentially contributes to reproductive isolation. Since geographic and phenological isolations can be disrupted by habitat disturbance and interannual climate change, the strong and stable pollinator isolation might compensate for the weakened early-acting barriers as an alternative reproductive isolation among the five Arisaema species.
... to the size advantage model predictions (Revel et al., 2012). In some species of the genus Arisaema, a complete inflorescence feminization exists, called paradioecy, since small reproductive individuals produce inflorescence bearing only male flowers whereas the same individuals when larger produce inflorescence bearing only female flowers (Barriault et al., 2010). ...
... Hence Helicodiceros muscivorus does not follow the size advantage model. This inflorescence feminization has been shown to exist in some aroid species such Arum italicum, A. cylindraceum or Arisaema triphyllum Barriault et al., 2010;Revel et al., 2012), but not in Arum maculatum (Chartier & Gibernau, 2009). ...
The pollination success of the dead horse arum, Helicodiceros muscivorus, was studied in one Corsican population. This aroid species is pollinated by deception, attracting blowflies by mimicking the floral volatiles emitted by mammal cadavers. The reproductive individuals were taller and larger than non-reproductive ones, indicating that the plant vigor and thus the available amount of resources are important factors in the production of an inflorescence. The reproductive success of the dead horse arum increased with the size of the inflorescence, as judged by a positive linear correlation between the appendix length and the total number of flies trapped within the floral chamber. Larger inflorescences had a longer appendix and thus a better probability to attract and dupe pollinating flies. The absence of correlation between floral sex-ratio and the spadix size indicated that there was no expression of the size-advantage model in H. muscivorus apparent in some other Araceae. The most probable explanation is that pollination efficiency is high because of low diversity and high abundance of pollinating insects.
... Typically, fungusmimetic flowers pollinated by fungus gnats are dark purplish brown and borne close to the ground, and they often exude a strong fungus-like odour, which is the main attractant (Vogel 1973). Although other mimetic characters such as visual and tactile cues are presumably important attractants, odours have the most important role, at least in Arisaema (Vogel & Martens 2000;Barriault et al. 2010) and in Dracula (Dentinger & Roy 2010;Endara et al. 2010). High humidity caused by intense local transpiration further intensifies the mushroom guise. ...
... Monoecious Araceae are protogynous, luring pollen-bearing flies and trapping them in contact with the female flowers, then releasing pollen and allowing the flies to escape (Albre et al. 2003). Sciaridae and Mycetophilidae attracted to the kettle trap blossoms of dioecious Arisaema escape through exit holes of male spathes, but die in female spathes after potential pollination (Vogel & Martens 2000;Barriault et al. 2010). In fungus-mimetic flowers pollinated by mycophagous Diptera such as Muscidae and Phoridae, there may be severe reduction of reproductive success of females ovipositing into the flowers. ...
This paper comprises Part II of a review of flower visitation and pollination by Diptera (myiophily
or myophily). While Part I examined taxonomic diversity of anthophilous flies, here we consider the rewards and
attractants used by flowers to procure visits by flies, and their importance in the lives of flies. Food rewards such as
pollen and nectar are the primary reasons for flower visits, but there is also a diversity of non-nutritive rewards such
as brood sites, shelter, and places of congregation. Floral attractants are the visual and chemical cues used by Diptera
to locate flowers and the rewards that they offer, and we show how they act to increase the probability of floral
visitation. Lastly, we discuss the various ways in which flowers manipulate the behaviour of flies, deceiving them to
visit flowers that do not provide the advertised reward, and how some flies illegitimately remove floral rewards
without causing pollination. Our review demonstrates that myiophily is a syndrome corresponding to elements of
anatomical, behavioural and physiological adaptations of flower-visiting Diptera. The bewildering diversity of
anthophilous Diptera and of the floral attractants and rewards to which they respond allows for only broad
generalizations on myiophily and points to the need for more investigation. Ecological relationships between flies
and flowers are critical to the survival of each group in many habitats. We require greater understanding of the
significance of flies in pollination, especially in the face of recent pollinator declines.
... Okuyama and S. Kakishima, personal observations). Likewise, in Pistillata, pollinators have been reported for at least 12 species (summarized in Figure 3; Barriault et al., 2010;Kakishima et al., 2019Matsumoto et al., 2019Matsumoto et al., , 2021Suetsugu et al., 2021) but their deception mechanisms remain unknown, except for the only well-examined mushroom mimicry system in Arisaema sikokianum (Kakishima et al., 2019). Suetsugu et al. (2021) suggested pollination by sexual mimicry in two species of Pistillata, Arisaema peninsulae and Arisaema angustatum, and it is possible that sexual mimicry is more widespread in the lineage. ...
The adaptive radiation of flowering plants as manifested by the floral diversity has long been considered associated with the diversity of plant–pollinator interactions, because changes in plant–pollinator interactions are hypothesized as one of the major mechanisms driving plant ecological speciation. To understand the relative contributions of various mechanisms for plant radiation, including pollinator changes, it is useful to study a plant group for which comparative study of the species life history across the whole lineage is feasible. To this end, we will focus on the plant lineages that have presumably radiated in the Japanese archipelago, namely, the genera Asimitellaria, Asarum, and Arisaema. By comparing these three genera, we will comment on the possible modes of adaptive radiation and diversification among the endemic flora of Japan. In this paper, we focus on the three plant lineages that have presumably radiated in the Japanese archipelago, namely, the genera Asimitellaria, Asarum, and Arisaema, in which detailed studies on phylogeny, reproductive isolation, and character evolution are underway. By comparing these three genera, we discuss the ecological mechanisms underlying the contrasting diversification modes among them.
... Adults are generally little known with their biology (Søli et al., 2017). Nonetheless, some adults are primary or efficient pollinators for flowering plants, such as those with long proboscises (Okuyama et al., 2004;Goldblatt et al., 2004) or Abbreviations: atp6, ATP synthase subunit 6; atp8, ATP synthase subunit 8; cob, cytochrome b apoenzyme; cox1, cytochrome oxidase subunit I; cox2, cytochrome oxidase subunit II; cox3, cytochrome oxidase subunit III; nad1, NADH dehydrogenase subunit 1; nad2, NADH dehydrogenase subunit 2; nad3, NADH dehydrogenase subunit 3; nad4, NADH dehydrogenase subunit 4; nad4l, NADH dehydrogenase subunit 4L; nad5, NADH dehydrogenase subunit 5; nad6, NADH dehydrogenase subunit 6; rrnL, large ribosomal subunit RNA; rrnS, small ribosomal subunit RNA; trnA, Transfer RNA specifying Alanine; trnC, Transfer RNA specifying Cysteine; trnD, Transfer RNA specifying Aspartic acid; trnE, Transfer RNA specifying Glutamic acid; trnF, Transfer RNA specifying Phenylalanine; trnG, Transfer RNA specifying Glycine; trnH, Transfer RNA specifying Histidine; trnI, Transfer RNA specifying Isoleucine; trnK, Transfer RNA specifying Lysine; trnL1, Transfer RNA specifying Leucine 1; trnL2, Transfer RNA specifying Leucine 2; trnM, Transfer RNA specifying Methionine; trnN, Transfer RNA specifying Asparagine; trnP, Transfer RNA specifying Proline; trnQ, Transfer RNA specifying Glutamine; trnR, Transfer RNA specifying Arginine; trnS1, Transfer RNA specifying Serine 1; trnS2, Transfer RNA specifying Serine 2; trnT, Transfer RNA specifying Tryptophan; trnV, Transfer RNA specifying Valine; trnY, Transfer RNA specifying Tyrosine.. those sexually deceived by certain Orchidaceae or Araceae (Blanco and Barboza, 2005;Tremblay and Ackerman, 2007;Barriault et al., 2010;Gaskett, 2011). ...
The family Mycetophilidae (Diptera: Sciaroidea) consists of more than 4,500 described species distributed worldwide. Among them, dozens of species were reported to be economically important to cultivated mushrooms and crops. Relationships among subfamilies in Mycetophilidae have been controversial by using morphological characters or gene markers. In this study, five mycetophilid mitogenomes representing four subfamilies were sequenced and analyzed with 15 published sciaroid mitogenomes as ingroup, while another two species representing two closely related families were chosen as outgroup. All of the sequenced mitogenomes contain 37 genes arranged in the ancestral order, including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNA) genes, two ribosomal RNA (rRNA) genes and a control region (CR). Among mycetophilid mitogenomes, Leu, Ile, Phe, and Met are the most frequently encoded amino acids (AA), with TTA (Leu), ATT (Ile), TTT (Phe) and ATA (Met) being the most frequent codons. Meanwhile, the phylogenetic results reconstructed based on PCGs, PCGs + rRNAs and AA sequences respectively show that the clade of Sciaroidea was well separated from outgroup, further approving its monophyly. The phylogenetic relationships within Mycetophilidae were recovered as (Manotinae + Sciophilinae) + (Mycomyinae + Mycetophilinae). Mapped to the phylogram, the gene rearrangements occur frequently in the crown group, implying the extremely high evolutionary rates in Sciaridae and Cecidomyiidae, which might be the reason why the two families have such high species diversity.
... The principal flower visitors of three Arisaema species studied in the present study, namely A. cucullatum, A. kishidae and A. yamatense, were fungus gnats (Mycetophilidae or Sciaridae) as in the cases reported previously in other Arisaema species (Sasakawa, 1993(Sasakawa, , 1994a(Sasakawa, , 1994bVogel and Martens, 2000;Nishizawa et al., 2005;Barriault et al., 2009Barriault et al., , 2010Tanaka et al., 2013;Kakishima and Okuyama, 2018). Other than the two sciarid species, only a few insect individuals were found to visit to the inflorescence in A. cucullatum (Table 1). ...
Arisaema (Araceae) is one of the most species-rich plant groups in Japan, while 20 out of 64 Arisaema taxa are categorized as endangered species (CR or EN) in the Red List of Japan. Although we need to comprehend their reproductive biology to conserve these species, the knowledge regarding their pollination systems is still limited. In this study, we examined the potential pollinators of A. cucullatum, a critically endangered species endemic to Kinki Region of Japan. To this end, we collected the insects trapped inside the spathes of A. cucullatum as well as the two sympatric Arisaema species in the two native populations, and identified by both morphology and DNA barcoding based on mitochondrial cytochrome oxidase subunit I (COI). Sciaridae were the most abundant family in the trapped insects of A. cucullatum, and one sciarid species accounted for 78.9% of the collected insects. Meanwhile, the insect assemblages trapped inside the spathes of A. kishidae and A. yamatense that grow sympatrically with A. cucullatum were distinct from those of A. cucullatum. Accordingly, the difference in the pollinator assemblages may be important for reproductive isolation among them, although further observation in different populations is needed.
... Fly-pollinated trap flowers comparable to Ceropegia also occur in Aristolochia (Aristolochiaceae) and Arisaema (Araceae) species, and plants of these genera also attract their flies by specific scents ( Barriault et al., 2010;Sakai, 2002). Scents of these plants can be described as faint earthy, meaty (resembling carrion), and mushroom like (see also Trujillo and Sérsic, 2006;Johnson and Jürgens, 2010). ...
... America (Barriault et al., 2009(Barriault et al., , 2010, this study is probably the first report for the species of sect. Clavata. ...
The pollinator assemblages of a critically endangered aroid species endemic to Toku- noshima Island (Central Ryukyus, Japan), Arisaema heterocephalum subsp. majus, were studied. The insects trapped inside the spathes were collected in the native populations. Tentative identification of the collected insects was made using DNA barcoding based on mitochondrial cytochrome oxidase subunit I (COI). Sciaridae was the most abundant family collected, followed by Mycetophilidae, suggesting that A. heterocephalum subsp. majus depends its pollination largely on fungus gnats as reported in the other species of the genus Arisaema.
... Fungus gnats are usually considered as ineffective pollen carriers due to their small bodies, inconstancy and weak flight ability (Mesler et al., 1980;Proctor et al., 1996;Larson et al., 2001;Willmer, 2011). Nevertheless, pollination by fungus gnats is known to occur in eight angiosperm families: Orchidaceae, Liliaceae, Asparagaceae, Araceae, Aristolochiaceae, Polygonaceae, Apocynaceae and Saxifragaceae (Vogel, 1973;Jones, 1974;Ackerman and Mesler, 1979;Mesler et al., 1980;Sugawara, 1988;Fuller, 1994;Vogel and Martens, 2000;Goldblatt et al., 2004;Okuyama et al., 2008;Yamashiro et al., 2008;Barriault et al., 2010;Duque-Buitrago et al., 2014;Ollerton et al., 2017;Suetsugu and Sueyoshi, 2017). Some of these plants are believed to mimic fungal oviposition sites because pollinator eggs are often observed on the flowers (Vogel, 1978;Sugawara, 1988;Scanlen, 2006), whereas others employ sexual deception (Blanco and Barboza, 2005;Phillips et al., 2014), offer nectar reward (Ackerman and Mesler, 1979;Mesler et al., 1980;Goldblatt et al., 2004;Okuyama et al., 2004) or even sacrifice developing ovules to seed-feeding pollinator larvae to accomplish the pollination (Song et al., 2014). ...
• Background and aims: Pollination by fungus gnats (Mycetophilidae and Sciaridae) is uncommon, but is
nevertheless known to occur in 20 genera among eight angiosperm families. Because many fungus gnat-pollinated plants possess a dark red floral display, we hypothesized that fungus gnat pollination is more widespread among plants with similar floral display than currently known. We thus studied the pollination biology of flowers with dark red pigmentation in five families, focusing particularly on plants having small, flat, actinomorphic flowers with exposed nectaries and short stamens, because these floral characteristics mirror those of a known fungus gnat-pollinated genus (Mitella).
• Methods: We observed daytime and night-time floral visitors for a total of 194.5 h in Aucuba japonica
(Garryaceae), Euonymus spp. (Celastraceae), Disanthus cercidifolius (Hamamelidaceae), Micranthes fusca
(Saxifragaceae) and Streptopus streptopoides (Liliaceae). Visitors were categorized into functional groups, and a pollination importance index (PII) was calculated for each functional group based on visitation frequency, pollen load and behaviour on flowers.
•Key results: Fungus gnats were dominant among the 1762 insects observed (36–92 % depending on the plant
species) and were the most important pollinators among all plants studied (PII: 0.529–1). Fungus gnat visits
occurred during the daytime and, more frequently, at dusk. Most often, pollen grains became clumped on the
ventral side of the head and/or thorax as the short-proboscid fungus gnats foraged on nectar and came into contact with anthers located close to the flower base.
• Conclusions: Pollination by fungus gnats is probably more common than previously thought, especially in
habitats similar to those of the plants studied (moist forest understorey, streamside or subalpine meadow) where fungus gnats are abundant year-round. Our results further suggest that there may be a previously unnoticed association between fungus gnat pollination and dark red coloration, and a shared overall floral architecture among the plants studied.
... In contrast to mutual relationships, some plants achieve pollination by deception without offering a reward. For example, flowers of jack-in-the-pulpit (Arisaema spp., Araceae; Fig. 2.16) attract fungus gnats (Mycetophilidae) by emitting a mushroomlike odor ( Barriault et al. 2010). The perennial monocot is dioecious and has an erect inflorescence known as a spadix, which is covered by a spathe. ...
This book presents a comprehensive overview of our current understanding of mutualism origin, plant–pollinator specificity, mutualism stability, and reciprocal diversification. In particular, it focuses on the natural history and evolutionary history of the third example of obligate pollination mutualism, leafflower–leafflower moth association, which was discovered in the plant family Phyllanthaceae by the lead editor and then established by the editors and their coworkers as an ideal model system for studies of mutualism and the coevolutionary process. This work brings together the knowledge they have gained through an array of research conducted using different approaches, ranging from taxonomy, phylogenetics, ecology, and evolutionary biology to biogeography.
Richly illustrated with numerous original color photographs, the volume consists of 13 chapters and is divided into three main parts: natural history, ecology, and evolution. It begins by showcasing numerous examples of plant–animal interactions and their origins to guide readers in the world of leafflowers and their pollinators. The immense diversity of Phyllanthaceae and pollinator moths is then explored, and in the following 7 chapters mutualism is discussed from a range of ecological and evolutionary points of view. The final chapter presents a review of the evolution and variety of obligate pollination mutualisms.
This book offers researchers and students in the field of ecology, botany, evolutionary biology, pollination biology, entomology, and tropical biology fascinating insights into why such a costly pollination system has evolved and why Phyllanthaceae is so diverse despite the inconspicuousness of their flowers.
... From the Levant to the Caucasus, the black iris (Iris bismarckiana) and its relatives accomplish pollen transfer using 'shelter pollination', in which the fl owers lure mate-seeking male bees to rest within dark fl oral chambers [3]. Jack-in-the-pulpit (Arisaema triphyllum), painted by O'Keeffe in the woodlands of New York, engages in 'brood-site mimicry' of fungi, luring female fungus gnats into their fl oral chambers with the scent and appearance of mushrooms used by the gnats as larval hosts [4]. Adding to the sexual intrigue of this plant is its ability to change sex -'Jacks' become 'Jills' as growing plants acquire reserves needed to mature fruits. ...
... Even if insect visits were low and infrequent, insect cross-pollination might not be negligible in Calla because throughout the long anthesis (female (2-5 d) and male (5-9 d) phases), each inflorescence may be visited by numerous insects during both sexual phases (from Figure 2, the visitation rate is (over)estimated to 7 insect visits day per inflorescence), potentially explaining the high fructification rate observed. In summary, Calla is likely to be generalist from a pollination point of view with low visitation rates like Lysichiton camtschatcense or Arisaema triphyllum (Tanaka, 2004, Barriault et al., 2010. ...
... Fungus-gnat pollinated flowers are ideal subjects with which to test the landing-site function, because their petals are likely to be less involved in visual attraction than those of bee-or syrphid fly-pollinated flowers. Fungus-gnat pollination is found in many forest-floor herbs, such as Aristolochia, Heterotropa (Aristolochiaceae), Arisaema (Araceae), Scoliopus (Liliaceae), Tolmiea (Saxifragaceae), Corybas, Lenpanthus and Pterostylis (Orchidaceae), which generally have dull-coloured (greenish, and/or pale or dark red) tepals, and/or floral scents (Mesler, Ackerman & Lu 1980;Sugawara 1988;Goldblatt et al. 2004;Blanco & Barboza 2005;Barriault et al. 2010). Mitella species have inconspicuous and pinnately branched petals, which are typical floral features of fungus-gnat pollinated flowers found in dark forest-floor environments (Mesler, Ackerman & Lu 1980;Goldblatt et al. 2004;Okuyama, Kato & Murakami 2004;Woodcock et al. 2014). ...
1. Despite the well-known visual-attraction function of angiosperm petals, additional roles of these floral organs (e.g. the provision of landing-site platforms for pollinators) have rarely been examined. This is likely because most petals perform multiple functions, making it difficult to isolate the importance of landing sites in pollination success. 2. We investigated the landing-site function of dull-coloured pinnately branched petals in Mitella pauciflora flowers, which are predominantly pollinated by fungus gnats. We conducted a field experiment, in which the effects of experimental petal removal on pollinators' approach, landing and visit duration, and floral reproductive success were examined in naturally pollinated flowers. Accepted Article This article is protected by copyright. All rights reserved. 3. According to direct and time-lapse camera observations, petal removal did not influence pollinators' approach frequency or visit duration, but did significantly decrease their landings. Fruit set and pollen dispatch both significantly decreased with petal removal, indicating that petals promote female and male reproductive success in M. pauciflora by facilitating pollinator landing. 4. This demonstrates that inconspicuous petals primarily have a landing-site function rather than a visual-attraction function in M. pauciflora. Discriminating between diverse petal functions is a challenging problem, and new approaches are required to elucidate the functional features of angiosperm flowers.
... According to Chartier et al. (2014), Anthurium present a rewarding mutualism with bees, while Xanthosoma present a mating mutualism with beetles. Thrips have been reported visiting only Arisaema inlorescences in temperate ecosystems but their pollinator status is not clearly established (Gibernau 2003;Barriault et al. 2010). Hence, our indings in a tropical mountain forest are original, since thrips were the dominant component of lower-visitor assemblages of Araceae. ...
In the Araceae, pollination biology has been extensively evaluated in several genera mainly in lowland tropical areas. However, the influence of physical factors such as elevation or precipitation on plant/flower-visitor interactions at the community level remains challenging for this plant family, specifically in tropical mountain forests. The aim of this study was to analyze how the species diversity and abundance of flowering Araceae and their flower-visitor assemblages change along an elevation gradient and through time, in response to changes in mean monthly precipitation in a tropical mountain forest located in Jardín, Antioquia, Colombia. Eighteen flowering Araceae species and floral visitors belonging to seven orders were recorded. Flower-visitor diversity decreased with elevation. A trend of increasing flowering Araceae and flower-visitor abundance richness at intermediate levels of precipitation was observed. Diptera were dominant in the lower part and Thysanoptera were dominant in the upper part of the gradient. The pattern of plant species distribution along the elevation and the amount of precipitation influenced the availability of flower resources, and, as a consequence, affected the spatial and temporal composition of flower-visitor assemblages. Local strategies for the conservation of the diversity of insect flower-visitors and their interactions should be focused on the implementation of agricultural practices that reduce the use of pesticides within adjacent commercial plantations and the avoidance of illegal clearings, maintaining unbroken elevational gradients of forest, which is the only way to protect the flowering resources for anthophilous insects. At the same time, continuous forest promotes the maintenance of macro and microclimatic conditions, preserving the stability of insect populations and diversity amongst several functional groups.
... Lack & Diaz 1991, Albre et al. 2003, Diaz & Kite 2006. Species of Arisaema attract fungus gnats (Mycetophilidae and Sciaridae), which are released in the few monoecious species, but die inside the female inflorescences of the dioecious ones, after pollen deposition on stigmas (Vogel & Martens 2000, Barriault et al. 2010. Anthurium and Spathiphyllum species are known to have several different pollination systems, among which are some pollinated by euglossine bees (Williams & Dressler 1976, Croat 1980. ...
An updated description of the pollination and reproductive biology of basal angiosperms is given to
show their principal associations with pollinating agents. The review considers members of the
ANITA grade, as well as some basal monocots, the magnoliids, Chloranthaceae and Ceratophyllaceae.
Morphological, physiological and behavioral characteristics of flowers and their pollinating insects
are evaluated. Based on current evidence, early-divergent angiosperms were and are pollination generalists,
even so there has been early specialization for either flies, beetles, thrips or bees. Although
there are many tendencies for development from generalist flowers to specialist ones, there are also
reversals with the development from specialist flowers to generalist ones. The earliest specialization
seems to be fly pollination. Adaptations to more recently evolved insect groups, such as scarab beetles
or perfume-collecting euglossine bees, demonstrate that several basal angiosperm lines were flexible
enough to radiate into modern ecological niches.
... Where, flowers mimic female structures and chemical pheromones of certain insects (Singer et al. 2004;Blanco & Barboza 2005), and are pollinated by male insects seeking a mate (Dressler 1981;Williams & Whitten 1983;Singer 2002). The emission of fragrances that resemble the insect sexual pheromones for reproduction is an important factor associated with the mimicry, including mating or oviposition sites (Albores-Ortiz & Sosa 2006; Barbosa et al. 2009;Barriault et al. 2010;Endara et al. 2010Peakall et al. 2010. ...
Contemporary patterns of plant biodiversity result from the ecological and evolutionary processes generated by species interactions. Understanding these interactions is key for effective biodiversity conservation at the species and the ecosystem level. Orchid species often have highly specialised pollinator interactions, and the preservation of these is critical for in situ orchid conservation. The majority of orchid species occur in tropical regions, and information regarding their interactions is limited. We present data on pollinator identities, pollination mechanisms and flowering phenology of the Colombian endemic orchid, Pleurothallis marthae. We evaluated the mechanisms of attraction, the presence of osmophores, and the reproductive system of the species. Pleurothallis marthae is self-compatible with nocturnal anthesis pollinated by Mycetophila sp. (Mycetophilidae), probably attracted by a string fungus like smell liberated by the flower and Bradysia sp. (Sciaridae) that feed on nectar in the labellum. Osmophores and nectaries were detected in the epidermis of the sepals and petals. We present new evidence that the genus Pleurothallis is adapted to Diptera pollination. Our study indicates that the pollination mechanism of P. marthae is based on the nocturnal attraction of two species of fungus gnats, probably combining food attraction and brood place deception.
... Hence Dieffenbachia seguine does not follow the size advantage model in terms of the variations of flower numbers. This inflorescence feminization has been shown to exist in some aroid species such Arum italicum, A. cylindraceum or Arisaema triphyllum Barriault et al., 2010;Revel et al., 2012), but not in Arum maculatum or Helicodiceros muscivorus (Chartier & Gibernau, 2009;Gibernau & Seymour 2014). But when considering the weight of the flowers, the result is different. ...
The reproductive ecology of two species of Dieffenbachia (D. seguine [Jacq.] Schott and D. paludicola N.E. Br. ex Gleason) was studied at the Nouragues field station research in French Guiana. As in other known Dieffenbachia, the two studied species presented the classical cyclocephaline (dynastine scarab beetle) pollination system: Nocturnal anthesis with a strong odor, protogynous and short anthesis over 2 (3) days, female flowers being receptive on the first night and pollen being released on the second night. Inflorescences of D. seguine were visited by two species of scarab beetles (Cyclocephalini, Dynastinae): the dark brown Cyclocephala rustica and the black Erioscelis proba; while Inflorescences of D. paludicola were only visited by Erioscelis proba. Scarab beetles were efficient pollinators resulting in a high reproductive success even if some self-pollination can occur. Original data were gathered on flower and fruit predation leading to pollen and seed loss but their effect of the reproductive success still needs to be quantified.
... Plants are believed to adapt to their most common or efficient pollinator, in order to increase their reproductive success . Whatever the degree of specificity, a few and stable proportion of "error" in pollinator attraction may constitute an adaptive advantage in the case were environmental perturbations lead to a decrease of the main pollinator , Barriault 2010). ...
... Where, flowers mimic female structures and chemical pheromones of certain insects (Singer et al. 2004;Blanco & Barboza 2005), and are pollinated by male insects seeking a mate (Dressler 1981;Williams & Whitten 1983;Singer 2002). The emission of fragrances that resemble the insect sexual pheromones for reproduction is an important factor associated with the mimicry, including mating or oviposition sites (Albores-Ortiz & Sosa 2006; Barbosa et al. 2009;Barriault et al. 2010;Endara et al. 2010Peakall et al. 2010. ...
Contemporary patterns of plant biodiversity result from the ecological and evolutionary processes
generated by species interactions. Understanding these interactions is key for effective biodiversity conservation
at the species and the ecosystem level. Orchid species often have highly specialised pollinator interactions, and
the preservation of these is critical for in situ orchid conservation. The majority of orchid species occur in
tropical regions, and information regarding their interactions is limited. We present data on pollinator identities,
pollination mechanisms and flowering phenology of the Colombian endemic orchid, Pleurothallis marthae.
We evaluated the mechanisms of attraction, the presence of osmophores, and the reproductive system of
the species. Pleurothallis marthae is self-compatible with nocturnal anthesis pollinated by Mycetophila sp.
(Mycetophilidae), probably attracted by a string fungus like smell liberated by the flower and Bradysia sp.
(Sciaridae) that feed on nectar in the labellum. Osmophores and nectaries were detected in the epidermis of the
sepals and petals. We present new evidence that the genus Pleurothallis is adapted to Diptera pollination. Our
study indicates that the pollination mechanism of P. marthae is based on the nocturnal attraction of two species
of fungus gnats, probably combining food attraction and brood place deception.
The genus Arisaema contains approximately 180 species of deciduous or evergreen perennial herbs characterized by spathaceous inflorescence and one to several leaves that emerge from underground stems (Murata et al. 2018). Most Arisaema species are distributed in subtropical to cool temperate regions of Asia, although several are endemic to North America and tropical East Africa (Murata et al. 2018). The genus is particularly diverse in the Japanese Archipelago (Murata et al. 2018), where 53 species have been recorded.
It is an exciting time for the study of obligate pollination mutualisms. New mutualisms continue to be discovered, and information on individual systems is rapidly growing. Presently, there are at least seven plant lineages apart from Phyllanthaceae that contain plants pollinated by seed-parasitic insects (Fig. 13.1, Table 13.1). There is little doubt that more such lineages will be discovered, inasmuch as one or two new mutualisms continue to be uncovered each decade. The abundance and heterogeneity of documented cases of obligate pollination mutualism offer an unprecedented opportunity to examine key topics of broad ecological and evolutionary relevance. In this chapter, we review the basic natural history of the seven mutualisms known outside of Phyllanthaceae (Fig. 13.1, Table 13.1) and address the following questions that are critical to our understanding of obligate pollination mutualisms.1.
Why do plants specialize to seed-parasitic pollinators despite the high cost imposed by the seed-feeding pollinator larvae?
2.
How are mutualisms maintained despite the potential for selfish partners to disrupt the interaction?
3.
Is pollinator specificity reinforced, and if so, why?
4.
Do obligate pollination mutualisms drive the reciprocal diversification of plants and pollinators?
Euphorbiaceae, one of the major components of tropical flora worldwide, has long been considered a heterogeneous group (Webster 1994; Radcliffe-Smith 2001). Recent molecular phylogenetic analyses have clearly shown that Euphorbiaceae is nonmonophyletic, and consequently, Pandaceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae, Peraceae, and Centroplacaceae have been removed from it, although these families all belong to the order Malpighiales together with the updated Euphorbiaceae (Euphorbiaceae s. str.; Angiosperm Phylogeny Group III 2009). Thus, the small unisexual flowers and trilocular capsule that characterize the plants of the former Euphorbiaceae are plesiomorphic or convergent characters. For example, Rafflesiaceae, the family with the world’s largest, unisexual but unilocular flowers, is embedded in the former Euphorbiaceae (Davis et al. 2007); the clade sister to Rafflesiaceae is now Euphorbiaceae s. str., and the lineage sister to (Rafflesiaceae + Euphorbiaceae s. str.) is split as Peraceae (Fig. 4.1). Of the seven former Euphorbiaceae families, Euphorbiaceae s. str. and Phyllanthaceae are by far the largest, with the former containing about 300 genera and about 7500 species, and the latter 54 genera and about 2000 species (Table 4.1). Webster (1994) noted an important morphological feature of Phyllanthaceae that clearly distinguishes them from Euphorbiaceae s. str.; the former has two ovules per locule whereas the latter only has one ovule per locule.
Gracillariidae, the family to which Epicephala belongs, is a large group of miniature moths with roughly 100 recognized genera and 2000 recognized species (De Prins and De Prins 2016). They have a global distribution and are found almost everywhere there are plants, except for extremely harsh environments (e.g., the arctic). Gracillariidae is one of several lepidopteran families that consist almost entirely of leaf-mining species, although the leaf-mining habit itself is known to occur in about 30 moth families (Powell et al. 1999). In most gracillariid species, early-instar larvae have remarkably flat head capsules without chewing mandibles, and feed exclusively on cell sap within the nongreen, epidermal layer of the leaf (sap feeder; Fig. 5.1). Later-instar larvae then feed on the palisade layer and finally the spongy layer of the leaf with functional mandibles, and excrete granular frass (tissue feeder; Fig. 5.1). The larvae of the genus Phyllocnistis are exceptional in that they spend all their instars as sap feeders in the leaf epidermal layer. Gracillariid moths are thus unique among insects in that they undergo hypermetamorphosis, a process by which some larval instars become functionally and morphologically distinct from other instars.
Life on Earth originated in the sea; thus, land is a frontier for aquatic organisms. Although colonization of land by plants occurred in the Ordovician about 450 million years ago (ma; Field et al. 2015), aquatic microorganisms colonized land as early as 3500 mya (Beraldi-Campesi 2013). When aquatic microorganisms (including cyanobacteria) headed to land, they encountered adverse terrestrial conditions such as drought, extreme diurnal and seasonal temperature changes, low nutrient supply, and strong sunlight. These microorganisms are considered to have achieved terrestrialization by developing a tough, pigmented cell wall, an agglutinated colony structure, and a symbiotic lifestyle. Although modern lichens are associations of internal algae with external advanced fungi belonging to Ascomycetes and Basidiomycetes, colonylike associations of microorganisms, including basal algae and fungi, are thought to have colonized land before the Phanerozoic. Colonization of terrestrial habitats by photosynthesizing multicellular organisms occurred in a clade of green plants containing chlorophyll a and b (Delaux et al. 2012). The order Charales in the division Charophyte adapted to life in ephemeral freshwater pools, which frequently dry up. The body of the Charales is a monoploid gametophyte and comprises a main axis and lateral branchlets occurring in whorls on each node of the axis (Fig. 2.1). The reproductive organs consist of the nucleus (i.e., archegonia-producing ova) and globules (i.e., antheridia-producing flagellate sperm; Fig. 2.2). The sperm swim to the archegonium and fertilize the ovum. The zygote develops into an oospore, which is protected by its tough cell wall containing an unusually stable polymer, sporopollenin. The oospore can resist desiccation by remaining in a dormant state, and undergoes meiosis before germination of protonema. Another charophyte order, Coleochaetales, is a parenchymatous disclike alga that grows on substrata in waterfront habitats (Fig. 2.1). In the Coleochaete, plural meiospores are produced from a zygote, suggesting that embryos are protected and nourished in maternal tissue (Graham and Wilcox 2000).
Emily Baird and Gavin Taylor describe how you can make three-dimensional models of biological samples using x-ray micro-computed tomography.
What is the link between morphogenesis and phylogeny? This question was addressed by Haeckel, in the nineteenth century, when he formulated his controversial biogenetic law, stating that ontogeny is a short and rapid recapitulation of phylogeny (Haeckel, 1866). Since that time, many zoological and botanical studies discussing the idea of the usefulness of ontogeny in determining phylogeny have been published (e.g. Gould, 1977; Nelson, 1978). Ontogenetic features have been used, for example, to determine the phylogenetic relationships of Saururaceae and Piperaceae (Tucker et al., 1993). On the other hand, Mishler (1986) considered that an independent phylogeny should be established to adequately interpret the evolution of ontogenetic characters. In the present chapter, I will address this general question by using the floral morphogenesis of Araceae as a case study. The Araceae family comprises 117 genera and nearly 3300 species (Haigh et al., 2010). In recent phylogenies, Araceae belong to the Alismatales and are positioned as a sister group of the rest of the order (Stevens, 2001). The family includes eight subfamilies: Gymnostachydoideae, Orontioideae, Lemnoideae, Pothoideae, Monsteroideae, Lasioideae, Zamioculcadoideae and Aroideae, if we accept the recently proposed Zamioculcadoideae (Bogner and Hesse, 2005, Cusimano et al., 2011).
Over the last decade, the field of plant ecology has significantly developed and expanded, especially in research concerning the herb layer and ground vegetation of forests. This revised second edition accounts for that growth, presenting research that approaches the ecology of the herb layer of forests from a variety of disciplines and perspectives. The book synthesizes the research of top ecologists and biologists on herbaceous layer structure, composition, and dynamics of a variety of forest ecosystem types in eastern North America. The 2003 first edition of this book was praised for containing the most extensive listing of herb-layer literature in existence. This second edition brings this material up to date, revised to include current research and data. The book incorporates quantitative data to support analyses that was previously unavailable during the publication of the first edition. Also featured are six entirely new chapters, focused on the response of the herbaceous layer to a wide variety of natural and anthropogenic disturbances.
The aim of this paper is to review progress in phylogenetic research of Araceae during the period since publication of the first major molecular study by French et al. (1995). This, the first cladogram of the whole family inferred from DNA molecular data (Fig 9.1), resulting from research by J.C. French, M. Chung and Y. Hur, was based on chloroplast restriction site data (RFLPs or restriction fragment length polymorphisms). Their paper was highly significant and marked the beginning of the modern era of molecular phylogenetics of Araceae, nowadays based on DNA sequence data (e.g. Cabrera et al., 2008; Cusimano et al., 2011; Nauheimer et al., 2012b). It was innovative for Araceae in other ways as well, being the first family-scale cladistic analysis using computer algorithms and the first published cladogram for the family as a whole using genera as the ultimate operational taxonomic units (OTUs). No attempt has been made in the present chapter to discuss in detail the work of the previous 25 years during which many significant advances in systematic knowledge of the family were made, both in morphological taxonomy, but also in other fields such as cytology, palynology, phytochemistry, anatomy, fossil aroids, pollination biology and seedling morphology. Reviews of this literature have been provided by various authors, including Petersen (1989), Grayum (1990), Mayo et al. (1997) and Keating (2003), and Nicolson (1960) and Croat (1990) summarized classifications published in this earlier period.
Background/Question/Methods: In dioecious plant species (those with separate sexes), it is frequently observed that males flower earlier in the season than females. However, the generality of this phenomenon has not been quantified, and the reasons for it have not been fully explained. The conventional hypothesis is that female plants require more time for resource acquisition prior to reproduction. An alternate hypothesis is that sexual selection for access to high-quality ovules favors early-flowering males. First, to quantify the prevalence of male precedence (protandry), I compiled published data on flowering phenology of 29 dioecious taxa and compared standardized flowering curves of males and females. I also assembled data on the relationship between plant size and time of flowering onset. Then, to test the role of sexual selection in driving early male flowering, I constructed a model of the evolution of flowering time in a simulated dioecious plant population in which timing of flowering onset is determined by plant size in combination with a sex-linked flowering-time gene, and probability of seed maturation is determined by maternal size and age.
Results/Conclusions: Protandry (earlier flowering by males) is indeed the usual, though not universal, pattern in dioecious plants. In the majority of plant populations growing in natural field conditions (whether dioecious or hermaphrodite), early individuals tend to be larger, and, therefore, more fecund. This seasonal decline in size of potential mates causes males in simulated plant populations to evolve earlier flowering than females. Seasonal declines in resource availability within individual females (another commonly observed pattern) can also select for protandry, though this effect is weaker. Associations between large size and early phenology are widespread in plants and animals and are likely strong contributors to the prevalence of protandry in all taxa, but their importance seems to have been neglected by botanists. I conclude that sexual selection (specifically, male–male competition for access to high-quality ovules) likely plays a more important role in the evolution of flowering phenology than has previously been recognized.
Abstract It is frequently observed that males of dioecious plant species flower earlier in the season than females, although the generality of this pattern has not been quantified. One hypothesis for earlier male flowering is that females require more time for resource acquisition before reproduction; another is that selection for access to unfertilized ovules favors early-flowering males. Here I show that protandry is indeed the usual pattern in dioecious plants-males typically initiate flowering before females-and I propose a new hypothesis to explain this pattern. In many natural plant populations, individuals that begin flowering early are larger and-in the case of females or hermaphrodites-therefore more fecund. When this population-level seasonal decline in size is included in simulations of flowering time evolution in a dioecious plant, males evolve earlier flowering onset than females. Correlations between size (or condition) and reproductive phenology are widespread and likely contribute to the prevalence of protandry in both plants and animals, but their importance seems to have been overlooked by botanists. I suggest that sexual selection (specifically, male-male competition for access to high-quality ovules) may play a more important role in the evolution of flowering phenology than has previously been recognized.
Velloziaceae are a monocot family of five genera and c. 250 species (Mello-Silva, 2009). The family is now assigned to the order Pandanales, a small but morphologically diverse monocot order of five families: Cyclanthaceae, Pandanaceae, Stemonaceae (including Pentastemona Steenis), Triuridaceae and Velloziaceae (APG III, 2009). Within Velloziaceae, three genera occur in South America, of which two are endemic to Brazil (Barbacenia Vand., Vellozia Vand.) and the third is Andean (Barbaceniopsis L.B.Sm.). A fourth genus, Xerophyta Juss., grows in tropical Africa and the fifth, Acanthochlamys P.C.Kao, is endemic to China. In this chapter, we present new data on the anther, ovule and embryology of Velloziaceae in the context of ongoing related studies on floral evolution (e.g. Sajo et al., 2010) and the systematics of Pandanales (Furness and Rudall, 2006; Rudall and Bateman, 2006). Earlier studies on ovule and seed development and androecial features were used to delimit the genera of Velloziaceae (Menezes, 1976, 1980). Embryological features of Pandanales are currently poorly known, though some studies suggest that they are potentially systematically useful. For example, Cheah and Stone (1975) reported an unusual megagametophyte in some Pandanus species, in which nucellar nuclei migrate into the developing embryo sac, and tapetum type is unusually variable within Pandanales (Furness and Rudall, 2006).
Ceropegia species (Apocynaceae, Asclepiadoideae) have pitfall flowers and are pollinated by small flies through deception. It has been suggested that these flies are attracted by floral scent. However, the scent that is emitted from Ceropegia flowers has not been studied using headspace and gas chromatography mass spectrometry methods. It has also been unclear whether or not the flowers are mimics of particular models that attract flies. In the present study, we determined the composition as well as the spatial and temporal patterns of floral scent emitted by C. dolichophylla. Furthermore, we determined the pollinators in the native (China) and non-native (Germany) range of this species, and tested the capability of the floral scent to attract flies in the non-native range. Our data demonstrate that the floral scent, which is emitted from morning until evening, primarily from the tips of the corolla lobes, consists mainly of spiroacetals and aliphatic compounds. Milichiid flies were common visitors/pollinators in the native as well as non-native range, and were attracted by floral scent in bioassays performed in the non-native range. The compounds emitted by C. dolichophylla are unusual for flowers, but are well known from insect pheromones and occur in the glandular secretions of insects. The milichiid flies that visit and pollinate the flowers are kleptoparasites that feed on the prey (haemolymph or other secretions) of predatory arthropods, e.g. spiders, to which they are attracted by scent. Our data thus suggest that the floral scent of C. dolichophylla mimics the feeding sites of kleptoparasitic flies.
Premise of the study:
Many flowers are pollinated by potentially hungry insects, yet flowers also contain gametes and embryos which must be protected from predation. Microscopic calcium oxalate crystals in plant tissues have been proposed to protect against herbivory. Aroids, which have an unusual diversity of such crystals, also exhibit diverse pollination strategies. Many species have pollinators that do not feed while visiting the flowers, while other species, especially those pollinated by beetles, offer sterile staminodia as food rewards. We examined flowers of 21 aroid species with various pollination strategies to test the hypothesis that crystals protect vital gametes and embryos while allowing consumption of food bribes.
Methods:
Aroid inflorescences collected from the field or from greenhouse material were sectioned, cleared, and examined by bright field and polarization microscopy.
Key results:
All species examined, regardless of pollination strategy, arrayed crystals around unshed pollen and ovules. Less vital tissues, such as odoriferous appendages, had few crystals. Staminodia offered as food to beetle pollinators, however, differed greatly between species in their crystal contents. Some had minimal crystals; some had crystals in patterns suggesting they limit beetle feeding; still others had abundant crystals in no obvious pattern.
Conclusions:
The results are consistent with crystals protecting against insect predation of gametes and embryos. However, the role of crystals in food-bribe staminodia is unclear. They may limit and direct feeding by beetles in some species, while in others they might have no protective role.
Arisaema triphyllum is a gender-labile woodland herb in which sex expression is correlated with the abundance of stored resources. Larger plants are female or monoecious, smaller ones are male. Among females larger plants produce more flowers, fruits and seeds, and the rate of successful fruit and seed formation is greater for plants of greater ht and corm diam. Average seed wt is greater in larger plants. Seed number per fruit and average seed wt per fruit taper towards the top of the infructescence. Pollinator limitation and resource supply may both contribute to the regulation of yield; their effects can be interpreted sequentially.
Fungus gnats (Sciaridae and Mycetophilidae) are the principal pollinators of Listera cordata (L.) R. Br. (Orchidaceae) and Scoliopus bigelovii Torr. (Liliaceae) in coastal redwood forests of northern California. Although primitive diptera have generally been regarded as relatively inefficient pollinators, fruit set for both species is high: 61–78% for L. cordata (1976–1978) and 94.3–98.5% for S. bigelovii (1978–1979). Since probability of pollination per visit is low, we attribute high fruit set to the large number of gnats present at our study sites and corresponding large number of visits to flowers. The relative frequency of geitonogamous vs. xenogamous pollen flow was estimated by emasculating flowers and subsequently comparing pollen reception or fruit set of emasculates with controls. Results for both species indicate that interplant movement of pollen is common. Thus, fungus gnats can be effective pollen vectors, both in terms of overall fruit set and potential for cross-pollination.
A size-classified transition matrix model of the demography of Arisaema triphyllum, a perennial herb of temperate deciduous forest, was constructed from 3 yr of field data from two different sites. Arisaema is quite unusual in that individuals change sex in a pattern determined by their sizes: small individuals do not flower, larger individuals reproduce as males, and the largest as females. As plants increase or decrease in size, they also may change sex. Though demographic parameters varied with the site and with the year, some consistent patterns were seen Mortality rates ranged from 20 to 40%/yr for small, nonflowering plants, but decreased to much lower levels as plants reached reproductive size. For these large plants, mortality rates did not differ between sexes or among size-classes. Because rates of sexual reproduction were severely pollinator limited, levels of seed production were low (averaging 7 seeds@?female^-^1@?yr^-^1) and were not correlated with plant size. All plants engaged in clonal reproduction, regardless of their size. Transition matrices based on these data were compared statistically and were found to vary in time, as a result of year-to-year environmental variability. No population had achieved a stable size distribution. The classical method of calculating rate of increase, @l, was therefore rejected, and an alternative method incorporating temporal stochasticity substituted. A sensitivity analysis was performed to evaluate the effect on population growth of changing various life history parameters. Differences in rates of individual growth and of clonal reproduction were found to be largely responsible for the relative success of the two populations, one of which was increasing, the other declining. Arisaema's status as a climax-forest herb suggests that temporally varying transition matrices might be common even in environments traditionally regarded as @'stable.@' The prevalence of temporal variability has consequences both for the future direction of demographic theory and for the design and analysis of field studies.
Fungus gnats (Sciaridae and Mycetophilidae) are the principal pollinators of Listera cordata (L.) R. Br. (Orchidaceae) and Scoliopus bigelovii Torr. (Liliaceae) in coastal redwood forests of northern California. Although primitive diptera have generally been regarded as relatively inefficient pollinators, fruit set for both species is high: 61-78% for L. cordata (1976-1978) and 94.3-98.5% for S. bigelovii (1978-1979). Since probability of pollination per visit is low, we attribute high fruit set to the large number of gnats present at our study sites and corresponding large number of visits to flowers. The relative frequency of geitonogamous vs. xenogamous pollen flow was estimated by emasculating flowers and subsequently comparing pollen reception or fruit set of emasculates with controls. Results for both species indicate that interplant movement of pollen is common. Thus, fungus gnats can be effective pollen vectors, both in terms of overall fruit set and potential for cross-pollination.
Jatropha curcas is a pantro pical shrub. It is mono- ecious and protandrous. The ratio of male to female flowers is 29 : 1. Both flower sexes open synchro- nously. The sexual system facilitates geitono gamy and xenogamy. The flower visitors include bees, ants, thrips and flies; bees and flies effect geitonogamy and xeno- gamy, while ants and thrips effect only geitonogamy. The fruiting behaviour indicates that the plant might selectively eliminate the growing offspring, e specially geitonogamous fruit to allocate the resources available to the plant, mostly for xenogamous fruit. The ability to self -pollinate through geitonogamy is considered to be adaptive for J. curcas for colonization. MONOECISM, the production of separate male and female flowers on the same plant, is relatively a common s exual system among flowering plants. It is widely prevalent in the members of Euphorbiaceae. Bullock 1 reported monoecy in the members of Euphorbia, Phyllanthus, Argythamnia, Chamaesyce, Cnidoscolus and Croton, and dioecy in Jat- ropha species. Studies made on the pollination ecology of some Euphorbiaceae species in Visakh apatnam region show that Cicca acida, Emblica officinalis 2
The genus Dioscorea L. (Dioscoreaceae) is widely distributed throughout Africa and Asia and includes 500 to 650 species (Burkill 1960; Miège and Lyonga 1982), almost all of which are dioecious (Terauchi 1990). Pollination of species in this genus has received little attention because many of the cultivated species are propagated vegetatively from tubers. Insect visitors to flowers have been reported for two species, D. alata L. from India (Abraham and Nair 1990) and D. rotundata Poir. from Nigeria (Pitkin 1973; Segnou et al. 1992; Bournier 1994). Dioscorea japonica Thunb. is found throughout Japan, Korea, and China (Ohwi and Kitagawa 1983), but insect visitors to the flowers have not previously been reported. We investigated the insect visitors to flowers of D. japonica because the insect fauna associated with one species of a genus often differs from that associated with other species of the genus and may vary within a single species between different geographic regions (Kobayashi et al. 1999).
Introduction Dioecious plants offer an opportunity to examine the susceptibility of male vs. female reproductive function to herbivory and the differential effects of herbivory on each sexual morph (Watson 1995). Several recent studies have compared damage by herbivores and pathogens between genders in a number of dioecious species. However, results are contradictory, and reported patterns of herbivory and attack by pathogens vary from male-biased (e.g., Danell et al.. These results suggest that different mechanisms underlie gender-biased herbivory, depending on the system. Variations in the level of herbivory may be explained by differences in the palatability of target organs, such as chemical and physical defenses (Ågren 1987, Krischik & Denno 1990, Jing & Coley 1990) and nutritional qualities (e.g., Danell et al. 1985, Boecklen & Hoffman 1993) of leaves in male vs. female plants. Variation in phenology, especially leafing phenology, between genders of the host plant may concentrate the herbivores on a specific gender (Boecklen et al. 1990). As a more entomocentric explanation, morphological and functional differences in reproductive organs of dioecious plants may alter behaviors of herbivores and consequently lead to gender-biased herbivore density. For example, if adults of a herbivore utilize resources specific to a certain gender (e.g., pollen in male plants) and their larvae feed on leaves, the level of herbivory may be determined by feeding behavior in the adult stage, influenced by the reproductive functions of host plants. Abstract: We document through observational, correlative, and experimental studies evidence of sex-biased herbivory in the gender-labile, functionally dioecious plant, Jack-in-the-pulpit (Arisaema triphyllum). Jack-in-the-pulpit is the host for a specialist thrips, Heterothrips arisaemae. Second instar larvae of this thrips feed on the abaxial surface of Jack-in-the-pulpit leaves. We found that the level of herbivory by H. arisaemae was dependent on the gender expressed by plants. Significantly more damage was found on leaves of male plants than on leaves of female and asexual plants. Concentration of total phenols and nitrogen concentrations of leaf tissue did not explain different herbivory levels between genders. Spathe removal significantly reduced thrips damage, particularly in male plants. Our results suggests that adult feeding behavior and developmental phenologies of H. arisaemae are major factors in determining the observed patterns of male-biased herbivory in Jack-in-the-pulpit, rather than differences in levels in defensive chemicals or nutritional quality of leaf tissue. Heterothrips arisaemae was the most common insect in Jack-in-the-pulpit spathes, and male plants consistently contained significantly more adult thrips and thrips eggs than female flowers. Adult H. arisaemae carried more pollen than any than other insects and appeared to be the primary pollinator for Jack-in-the-pulpit at our study sites.
The pollination ecology of Arum italicum was studied in south-western France. This plant attracts olfactory dung-breeding flies through deceit. These insects are principally represented by Diptera, all belonging to saprophyte families. The volatilization of the odouriferous compounds, responsible for their attraction, is achieved through the production of heat by the appendix. The insects are trapped for 24 h in order to participate in both sexual phases of the protogynous inflorescence. The male flowers produce three heat events during flowering. These peaks of heat seem to be involved in the spathe movements, since they occur during the opening of the inflorescence and the liberation of the insects. The last male heat event may be linked with the liberation of pollen and its dispersion by stimulating trapped flies. According to their frequency and pollen-load, two Psychoda species appear to be the most efficient pollinators (P. crassipenis and P. pusilla). Nevertheless, each of the other attracted species could play a significant role under different spatio-temporal conditions. Experiments on self-pollination have shown that obligate cross-pollination is necessary for A. italicum to set seeds. Moreover, hand- and natural-pollinated plants showed similarly high abortion frequencies suggesting that seed set may be more constrained by resources rather than by pollination limitation. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 141, 205–214.
Evidence from recent research combined with an evaluation of the literature indicates thatArisaema is adapted to pollination by fungus gnats. It apparently shares this peculiarity among aroids only with the distantly related genus Arisarum. In addition to previous records from Japan and North America, systematic collections from nine Arisaema species during several expeditions in the Himalayas in Nepal showed that, although other less efficient insect groups may participate, the nematoceran families Mycetophilidae and Sciaridae are the principal pollen vectors; they best fit the pollination apparatus of the mainly (para)dioecious kettle trap blossoms. A total of 16 fungus gnat genera (both Mycetophilidae and Sciaridae) comprising 47 identified species (among them one genus and 22 species new to science) were observed. Usually members of more than one taxon are attracted per Arisaema species, and both sexes of gnats are involved. Visitor sets differed to some degree, depending on host species, area, and altitude; they do not, however, represent the complete fungus gnat fauna of a region. Relevant traits of growth habit and inflorescence structure are surveyed, and a detailed description of the pollination process is given, based on observations made on specimens cultivated in Europe, where vicariant fungus gnats are the pollinators. Attraction is deceptive by mimicking olfactory, visual and tactile cues characteristic of fungi where the gnat sexes normally meet and females oviposit. Odours produced by osmophores (the spadix appendage or spathe tip) play the most important part. The identified volatile compounds are mainly short-chained aliphatic aldehydes and alcohols. Flagelliform osmophores of some species, up to several dm long, reach the substrate and serve as conducting paths. Gnats become imprisoned when they inadvertently slide down the inner wall of the spathe tube. Its surface including the spadix is covered with ablative wax particles that inactivate the insects» tarsal pulvilli. This gliding device, in some species reinforced by zones of imbricate papillae, is irreversible, and no movements of floral parts allowing escape via the spathe mouth occur. Anthesis lasts several weeks. In the male spathes, victims are forced to wade through the pollen masses that have accumulated at the spathe's bottom; there they find an exit hole formed by local gaping of the spathe rims. The female spathes lack such an aperture. After potentially depositing pollen on the stigmas during their efforts to escape, gnats are detained until death. Except for an autogamous subspecies of A. flavum Schott, the few monoecious taxa of Arisaema are protogynous and possibly self-sterile. In monoecious A. tortuosum (Wall.)Schott, exit forming is delayed until pollen release. Three Arisarum species that are suspected to deviate in their floral syndrome are discussed along with araceous genera possessing similar one-way pitfall mechanisms.
Observations of insects visiting strongly protandrous flowers of Tolmiea menziesii (Saxifragaceae) show that Gnoriste megarrhina (Mycetophilidae), a large fungus gnat with a body ca. 7 mm long and a proboscis ca. 6.5 mm long, is the primary pollinator. Pollen is transferred to ventral portions of the gnat’s thorax while it probes for an unusually dilute nectar (8.3% to 12% sucrose equivalents) produced at the base of the floral tube. Grains are transferred to the two receptive stigmas on each pistil when it forages for nectar on a female phase flower. Pollen load analyses indicate that Tolmiea menziesii may be the only nectar source visited by the gnat while it is in bloom. While hoverflies (Syrphus spp.) and bumblebees (
Bombus spp.) also visit T. menziesii flowers, they do not forage for nectar and usually behave as pollen robbers visiting only male phase flowers after earlier visits by G. megarrhina. When the modes of floral presentation of T. menziesii are compared to other species pollinated primarily by micro-dipterans, and mycetophilids in particular, there appears to be a floral convergence in some spring-flowering, perennial herbs of moist, evergreen woodlands and forests. Analyses of open (gnat-pollinated) vs. hand-pollinated pistils show that manual cross-pollinations are slightly more successful than open pollinations. Fluorescence microscopy confirms two sites of self-recognition and rejection within the pistil: following controlled self-pollination experiments almost half of the pollen tubes produced either stop growing once they reach the top of the ovary and/or grow horizontally. The remaining tubes produced by self-pollination penetrate ovules but seed is never set. This double mode of self-recognition and rejection is similar to the one described for Heuchera micrantha var. diversifolia (Saxifragaceae) but may also confirm an earlier report of post-zygotic rejection made for Tolmiea.
Jack-in-the-pulpit, Arisaema triphyllum, is a perennial forest herb with the ability to change sex. At two sites in upstate New York, plant sex was correlated with plant size: males were smaller than females, nonflowering plants were smaller than males. Changes in plant size were accompanied by changes in sex. Sex change occurred quite frequently; at one site, 8% of nonflowering plants, 64% of males, and 63% of females changed their sex from one season to the next. The probability that a plant will change size and sex between years was altered by artificial defoliation and by the production of seeds, but was not affected by supplementing plants with nutrient fertilizer. Discriminant analysis indicated that several historical factors significantly affected plant sex: a model including the variables of current plant size, previous year's plant size, and previous year's sex was significantly better at predicting the current sex of individuals than was a model containing only current plant size. However, even the consideration of these three variables left up to a third of the plants misclassified with respect to gender. This analysis explains in part why plants at the two sites changed sex at different sizes, but it is likely that other factors-e.g. genetic differences-are involved.
The relationship between flowering time and reproductive success was investigated in the fly-pollinated, monoecious perennial
herb Arum maculatum L. (Araceae). This species temporarily traps its principle pollinator, a psychodid midge. Probability of fruit set was analysed
in relation to early, peak and late periods of the flowering phenology of four British populations between 1992 and 1997.
In three out of five cases, plants which flowered during early and late periods were significantly less likely to set fruit.
In addition, one population showed a similar relationship for percentage fruit set of individual inflorescences, and seeds
from peak-flowering plants were significantly heavier. There was no variation in number of female flowers per inflorescence
over the flowering season. Probability of fruit set appears to be mediated by the likelihood of trapping psychodid midges
that have previously been trapped and picked up pollen, an unlikely event during early and late flowering periods when few
inflorescences are open. The majority of plants in all populations produce only one inflorescence which means that timing
of flowering may be crucial to reproductive success. We interpret our findings as evidence that stabilising selection may
be acting on some populations and/or during some years. The ultimate cause, however, can be related to the very short (12–18 h)
female phase of each inflorescence, a phylogenetically conservative trait within the Araceae.
Androdioecy is a rare sexual system in nature, as predicted theoretically. Among the androecious species reported so far, Castilla elastica (Moraceae) is unique in that flowers are unisexual and staminate and pistillate flowers on cosexual plants are produced on different inflorescences. In addition, inflorescence structure of staminate inflorescences on males and staminate and pistillate inflorescences on cosexes is markedly different. Staminate inflorescences on males are bivalvate, while staminate inflorescences on cosexes are "fig-like" and urceolate. Pistillate inflorescences are discoidal. The difference may reflect different roles and requirements of the three inflorescences in pollination and protection from herbivores. This study reports thrips pollination of C. elastica, demonstrated by a pollinator introduction experiment. Thrips pollination of the species may be an example of mutualism originating from plant-herbivore interactions. In the Moraceae, shifts from simple herbivores on flowers to pollinators might have occurred many times, evolving into diverse pollination systems including the fig-fig wasp mutualism. The family, of which little is known about pollination systems, provides interesting and unique opportunities to study evolution of pollination systems and roles of nonpollinating associates of inflorescences.
Arisaema serratum possesses a pitfall-trap flower pollination system. However, little is known about the efficiency and pattern of pollen movement in A. serratum. Thus, the aims of this study are to (1) determine the paternal parents of the seeds and (2) elucidate pollen movement in a natural population. Paternity analysis using microsatellite markers was performed. Seeds were collected from a natural population of A. serratum in 2001 at Horigane, Japan. Small midges became trapped in female spathe tubes during the flowering period. We found that (1) seeds in a fruit were fertilized by multiple sires; (2) seeds sired by a paternal parent were either clumped, exclusively, or randomly distributed on the spadix, depending on the parent; (3) to a great extent, a few males contributed as sires; (4) distance from a female was not a factor in the inequality of reproductive success among males; (5) male reproductive success was not correlated with its size. We conclude that pollen carryover and the trap-flower pollination system are likely to result in multiple paternity and inequality in male success.
Deceit by resource mimicry has evolved as a pollination strategy in several plant species and is particularly elaborate in a plant known as dead-horse arum (Helicodiceros muscivorus; Araceae: Aroideae), which may fool flies into pollinating it by emitting a smell like a dead animal - an important oviposition resource for these insects. Here we confirm that the composition of volatiles from these flowers and from a rotting carcass is strikingly similar and show that the pollinators respond in the same way to chemicals from both sources. This remarkably complex mimicry must have evolved to exploit insects as unrewarded pollinators.
Arisaema triphyllum is a perennial herb whose sex and size often change from one growing season to the next. The proportional gain in reproductive success (RS) with size is much greater for female (carpellate) plants than it is for male (staminate) plants. I constructed RS-size curves for males and females; the curves intersect at a point t = 398 mm. According to theory derived from the size advantage model, t is the point below which the plants should be male and above which they should be female. Plots of size-frequency distributions of males and females show that below 380 mm the proportion of males is greater than the proportion of females, whereas above that point the proportion of females is greater than the proportion of males. Thus prediction and observed results are in very close conformity.
The breeding mechanism of Arisarum vulgare was studied both in the field and at the Botanical Garden of Tel Aviv University. Despite a general resemblance to Amm (both are pit-fall flowers), Arisarum differs in many important respects, which contribute to an entirely different type of breeding mechanism. The trap formed by the inflorescence chamber is not a compulsory one, and the temporarily captured insects escape very rapidly (in less than 60 minutes), as soon as they find the way out. Arisarum is self-incompatible, and the pollen germination may take place with the aid of insects which are devoid of pollen. They cause mechanical abrogation of self-incompatibility, without introducing foreign pollen into the chamber of the inflorescence. Considering the adverse climatic conditions during the winter - flowering and the slim prospects for crossing in its vegetatively propagated populations, such insect induced self - fertilization is an effective substitute for ordinary selfing which does not occur in Arisarum.
The species Theriophonum crenatum is a rare aroid collected from the open forest of Bilaspur (MP). It exhibited a crepuscular pollination syndrome and monophily towards a midge, Ceratopogon sp. The midges get trapped during the night hours, locked the following day, and released during the next day after having been dusted by the pollen released from the collar of male flowers. As many as 380 midges have been collected from a single blossom. The blossom is bisexual and reveals protogyny to avoid self-pollination.
Pollen movement in dioecious individuals of Arisaema triphyllum is by the insect, Heterothrips arisaemae (Thysanoptera). Females within 1 meter of a male plant produce significantly more seeds than ones more distant. Within the 1 meter distance, pollinator movements were random. Increasing the density of male plants does not increase seed production but may reduce pollen movement. Female plants do not compete for pollen.
Jack-in-the-pulpit, Arisaema triphyllum (L.) Schott., may bear monoecious or dioecious flowering stalks. Sex expression is not fixed, but may vary from season to season. Pistillate plants tended to be larger than staminate plants, with monoecious plants being intermediate in size, but no single morphometric measurement or combination of measurements separated these plants. Spathe and spadix colors varied independently and appear to be under genetic rather than environmental control
The Araceae are exceptionally diverse by nearly all phenetic criteria. The two most widely accepted infrafamilial classification systems, those of Engler and Hutchinson, emphasize vegetative and floral morphology, respectively, and are thus rather dissimilar. A more balanced scheme, in which all available phenetic data are considered, is attempted here. Character state polarities are inferred, and synapomorphies utilized to circumscribe infrafamilial taxa. Among the character states considered primitive for Araceae are: a rhizomatous or caulescent growth habit; simple, cordate leaf blades; parallel venation; a simple, green spathe; bisexual, perigoniate flowers; trilocular ovaries with axile placentation; anatropous, crassinucellate ovules; elongate stamens with longitudinal anther dehiscence; a base chromosome number of x = 7 or 14; and monosulcate, reticulate, binucleate pollen grains lacking starch. These and other conclusions have been employed in a character analysis of araceous subtaxa accepted a priori as natural. Significant features of the classification derived from a cladogram reflecting this analysis include: the merger of Engler's subfamilies Pothoideae and Monsteroideae, and the dissolution of his Calloideae; a drastic internal rearrangement of the Colocasioideae; and the recharacterization of the Aroideae, involving the transfer of several tribes to the Philodendroideae and the assimilation of the subfamily Pistioideae (Pistia stratiotes L.) and the tribe Thomsonieae (formerly included in subfamily Lasioideae). The following suprageneric nomenclatural novelties are created: Cercestideae Grayum, trib. nov.; Protarinae (Engl.) Grayum, stat. nov.; Remusatiinae Grayum, subtrib. nov.; Jasarinae Grayum, subtrib. nov.; and Scaphispathinae Grayum, subtrib. nov.
Evidence from recent research combined with an evaluation of the literature indicates thatArisaema is adapted to pollination by fungus gnats. It apparently shares this peculiarity among aroids only with the distantly related genus Arisarum. In addition to previous records from Japan and North America, systematic collections from nine Arisaema species during several expeditions in the Himalayas in Nepal showed that, although other less efficient insect groups may participate, the nematoceran families Mycetophilidae and Sciaridae are the principal pollen vectors; they best fit the pollination apparatus of the mainly (para)dioecious kettle trap blossoms. A total of 16 fungus gnat genera (both Mycetophilidae and Sciaridae) comprising 47 identified species (among them one genus and 22 species new to science) were observed. Usually members of more than one taxon are attracted per Arisaema species, and both sexes of gnats are involved. Visitor sets differed to some degree, depending on host species, area, and altitude; they do not, however, represent the complete fungus gnat fauna of a region. Relevant traits of growth habit and inflorescence structure are surveyed, and a detailed description of the pollination process is given, based on observations made on specimens cultivated in Europe, where vicariant fungus gnats are the pollinators. Attraction is deceptive by mimicking olfactory, visual and tactile cues characteristic of fungi where the gnat sexes normally meet and females oviposit. Odours produced by osmophores (the spadix appendage or spathe tip) play the most important part. The identified volatile compounds are mainly short-chained aliphatic aldehydes and alcohols. Flagelliform osmophores of some species, up to several dm long, reach the substrate and serve as conducting paths. Gnats become imprisoned when they inadvertently slide down the inner wall of the spathe tube. Its surface including the spadix is covered with ablative wax particles that inactivate the insects» tarsal pulvilli. This gliding device, in some species reinforced by zones of imbricate papillae, is irreversible, and no movements of floral parts allowing escape via the spathe mouth occur. Anthesis lasts several weeks. In the male spathes, victims are forced to wade through the pollen masses that have accumulated at the spathe's bottom; there they find an exit hole formed by local gaping of the spathe rims. The female spathes lack such an aperture. After potentially depositing pollen on the stigmas during their efforts to escape, gnats are detained until death. Except for an autogamous subspecies of A. flavum Schott, the few monoecious taxa of Arisaema are protogynous and possibly self-sterile. In monoecious A. tortuosum (Wall.)Schott, exit forming is delayed until pollen release. Three Arisarum species that are suspected to deviate in their floral syndrome are discussed along with araceous genera possessing similar one-way pitfall mechanisms.
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This is the first in a series of papers on the fungus gnats associated with the flowers of Arisaema spp. in Japan. It includes the records of three species of the genera Mycomya and Rymosia, and description of a new species, Exechia arisaemae. TANAKA (1990) observed a large number of sciarid-gnats had been dead on both staminate and pistillate flowers of Arisaema angustatum FRANCH. et SAVAT. It is stated that their response to flower smell was extremely high as compared with those of other insect groups. But, no species of the Mycetophilidae has hitherto been recorded. I have had a good chance to examine some specimens of the Mycetophilidae and Sciaridae collected from the spadices of Arisaema spp. at various localities in Japan. Of the four species of mycetophilid-gnats now reported, Exechia arisaemae is new to science. Species of the Sciaridae will be reported in the next part of this series. The holotype is deposited in the collection of the Entomological Laboratory, Kyoto Prefectural University, Shimogamo, Kyoto.
Data on aroid pollinators or inflorescence visitors were reviewed lately by Gibernau (2003), documenting the pollinators of 49 genera and about 125 species. This addendum adds information on 35 genera, of which 9 are newly documented, and about 60 species. In summary, we have actually some information on pollinators or inflorescence visitors on 58 genera and about 165 species. Such numbers are very still low in comparison of the family diversity (more than 110 genera and about 4,000 species). The pollination of entire groups of Araceae is still unknown. The knowledge on the pollination of each tribe is discussed. 2 KEY WORDS Araceae, Coleoptera, Diptera, Hymenoptera, Pollination DEDICATION I would like to dedicate this paper to Patricia Frank and Julius Boos.
Macrozamia macdonnellii (Zamiaceae) grows at a few isolated sites in central Australia. Male cones support large populations of a host-specific thrips, Cycadothrips albrechti n.sp. (Thysanoptera, Aeolothripidae). This insect breeds only in these male cones, from which the adults swarm in late afternoon as the temperature falls and humidity rises. A small sticky trap at one female cone caught 3844 adults on a single afternoon; large numbers of thrips were observed entering this cone. Each thrips carried an average of 15 pollen grains, and pollen delivery into the cone was thus estimated to average more than 5500 grains per ovule. No other potential pollinators were found on these cycads, and it is concluded that C. albrechti is the sole pollinator of M. macdonnellii. Since Cycadothrips constitutes a basal clade within the Thysanoptera, the possibility is considered that thrips were involved in pollen transfer before the radiation of flowering plants.
The size-sex relationship and sexual differences of sixArisaema species native to Japan were investigated. The size-sex relationship showed almost the same pattern in all species. When the plant was small in size, the sex expression was male, and sex expression changed from male to female as the plant grew larger. Male ratios decreased rapidly around a critical size, but this critical size differed from one species to another.
Sexual differences were detected in reproductive structures and behavior, although no difference was detected in vegetative structures. The stoutness, longevity and inner tissue of the scape showed remarkable differences between males and females, and this difference was represented most clearly as the size-weight relationship. Earlier initiation of flowering in males was also observed.
No difference was found in resource allocation to reproductive structures between male and female plants at the flowering stage. However, a broad variation in the amount of resource allocation to reproductive structures was found at the fruiting stage in female individuals, which was attributed to differences in the setting rate of mature fruits.
Jack-in-the-Pulpit (Arisaema triphyllum (L.) Torr.) is a perennial forest herb of southern Canada and the eastern United States. The flowering periods of male and female inflorescences in relation to the temperature of the inflorescence and the activity pattern of visiting insects were studied in one population in western Montreal Island (Quebec, Canada). The flowering period of A. triphyllum was long (20 d in male and female plants), which is unusual in temperate Aroideae. This floral trait could have evolved secondarily as an adaptation to increase pollination efficiency under highly variable weather conditions at high latitude. In male and female plants, no significant temperature increase of the appendix was recorded. The warming effect of sunlight during the day could be sufficient for the emission of the attractive odour. Two Dipteran families, the Mycetophilidae and the Cecidomyiidae, were the most frequent insect visitors of A. triphyllum. Our observations showed that odour production is linked with the pollination activity beginning with insect visits.
A new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) was discovered from inflorescences of Steudnera colocasiifolia K. Koch (Araceae) in Yunnan, China. The new species is described as Colocasiomyia steudnerae Takenaka and Toda, sp. nov., and we investigated the reproductive ecology of both the fly and the plant species. This fly species reproduces in the inflorescences/infructescences of the plant, and depends almost throughout its entire life cycle on the host plant. The fly species is the most abundant flower visitor for S. colocasiifolia and behaves intimately with the flowering events, suggesting that it is the unique and most efficient pollinator for the host plant. Bagging (insect-exclusion) treatment of inflorescences resulted in no fruits. These findings strongly suggest that intimate pollination mutualism has evolved between the fly and the host plant, as are known in other Colocasiomyia flies and Araceae plants. One notable feature of this system is that the new species almost monopolizes the host-plant inflorescence as a visitor, without any cohabiting Colocasiomyia species. In comparison to other cases where two Colocasiomyia species share the same inflorescence and infructescence of Araceae host plants for reproduction by separating their breeding niches microallopatrically between the staminate (upper male-flower) and the pistillate (lower female-flower) regions on the spadix, C. steudnerae exhibits a mixture of stamenicolous and pistillicolous breeding habits.
Abstract A projection matrix model was adopted to describe the population dynamics of Arisaema serratum (Thunb.) Schott. This method is most appropriate for describing a complex life history, such as size-specific determination of sex expression in Arisaema. Size classification was determined from both the life history stage and the pseudostem diameter at ground level, which was transformed into natural logarithms.
The calculated population growth rate based on averaged data from 1981 to 1986 was very close to unity. The survival rate was lowest at the seedling stage and gradually increased for larger size classes. But the survival rate was almost the same for the male stage and female stage irrespective of size classes.
Individuals in small size classes made greater contributions to the population growth rate (λ) if they were in the asexual stage than in male or female stages. Those individuals in intermediate size classes had greater effects on λ if they were in the male phase and those in large size classes had greater effects on λ if they were in the female stage.
Colocasiomyia, a moderate-sized genus in the subfamily Drosophilinae, comprises seventy (twenty-six described and forty-four undescribed) species. Several Colocasiomyia species have evolved intimate mutualisms with specific host plants, especially of the family Araceae: the flies depend throughout the entire life cycle, oviposition, larval growth, pupation, and adult feeding and mating, on inflorescences of their host plants, and in turn act as species-specific pollinators for their host plants. To understand the evolution of this mutualism between Colocasiomyia flies and their host plants, the phylogenetic relationships of this genus and some possibly related taxa are inferred from a cladistic analysis based on sixty-two characters of adult morphology. We conclude that Colocasiomyia is polyphyletic, with the C. arenga species group clearly separate. Colocasiomyia without the arenga group (Colocasiomyia proper) is sister to all other studied drosophilines, whereas the arenga group is relatively derived within the Drosophilinae. Within Colocasiomyia proper, four clades are recognized, three of which correspond to previously proposed species groups: the cristata, toshiokai and baechlii groups. The other clade, C. sp.1 aff. nepalensis+C. sp.2 aff. nepalensis, is defined as a new species group. Relationships amongst the four clades and three independent species (C. micheliae, C. gigantea and C. sp.K1) remain almost unresolved, except for a sister group relationship between the toshiokai and baechlii groups. The classification of species groups in Colocasiomyia is revised by erecting two new species groups (crassipes and zeylanica groups) in addition to the three known (baechlii, cristata and toshiokai) groups. Revision of the arenga group, which should be removed from Colocasiomyia, is left for future studies. The evolution of host plant selection in Colocasiomyia is discussed by mapping host plant taxa (families, subfamilies and tribes) on the phylogenetic tree deduced from the cladistic analysis. Cohabitation in the same host inflorescence by a pair of species with microallopatric niche separation on the spadix is hypothesized to have evolved independently at least more than twice in Colocasiomyia.
This paper reports thrips (Thysanoptera) cross-pollination in the primitive angiosperm, Popowia pisocarpa (Annonaceae), in lowland rain forest of Sarawak, Malaysia. Flowers of P. pisocarpa have a tiny pollination chamber (3–4 mm in depth) with the entrance almost closed by the disk-shaped stigmatic heads, allowing only small insects to enter. Experiments showed that thrips were effective pollinators and flowers ofP. pisocarpa were self-incompatible. Seed set was limited by pollen. Clumped adult trees had higher seed-set than more distant individuals (>5 m from nearest flowering neighbor), indicating limited inter-tree movement by thrips.
Data on aroid pollinators was first sum-marized by Grayum (1984) who docu-mented 35 genera and about 90 species. A second summary was published in 1997 in The Genera of Araceae (Mayo et al., 1997) with 38 genera and less than 100 species listed including data from Grayum (1986, 1990). This paper brings the reference list up to date since 1997, documenting the pollinators of 49 genera and about 125 species. These numbers are still very low in comparison with the diversity of the Ar-aceae family which contains 105 genera and about 3,300 species. Some questions on aroid pollination are developed in the discussion.
The 28 species of the genus Arum (Araceae) attract and temporarily trap insects (mainly flies, and beetles in a few cases) during a complex pollination process. At anthesis, the appendix of the inflorescence produces heat and emits a specific odour which attracts insects. The lured insects are trapped within the floral chamber when stigmas are receptive. They will be released about 24h later after pollen emission, ensuring pollen dissemination. Studies on the reproductive biology of the genus have shown some degree of variability in the pollination strategies: morphological variations, flowering and heating periods, odour types and the type of pollinating insects. Most of Arum species have never been studied in depth but data available from the literature indicate quite a high diversity of pollination strategy within this genus. Consequently, a general pollination model is not valid at the level of the whole genus. The origin of this diversity certainly results from the biogeographic history of the genus. The plants (i.e. species) have developed adaptations in response to different climatic, ecological and biotic (i.e. entomofauna) constraints (i.e. selective pressures) according to the various habitats occupied in the different regions of Europe and the Middle East. However, in the absence of phylogenetic data, it is actually impossible to determine how these different reproductive strategies have developed and evolved during the history of this genus.
Summary In central Corsica, Helicodiceros muscivorus (Schott ex. K. Koch) produces a protogynous inflorescence that resembles the anal area of a dead mammal and produces a foetid scent during the few hours after sunrise. Flies enter the floral chamber, pollinate the female florets and become trapped until the next morning, when pollen is shed from the male florets and the flies are released. The exposed appendix exhibits a strong, unimodal episode of thermogenesis associated with scent production, reaching a maximum of 30 °C at 15 °C ambient temperature. The male florets in the floral chamber are highly thermogenic throughout the second night and generally maintain stable floret temperatures of about 24 °C at ambient temperatures down to 13 °C. Maximum respiration rates of the appendix (0·45 µmol CO2 s−1 g−1) and the male florets (0·82 µmol s−1 g−1) may be the highest recorded for plant tissue. Thermogenesis of the appendix does not depend on ambient temperature, but that of the male florets increases with decreasing ambient temperature in most cases. However, the pattern of heat production by the males appears related more to time than to ambient temperature, hence the term ‘pseudo-thermoregulation’. The behaviour and thoracic temperatures of flies emerging from captivity suggests that male floral warming does not enhance their activity.
The first example of pollination by fungus gnats in the eudicots is reported. The genus Mitella (Saxifragales) is characteristically produces minute, inconspicuous, mostly dull-coloured flowers with linear, sometimes pinnately branched, petals. To understand the function of these characteristic flowers, we studied the pollination biology of four Mitella species with different floral traits and different sexual expression: dioecious M. acerina, gynodioecious M. furusei var. subramosa, and hermaphroditic M. stylosa var. makinoi and M. integripetala. Flower-bagging experiments showed that wind pollination did not occur in the dioecious and gynodioecious species. Two years of observations of flower visitors at six study sites in Japan revealed that the principal pollinators of all four Mitella were specific species of fungus gnats (Mycetophilidae), which landed on the flowers with their long spiny legs settling on the petals. Characteristically, numerous pollen grains were attached to the fungus gnats in specific locations on the body. Although, on average, 1.3–2.6 fungus gnats visited each inflorescence per day, the fruit set of both bisexual and female flowers exceeded 63%. These results suggest that fungus gnats are highly efficient pollinators of Mitella spp., and that Mitella flowers are morphologically adapted to pollination by fungus gnats. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144, 449–460.
The distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil subtropical convergence ecosystem were studied from demersal trawl surveys conducted along the continental shelf and upper slope from Cape Santa Marta Grande (28 °36′S) to Chui (34 °45′S) between 1981 and 1987. Trichiurus lepturus was more abundant at bottom water temperatures of over 16 °C and in the 40–120 m depth range. From late spring to fall, juveniles of 5–30 cm total length (TL) were found in coastal waters, subadults (TL 30–70 cm) mainly in inner shelf waters and adults (TL > 70 cm) in coastal, inner and outer shelf waters. Higher catches of subadults and adults were found associated with thermal fronts in the western boundary of the Subtropical Convergence or with a shelf break upwelling observed in summer. The standing stock in a 58 000 km2 shelf area estimated by the swept area method, ranged from 3066 t (±46% CI) in September 1981 to 37814 t (±22% CI) in January 1982. Correlation between occurrences of different size groups of cutlassfishes and other fishes caught in 250 bottom trawl hauls was analyzed. A positive correlation between cutlassfish and juvenile weakfish, Cynoscion guatucupa, was associated with similar spatial distribution but also indicated trophic competition.
We studied the relative role of inflorescence traits, flowering synchrony, and pollination context for infructescence and fruit initiation in two Spanish populations of Arum italicum, a species in which inflorescences are the pollination unit. In this species, a specialized inflorescence organ, the appendix, is important for pollinator attraction. However, the short floral longevity and the production of mostly one inflorescence per plant make its pollination potentially dependent on strong flowering synchrony and on external factors not controlled by the plant (the pollination context). The flowering period in both sites lasted >3 mo. Day-to-day variation in simultaneous antheses was high, and 11-50% of antheses occurred on days during which no pollen donor was present. Inflorescence traits, flowering synchrony, and between-plant distance all influenced infructescence and fruit initiation, but their relative importance differed between sites. In one large population, infructescence initiation was positively related to inflorescence traits; in a smaller population infructescence initiation increased with the number of donor inflorescences. In both sites, percentage of fruits initiated per infructescence was dependent on a combination of inflorescence traits, flowering synchrony, and between-plant distance. Plants producing 2-4 inflorescences had higher probability of infructescence initiation and overlapped their antheses with more plants than single-inflorescence ones.
Thesis (Ph. D.)--University of North Carolina, 1980. Includes bibliographical references (leaves [236]-247). Photocopy.
The Natural History of Pollination Pollen movement and reproduction in Arisaema triphyllum
- M C F Proctor
- P F Yeo
- A Lack
- Usa Rust
Proctor M.C.F., Yeo P.F., Lack A. (1996) The Natural History of Pollination. Timber Press, Portland, OR, USA. Rust R.W. (1980) Pollen movement and reproduction in Arisaema triphyllum. Bulletin of the Torrey Botanical Club, 107, 539–542.
Gibernau Pollination of Arisaema triphyllum
- Barriault
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Biological diversity
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Mound L.A. (1997) Biological diversity. In: Lewis T. (Ed.),
Thrips as Crop Pests. Institute of Arable Crops Research,
Harpenden, Hertfordshire, UK: 197-215.
Flowering period, thermogenesis and pattern of visiting insects in Arisaema triphyllum (Araceae) in Qué (Canada) Botany, in press The Demography of Jack-in-the-Pulpit, a Forest Perennial that Changes Sex The demography of Jack-in-the-Pulpit, a forest perennial that changes sex
- I Barriault
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- D Barabé
Barriault I., Gibernau M., Barabé D.. (2009) Flowering period, thermogenesis and pattern of visiting insects in Arisaema triphyllum (Araceae) in Qué (Canada). Botany, in press. Bierzychudek P. (1981) The Demography of Jack-in-the-Pulpit, a Forest Perennial that Changes Sex. Ph.D. thesis, Cornell University, New York, USA. Bierzychudek P. (1982) The demography of Jack-in-the-Pulpit, a forest perennial that changes sex. Ecological Monographs, 52, 335–351.
Systat for Windows Statistics, Version 11 Edition Overview Reproduc-tive ecology of a new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) and its host plant Steud-nera colocasiaefolia (Araceae) in Yunnan
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- J T Yin
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- M J Toda
Pollination of Arisaema triphyllum Barriault, Barabé, Cloutier & Gibernau Systat 8 (2004) Systat for Windows Statistics, Version 11 Edition Overview. Systat, Evanston, IL. Takenaka K., Yin J.T., Wen S.Y., Toda M.J. (2006) Reproduc-tive ecology of a new species of the genus Colocasiomyia de Meijere (Diptera: Drosophilidae) and its host plant Steud-nera colocasiaefolia (Araceae) in Yunnan, China. Entomologi-cal Science, 9, 79–91.
Biosystematics of the Arisaema Triphyllum Complex The University of North Carolina at Chapel Hill, A survey of the function of the lethal kettle traps of Arisaema (Araceae), with records of pollinating fungus gnats from Nepal
- M Treiber
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Treiber M.. (1980) Biosystematics of the Arisaema Triphyllum Complex. Ph.D. thesis, The University of North Carolina at Chapel Hill, NC, USA, 357pp. Vogel S., Marten J. (2000) A survey of the function of the lethal kettle traps of Arisaema (Araceae), with records of pollinating fungus gnats from Nepal. Botanical Journal of the Linnean Society, 133, 61–100.