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The genus Zamia (Zamiaceae: Cycadales) exhibits its greatest diversity in Colombia and is highly threatened by habitat loss, extraction for ornamental plant trade, and mining, among other factors. One of the most important considerations for the effective conservation of Zamia is its highly specialized reproductive biology. Despite the importance of pollination for the populations’ viability, no studies have examined the pollination process of cycads in Colombia. Herein, we describe the pollination process of Zamia incognita A. Lindstr. & Idárraga, in a natural population. Exclusion experiments were performed by selectively excluding wind, beetles, both, or neither, which demonstrated that Pharaxonotha beetles are effective pollinators of Zamia incognita and that wind does not play any role as pollen vector. By following beetles marked with fluorescent dyes and directly observing beetle movements on and into female cones and micropyles, we confirmed that Pharaxonotha sp. is the effective pollinator of Z. incognita . The beetles traveled a maximum dispersal distance from a male to female cone of nearly 22 m and a minimum distance of 5 m. We found Pharaxonotha beetles in male cones, where they complete their life cycle. Cones produce heat in a circadian pattern associated with the elongation of the cones and pollen shedding. The increase in cones’ temperature appears to play an important role in beetle attraction. We suggest that pollination droplets on the micropyles would be a reward to pollinators. We also discuss the relationship of this Zamia species with other insects, which have important consequences for the conservation of web interactions.

Two major lineages of beetles inhabit cycad cones in the New World: weevils (Curculionoidea) in the subtribe Allocorynina, including the genera Notorhopalotria Tang and O’Brien, Parallocorynus Voss, Protocorynus O’Brien and Tang and Rhopalotria Chevrolat, and beetles in the family Erotylidae, including the genus Pharaxonotha Reitter. Analysis of the 16S ribosomal RNA (rRNA) mitochondrial gene as well as cladistic analysis of morphological characters of the weevils indicate four major radiations, with a probable origin on the cycad genus Dioon Lindl. and comparatively recent host shifts onto Zamia L. Analysis of the 16S rRNA gene for erotylid beetles indicates that an undescribed genus restricted to New World Ceratozamia Brongn. is the most early-diverging clade, and this lineage is sister to a large radiation of the genus Pharaxonotha onto Zamia, with apparent host shifts onto Dioon and Ceratozamia. Analysis of beetles are in accord with current models of continental drift in the Caribbean basin, support some proposed species groupings of cycads, but not others, and suggest that pollinator type may impact population genetic structure in their host cycads.

Premise of research. The role of specialist insects in the pollination of cycads is well established, with wind playing little to no role. Questions remain for species within the Cycas rumphii complex that have dispersed via floating seeds to islands far from mainland ancestors. One such species, Cycas micronesica, resides in habitats on the island of Guam that are exposed to trade winds that enhance the potential for wind pollination. Methodology. We examined the distance and direction of horizontal pollen movement either from microstrobili or from experimentally released pollen relative to wind direction and velocity in several different Guam cycad habitats. Wind-dispersed pollen was also captured around megasporophylls and then examined relative to wind and distance from dehiscing microstrobili. Pivotal results. Wind velocity, trap direction, and trap distance from the pollen source were the most important factors affecting pollen capture. In habitats where C. micronesica grows in the deep understory with <0.08 m/s mean wind velocities, pollen capture was near zero even at 4 m from the pollen source. In understory habitats with higher wind velocities, downwind traps captured substantial pollen up to at least ∼8 m. In open habitats where wind velocities averaged >2 m/s, some downwind traps captured significant pollen even at 32 m but with a dramatic decrease after 8 or 16 m, and upwind traps captured little pollen. Pollen capture around megasporophylls was substantial for those up to the experimental limits of ∼6 m downwind from a dehiscing microstrobilus. Conclusions. These results, along with previous studies that verified specific insect associations with reproductive organs of C. micronesica, indicate ambophily but with a stronger role for wind as a pollen vector than in previous Cycas studies. However, wind as a vector is limited to open areas or forested habitats with some exposure to winds and is not found in deep understory habitats.

Cone traits (volatile components and thermogenesis) of three cycad species in the genus Macrozamia were examined for differences related to their specific insect pollinators, the weevil, Tranes spp., or the thrips, Cycadothrips chadwicki. Linalool (>80% of emissions) dominated cone volatile components of M. machinii (Tranes-pollinated) and beta-myrcene was a minor component (<9% of emissions). Volatiles of M. lucida and M. macleayi cones (Cycadothrips-pollinated) were dominated by beta-myrcene (up to 97% of emissions), but no linalool was detected. Pollinator movement into and out of cones coincided with cone thermogenesis and peak odor emission: around sunset for Tranes, and at mid-day for Cycadothrips. Female cone traits were similar to those of their conspecific male cones. Differences in cone traits between Macrozamia species may thus be responsible for conferring pollinator specificity in areas of sympatry.

Cycads in the Zamiaceae are well known for their host-specific insect pollination mutualisms. Pollination of Cycas in the sister family Cycadaceae is less well-documented, with beetle pollination possibly coexisting with a limited potential for wind pollination, a hypothesis we tested for C. ophiolitica in Central Queensland, Australia. Cones were associated with three species of beetle: an undescribed weevil (Curculionidae), Hapalips sp. (Erotylidae) and Ulomoides sp. (Tenebrionidae). Pollination-vector exclusion experiments compared the pollination success (quantified as % ovules pollinated per cone) of control cones against bagged or netted cones that excluded wind or insects respectively (n = 10 for all treatments). Insects do pollinate C. ophiolitica in the absence of wind, the median (first quartile-third quartile) pollination success of control plants being 83.7% (60.8–87.2%) while bagged cones, from which wind, but not insects, were excluded, pollinated at 52.9% (19.5–74.8%). For netted cones, (excluding insects but not wind), pollination fell to 12.6% (10.9–45.9%). Airborne pollen (as quantified by capture on a series of adhesive pollen traps) decreased rapidly with distance from male cones, potentially becoming ineffective for wind pollination at ~5 m. Airborne pollen load in the vicinity of female cones, and distance of females from neighbouring males, suggests wind pollination may occur sporadically, but only at high spatial densities. Although Cycas appears to be primarily insect pollinated, this limited potential for ambophily may be significant given the history of dispersal and pollinator host shifts among these cycads.

Zamia integrifolia L.f. (Cycadales), a threatened cycad native to Florida, depends on 2 native beetle species for pollination: Rhopalotria slossoni (Chevrolat; Coleoptera: Belidae) and Pharaxanotha floridana (Casey; Coleoptera: Erotylidae). Both insects are brood-site pollination mutualists, known to live and feed within the pollen (male) cone. However, for pollination to occur, beetles must also visit ovulate (female) cones, which have been assumed to offer no benefits to them as food or nurseries. We tested the potential for beetle pollinator use of ovulate cones by performing no-choice behavior and feeding trials for adults of both beetle species on both ovulate cones and pollen cones of Z. integrifolia. Rhopalotria slossoni beetles showed greater survival on ovulate cone tissues despite showing no significant difference in total tissue mass consumed between cone sexes. Conversely, P. floridana consumed more tissue mass from ovulate cone scales yet showed no difference in survivorship on ovulate vs. pollen cone scales. Although neither beetle species is found in large numbers on ovulate cones in the field, our laboratory study suggests that both species could potentially benefit from feeding on ovulate cone tissues, questioning the standing hypothesis that Z. integrifolia pollination occurs by deceit. Zamia integrifolia L. f. (Cycadales), una cicadácea nativa amenazada en la Florida, depende de 2 especies nativas de escarabajos para la polinización: Rhopalotria slossoni (Chevrolat; Coleoptera: Belidae) y Pharaxanotha floridana (Casey; Coleoptera: Erotylidae). Ambos insectos son mutualistas de la polinización del sitio de cría, y se sabe que viven y se alimentan dentro del cono de polen (macho). Sin embargo, para que ocurra la polinización, los escarabajos también deben visitar conos de ovulación (femeninos), que se supone que no les ofrecen ningún beneficio como alimento o vivero. Probamos el potencial para el uso de conos de ovulación por parte de escarabajos polinizadores, esto mediante la realización de pruebas de alimentación y comportamiento de no elección para adultos de ambas especies de escarabajos tanto en conos de ovulación como en conos de polen de Z. integrifolia. Los escarabajos Rhopalotria slossoni mostraron una mayor sobrevivencia en los tejidos del cono ovulado a pesar de no mostrar diferencias significativas en la masa total de tejido consumido entre los sexos del cono. Por el contrario, P. floridana consumió más masa de tejido de las escamas de los conos de ovulación, pero no mostró diferencias en la sobrevivencia en las escamas de los conos de ovulación frente a las de los conos de polen. Aunque ninguna de las especies de escarabajos se encuentra en grandes cantidades en los conos de ovulación en el campo, nuestro estudio de laboratorio sugiere que ambas especies podrían beneficiarse potencialmente al alimentarse de los tejidos de los conos de ovulación, lo que cuestiona la hipótesis actual de que la polinización de Z. integrifolia se produce por engaño.

Key message Complex protein-containing reproductive secretions are a conserved trait amongst all extant gymnosperms; the pollination drops of most groups include carbohydrate-modifying enzymes and defence proteins. Pollination drops are aqueous secretions that receive pollen and transport it to the ovule interior in gymnosperms (Coniferales, Cycadales, Ginkgoales, Gnetales). Proteins are well established as components of pollination drops in conifers (Coniferales) and Ephedra spp. (Gnetales), but it is unknown whether proteins are also present in the pollination drops of cycads (Cycadales), Ginkgo (Ginkgoales), Gnetum (Gnetales), or in the pollination drops produced by sterile ovules occurring on pollen plants in the Gnetales. We used liquid chromatography–tandem mass spectrometry followed by database-derived protein identification to conduct proteomic surveys of pollination drops collected from: Ceratozamia hildae , Zamia furfuracea and Cycas rumphii (Cycadales); Ginkgo biloba (Ginkgoales); Gnetum gnemon and Welwitschia mirabilis , including pollination drops from both microsporangiate and ovulate plants (Gnetales). We identified proteins in all samples: C. hildae (61), Z. furfuracea (40), C. rumphii (9), G. biloba (57), G. gnemon ovulate (17) and sterile ovules from microsporangiate plants (25) and W. mirabilis fertile ovules (1) and sterile ovules from microsporangiate plants (138). Proteins involved in defence and carbohydrate modification occurred in the drops of most groups, indicating conserved functions for proteins in pollination drops. Our study demonstrates that all extant gymnosperm groups produce complex reproductive secretions containing proteins, an ancient trait that likely contributed to the evolutionary success of seed plants.

There has been considerable uncertainty about the importance of wind vs. insects in cycad pollination, but recent studies in several cycad genera have indicated that these are pollinated primarily, if not exclusively, by insects. Stangeria represents an isolated southern African cycad lineage previously thought to be wind-pollinated. Unlike in most other cycads, there is no evidence of cone thermogenesis in STANGERIA: We found that the scent of both male and female Stangeria cones mimics that of fermented fruit, the main volatiles being esters of acetic acid, ketones, and aldehydes. We found a large variety of insect visitors on the cones, the most common ones being sap and rove beetles (Coleoptera: Nitidulidae, Staphylinidae) and fruit flies (Diptera: Drosophilidae). Of these, only sap beetles (Nitidulidae) were able to effect pollination under experimental conditions. Because sap beetles are also pollinators of Cycas and members of several ancient angiosperm families, their role in the pollination of Stangeria adds interesting details to the role this group of insects has played in the history of plant-pollinator interactions.

In this study, we report the observation of potential seed dispersers of the endemic to Mexico and narrowly distributed Ceratozamia norstogii (Zamiaceae). Camera traps were installed in front of two plants of Ceratozamia norstogii and cone phenology until their maturity and disintegration was determined. The female cone of Ceratozamia norstogii has a development of ten months, from the time it emerges until it disintegrates. We were able to identify three stages of cone development: 1) Pre-pollination phase, 2) Pollination phase and 3) Seed maturation phase. Our results support an animal-dispersal hypothesis in Ceratozamia . Three mammals [a mouse ( Pteromiscus sp.), a southern spotted skunk ( Spilogale angustifrons ) and a kinkajou ( Potus flavus )] were recorded biting, carrying or removing seeds of Ceratozamia norstogii . The camera traps recorded no evidence of birds or other mammals coming to the cones to feed. Thus, interaction of frugivores with seeds occurs at night. The most frequent visitor was the mouse, followed by the southern spotted skunk and the kinkajou. Significant differences (GLM, p< 0.05) in visitor frequency and time for interaction were found between species. We believe that the mouse is probably the most effective seed disperser for Ceratozamia norstogii . The results presented here have evolutionary implications that can be scaled to the entire genus Ceratozamia . Specifically, short-distance dispersal promotes allopatric speciation in this group of plants.

Background and AimsOntogenetic patterns of odour emissions and heating associated with plant reproductive structures may have profound effects on insect behaviour, and consequently on pollination. In some cycads, notably Macrozamia, temporal changes in emission of specific odour compounds and temperature have been interpreted as a ‘push–pull’ interaction in which pollinators are either attracted or repelled according to the concentration of the emitted volatiles. To establish which mechanisms occur in the large Encephalartos cycad clade, the temporal patterns of volatile emissions, heating and pollinator activity of cones of Encephalartos villosus in the Eastern Cape (EC) and KwaZulu Natal (KZN) of South Africa were investigated.Methods and Key ResultsGas chromatography–mass spectrometry (GC-MS) analyses of Encephalartos villosus cone volatiles showed that emissions, dominated by eucalyptol and 2-isopropyl-3-methoxypyrazine in EC populations and (3E)-1,3-octadiene and (3E,5Z)-1,3,5-octatriene in the KZN populations, varied across developmental stages but did not vary significantly on a daily cycle. Heating in male cones was higher at dehiscence than during pre- and post-dehiscence, and reached a maximum at about 1830 h when temperatures were between 7·0 and 12·0 °C above ambient. Daily heating of female cones was less pronounced and reached a maximum at about 1345 h when it was on average between 0·9 and 3·0 °C above ambient. Insect abundance on male cones was higher at dehiscence than at the other stages and significantly higher in the afternoon than in the morning and evening.ConclusionsThere are pronounced developmental changes in volatile emissions and heating in E. villosus cones, as well as strong daily changes in thermogenesis. Daily patterns of volatile emissions and pollinator abundance in E. villosus are different from those observed in some Macrozamia cycads and not consistent with the push–pull pattern as periods of peak odour emission do not coincide with mass exodus of insects from male cones.