Abstract: We review the effects of herbivory and other environmental factors on pollen performance in plants. We conclude that natural levels of variation in herbivory and other environmental factors during pollen development are often sufficient to cause significant differences in pollen performance, and that the differences in pollen performance are likely to be caused by differences in the provisioning of pollen grains. From an evolutionary perspective, we discuss how pollen and ovule provisioning may be negatively genetically correlated and how this would maintain genetic variation for pollen performance within populations. Furthermore, the highly plastic nature of pollen performance provides the potential for genotypes to respond differently to environmental variation (genotype–environment interactions), which would also promote the maintenance of genetic variation in pollen performance.

Abstract: Preface List of abbreviations List of DNA clones, genes, protein products and mutants 1. Reproductive biology of angiosperms - retrospects and prospect Part I. Gametogenesis: 2. Anther developmental biology 3. Pollen development and maturation 4. Gene expression during pollen development 5. Pollen abortion and male sterility 6. Megasporogenesis and megagametogenesis Part II. Pollination and Fertilization: 7. Stigma, style and pollen-pistil interactions 8. Invitro pollen germination and pollen tube growth 9. Developmental biology of incompatibility 10. Molecular biology of self-incompatibility 11. Fertilization - the beginning of sporophytic growth Part III. Zygotic Embryogenesis: 12. Developmental biology of the endosperm 13. Embryogenesis and physiology of growth of embryos 14. Genetic and molecular aspects of embryogenesis 15. Storage protein synthesis in developing embryos Part IV. Adventive Embryogenesis: 16. Somatic embryogenesis 17. Embryonic development of pollen grains 18. Genetic transformation of embryos References Index.

Abstract: In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube’s journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the haploid female gametophyte or the diploid sporophytic cells. In an effort to distinguish genetically between these two possibilities, we have used a reciprocal chromosomal translocation to generate flowers wherein approximately half the ovules do not contain a functional female gametophyte but all ovules contain genotypically normal sporophytic cells. In these flowers, pollen tubes are guided to the normal but not to the abnormal female gametophytes. These results strongly suggest that the female gametophyte is responsible for pollen tube guidance, but leave open the possibility that the gametophyte may accomplish this indirectly through its influence on some sporophytic cells. SUMMARY

Abstract: In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. Here we describe four mutant alleles of TETRASPORE (TES), a gene essential for microsporocyte cytokinesis in Arabidopsis thaliana. Following failure of male meiotic cytokinesis in tes mutants, all four microspore nuclei remain within the same cytoplasm, with some completing their developmental programmes to form functional pollen nuclei. Both of the mitotic divisions seen in normal pollen development take place in tes mutants, including the asymmetric division required for the differentiation of gametes; some tes grains perform multiple asymmetric divisions in the same cytoplasm. tes pollen shows a variety of abnormalities subsequent to the cytokinetic defect, including fusion of nuclei, formation of ectopic internal walls, and disruptions to external wall patterning. In addition, ovules fertilized by tes pollen often abort, possibly because of excess paternal genomes in the endosperm. Thus tes mutants not only reveal a gene specific to male meiosis, but aid investigation of a wide range of processes in pollen development and function.

Abstract: In vegetative organs of plants, the metabolic switch from respiration to fermentation is dictated by oxygen availability The two genes dedicated to ethanolic fermentation, pyruvate decarboxylase and alcohol dehydrogenase, are induced by oxygen deprivation and the gene products are active under oxygen stress In pollen, these two genes are expressed in a stage-specific manner and transcripts accumulate to high levels, irrespective of oxygen availability We have examined the expression pattern of pyruvate decarboxylase and alcohol dehydrogenase at the protein level in developing pollen and show that the active proteins are localized to the gametophytic tissue and begin to accumulate at microspore mitosis A flux through the ethanolic fermentation pathway could already be detected very early in pollen development, occurring in all stages from premeiotic buds to mature pollen This flux was primarily controlled not by oxygen availability, but rather by sugar supply At a high rate of sugar metabolism, respiration and fermentation took place concurrently in developing and germinating pollen We propose that aerobic fermentation provides a shunt from pyruvate to acetyl-CoA to accommodate the increased demand for energy and biosynthetic intermediates during pollen development and germination A possible undesirable side-effect is the potential accumulation of toxic acetaldehyde Our results support a model for cms-T-type male sterility in maize, in which degeneration of the tapetum is caused by the toxic effects of acetaldehyde on mitochondria weakened by the presence of the URF13 protein

Abstract: Background: Birch tree pollen allergens are an important cause of early spring hay fever and allergic asthma. Pollen counts provide a guide for individuals with birch pollen allergy. However, birch pollen, because of its size, has a low probability of entering the lower airways to trigger asthma. Yet birch pollen allergens are known to be associated with respirable particles present in the atmosphere. Objective: We sought to determine the concentration of major allergen Bet v 1 in birch pollen and respirable particles in the atmosphere during the birch pollen season. Methods: We used a two-site monoclonal antibody–based assay (ELISA) to quantitate Bet v 1 in pollen extracts and high-volume air sampler filters collecting particles larger and smaller than 7.2 μm. Results: Bet v 1 (0.006 ng) is detectable per birch pollen grain, of which 0.004 ng is present in aqueous extracts (13.9% of soluble proteins). Atmospheric Bet v 1 concentrations are correlated with birch pollen counts. Heavy rainfall tended to wash out pollen and particles, indicated by a mean daily Bet v 1 concentration of 0.12 ng/m 3 (20 pollen equivalents), but light rainfall produced a dramatic increase in allergen-loaded respirable particles with Bet v 1 concentrations of 1.2 ng/m 3 (200 pollen equivalents). Conclusion: These results highlight the different environmental risk factors for hay fever and allergic asthma in patients sensitized to Bet v 1. Light rainfall causes an increase in respirable particles; hence, this is an important risk factor for asthma. (J Allergy Clin Immunol 1997;100:656-61.)

Abstract: The expression of foreign genes in pollen may pose potential problems in the field release of transgenic plants, since pollen represents a route whereby foreign genes and their products may escape into the wider environment. The possible risks posed by crosshybridization with wild relatives have been extensively explored, but problems that may arise due to the expression of foreign gene products in pollen have not been so widely studied. The activities of the CaMV 35S and nos promoters in pollen in populations of stably transformed plants and in transient expression analysis are described. These promoters are commonly used in all areas of plant molecular biology research and their expression patterns will be of interest to those involved in field release studies. The results show that both promoters had no detectable pollen activity in Arabidopsis, but both showed activity in tobacco pollen. The CaMV 35S-gus gene fusion showed heritable expression levels in tobacco pollen of up to a maximum of 64.6 pmol 4-ML) min"1 mg ~1 total protein, nos promoter activity in transgenic tobacco pollen was highly variable, with GUS activities ranging from undetectable levels up to 2561 pmol 4-MU min"1 mg~1 total protein within the transgenic population. Histochemical staining of anther sections from 10-12 mm buds revealed that the CaMV 35S promoter had some activity in the vascular bundle, stomium and tapetum, while GUS expression from the nos promoter in sporophytic tissues was confined entirely to the stomium.

Abstract: Records of the start of Birch pollen seasons monitored at three sites in the UK for periods of up to forty two years indicate a recent trend for the pollen seasons to begin earlier. This trend shows a close relationship to an increase in cumulative temperatures in the months of January, February and March recorded near each of the sites during the study period.

Abstract: Pollen, the male gametophyte of flowering plants, is a high energy material, which is collected by insects and stored as food reserve. Pollen has been used traditionally by humans for religious purposes and as supplementary food. Pollen is a concentrated, energy and vitamin rich food that in contemporary times is not only consumed as a dietary component, but also is used in alternative medical treatments. Pollen has potential imporiance as a supplementary and survival food, and for conditioning of athletes. Pollen has been used medically in prostatitis, bleeding stomach ulcers and some infectious diseases, although such use has been questioned by the medical profession. Pollen may also be used for treatment and prevention of the high-altitude-sickness syndrome. Because some individuals are allergic to pollen, and various pollen species contain specific allergens, individual sensitivities must be tested before pollen is used as a treatment or as a supplementary food.

Abstract: 1. We quantified pollen deposition on the stigma, pollen removal from the anthers and pollen losses in Echium vulgare, visited by workers of Bombus terrestris under controlled conditions. We used dye as a pollen analogue. Bumble-bees were trained to visit a sequence of non-emasculated flowers to estimate pollen carryover and to visit individual flowers to estimate pollen loss. 2. Carryover of pollen grains and dye particles between flowers was similar, which justifies using dye as a pollen analogue. On average 93·8% of the dye particles on the bee were carried over to the next flower. Only a small fraction of the pollen grains was deposited on the stigma (0·15%). A much larger fraction (6·1%) was lost in another way: passively during flight, through grooming or on floral parts other than the stigma. The bees removed 44% of the pollen grains from a fresh flower and 50·3% of this removed pollen adhered to the bee. 3. We predict that, using the parameters mentioned above, during a single visit to a newly opened flower, a bee collects an amount of pollen grains which will bring about 60% geitonogamous self-pollination in the next flower visited. The expected percentage of self-pollination is considerably less if bees visit flowers that have been visited before.

Abstract: Pollen from 13 species of gymnosperms and angiosperms was studied for soluble and insoluble carbohydrates at dispersal. Starch reserves stored during pollen development give rise to carbohydrates at maturity. Combinations of different types of carbohydrates in mature pollen may depend on the extent of starch hydrolysis. An inverse relationship was found between the extent of starch hydrolysis and sucrose content. If the starch was scarcely de-polymerized, the cytoplasm had very low levels of soluble sugars and none of the periodic acid-Schiff (PAS)-positive material as found in pollen not subject to high dehydration (Cucurbita pepo L., Zea mays L.). After total or partial starch hydrolysis, insoluble PAS-positive oligo/polysaccharides were found in the cytoplasm associated with much soluble sugar, and the pollen grains were dehydrated at dispersal as in Typha latifolia L., Chamaerops humilis L., Trachycarpus excelsa Wendl., and other specimens. Intermediate levels of starch and soluble sugars, together with cytoplasmic PAS-positive material, characterized species with dehydrated pollen such as Pinus halepensis Miller. Carbohydrates may be related to pollen longevity, which largely depends on the abundance of sucrose, which is known to protect membrane integrity. The relationship between PAS-positive material and pollen viability is unclear at present.

Abstract: Silene alba is an insect-pollinated weedy plant that is distributed into numerous ephemeral roadside patches in the study area in southwestern Virginia. Gene flow in S. alba arise as a consequence of the movement of two life stages, seed, and pollen. In an effort to evaluate the relative contributions of seed and pollen movement to total gene flow, genetic structure was estimated from among-population allele frequency variation using allozymes, the product of nuclear genes that can move in either seeds or pollen, and chloroplast DNA (cpDNA), which if maternally inherited can move only in seeds. Genetic structure was evaluated at three spatial scales--among collections separated by kilometers, tens of meters, and meters. Among-population allele frequency variation was much greater in cpDNA than in allozymes at all spatial scales. The ratio of pollen to seed movement was estimated from these data to range from 3.4 at the largest spatial scale to 124.0 at the finest scale. The broader application of maternally inherited genetic markers to questions in plant population biology is also discussed.

Abstract: Reproduction and longevity of the anthocorid predators Orius laevigatus (Fieber) and Orius albidipennis (Reuter) (Heteroptera: Anthocoridae) were studied under controlled conditions in the laboratory. Three different diets were tested: eggs of the Mediterranean flour moth. Ephestia kuehniella Zeller, E. kuehniella eggs plus pollen, and pollen only. Small rooted plants of Spanish pepper (Capsicum annuum L. cv. ‘Creta’, long red) served as oviposition substrate and moisture source. In all treatments, total fecundity, oviposition period and female longevity of O. laevigatus were greater than that of O. albidipennis. When a diet of E. kuehniella eggs was supplemented with pollen, total fecundity of O. albidipennis was increased by about 40%. Female O. albidipennis fed only pollen laid five times less eggs than those fed flour moth eggs and pollen; also, longevity of females was shorter when only pollen was offered as food. Fecundity and longevity of O. laevigatus were not influenced when supplementing a diet of E. kuehniella eggs with pollen. Females of O. laevigatus receiving only pollen reduced egg production by about 60% but had a similar longevity as those receiving a diet including flour moth eggs. In either species, preoviposition period and egg hatch were not affected by diet. The ability of both anthocorids to use pollen as an alternative or additional food is discussed in relation to their practical use in integrated control programmes.

Abstract: We used spot checks of stigmatic pollen deposition and hand-pollination experiments to test whether fruit production in Cape wildflower populations is limited by pollen availability. Natural levels of stigmatic pollen deposition were very low (median = 30.0% of flowers) in populations of 33 orchid species. We found similarly low levels of fruit set (median = 32% of flowers per plant) in six Orchidaceae and four Amaryllidaceae species. Experimental hand pollination at the whole plant level caused significant increases in fruit production in 11 of the 12 study populations. These results indicate that pollen limitation of fruit set may occur frequently among some plant families in the Cape flora.

Abstract: This paper presents the results of pollen analyses from organic sediments of seven cores (299 spectra) in a mountainous area of the north-west Iberian peninsula. The pollen diagrams, supported by seven14C dates, are used to construct a regional pollen sequence covering the main stages of vegetation dynamics, from the last phases of the Late-glacial until the present. During the Late-glacial Interstadial an important development of cryophilous forests (Betula andPinus) was recorded, although various mesophilous and thermophilous tree elements were also present. The Younger Dryas, palynologically clearly defined, is characterized by an important reduction in tree pollen percentages and the expansion of steppe formations (Poaceae andArtemisia). At the beginning of the Holocene, there was an expansion ofQuercus and a spread of other trees, which combined to give a vegetation cover of varied composition but dominated by mixed deciduous forests. Such forest formations prevailed in these mountains until 3000 years ago, when successive deforestation phases are recorded at various times as a result of increased farming activity. The results are compared with data from other mountainous areas in the northern Iberian peninsula and southern France.

Abstract: Documenting the floral biology of species throughout the Rubiaceae family is of particular interest since heterostyly and dioecy may have evolved more than once in this large family. Unfortunately many species in several tropical regions remain unstudied. The purpose of this paper is to describe the floral biology, the nature of self-incompatibility, morph ratios, and fecundity in natural populations of Gaertnera vaginata, a small tree endemic to the island of La Reunion in the Indian Ocean. Measurements of floral characters in populations across the entire distribution of this species showed that G. vaginata exhibits a reciprocal stigma height and anther height dimorphism characteristic of a distylous species. Pollen grain size and corolla tube length are consistently greater in short-styled plants and long-styled plants produce more pollen per flower. Controlled pollinations in a natural population showed that 25% of the short-styled plants gave at least one fruit on intra- morph (illegitimate) pollination, whereas no long-styled plants set fruit on illegitimate pollination. In total, 19.4% of ille- gitimate pollinations produced fruit on short-styled plants. No self-pollination gave fruit on either morph and between-morph pollinations produced 92.2 and 92.8% for short and long-styled plants, respectively. Overall, short-styled plants were sig- nificantly more abundant than long-styled plants. Short-styled plants outnumbered long-styled plants in 16 of the 19 popu- lations. In three of these populations the morph ratio was significantly different from 1:1. In two natural populations, fruit set was significantly higher on long-styled plants, although the number of seeds per fruit was not significantly different between the two morphs. The possible effect of variation in the strength of heteromorphic incompatibility on observed variation in morph abundance and the possible causes for the variation in fruit set are discussed.

Abstract: Isozyme markers were used to characterize levels of diversity, genotypic structure and spatial genetic structure for the low-density tree species, Carapa procera (five adults per ha), within 300 ha of a continuous tropical rain forest stand Both seed and adult stages were investigated, a high level of genetic diversity being found in both Fixation indices showed excess homozygosity in seeds, and excess heterozygosity in adults, which might be caused by selection in favour of heterozygotes Autocorrelation analysis of the spatial distribution of genotypes revealed no significant pattern in adults or in seeds before dispersal, and there was a high variability in correlogram shapes among alleles This suggests that gene flow is extensive in C procera, probably mainly through long-distance pollen dispersal, as seed dispersal is expected to be rather limited in this species (maximum distances of about 50 m) No clear-cut spatial pattern was observed in pollen allele frequencies, which supports the hypothesis of extensive pollen flow This overall lack of structure is consistent with the data already available on the mating system of this predominantly outcrossing species

Abstract: More than 200 specimens of Limnobiophyllum scutatum(Dawson) Krassilov have been recovered from lacustrine claystones in the Paleocene Paskapoo Formation near Red Deer, Alberta. The plant was a floating, aquatic angiosperm with helically arranged, ovate leaves attached in small rosettes. Rosettes are interconnected by stolons and bear simple adventitious roots as well as larger branching roots that appear to have vascular tissue. Leaves are pubescent, aerenchymatous, with 12‐ 14 campylodromous primary veins that curve toward the apex, joining a fimbrial vein, often an apical notch. Staminate flowers with two, four-loculate stamens, are borne in the axils of second leaves. Anthers contain monoporate, globose, echinate pollen, 20‐25 mm in diameter. The pollen wall is 0.8 mm thick, with a homogeneous foot layer, granular to slightly columellate infratectal layer and an echinate tectum. Pollen most closely resembles the sporae dispersae genus Pandaniidites Elsik. The completeness of L. scutatum has allowed for its inclusion in a numerical cladistic analysis to resolve relationships among taxa of the Lemnaceae, Pistia, and selected genera of Araceae. Results of the analysis indicate that the Lemnaceae plus Pistia form a monophyletic group within the Araceae.

Abstract: Opuntia brunneogemmia andO. viridirubra occur sympatrically in the Serra do Sudeste, Rio Grande do Sul, Brazil. Their flowers have 450–600 thigmonastic stamens and provide large amounts of pollen and nectar for bees. Bees of 41 species were registered at the flowers ofO. brunneogemmia and 30 at the flowers ofO. viridirubra. Females of three oligolectic species are the only effective pollinators:Ptilothrix fructifera (Anthophoridae),Lithurgus rufiventris (Megachilidae), andCephalocolletes rugata (Colletidae). During their visits inOpuntia-flowers, bees touch the filaments and stimulate the movement of the stamens to the centre of the flower. At the end of this movement, the anthers are densely packed around the style. As a consequence the pollen is presented in an easily accessible upper layer of anthers and various, nearly inaccessible lower layers. The lower layers contain about 80% of the pollen reward. Only females of the three oligolectic pollinators exploit the pollen from the lower layers and reach the nectar furrow. Therefore, through their stamen movements,Opuntia flowers hide most of their pollen from flower visitors but favour effectively pollinating, oligolectic bees.

Abstract: Hybridization between two diploid (2n = 2x = 16) species ofBrassicaceae, Cardamine rivularis andC. amara, at Urnerboden, Central Switzerland, resulted in the rather unusual triploid hybridC. insueta (2n = 3x = 24), and later on in the amphiploidC. schulzii (2n = 6x = 48). The hybrid and the neopolyploid species colonized successfully some man-made biotopes. Plants ofC. insueta are mostly functional females with non-dehiscent anthers, but true hermaphrodite individuals with partly sterile pollen grains also occur within the population. Analyses of cpDNA and nuclear DNA permitted to establish the parentage of the hybrid: the maternal parent which contributed unreduced egg cells proved to beC. rivularis whereas the normally reduced pollen originated fromC. amara. The pronounced genetic variability inC. insueta revealed by isozyme and RAPD analyses, at variance with the polarized segregation, heterogamy and strong vegetative reproduction of the hybrid, is possibly influenced by recurrent formation ofC. insueta which party results from backcrosses betweenC. insueta andC. rivularis but may also proceed by other pathways. The amphiploidCardamine schulzii has normally developed anthers but its pollen is sometimes highly sterile. The surprisingly uniform genetic make-up of the new amphiploid species might be related to its possible monotopic origin and/or young phylogenetic age but should be further assessed. Site management seems to be very important to a further development of hybridogenous populations and their parent species. In conclusion, the evolution at Urnerboden is discussed in the context of the traditional concept of multiple plant origins.

Abstract: Palicourea padifolia is a distlous shrub visited primarily by hummingbirds and bees in mid-elevation rain forests in Costa Rica. At Las Cruces Biological Station, the population of P. padifolia is composed of equal numbers of pin and thrum plants and morphs are randomly distributed. Like the majority of distylous species, P. padifolia exhibits a self and intramorph-incompatible mating system. The analysis of stigmatic pollen loads obtained from emasculated flowers shows that pollen flow between floral morphs is disassortative, which supports the Darwinian hypothesis concerning the adaptive significance of heterostyly. Pins experience greater disassortative pollination than thrums. Pins also set more seed than thrums, suggesting that the higher frequency of compatible pollen deposited on pin stigmas results in greater fecundity; alternatively, greater seed set in pins could be due to the differential allocation of resources to male and female function between morphs. Overall, seed set for the Las Cruces popularion of P. padifolia is much lower than the potential maximum. Factors which could contribute to seed set limitation include the frequency and/or spatial pattern of pollinator visits, pollen availability, and resource availability.

Abstract: Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf. A. africana Pant and Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Playford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential p...

Abstract: A guild of 20 late spring- and early summer-flowering species ofIridaceae, Geraniaceae andOrchidaceae is pollinated partly or exclusively by the long-proboscid flyMoegistorhynchus longirostris (Nemestrinidae). This large-bodied fly, active in late spring and early summer, has mouthparts 40–70 (∓90) mm long and forages for nectar from a variety of species. These plants share a suite of convergent floral features including a straight or weakly curved floral tube usually 50–70 mm long but sometimes to 90 mm, relatively short petals or tepal lobes coloured white, cream or salmon with reddish nectar guides, and often violet or red anthers and pollen. Flowers of most species with these characteristics are zygomorphic with the stamens either arcuate (mostIridaceae) or declinate (Geraniaceae and someIridaceae). The flowers are odourless and typically secrete large amounts of nectar of relatively constant sugar concentration, mostly 24–29%, with a high sucrose:hexose ratio. Guild members utilize five separate sites of pollen deposition on the body of the fly, typically utilizing different deposition sites when two or more co-occur, indicating strong selection to aviod pollen contamination.M. longirostris is restricted to the west coast of southern Africa and at least 8 species appear to depend exclusively on the insect for pollination. The remaining species in the guild are pollinated by one or both of the long-proboscid fliesPhiloliche gulosa andP. rostrata (Tabanidae) over other parts of their range. Species and races pollinated entirely byM. longirostris have longer floral tubes which makes nectar unavailable to other insects, including other species of long-proboscid fly. The only insect with mouthparts long enough to forage effectively on these long-tubed flowers isM. longirostris and this fly must be considered a keystone species in the ecosystems in which it occurs.

Abstract: Insects whose larvae depend on developing seed are very common, but active pollination, meaning that the insect possesses specific structures and behaviors for the purpose of assuring pollination, is only known to have evolved twice in such insects, namely in yucca moths and in fig wasps. This rarity could be due to high cost of pollination, phylogenetic constraints, alternative life history shifts to reduce or avoid risk of seed nondevelopment, or ecological factors such as co-pollinators that can satiate pollen requirements and mask variation in pollinator effectiveness among ovipositing seed eaters. Ecological costs of being a pollinator were measured for a yucca moth species and were found to be low: active time allocated to pollen pickup and deposit was on average 4.1%, an average of 0.42% of female body mass was allocated to specific structures for pollen manipulation, and the average pollen load weighed <4% of moth body mass. These estimates suggest that ecological costs need not be a major obstacle to evolution of active pollination. In contrast, recent combined ecological–phylogenetic analyses for the yucca moth family suggest that the evolution of active pollination and transition to mutualism depended largely on preadaptations, and that few traits were truly novel. If general, active pollination would be predicted to be likely to evolve only in lineages with life histories that facilitate mutualism. Alternative outcomes to evolution of active pollination include delayed oviposition, detection of floral pollination status, egg placement that allows the larva to select a fruit, and modified egg dispersion strategies to balance the cost of pollination. The historical significance of these factors can be assessed only when mechanisms are documented in many lineages and analyzed in a phylogenetic framework. Active fungal inoculation among arthropods is ecologically analogous to active pollination, and offers a complement for comparative analyses. Specific structures for spore transport have evolved many times in at least three orders of insects, and several times in mites. The large number of independent lineages of active pollen and fungus dispersers jointly provide a platform for testing hypotheses about, e.g., the role of preadaptations in evolution of mutualism, reversals of mutualism, and the role of mutualism in diversification.