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Myrmecochory, or seed dispersal by ants, occurs widely in angiosperms, and particularly in temperate forest herbs in the northern Hemisphere and sclerophyll shrubs in Mediterranean-climate landscapes. The lipid-rich elaiosome on the seed provides nutrition to the ants; however, how the plant benefits from myrmecochory remains unclear. Here, we provide the first comprehensive analysis of the Euphorbiaceae species in the semi-arid Caatinga vegetation region of northeastern Brazil, and show that myrmecochory strongly associates with small plant stature, even after controlling for seed size. The association of myrmecochory with small stature suggests that the primary benefit to plants concerns distance of dispersal, which reduces parental and sibling competition.

In myrmecochory, the relocation of diaspores to ant nests may lead to the enhancement of plant fitness because ant nests and their middens are often richer in essential nutrients than surrounding areas. This idea is the basis of the nutrient-enrichment hypothesis (NEH), which suggests that nutrient enrichment may be a major selective influence in the evolution of myrmecochory. However, there is little evidence regarding whether the greater plant performance and fitness enhancement in ant nests is due to nutrient enrichment or other benefits of directed dispersal. Here, we present the results of a large-scale seed-sowing experiment that tests the NEH in the ant-dispersed perennial herb Helleborus foetidus, exploring geographical and inter-ant taxa variation. Experiments were conducted in three well-separated regions of the Iberian Peninsula, targeting the nests of major and minor local ant dispersers (nine ant species in total) and the soil beneath maternal plants as seed destinations. Seedling emergence, survival and early establishment rates, as well as variation in soil characteristics, were obtained for each seed destination at each region. Our results do not fully support the NEH in our study system. Instead, we found that the advantage of ant nest soil for establishment in H. foetidus was conditional. Differences in soil fertility and concomitant differences in seedling establishment between ant nests and beneath the canopy of maternal plants were observed in some regions and for some ant species, but not in others. Thus, the conditional outcomes arise from inconsistencies among regions, between stages of seedling regeneration and among ant species in the advantages of being dispersed to nests. Because variation in the guilds of ant dispersers of myrmecochore plants across their ranges is common, this study illustrates the need to consider geographic and inter-ant taxa variation for a complete evaluation of the NEH.

Mutualisms play a key part in ecological systems and drive the evolution of much of the world's biological diversity. Among them, myrmecochory, seed dispersal by ants, is a worldwide mechanism throughout many ecosystems. However, the classic representation of myrmechocory as a mutualism could be put into question if one of the two players did not garner a real advantage. A controlled diet experiment was conducted in which ants were given five diets (supplemented or not with elaiosomes). First, using an ant-seed mutualism system, the aim was to understand if elaiosome consumption could modify reproductive output and sex allocation. Second, nitrogen isotopic values were used as a nutrient tracer in the brood to estimate the consumption and selection of elaiosome in comparison to other diets. A significant difference was found in the production of pupae between some diets, but pupae production was not linked to the elaiosome supplementation. Repartitions between pupa type and the effect of the diets were also not significantly different. Moreover, the nitrogen isotopic values of pupae differed among diets but not pupa types. The mutualistic aspects of myrmechory remain unclear, especially when it comes to estimating the benefits to ants. It is clear that ants assimilate the elaiosome nutrients, but the effect of this assimilation on the reproductive output or sex allocation appears limited. Elaiosomes could provide a nutritional advantage under certain conditions when resources are scarce (qualitative or quantitative), but they are not nutritionally required, and thus represent a food source with no specific advantage to the ant.

The removal rates of fruits (the diaspore) were assessed in exclusion experiments in three shrubby species of Darwinia, endemic to the Sydney Basin of south-eastern Australia. There was a clear pattern of fruit removal in just a few days by small species of ants from the genera Iridomyrmex, Crematogaster and Pheidole. When only ants had access to fruits an average of 41% of fruits were removed, whereas when only vertebrates had access an average of 13% of fruits were removed. There was some variation in the number of fruits removed both between species and within species across study sites or annual seed crops. When ants had access to seeds this variation in removal amounted to 10–80% over 1–4 days. Uniquely in Darwinia, it is the old petals (which remain attached to the fruit) that are attractive to the ants, rather than a specific lipid body. This likely represents a case of successful ecological fitting by Darwinia to take advantage of the widespread presence of myrmecochory in the Australian flora.

Myrmecochory, or seed dispersal by ants, is a dispersal syndrome found among several thousand plant species occupying different ecosystems and geographical regions. Typically, ants benefit from consuming a lipid-rich appendage on the seed and in return provide seed dispersal service to the plant. Several hypotheses have been proposed to explain the selective advantage for plants resulting from myrmecochory, including directed dispersal, dispersal for distance and escape from seed predators. I contrast the evidence available in the literature for these hypotheses and distinguish the studies on the basis of ecosystem and plant growth forms. The predator-avoidance and the distance dispersal hypotheses were supported in most studies that addressed them, and the directed dispersal hypothesis was supported in about half of the studies that tested it. Multiple hypotheses were supported in most studies that tested more than one hypothesis, suggesting that the various selective advantages conferred from myrmecochory are seldom exclusive. I also review evidence for the hypothesis that plants have evolved adaptations both for selecting seed dispersers and for manipulating the behavior of those dispersers. Based on this evidence, I argue that focusing future research on the evolution of partner choice by myrmecochores and its effects on the overall plant fitness will be more fruitful than putting an emphasis on classifying the selective advantage to plants into distinct categories and test for their existence separately.

Fremontodendron decumbensgrows in a single county in central California, USA. Prior research showed that its elaiosome-bearing seeds are dispersed by the harvester ant Messor andrei. I tested several hypotheses regarding the positive role of ant-mediated dispersal to F. decumbens: (1) Does ant-mediated seed dispersal facilitate seed escape from rodent predation?; (2) Does ant processing of seeds stimulate germination?; (3) Are ant middens more suitable microsites for seed or seedling survival in unburned chaparral areas?; and (4) Do survival benefits of dispersal occur post-fire in the form of differences in seedling survival probabilities and, if so, why? Results of tests of each hypothesis were: (1) similar percentages of seeds placed on ant middens and under F. decumbens shrub canopies were destroyed by rodents, but seeds from which elaiosomes had been removed were more likely to escape rodent predation; (2) seeds processed by ants did not germinate more readily than seeds removed directly from shrub branches; (3) seedling predation was a major cause of mortality in unburned chaparral on both ant middens and under shrubs, and overall seedling survival did not differ between the two microsites; (4) post-burn seedling survival was significantly greater for seedlings dispersed away from F. decumbens shrub canopies, because dispersed seedlings were both less likely to be killed by predators and more likely to be growing in a gap created by the fire-caused death of an established shrub. I concluded that the major ecological benefit toF. decumbens of ant-mediated seed dispersal was elevated post-fire seedling survival resulting from enhanced escape by dispersed seedlings from both predation and competition.

Successful ecosystem restoration requires the re-establishment of fundamental ecological processes, many of which involve plant-animal interactions. Myrmecochory (seed dispersal by ants) is a particularly important plant-animal mutualism in Australia, but little is known about its response to either disturbance or restoration following disturbance. Here we investigate the effects of disturbance on seed dispersal by ants, and the extent to which the ant-seed relationship has re-established at sites undergoing rehabilitation, at Ranger uranium mine in the seasonal tropics of Australia's Northern Territory. We focused on the composition of seed-dispersing ant assemblages, rates of seed removal by ants, and the dispersal curves generated by ants, as determined by observations of removal from seed depots. Ten sites were studied, comprising four 'natural' (undisturbed) sites representing a range of savanna habitats occurring in the region, four disturbed sites representing a range of habitat disturbance but with intact soil, and two waste rock sites subject to preliminary revegetation trials. A total of 22 ant species from 10 genera were observed during 154 observations of seed removal, most commonly Rhytidoponera aurata (53 records), Monomorium (rothsteini gp) sp. 1 (14), Iridomyrmex sanguineus (13), Iridomyrmex pallidus (12) and Pheidole sp. 3 (10). Removal rates (over 3 h) averaged 29% across all sites and time periods, varying markedly both between and within sites. However, mean rates of removal were similar between natural, disturbed and waste rock sites (29%, 28% and 31%, respectively). A high incidence (62% of all depots) of 'aril robbing' by ants (primarily Monomorium spp.) eating arils in situ, without removal, was observed. Dispersal distances varied markedly between ant species, with Iridomyrmex sanguineus having both the highest mean (7.25 m) and maximum (13.08 m) dispersal distances. Species of Pheidole typically dispersed seeds less than 0.5 m, and Meranoplus, Monomorium and Tetramorium spp. only ever moved seeds a few centimetres, usually dropping and abandoning them before reaching the nests. The dispersal curves characteristic of each site varied markedly due to the different composition of seed-dispersing ants. The mean dispersal distance at disturbed sites (3.91 m) was significantly higher than at natural sites (2.19 m), and the curves were strongly skewed in the former, but relatively uniform in the latter. The implications of these differences for recovery following disturbance are unclear. At rehabilitated waste rock sites, all observed removals involved distances less than 0.5 m, with a mean of 17 cm. This lack of effective ant-seed relationships might represent a barrier to further vegetation development at rehabilitated sites.

Summary The growth and mineral nutrition of developing fruits of the perennial Australian legume Hardenbergia violacea (Schneev.) Steam (Fabaceae) was studied using plants from a natural habitat near Rankins Springs, central-western New South Wales, Australia. The accumulation and partitioning of dry matter and 12 mineral nutrients in pods and seeds of fruits is described. Seeds accumulated about 50% of the dry matter of a mature fruit, over 90% of its N and P content, 50 to 75% of its K, Ca, Mn, Cl, S, Zn, Cu and Mg, but less than 50% of its Fe and Na. Over 75 % of the N and P content of pods was redistributed during senescence, although other nutrients and dry matter were not redistributed to the same extent; there was negligible redistribution of Ca, Cl, Na, Fe and Mn from the pod. Redistribution of N and P from the pod could have provided up to 30% of these nutrients accumulated by mature seeds. Concentrations of most nutrients were higher in seeds than pods. The testa made up 60% of the dry matter content of a seed and contained the major proportion of its Ca, Mg, Cl, Na and Mn; the embryo contained most of the seed's contents of N, P, K, S, Zn and Cu. The elaiosomes had less than 5% of the seed's dry matter and mineral nutrient content. The oil content of the elaiosome was 34%, compared to 12% for the embryo. Oleic acid made up over 60% of the fatty acid content of elaiosome oil. Aspartic acid, arginine and glycine were the major amino acids in the elaiosome. The embryo contained 10% of the non-protein anti-metabolic amino acid, canavanine, the elaiosome only 1%. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that the subunit protein compositions of the elaiosome and embryo were different. The composition of the elaiosome is discussed in relation to the nutrition of ants. It is concluded that, in H. violacea, the elaiosome represents a nutritionally cheap means to the plant of achieving secondary seed dispersal by ants.

Habitat fragmentation impacts ecosystems worldwide through habitat loss, reduced connectivity, and edge effects. Yet, these landscape factors are often confounded, leaving much to be investigated about their relative effects, especially on species interactions. In a landscape experiment, we investigated the consequences of connectivity and edge effects for seed dispersal by ants. We found that ants dispersed seeds farther in habitat patches connected by corridors, but only in patch centers. We did not see an effect on the total number of seeds moved or the rate ants detected seeds. Furthermore, we did not see any differences in ant community composition across patch types, suggesting that shifts in ant behavior or other factors increased ant seed dispersal in patches connected by corridors. Long-distance seed dispersal by ants that requires an accumulation of short-distance dispersal events over generations may be an underappreciated mechanism through which corridors increase plant diversity. U.S. National Science Foundation [DEB-1912729, DEB-1913501]; USDA Forest Service and Department of Energy at the SavannahRiver Site [DE-AI09-00SR22188]; U .S. National Science Foundation Graduate Research Fellowship Program Published version U.S. National Science Foundation,Grant/Award Numbers: DEB-1912729,DEB-1913501; USDA Forest Service andDepartment of Energy at the SavannahRiver Site, Grant/Award Number:DE-AI09-00SR22188; U.S. NationalScience Foundation Graduate ResearchFellowship Program

The combination of two dispersal syndromes (diplochory) brings additional benefits to seeds, yet the relative costs and benefits of the two phases are poorly understood. Our goal is to provide the first quantification to test the long-standing assumption that there are trade-offs between the two phases in ballistic–ant diplochory. Dispersal investment data were empirically measured for 91 Euphorbiaceae species across different regions of the world. Dispersal distance data of ballochory (seed dispersal by explosion), myrmecochory (seed dispersal by ants) and diplochory was collated from the literature for 210 records (148 species from 44 families). The data were analysed using Model II regression, Kolmogorov–Smirnov test and t test, complemented by phylogenetic comparative approaches. Across diaspores of diplochorous species, the relative investment in myrmecochory increased more than that in ballochory. Fruit coat mass and elaiosome mass covaried in an allometric manner, regardless of seed mass. Diplochorous diaspores were significantly heavier than diaspores dispersed solely by ballochory. Dispersal distances of the two diplochorous phases were independent and comparable to that of sole ballochory or sole myrmecochory. Our results do not support a trade-off, but a coordinated dispersal strategy between the two diplochorous phases. Large diaspores may evolve diplochory to overcome dispersal difficulties in term of dispersal distance. As the most comprehensive study of ballistic–ant diplochory, our findings advance the understanding of the relative importance of the two phases in diplochory. A plain language summary is available for this article.

AIM: Invertebrate‐mediated dispersal has previously been proposed to promote angiosperm diversification and distribution. However, little is known about the specific impact of invertebrate‐mediated dispersal on the biogeography and current distribution of plants. We aim to infer the influence of vespicochorous (hornet) and myrmecochorous (ant) dispersal on the historical biogeography of herbaceous monocot species. LOCATION: Southeast Asia, East Asia, Australia, North America. TAXON: Family Stemonaceae. METHOD: We sampled ca. 75% of the species diversity in Stemonaceae (28 out of 37 species), covering the entire distribution range of the family, to reconstruct the biogeographic history of this family. Using phylogenetic logistic regression analyses, we then tested the relationship between dispersal modes and geographic distributions. RESULTS: Stemonaceae originated on the Asian mainland during the late Cretaceous and then dispersed to North America, the western Malay Archipelago and eastern Malay Archipelago and Australia between the late Cretaceous and Pliocene. Geographical ranges of ant‐ versus hornet‐dispersed Stemonaceae species are significantly different, with vespicochorous species having broader distribution ranges than myrmecochorous species. MAIN CONCLUSIONS: Invertebrate‐mediated dispersal in Stemonaceae may promote narrow endemism and play an important role in shaping the current distribution of species. Most lineages dispersed by ants failed to cross biogeographic barriers and exhibit limited range expansion overland. Vespicochorous lineages were able to cross oceanic barriers and occupy larger continental areas and/or occur on oceanic islands.

1. Myrmecochory sensu stricto is an ant–plant mutualism in which non‐granivorous ants disperse plant diaspores after feeding on their nutrient‐rich seed appendage, the elaiosome. Phenological traits associated with the diaspore can influence the behaviour of ants and thus their ultimate efficiency as seed dispersers. 2. This study investigated how a contrasting availability of seeds (20 vs. 200 seeds) from the diplochorous Chelidonium majus (Papaveraceae, Linnaeus) plant species influences the behaviour of Myrmica rubra (Formicidae, Linnaeus) ants, from the retrieval of seeds until their dispersal outside the ant nest. 3. Regardless of seed abundance, the ants collected the first diaspores at similar rates. Then, seed retrieval sped up over time for large seed sources until satiation took place with only one‐third of the tested colonies wholly depleting abundant seed sources. 4. No active recruitment by trail‐laying ants was triggered, even to an abundant seed source 5. In both conditions of seed abundance, the majority of the diaspores retrieved inside the nest were discarded with the elaiosome removed and were dispersed at similar distances from the nest. 6. The paper concludes with a discussion of how the quantity of seeds released by a plant with a dual mode of dispersal can potentially influence the behaviour of ant dispersers and hence the dispersal efficiency derived from myrmecochory.

Seed re-dispersal following initial harvesting by ants may have important implications for the distribution and fate of myrmecochorous seeds. However, the probability of seed re-dispersed by ants and the effect it may have on subsequent survival appear variable, the functional role of diaspore, disperser and seed predator to the fate of discarded seeds remain unclear. To clarify the ecology, we compared the consequences of seed re-dispersal by a keystone seed-dispersing ant (Myrmica ruginodis Nylander) for four sympatric myrmecochorous plants common to the temperate deciduous forests in Qinling Mountains, central China. Plants varied in the probability of re-dispersal and in elaiosome condition. Ants preferred seeds with residual elaiosomes, while rodents only consumed the two larger-seeded species, regardless of the elaiosome presence. The scattered distribution of discarded seeds increased the probability of ant re-harvesting and, to some extent, reduced rodent predation. Thus, difference in the probability of seed re-dispersal and its subsequent effect on seed fate in relation to ants and rodents was attributed primarily to the elaiosome condition, seed size and seed spatial pattern. The results imply that seed re-dispersal could affect the fitness of plants and ultimately influence the plant abundance and distribution pattern. This highlights the necessity to incorporate re-dispersal into myrmecochory to advance our understanding of the benefits of myrmecochory to plants.

Aim We determine the prevalence of mutualistic seed-dispersal interactions across the North American landscape and then test the hypothesis that patterns in interaction diversity are correlated with latitude, longitude, precipitation, midpoint elevation and the elevational range of sites. Location North America north of the Mexican border. Methods We used regional plant lists to determine the diversity of animal seed-dispersal interactions across North America (over more than 48° of latitude). For each plant list (n = 197 sites, 12,424 terrestrial plant species and 123,519 plant records), we assigned plant species to one of four seed-dispersal modes (i.e. frugivory, scatter hoarding, myrmecochory or non-mutualist) and to an animal vector (e.g. bird, carnivorous mammal, rodent, ant). Results We identified 14 types of animal-mediated seed dispersal. Plants with seed-dispersal mutualists are most diverse in the south-eastern portion of the continent. Dispersal by frugivores and scatter hoarders is strongly negatively correlated with latitude but myrmecochory is not. The diversity of interaction types is significantly correlated with precipitation and elevational range and negatively correlated with latitude, longitude and midpoint elevation. Main conclusions The diversity of seed-dispersal mutualisms varies dramatically across the continent, suggesting that the co-evolutionary processes that produce these interactions are stronger in certain regions and vegetation types and weaker in others. Elucidation of these patterns and their causes will help us to better understand the co-evolutionary processes that shape communities.

Seed dispersal by ants is an important interaction in North American eastern deciduous forests, where 30–40% of understory plants are myrmecochores, with seeds that possess lipid‐rich appendages (elaiosomes) that attract seed‐dispersing ants. Contemporary forests are fragmented and have regenerated from being previously cleared (secondary forests). In secondary forests, and especially along edges, myrmecochores are a depauperate component of forests. Here, we assess if seed dispersal of myrmecochores by ants, particularly the keystone disperser, Aphaenogaster sp., is intact in forest interiors compared to edges. In three North American northeastern deciduous forests, we compared myrmecochore cover and richness, seed dispersal by ants, and the abundance and richness of ants and other forest floor invertebrates between interiors and edges. We also conducted a seed removal experiment, excluding either ants, rodents (seed predators), or ants and rodents, to test their effects on seed dispersal between interiors and edges. We found differences in the composition of understory plants between interiors and edges, with edges lacking myrmecochores. We also found that seed dispersal by ants was lower in two of the three edges and corresponded to Aphaenogaster sp. abundance. Antagonistic interactions with an invasive slug that is an elaiosome robber, Arion subfuscus, was more apparent than damage by rodents in the experiment, negatively affected dispersal by ants more at edges than in interiors. Here we show that changes in mutualistic and antagonistic interactions affect seed dispersal at forest edges and that not all forest edges are the same, with some more intact than others. Understanding how seed dispersal is impacted in contemporary forests is important towards the goal of conserving and restoring depauperate forest understory communities.

Secondary seed dispersal by ants (myrmecochory) is an important process in semi-arid environments where seeds are transported from the soil surface to an ant nest. Microsites from which ants often remove seeds are the small pits and depressions made by native and exotic animals that forage in the soil. Previous studies have demonstrated greater seed retention in the pits of native than exotic animals, but little is known about how biotic factors such as secondary seed dispersal by ants affect seed removal and therefore retention in these foraging pits. We used an experimental approach to examine how the morphology of burrowing bettong (Bettongia lesueur), greater bilby (Macrotis lagotis), short-beaked echidna (Tachyglossus aculeatus) and European rabbit (Oryctolagus cuniculus) foraging pits and ant body size influenced ant locomotion and seed removal from pits along an aridity gradient. Ants took 3.7-times longer to emerge from echidna pits (19.6 s) and six-times longer to emerge from bettong pits (30.5 s) than from rabbit pits (5.2 s), resulting in lower seed removal from bettong pits than other pit types. Fewer seeds were removed from pits when cages were used to exclude large body-sized (>2 mm) ants. Few seeds were removed from the pits or surface up to aridity values of 0.5 (humid and dry sub-humid), but removal increased rapidly in semi-arid and arid zones. Our study demonstrates that mammal foraging pit morphology significantly affects ant locomotion, the ability of ants to retrieve seeds, and therefore the likelihood that seeds will be retained within foraging pits.

Heterotrophic plants normally produce a vast number of dust-like seeds containing minimal energy reserves, which are usually wind dispersed. However, some heterotrophic species have evolved adaptive strategies to use zoochorous seed dispersal. Seed dispersal by ants, known as myrmecochory, is one of the most widespread animal dispersal systems and has been reported in a diverse range of plant taxa. However, the combination of myrmecochory and heterotrophy seems to be very rare. Here I report the discovery of myrmecochory in the hemiparasitic plant Thesium chinense by Tetramorium tsushimae and Pristomyrmex punctatus. Myrmecochory would be an advantageous dispersal system for T. chinense because its fruits are quickly transferred to the ants' nests, which provide a refuge from the seed predator Canthophorus niveimarginatus. Myrmecochory is also potentially beneficial for T. chinense, as the nests of these ants are frequently located close to poaceous plants, which are the preferred hosts.

Vespicochory, seed dispersal by hornets, is an uncommon seed dispersal pattern in angiosperms. To date, this phenomenon has been recorded in only four families. Because of its rarity, the causes and consequences of vespicochory remain unclear. Hence, this seed dispersal syndrome is often regarded as anecdotal. Through field investigations, chemical analyses, electrophysiological tests, identification of chemosensory proteins from the antennae of hornets, and behavioral assays, we investigated whether olfactory and/or visual cues of the diaspores of Stemona tuberosa mediate the behavior of the social hornets and maintain their mutualism. This study demonstrated that the elaiosome of S. tuberosa emits hydrocarbons, which are attractive to hornets. However, these compounds, which induce responses in the antennae of naive hornets, are ubiquitous substances on insect cuticle surfaces. Innate preference and experienced foraging behavior of hornets can increase their seed dispersal efficiency. This is the first example in which hydrocarbons have been identified as a diaspore odour involved in the attraction of hornets. Given that the ubiquity of hornets, and the communication function of hydrocarbons in insects, we predict that this rare seed dispersal mechanism may be an overlooked mechanism of insect-plant mutualism.

Vespicochory, seed dispersal by hornets, is a rare seed dispersal mechanism in angiosperms and, to date, there are few records of this phenomenon. Through field investigations and behavioral assays conducted in four populations of Stemona tuberosa from 2011-2016, we demonstrate that hornets are the primary seed dispersers of S. tuberosa and play an important role in "long-distance" seed dispersal in this species. Furthermore, some ant species act as secondary dispersers and may transport the seeds to safe sites. Hornets and ants provide complementary seed dispersal at different spatial scales. This unique example of insect-plant mutualism may be an underestimated but important strategy to ensure "long-distance" seed dispersal in other myrmecochorous plants.

Synchronisation of fruiting phenology with disperser activities is an important component of plant adaptation to seed dispersal mutualisms. Although most previous studies have exclusively evaluated the effects of fruiting phenology on seed removal rate, seed dispersal effectiveness is determined by both the number of dispersed seeds (quantitative effectiveness) and the probability of a dispersed seed becomes an adults (qualitative effectiveness). Therefore, the adaptive significance of fruiting phenology should be assessed for both components of dispersal effectiveness. This study investigates the adaptive significance of fruiting phenology for two ant-dispersed sedges, Carex lanceolata and C. tristachya. Because C. lanceolata is known to require a longer seed dispersal distance than C. tristachya, we hypothesized that C. lanceolata produces seeds when high qualitative dispersal effectiveness can be achieved, while C. tristachya bears seeds when seed disperser ants are abundant to give priority to quantitative dispersal effectiveness. Field observations of ant activity around the sedges revealed that the relative abundance of ant species with the longest seed dispersal distance, Formica japonica, was higher during the fruiting period of C. lanceolata than in that of C. tristachya, which is consistent with the requirement of C. lanceolata to achieve high qualitative effectiveness. In addition, our fruiting manipulation experiment revealed that C. tristachya fruits when the overall seed removal rate is high, resulting in high quantitative effectiveness. Overall, our results support the idea that variations in both qualitative and quantitative dispersal effectiveness should be considered to understand the adaptive significance of fruiting phenology in animal-dispersed plants.

Invasive species present serious problems for ecosystems and economies. One such species, the invasive cutleaf coneflower (Rudbeckia laciniata L.), has several modes of seed dispersal, namely autochory, anemochory, epizoochory, myrmecochory and anthropochory. Because we found caches of this invasive plant's seeds in two nest boxes, suggesting the possibility of synzoochory, we report here the details of the caches. In one of the boxes, many of the seeds were cached in autumn and eaten during the winter. Automatic sensor cameras directed at the boxes revealed that three rodent species and two avian species visited the boxes. The characteristics of the caches and the nest-box visitors suggested that the small Japanese field mouse (Apodemus argenteus Temm.) was the animal most likely to have cached the seeds in the boxes.