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The growing global population size and the increasing mobility of people can make humans as a potentially super-effective dispersal vector of plant propagules. Therefore, human-vectored dispersal (HVD) on clothing and footwear can be an effective way of the dispersal of invasive alien species (IAS). This can be especially problematic in protected areas, which are not exposed to the mass invasions caused by vehicles, construction works, trade or agriculture, but still exposed to HVD by tourists. In this study, we collected those biosecurity measures which currently apply to the control of IAS dispersed on human clothing. We also extracted relevant findings from studies on HVD for giving recommendations in order to improve policy measures aiming the prevention and mitigation of the spread of propagules of IAS on clothing. Even though many peculiarities of HVD are already known, e.g., retention potential of different fabric and cloth types, traits of the species of the most successful IAS dispersed by HVD and potential dispersal efficiency of HVD, we found that current IAS control measures usually do not consider and do not address sufficiently the threats represented by HVD on cloths. We suggest a number of voluntary and institutional measures that could be easily applied to decrease the chance of dispersing IAS by HVD, including information, self-regulation, legislation, quarantine measures, monitoring, interception and visitor management.

Spore characteristics of wood-inhabiting fungi suggest that wind is their predominant dispersal vector. However, since they are restricted to ephemeral habitats, colonizing new patches should benefit from dispersal by animals with similar habitat preferences because the directed, resource-searching movement of animals increases the likelihood of reaching suitable habitats. Here we determine which fungal guilds are carried by wood-inhabiting beetles and what influences beetle-associated fungal communities. High-throughput sequencing identified >1800 fungal taxa from beetle communities that emerged from 64 experimental logs. Beetle-associated fungi included mutualistic, decomposing, pathogenic and mycorrhizal fungi; decomposers were the most diverse. Partial-procrustes analysis revealed that the total beetle-associated community and mutualists were correlated (p ≤ 0.05) with beetle community composition and decomposers were marginally correlated (p ≤ 0.10) with beetle community composition. All three groups were marginally correlated with the total fungal communities that inhabit the dead wood. Our results show that beetles carry a broad range of wood-inhabiting fungi and beetle-associated fungal communities are determined by environmental factors and the vectoring beetle community and to some degree by the fungal source community. This suggests that wood-inhabiting beetles contribute to fungal dispersal, including directed dispersal, which could affect fungal community assembly and ecosystem processes like wood decomposition.

Contains fulltext : 199715.pdf (Publisher’s version ) (Open Access) 34 p.

Aim We assessed the role of mowing machinery and endozoochory by migratory sheep as dispersal vectors in semi-natural grasslands by comparing the species compositions and traits of species found in the vectors to the regional above-ground vegetation and soil seed bank. Furthermore, we discuss how their interplay may affect the conservation of semi-natural grasslands. Location Rhon Mountains, central Europe. Methods Plant material from mowers (n = 12 from one date) and dung samples from migratory sheep (n = 39 from 13 dates) were collected and the dispersed plant species were determined using the emergence method. We compared the species compositions to the regional above-ground vegetation and seed bank using non-metric multidimensional scaling (NMDS) and indicator species analysis. Furthermore, we compared functional traits of the dispersed species to traits of non-dispersed species of the regional species pools by calculating log-response ratios and performing metaregressions. Results While 43 species were shared between the vectors, the vegetation compositions differed from each other. Mower samples were more similar to the above-ground vegetation whereas dung samples were more similar to the seed bank. Mowers and sheep endozoochory favoured the dispersal of species with different traits and phenologies. Species with small seed sizes were prevalent in both vectors. Mowers were less selective concerning most traits, but favoured high-growing grasses such as Alopecurus pratensis and Trisetum flavescens. Sheep dung samples contained less grasses and more palatable species, such as Urtica dioica. Mowers were most selective concerning phenology, whereas endozoochory by migratory sheep also included late-flowering species. Conclusion Sheep endozoochory and mowing machinery are complementary dispersal vectors favouring species with differing functional traits. Sheep endozoochory enables dispersal of species that have unfavourable traits (e.g. low releasing heights) or phenologies for dispersal by mowing machinery. To ensure the dispersal of a high number of plant species in semi-natural grasslands, the interplay of different vectors should be considered.

Plastic debris constitutes up to 87% of marine litter and represents one of the most frequently studied vectors for marine alien species with invasive potential in the last 15 years. This review addresses an integrated analysis of the different factors involved in the impact of plastic as a vector for the dispersal of marine species. The sources of entry of plastic materials into the ocean are identified as well as how they move between different habitats affecting each trophic level and producing hot spots of plastic accumulation in the ocean. The characterization of plastic as a dispersal vector for marine species has provided information about the inherent properties of plastics which have led to its impact on the ocean: persistence, buoyancy, and variety in terms of chemical composition, all of which facilitate colonization by macro and microscopic species along with its dispersion throughout different oceans and ecosystems. The study of the differences in the biocolonization of plastic debris according to its chemical composition provided fundamental information regarding the invasion process mediated by plastic, and highlighted gaps of knowledge about this process. A wide range of species attached to plastic materials has been documented and the most recurrent phyla found on plastic have been identified from potentially invasive macrofauna to toxic microorganisms, which are capable of causing great damage in places far away from their origin. Plastic seems to be more efficient than the natural oceanic rafts carrying taxa such as Arthropoda, Annelida, and Mollusca. Although the differential colonization of different plastic polymers is not clear, the chemical composition might determine the community of microorganisms, where we can find both pathogens and virulent and antibiotic resistance genes. The properties of plastic allow it to be widely dispersed in practically all ocean compartments, making this material an effective means of transport for many species that could become invasive.

Symbiotic nitrogen (N)‐fixing plants have important effects on the biogeochemical processes of the sites they inhabit, but their ability to reach these sites is determined by the dispersal of their seeds. Differences in seed size and dispersal vectors of N‐fixing and non‐fixing plants could influence the spatial and temporal distributions of N fixers, and thus could have important impacts on biogeochemical cycling. Using seed mass, dispersal vector, and biome data retrieved from online public databases, we ask if there are systematic differences in seed mass and dispersal vectors between N‐fixing and non‐fixing plants. We demonstrate that rhizobial N fixers tend to have larger seeds that are more likely to be biotically dispersed than seeds of non‐fixers, whereas actinorhizal N‐fixing trees tend to have small, abiotically dispersed seeds. We then synthesize existing evidence from the literature to draw links between these dispersal traits and the spatio–temporal patterns of N fixers, as well as their biogeochemical effects on terrestrial ecosystems. Using this literature, we argue that the spatio–temporal distributions of N fixers are influenced by their seed dispersal characteristics, and that these distribution patterns have important effects on the total amount of N fixed at a site and the timing of N inputs during processes such as succession.

This study was funded by the Asturias Principality Excellence Grant GRUPIN-2014-093 and the Spanish MINECO project BLUEPORTS CGL-2016-79209-R. This is a contribution from the Marine Observatory of Asturias (OMA), and the Research Group of Excellence ARENA.

Aim: Long-distance dispersal (LDD) events occur rarely but play a fundamental role in shaping species biogeography. Lying at the heart of island biogeography theory, LDD relies on unusual events to facilitate colonisation of new habitats and range expansion. Despite the importance of LDD, it is inherently difficult to quantify due to the rarity of such events. We estimate the probability of LDD of the seagrass Heterozostera nigricaulis, a common Australian species, across the Pacific Ocean to colonise South America. Location: Coastal Chile, Australia and the Pacific Ocean. Methods: Genetic analysis of H. nigricaulis collected from Chile and Australia were used to assess the relationship between the populations and levels of clonality. Ocean surface current models were used to predict the probability of propagules dispersing from South East Australia to Central Chile and shipping data used to determine the likelihood of anthropogenic dispersal. Results: Our study infers that the seagrass H. nigricaulis dispersed from Australia across the entire width of the Pacific (~14,000 km) to colonise South America on two occasions. Genetic analyses reveal that these events led to two large isolated clones, one of which covers a combined area of 3.47 km252. Oceanographic models estimate the arrival probability of a dispersal propagule within 3 years to be at most 0.00264%. Early shipping provides a potential alternative dispersal vector, yet few ships sailed from SE Australia to Chile prior to the first recording of H. nigricaulis and the lack of more recent and ongoing introductions demonstrate the rarity of such dispersal. Main Conclusion: These findings demonstrate LDD does occur over extreme distance despite very low probabilities. The large number of propagules (100s of millions) produced over 100s of years suggests that the arrival of propagules in Chile was inevitable and confirms the importance of LDD for species distributions and community ecology.

We provide an integrative view of the evolution of dispersal strategies in modern conifers, by characterizing and examining the phylogenetic distribution of diaspore functional morphotypes, diaspore structural compositions, seed coat modifications, and dispersal syndromes using the phylogeny of Leslie et al. (2012). We first classified diaspores into nine functional morphotypes, which represent overall dispersal strategies that encompass the multiple phases of dispersal. We mapped these morphotypes, the eight different structural compositions of diaspores, two types of seed coat modifications, and the four recognized dispersal vectors onto the phylogeny and used maximum parsimony and maximum likelihood to infer ancestral states and assess shifts in dispersal characteristics. We found that structural traits (diaspore composition and seed coat modifications) are more conserved than ecological traits (functional morphotype and dispersal vector/syndrome). Almost all diaspore functional morphotypes have multiple independent origins, with several instances of parallelism (using the same structures to generate a morphotype) within families, but generally functional convergence (using different structures to generate a morphotype) between families. Within extant conifer families, shifts in the dispersal syndrome occur most frequently with simultaneous shifts in both diaspore morphotype and composition. Shifts from winged wind-dispersed to fleshy animal-dispersed diaspores are infrequent and occur only in the direction from wind to animal dispersal. Shifts to gravity or water dispersal occur from both wind and animal dispersed diaspores, concurrent with the loss of dispersal structures from the diaspore. Within both wind and animal-dispersed syndromes, shifts between functional morphotypes represent further differentiation of overall dispersal strategies, and occur most frequently without corresponding changes in the structural composition of the diaspore. The recurrent evolution of distinct functional morphologies suggests that there are local adaptive maxima that balance tradeoffs in traits related to both transport and establishment, within developmental limitations. Overall, our results suggest that the ancestral diaspore type for all modern conifers consisted only of a seed. Conifers diversified in their dispersal strategies through seed coat modifications or by the incorporation of various parts of the seed cone into the diaspore, with the modern conifer families independently evolving their characteristic diaspore compositions. Almost all functional morphotypes were present prior to the Cenozoic in at least one lineage, with more recent shifts in morphotypes representing functional convergence or parallel evolution rather than ecological novelties.

1. Plant species around the world invest in seed dispersal by producing large numbers of seeds, with a wide range of morphological adaptations that facilitate dispersal. Not all dispersed seeds reach suitable sites, however, and plants can significantly improve their fitness by increasing the proportion of seeds arriving at suitable sites for germination and establishment. Disproportionate dispersal to suitable sites is known as ‘directed dispersal’. Yet, mechanisms of directed dispersal are only known for a limited number of animal-dispersed plant species. 2. We tested the hypothesis that directed dispersal can also be driven by abiotic vectors, such as water or wind. We used a tiered approach, combining analyses of experimental, field and literature data on wetland plant species and evaluating the potential for evolution of directed dispersal with a spatially explicit individual-based model. 3. The data collected demonstrate that wetland plants produce seeds with adaptations to promote transportation and deposition by water towards microsites along the hydrological gradient where they germinate and establish best. Aquatic species produce seeds that sink and are transported by water as bed load towards inundated sites. In contrast, shoreline species produce seeds that float for very long periods of time so that they are eventually entrapped by shoreline vegetation or deposited at the waterline. Our model simulations confirm that the patterns we observed in nature can evolve under natural selection through adaptations in seed buoyancy. 4. For wind dispersal, the situation is more complex. Wind does not provide directed dispersal in the strictest sense but, rather, simply appears to be the best available dispersal vector for more terrestrial wetland plant species to reach drier areas in a wet environment. 5. Synthesis. We show that directed dispersal towards specific, suitable microsites is not exclusive to animal-dispersed plant species, but may be far more common in plants – also in species dispersed by abiotic vectors, in particular water. As water and wind are very common dispersal vectors throughout the plant kingdom, directed dispersal (and not just dispersal distance) seems to be of general importance for the ecology of plants. Plant species around the world invest in seed dispersal by producing large numbers of seeds, with a wide range of morphological adaptations that facilitate dispersal. Not all dispersed seeds reach suitable sites, however, and plants can significantly improve their fitness by increasing the proportion of seeds arriving at suitable sites for germination and establishment. Disproportionate dispersal to suitable sites is known as 'directed dispersal'. Yet, mechanisms of directed dispersal are only known for a limited number of animal-dispersed plant species. We tested the hypothesis that directed dispersal can also be driven by abiotic vectors, such as water or wind. We used a tiered approach, combining analyses of experimental, field and literature data on wetland plant species and evaluating the potential for evolution of directed dispersal with a spatially explicit individual-based model. The data collected demonstrate that wetland plants produce seeds with adaptations to promote transportation and deposition by water towards microsites along the hydrological gradient where they germinate and establish best. Aquatic species produce seeds that sink and are transported by water as bed load towards inundated sites. In contrast, shoreline species produce seeds that float for very long periods of time so that they are eventually entrapped by shoreline vegetation or deposited at the waterline. Our model simulations confirm that the patterns we observed in nature can evolve under natural selection through adaptations in seed buoyancy. For wind dispersal, the situation is more complex. Wind does not provide directed dispersal in the strictest sense but, rather, simply appears to be the best available dispersal vector for more terrestrial wetland plant species to reach drier areas in a wet environment. Synthesis. We show that directed dispersal towards specific, suitable microsites is not exclusive to animal-dispersed plant species, but may be far more common in plants - also in species dispersed by abiotic vectors, in particular water. As water and wind are very common dispersal vectors throughout the plant kingdom, directed dispersal (and not just dispersal distance) seems to be of general importance for the ecology of plants.

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling-safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.

Dispersal is an essential component of plant life, especially under the current threats of anthropogenic habitat fragmentation and climate change. For many wetland species, water is a key dispersal vector, as it can presumably disperse seeds long distances and towards suitable sites for establishment. Seed dispersal distance is affected by stream characteristics and seed traits. Yet, the effect of relevant seed traits, such as size, remains largely unknown. Here, we report on an experimental field study examining the effect of seed size on dispersal distance in lowland streams. We released cork seed mimics of different sizes in four Dutch lowland streams in restored and channelized sections. After 24 hr, we recorded their entrapment location, entrapment mechanism, and the vegetation type in which they were caught. Large seeds generally dispersed over longer distances than smaller seeds. This effect of seed size is likely caused by the different entrapment mechanisms—net trapping, surface tension, and wake trapping—which were highly correlated with seed size. Especially net trapping was responsible for the capture of a large proportion of small seed mimics in vegetation such as aquatic and riparian grasses, starwort, and reed. Due to the prevalent occurrence of these vegetation types in lowland streams, particularly during summer, smaller seeds are more likely to become entrapped and, hence, disperse less far. Our analysis on existing seed data reveals that water-dispersed riparian plants have relatively large seeds and are thereby evolutionarily adapted to long-distance dispersal. Furthermore, our results indicate that median dispersal distances are 0.02–1.8 km (99-percentile

Plant invasions are a threat to rangelands in California. Understanding how seeds of invasive plants are dispersed is critical to developing sound management plans. Domestic livestock can transport seeds long distances by ingesting and passing seeds in dung (endozoochory) or by the attachment of seeds to skin and fur (epizoochory). Our objective was to characterize the role of cattle as seed dispersers of both invasive and noninvasive species via endozoochory and epizoochory in a Sierra foothills rangeland. To quantify endozoochory, we sampled dung from two dry-season grazing periods and evaluated seed content by growing dung for 3 months in a greenhouse. To quantify epizoochory, we collected seeds directly from the fur of 40 cattle. We categorized the invasion status and functional groups of all species found and quantified landscape-scale vegetation composition in order to determine whether dispersal mode was associated with functional group, invasion status, or vegetation composition. Finally, we evaluated the potential for the noxious weed medusahead (Taeniatherum caput-medusae [L.] Nevski) to travel long distances on cattle fur using a detachment experiment with a model cow. We found that forbs were more likely to be dispersed by endozoochory, and invasive species were more likely to be dispersed by epizoochory. Medusahead was dispersed exclusively by epizoochory and was able to travel up to 160 m on a model cow. Our results suggest that cattle may be an important dispersal vector for both invasive and noninvasive plants.

Dispersal is one of the most important but least understood processes in plant ecology and evolutionary biology. Dispersal of seeds maintains and establishes populations, and pollen and seed dispersal are responsible for gene flow within and among populations. Traditional views of dispersal and gene flow assume models that are governed solely by geographic distance and do not account for variation in dispersal vector behavior in response to heterogenous landscapes. Landscape genetics integrates population genetics with Geographic Information Systems (GIS) to evaluate the effects of landscape features on gene flow patterns (effective dispersal). Surprisingly, relatively few landscape genetic studies have been conducted on plants. Plants present advantages because their populations are stationary, allowing more reliable estimates of the effects of landscape features on effective dispersal rates. On the other hand, plant dispersal is intrinsically complex because it depends on the habitat preferences of the plant and its pollen and seed dispersal vectors. We discuss strategies to assess the separate contributions of pollen and seed movement to effective dispersal and to delineate the effects of plant habitat quality from those of landscape features that affect vector behavior. Preliminary analyses of seed dispersal for three species indicate that isolation by landscape resistance is a better predictor of the rates and patterns of dispersal than geographic distance. Rates of effective dispersal are lower in areas of high plant habitat quality, which may be due to the effects of the shape of the dispersal kernel or to movement behaviors of biotic vectors. Landscape genetic studies in plants have the potential to provide novel insights into the process of gene flow among populations and to improve our understanding of the behavior of biotic and abiotic dispersal vectors in response to heterogeneous landscapes., Plant dispersal is affected by both the habitat requirements of the plant and the effects of geographic features on vector behavior. This review discusses the advantages of using plants in landscape genetics studies and provide examples of a novel method for delineating the effects of habitat quality from those of geographic features that influence vector behavior when evaluating patterns of effective dispersal in heterogeneous landscapes.

Plant species distributions are determined by various factors (including the dispersal modes and the complex physical environment) across multiple spatial scales, in which the dispersal distance of different dispersal modes and the external environment (including local characteristics and landscape patterns) are closely related. Therefore, understanding the response mechanism of plant species with different dispersal abilities to environmental factors is critical for developing effective landscape management strategies and prioritizing biodiversity conservation efforts at the appropriate scale. In this study, we aimed to explore: (1) the spatial distribution of plant species richness; (2) the spatial scale at which plant species have the strongest response to environment variables (scale of effect); and (3) to identify the key factors that affect the plant species at local and six landscape scales (a 0.5 km, 1 km, 1.5 km, 2 km, 3 km and 4 km-radius circle) considering multiple dispersal traits. We conducted vegetation surveys at 53 sites and classified plant species into three dispersal modes, including biotic dispersal (BD), abiotic dispersal (AD) and autochorous (AT), based on the respective dispersal vector of the seed. We classified land use types into 15 categories and clipped 6 specified radii around each sampling site using ENVI 5.1 and ArcGIS 10.3 software. We applied linear mixed effects models (LMM) to analyze the local and the surrounding landscape variables in predicting plant species richness in Qingshui town of Beijing, China. Our results revealed that the response traits of species to environment factors varied across different scales, proving the existence of scale effect in our study area. The biotically-dispersed (BD) and abiotically-dispersed (AD) species favored structurally complex habitats with greater tree height and cover of herb at the local scale. The area-weighted mean of shape metric (SHAPE_MN) of shrubbery and the euclidean nearest neighbor distance distribution (ENN_AM) of bare land play a major role in determining BD and AD species at large spatial extents, which suggest that the patterns and ecological attributes of patches of these two land use types hinder the migration and colonization ability of species and thus affect the species richness. These results suggest that a multi-scale approach should be encouraged to help guide effective landscape managements in conserving biodiversity for different response traits.

Aquatic ecosystems serve as a dissemination pathway and a reservoir of both antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG). In this study, we investigate the role of the bacterial sporobiota to act as a vector for ARG dispersal in aquatic ecosystems. The sporobiota was operationally defined as the resilient fraction of the bacterial community withstanding a harsh extraction treatment eliminating the easily lysed fraction of the total bacterial community. The sporobiota has been identified as a critical component of the human microbiome, and therefore potentially a key element in the dissemination of ARG in human-impacted environments. A region of Lake Geneva in which the accumulation of ARG in the sediments has been previously linked to the deposition of treated wastewater was selected to investigate the dissemination oftet(W) andsul1, two genes conferring resistance to tetracycline and sulfonamide, respectively. Analysis of the abundance of these ARG within the sporobiome (collection of genes of the sporobiota) and correlation with community composition and environmental parameters demonstrated that ARG can spread across the environment with the sporobiota being the dispersal vector. A highly abundant OTU affiliated with the genusClostridiumwas identified as a potential specific vector for the dissemination oftet(W), due to a strong correlation withtet(W) frequency (ARG copy numbers/ng DNA). The high dispersal rate, long-term survival, and potential reactivation of the sporobiota constitute a serious concern in terms of dissemination and persistence of ARG in the environment.

Ants provide a common dispersal vector for a variety of plants in many environments through a process known as myrmecochory. The efficacy of this dispersal mechanism can largely determine the ability of species to track changes in habitat availability caused by ongoing land-use and associated disturbances, and can be critical for population gene flow and persistence. Field studies were conducted in a typical fragmented agricultural landscape in southern NSW, Australia, to investigate the extent to which dispersal services by ants are influenced by anthropogenic disturbances associated with roadwork activities (i.e., soil disturbance as the result of grading of roads). Observational experiments were performed in road segments that were divided into disturbed and non-disturbed zones, where Acacia pycnantha seeds were offered at multiple bait stations and monitored. For combined species, the mean dispersal distance recorded in the disturbed zone (12.2 m) was almost double that recorded in the non-disturbed zone (5.4 m) for all roadside sites. Our findings show that myrmecochory is an unevenly diffuse mutualism, where few ant species contributed to much of the dispersal of seeds. Iridomyrmex purpureus was responsible for all seed dispersal distances >17 m, where a maximum of 120 m in disturbed, vs. 69 m in non-disturbed zones, was recorded. Rhytidoponera metallica and Melophorus bruneus were important seed dispersers in non-disturbed and disturbed zones, respectively. In general, large bodied ants tended to move more seeds to longer distances in disturbed zones, as opposed to non-disturbed zones, where smaller bodied species carried out a greater percentage of short distance dispersals (

Seed dispersal plays a significant role in forest regeneration and maintenance. Flying foxes are often posited as effective long-distance seed dispersers due to their large home ranges and ability to disperse seeds when flying. We evaluate the importance of the Madagascan flying fox Pteropus rufus in the maintenance and regeneration of forests in one of the world's priority conservation areas. We tested germination success of over 20,000 seeds from the figs Ficus polita, F. grevei and F. lutea extracted from bat faeces and ripe fruits under progressively more natural conditions, ranging from petri-dishes to outdoor environments. Seeds from all fig species showed increased germination success after passing through the bats' digestive tracts. Outside, germination success in F. polita was highest in faecal seeds grown under semi-shaded conditions, and seeds that passed through bats showed increased seedling establishment success. We used data from feeding trials and GPS tracking to construct seed shadow maps to visualize seed dispersal patterns. The models use Gaussian probability density functions to predict the likelihood of defecation events occurring after feeding. In captivity, bats had short gut retention times (often < 30 mins), but were sometimes able to retain seeds for over 24h. In the wild, bats travelled 3-5 km within 24-280 min after feeding, when defecation of ingested seeds is very likely. They produced extensive seed shadows (11 bats potentially dispersing seeds over 58,000 ha over 45 total days of tracking) when feeding on figs within their large foraging areas and dispersed the seeds in habitats that were often partially shaded and hence would facilitate germination up to 20 km from the feeding tree. Because figs are important pioneer species, P. rufus is an important dispersal vector that makes a vital contribution to the regeneration and maintenance of highly fragmented forest patches in Madagascar.

Bipolar disjunct distributions are a fascinating biogeographic pattern exhibited by about 30 vascular plants, whose populations reach very high latitudes in the northern and southern hemispheres. In this review, we fi rst propose a new framework for the defi nition of bipolar disjunctions and then reformulate a list of guiding principles to consider how to study bipolar species. Vicariance and convergent evolution hypotheses have been argued to explain the origin of this fragmented distribution pattern, but we show here that they can be rejected for all bipolar species, except for Carex microglochin . Instead, human introduction and dispersal (either direct or by mountain-hopping) — facilitated by standard and nonstandard vectors — are the most likely explanations for the origin of bipolar plant disjunctions. Successful establishment after dispersal is key for colonization of the disjunct areas and appear to be related to both intrinsic (e.g., self-compatibility) and extrinsic (mutualistic and antagonistic interactions) characteristics. Most studies on plant bipolar disjunctions have been conducted in Carex (Cyperaceae), the genus of vascular plants with the largest number of bipolar species. We found a predominant north-tosouth direction of dispersal, with an estimated time of diversifi cation in agreement with major cooling events during the Pliocene and Pleistocene. Bipolar Carex species do not seem to depend on specialized traits for long-distance dispersal and could have dispersed through one or multiple stochastic events, with birds as the most likely dispersal vector., Th is research was supported by the Spanish Ministry of Economy and Competitiveness (projects CGL2012-3874 and CGL2016-77401-P).

Propagules of several freshwater invertebrates are passively dispersed by wind, but the importance of wind as a dispersal vector remains poorly understood. We examined the historical frequency of wind dispersal events in cysts of Artemia franciscana. A threshold wind speed of ~5 km/h was required to begin dispersing surface-resting cysts, beyond which cyst dispersal increased rapidly with increasing wind speed. The analysis of wind speed and cyst dispersal data from our field experiment and wind data for the last 45 years from a nearby airport revealed that wind events strong enough to disperse most cysts at a wind-exposed site are common, occurring on ~16 snow-free days per year and occurring consistently over long time periods. In a topographically uneven landscape, however, wind speeds vary substantially from one location to another; wind speeds at our exposed site were 69% higher than in a nearby wind-sheltered depression. Accordingly, winds strong enough to disperse most cysts from this sheltered site occurred on only 5 days of the 45 year period. Cysts are thus less likely to disperse from, and more likely to settle in, sheltered depressions than wind-exposed areas. Sheltered areas could thus function as traps for wind-dispersing propagules.