Seed Dispersal Research Articles

Stochastic Inoculum, Biotic Filtering and Species-Specific Seed Transmission Shape the Rare Microbiome of Plants.

A plant’s health and productivity is influenced by its associated microbes. Although the common/core microbiome is often thought to be the most influential, significant numbers of rare or uncommon microbes (e.g., specialized endosymbionts) may also play an important role in the health and productivity of certain plants in certain environments. To help identify rare/specialized bacteria and fungi in the most important angiosperm plants, we contrasted microbiomes of the seeds, spermospheres, shoots, roots and rhizospheres of Arabidopsis, Brachypodium, maize, wheat, sugarcane, rice, tomato, coffee, common bean, cassava, soybean, switchgrass, sunflower, Brachiaria, barley, sorghum and pea. Plants were grown inside sealed jars on sterile sand or farm soil. Seeds and spermospheres contained some uncommon bacteria and many fungi, suggesting at least some of the rare microbiome is vertically transmitted. About 95% and 86% of fungal and bacterial diversity inside plants was uncommon; however, judging by read abundance, uncommon fungal cells are about half of the mycobiome, while uncommon bacterial cells make up less than 11% of the microbiome. Uncommon-seed-transmitted microbiomes consisted mostly of Proteobacteria, Firmicutes, Bacteriodetes, Ascomycetes and Basidiomycetes, which most heavily colonized shoots, to a lesser extent roots, and least of all, rhizospheres. Soil served as a more diverse source of rare microbes than seeds, replacing or excluding the majority of the uncommon-seed-transmitted microbiome. With the rarest microbes, their colonization pattern could either be the result of stringent biotic filtering by most plants, or uneven/stochastic inoculum distribution in seeds or soil. Several strong plant–microbe associations were observed, such as seed transmission to shoots, roots and/or rhizospheres of Sarocladium zeae (maize), Penicillium (pea and Phaseolus), and Curvularia (sugarcane), while robust bacterial colonization from cassava field soil occurred with the cyanobacteria Leptolyngbya into Arabidopsis and Panicum roots, and Streptomyces into cassava roots. Some abundant microbes such as Sakaguchia in rice shoots or Vermispora in Arabidopsis roots appeared in no other samples, suggesting that they were infrequent, stochastically deposited propagules from either soil or seed (impossible to know based on the available data). Future experiments with culturing and cross-inoculation of these microbes between plants may help us better understand host preferences and their role in plant productivity, perhaps leading to their use in crop microbiome engineering and enhancement of agricultural production.

Responses to nutrient addition, shading and clipping in a range expanding invasive plant, Mikania micrantha

AbstractInvasive plants often spread in their new range. During range expansion, the population density at the invasion front may be low compared to that at the invasion centre, and this may select for an acquisitive growth strategy, such as rapid growth, stronger responses to nutrient addition, less tolerance to shading and more tolerance to biomass removal. In this study, we tested this idea using 27 populations of an invasive plant, Mikania micrantha, which is spreading on Hainan island of China in the past 20 years. Nutrient addition increased biomass of M. micrantha, and shading and clipping reduced it. Population density, frequency of occurrence and their interaction with nutrient addition, shading or clipping did not influence plant biomass and root to shoot ratio (RSR). For the western populations, both population density and frequency of occurrence were negatively correlated with RSR in the shading treatment. Overall, populations of M. micrantha differed little in growth. The reasons for these results may be that the spread distance and residence time of M. micrantha on Hainan island are too short to drive any evolutionary change, strong interspecific invaders may prevent M. micrantha from acquiring abundant resources when population density and frequency are low, and long distance dispersal of seeds and pollen may potentially mix genes, preventing adaptive evolution. These results indicate that M. micrantha may not evolve to be more invasive during range expansion. Future studies can examine if populations of M. micrantha differ in other aspects, such as seed dispersal ability and competitive ability.

Disentangling the Regeneration Niche of Vatica odorata (Griff.) Symington Using Point Pattern Analysis

Seed dispersal and environmental heterogeneity, and the effects of their interaction, are perceived to be determinants of the spatial patterns of trees. We applied the spatial point process to analyse Vatica odorata (Griff.) Symington (Dipterocarpaceae) in Cuc Phuong National Park of Vietnam to understand its spatial patterns, and to decipher the main factors affecting seedling establishment of the species. We established a total of 12 replicated plots, each of which had one or two seed trees in the centre, and recorded all regeneration plants of V. odorata with their positions. A total of 671 regeneration plants were found. Covariates, including canopy, ground cover, and distance to seed trees, were measured on systematic grids of 4 × 4 m. In the context of the spatial point processes, we used a generalised linear mixed model, considering a random effect of the plot. In the model, the greatest distance observed is about 35 m from the seed tree. The canopy and ground cover have a significant impact on the regeneration of the species: The intensity of regenerating stems was greatest with a canopy cover of 70%. The ground cover range for good development of regenerating plants was between 10 and 30%.

Unmasking the perching effect of the pioneer Mediterranean dwarf palm Chamaerops humilis L.

Although farmlands are the most extensive terrestrial biomes, the abandonment of traditional agriculture in many parts of the world has brought opportunities and challenges for the restoration of such human-disturbed habitats. Seed arrival is a crucial necessary ecological process during plant recolonization that can be enhanced by the use of the so-called "perch plants". Little is known, however, about whether the seed arrival via frugivorous birds is affected by the spatial distribution of the perch plants in disturbed habitats. To evaluate several spatial aspects of "perching" effect, we used a spatially explicit approach in two disturbed plots within the Doñana National Park (SW Spain). Specifically, we chose as study system the pioneer Mediterranean dwarf palm Chamaerops humilis L., which is often used as a perch by a variety of frugivorous bird species. A total of 289 C. humilis individuals were sampled in search of bird feces (N = 2998) and dispersed seeds (N = 529). Recorded seeds belonged to six different woody species from five different families. Nine bird species from six different families were recorded using C. humilis as perches. GLMs analyses indicated that taller C. humilis males with higher numbers of spatially associated woody species received more dispersed seeds. We detected a random spatial structure of bird feces and dispersed seeds in one study plot, while a nonrandom spatial structure was found in the other one, where isolated C. humilis received a higher number of bird feces and dispersed seeds than expected under spatial null models. The difference in spatial patterns between both study plots could relate, among other factors, to their different state of development in the ecological succession. Most of dispersed seeds were concentrated in a small number of C. humilis individuals, usually male and large ones, that acted as "hotspots" of seed arrival. The fact that frugivorous birds in one study site visited most often isolated C. humilis questions the aggregated spatial structure of revegetation designs typically used in restoration projects. This study reveals novel spatial aspects of the "perching" effect which could be helpful in the restoration of human-disturbed habitats worldwide.

Effect of Altitude on Seed Dispersal and Seedling Establishment of Roth. in Garhwal Himalaya

Effect of Altitude on Seed Dispersal and Seedling Establishment of Roth. in Garhwal Himalaya

Improving measurements of the falling trajectory and terminal velocity of wind-dispersed seeds.

Seed dispersal by wind is one of the most important dispersal mechanisms in plants. The key seed trait affecting seed dispersal by wind is the effective terminal velocity (hereafter “terminal velocity”, V t ), the maximum falling speed of a seed in still air. Accurate estimates of V t are crucial for predicting intra‐ and interspecific variation in seed dispersal ability. However, existing methods produce biased estimates of V t for slow‐ or fast‐falling seeds, fragile seeds, and seeds with complex falling trajectories. We present a new video‐based method that estimates the falling trajectory and V t of wind‐dispersed seeds. The design involves a mirror that enables a camera to simultaneously record a falling seed from two perspectives. Automated image analysis then determines three‐dimensional seed trajectories at high temporal resolution. To these trajectories, we fit a physical model of free fall with air resistance to estimate V t . We validated this method by comparing the estimated V t of spheres of different diameters and materials to theoretical expectations and by comparing the estimated V t of seeds to measurements in a vertical wind tunnel. V t estimates closely match theoretical expectations for spheres and vertical wind tunnel measurements for seeds. However, our V t estimates for fast‐falling seeds are markedly higher than those in an existing trait database. This discrepancy seems to arise because previous estimates inadequately accounted for seed acceleration. The presented method yields accurate, efficient, and affordable estimates of the three‐dimensional falling trajectory and terminal velocity for a wide range of seed types. The method should thus advance the understanding and prediction of wind‐driven seed dispersal.

Сошниковая секция с дисковым рассеивателем семян

The issue of seed distribution during strip sowing of agricultural crops by using a disk seed disperser in the design of the joint is considered. The development of an optimal design of a coulter for strip sowing of vegetable seeds with a technologi-cally expedient method of sowing is presented. In confirmation of the advantages of strip sowing over ordinary, compara-tive experimental studies on the quality of seed distribution were conducted and the following results were obtained: - with an increase in the seeding rate, the coefficients of uniformity of sow-ing KV and density of sowing KP increase; - the feeding area of one plant SP at the seeding rate Q = 3 kg / ha in a two-disc coulter is greater and equal to 6.11 cm2, and at Q= 4 kg / ha it is greater in a coulter with an active seed disperser and is 5.01 cm2. Keywords: VEGETABLE CROPS, STRIP SOWING, PLANT FEEDING AREA, DISC SEED DISPERSER, COULTER, SOWING UNIT

Mountain bike riding and hiking can contribute to the dispersal of weed seeds

Mountain biking and hiking are popular, but both recreational activities can contribute to the unintentional dispersal of seeds including non-native plants that cause environmental harm (e.g. environmental weeds). Addressing the requirement for more information about the ecological impacts of recreational activities, seed dispersal from mountain biking and hiking were compared under different climatic and environmental conditions. Seeds from a range of graminids and forbs were found to attach to the mountain bike, rider and hiker, including environmental weed seeds, on trails and in-field in montane Australia. While the composition of seeds differed between the two activities, no significant differences were found between traits, such as natives or environmental weed, graminids or forbs, perennial or annual, large or small, attachment or no attachment structures, although sample sizes were small. Few seeds attached to the mountain bike, rider or hiker on dry trails, some seeds attached when trails were wet, but more seeds attached when riding/hiking off trail in a field. Cleaning clothing and bikes and avoiding areas with environmental weed seeding could reduce the risk of this type of unintentional human mediated dispersal, but compliance with such measures may be challenging. Given the increasing popularity of mountain biking and the current controversy about the relative impacts of mountain biking in areas of high conservation concern, additional research assessing severity, duration and range of impacts of mountain biking on soil, wildlife, waterways and vegetation is critical.

What are elaiosomes for? Effects of elaiosomes on ant attraction, seed removal and germination in wild chaya (Cnidoscolusaconitifolius)

Seed dispersal by ants is common in arid lands. The seeds of myrmecochorous plants bears an elaiosome, an appendage that acts as a reward for ants. Once an ant identifies an elaiosome-bearing seed, it carries the diaspore to the nest, removes the elaiosome and discards the seed. During elaiosome removal, ants also scarify the seed, which may favor seed germination or facilitate pathogen attack. Some elaiosomes are hygroscopic and therefore, this could increase water intake and retention. We assessed the effect of elaiosome removal, seed scarification and fungal infection on germination in Cnidoscolus aconitifolius, a plant species common in the arid tropics of the Americas. The effects of elaiosome removal on ant attraction and seed removal were also assessed. According to the results, the elaiosome of C. aconitifolius increases the attractiveness of its seeds to ants, but did not affect seed removal or seed germination. Also, the elaiosome significantly increased the chance of pathogen attack on the seed. The benefits of elaiosome removal on seed germination were mediated by physical scarification, with greater germination in scarified seeds without elaiosomes. Seed scarification did not affect the likelihood of fungal attack.

Mineral composition and technological and morphological performance of beans as influenced by organic seaweed-extracted fertilizers applied in different growth stages

Organic farming is an environment-friendly agricultural system able to eliminate negative impacts of chemicals on agricultural lands and environment. Experiments were conducted in 2020 and 2021 growing seasons to investigate the effects of organic-certificated liquid fertilizers obtained from seaweed extracts on morphological and technological traits and mineral composition of beans(Phaseolus vulgaris L.). Organic-certified fertilizers namely as Hygro Amin (HAM), Hygro Algin (HAL) and Rooting Plus (RP) obtained from seaweed were used as fertilizer sources. Positive effects were especially encountered on seed yield, cooking time, number of dispersed seeds after cooking and mineral composition (Fe, Zn, Na, Mg). Biplot analysis on morphological and technological traits and mineral composition revealed that there were positive relationships among Fe, Co, seed yield, number of pods per plant, number of seeds per plant, plant height and the first pod height since these parameters had close vector lengths to each other and placed into the same region and all hygro algin treatments increased these parameters.

Rivers as a potential dispersing agent of the invasive tree Acacia dealbata

BackgroundThe silver wattle Acacia dealbata is a fast-growing tree from Australia that has become naturalised in different regions of the world, attaining invasive status in most of them. In Chile, A. dealbata reaches large abundances along banks and floodplains of invaded fluvial systems, suggesting that rivers may act as a vector for seed dispersal. As hydrochory has not been documented previously in this species, the aim of this study is to evaluate the potential for water dispersal of seeds of this invasive tree along rivers.MethodsSeed samples from rivers were collected at three sites along two A. dealbata-invaded rivers within the Cachapoal basin, central Chile. Number of seeds collected was contrasted versus hydraulic and local conditions with RDA. Seed buoyancy and sedimentation velocity were determined and compared between sites with an ANCOVA. Finally, the probability of seed germination after long periods of immersion in water was assessed, simulating transport conditions in the flow. Germination results were tested with a GLM.ResultsResults indicate that increasing abundance of A. dealbata seeds in the flow is related to the level of turbulence of the flow. Seeds display high floatability but their sedimentation velocity is high when they do sink. Finally, silver wattle seeds can germinate after long periods (many weeks) of immersion in water; however, their probability of germination depends to a large extent on whether seeds are scarified or not.ConclusionsBased on the evidence collected, we suggest that the seeds of A. dealbata have the necessary traits to be dispersed by rivers, this being the first research testing this hypothesis. The success of hydrochory of A. dealbata would depend on river flow turbulence, and whether there are natural mechanisms for scarifying the seeds either before or during transport. The proposed methodology can be used to assess river hydrochory for any tree species.

Seed germination ecology of common bladderwort (Utricularia vulgaris L.)

Generative reproduction of the carnivorous aquatic plant Utricularia vulgaris (Lentibulariaceae) from seeds may be a critical process in the recovery of natural populations following temporary drying of habitat, and in the colonisation of new potential sites through dispersal of seeds by water birds. However, little is presently known about the seed ecology and germination biology of this species. We tested the germination response of seeds under various temperature and seed storage regimes, to examine the processes required for seed dormancy alleviation and the effects of different germination solution and temperature on germination probability. Seeds likely possess non-deep simple morphophysiological dormancy alleviated by warm stratification. Highest germination success was recorded for warm-stratified seeds and seeds exposed to ethylene. Seeds were photophilous, with germination more successful at 21 °C than at 25 °C and greatest in slightly alkaline (pH 8) germination solution containing KHCO3, CaCl2 and MgSO4 mimicking the mesotrophic humic waters in which the species naturally occurs. In the alkaline solution, 97 % of seeds rose to the surface prior to germination. In natural habitats, this effect may facilitate seedlings reaching the warmer and irradiated water surface. As seed germination success appears linked to light availability, water chemistry, and seed position in the water column, careful management and ecological restoration of remnant habitats harbouring this species may need to ensure positive conservation outcomes.

Plant-defense mimicry facilitates rapid dispersal of short-lived seeds by hornets

Rates of seed dispersal have rarely been considered important. Here, we demonstrate through field observations and experiments that rapid dispersal is essential for the unusually short-lived seeds of Aquilaria sinensis (agarwood; Thymelaeaceae), which desiccate and die within hours of exposure by fruit dehiscence in the hot, dry forest canopy in tropical southwest China. We show that three species of Vespa hornets remove most seeds within minutes of exposure. The hornets consume only the fleshy elaiosomes and deposit most seeds in damp shade, where they can germinate, a mean of 166m from the parent tree. Electrophysiological assays and field experiments demonstrate that the hornets are attracted by highly volatile short-carbon-chain (C5-C9) compounds, including aldehydes, ketones, alcohols, and acids, emitted from the dehiscent fruit capsule. These attractive fruit volatiles share 14 of 17 major electrophysiologically active compounds with those emitted from herbivore-damaged leaves, which attract predators, including hornets. Rapid seed dispersal thus appears to have been achieved in this species by the re-purposing of a rapid indirect defense mechanism. We predict that rapid seed dispersal by various mechanisms will be more widespread than currently documented and suggest that volatile attractants are more effective in facilitating this than visual signals, which are blocked by vegetation.

Role of germline variants in the metastasis of breast carcinomas.

Most cancer-related deaths in breast cancer patients are associated with metastasis, a multistep, intricate process that requires the cooperation of tumour cells, tumour microenvironment and metastasis target tissues. It is accepted that metastasis does not depend on the tumour characteristics but the host’s genetic makeup. However, there has been limited success in determining the germline genetic variants that influence metastasis development, mainly because of the limitations of traditional genome-wide association studies to detect the relevant genetic polymorphisms underlying complex phenotypes. In this work, we leveraged the extreme discordant phenotypes approach and the epistasis networks to analyse the genotypes of 97 breast cancer patients. We found that the host’s genetic makeup facilitates metastases by the dysregulation of gene expression that can promote the dispersion of metastatic seeds and help establish the metastatic niche—providing a congenial soil for the metastatic seeds.

Multimodal synchrotron X-ray fluorescence imaging reveals elemental distribution in seeds and seedlings of the Zn-Cd-Ni hyperaccumulator Noccaea caerulescens.

The molecular biology and genetics of the Ni–Cd–Zn hyperaccumulator Noccaea caerulescens has been extensively studied, but no information is yet available on Ni and Zn redistribution and mobilization during seed germination. Due to the different physiological functions of these elements, and their associated transporter pathways, we expected differential tissue distribution and different modes of translocation of Ni and Zn during germination. This study used synchrotron X-ray fluorescence tomography techniques as well as planar elemental X-ray imaging to elucidate elemental (re)distribution at various stages of the germination process in contrasting accessions of N. caerulescens. The results show that Ni and Zn are both located primarily in the cotyledons of the emerging seedlings and Ni is highest in the ultramafic accessions (up to 0.15 wt%), whereas Zn is highest in the calamine accession (up to 600 μg g–1). The distribution of Ni and Zn in seeds was very similar, and neither element was translocated during germination. The Fe maps were especially useful to obtain spatial reference within the seeds, as it clearly marked the vasculature. This study shows how a multimodal combination of synchrotron techniques can be used to obtain powerful insights about the metal distribution in physically intact seeds and seedlings.

Comparative Analysis of the Ecological Functions of Dung Removal and Seed Dispersal among Two Telecoprid and Two Paracoprid Dung Beetles (Coleoptera: Scarabaeidae: Scarabaeinae)

We evaluated the functional capacities of dung removal and secondary seed dispersal by two telecoprid dung beetles, Canthon rutilans cyanescens (Harold) and Deltochilum multicolor Balthasar, and two paracoprid dung beetles, Dichotomius sericeus (Harold) and Phanaeus splendidulus (Fabricius), in a remnant of Atlantic Forest in southern Brazil. We aimed to describe and understand the variability of these behaviors among these species and compare their dung removal capacities by standardized biomass. Two experiments were conducted to evaluate the effect of exposure time to the resource on the functional capacity of the four species and the effect of density on C. r. cyanescens and D. sericeus in arenas with single male/female pairs or groups of three pairs. Beetles were exposed to 30 g of canine feces with artificial seeds, which remained in the field for two, seven, or 21 days in four replicates. The paracoprids were more efficient than the telecoprids in all ecological functions. Canthon r. cyanescens removed significantly more dung with increasing exposure time and density, while D. multicolor showed no significant differences in any ecosystem function. For D. sericeus, time was relevant for increasing dung removal and dispersion of large seeds, while density only affected dung removal. Phanaeus splendidulus removed more dung with increasing exposure time, but its effect on seed dispersal was not significant. When evaluating dung removal capacity by standardized biomass, C. rutilans and D. sericeus were the most efficient species, demonstrating that paracoprids are usually more efficient because of their greater body biomass. As much as the functional capacity of certain ecological functions differs among species, different functional groups provide complementarity in communities. Thus, data on the biology and behavior of species are important in ecosystem functions.

Simple Mechanisms of Plant Reproductive Benefits Yield Different Dynamics in Pollination and Seed Dispersal Mutualisms.

AbstractPollination and seed dispersal mutualisms are critical for biodiversity and ecosystem services yet face mounting threats from anthropogenic perturbations that cause their populations to decline. Characterizing the dynamics of these mutualisms when populations are at low density is important to anticipate consequences of these perturbations. We developed simple population dynamic models detailed enough to distinguish different mechanisms by which plant populations benefit from animal pollination or seed dispersal. We modeled benefits as functions of foraging rate by animals on plant rewards and specified whether they affected plant seed set, germination, or negative density dependence during recruitment. We found that pollination and seed dispersal mutualisms are stable at high density but exhibit different dynamics at low density, depending on plant carrying capacity, animal foraging efficiency, and whether populations are obligate on their partners for persistence. Under certain conditions, all mutualisms experience destabilizing thresholds in which one population declines because its partner is too rare. Plants additionally experience Allee effects when obligate on pollinators. Finally, pollination mutualisms can exhibit bistable coexistence at low or high density when plants are facultative on pollinators. Insights from our models can inform conservation efforts, as mutualist populations continue to decline globally.

Identifying Avian Seed Dispersers through DNA Barcoding After Rapid Field Sampling

Las aves dispersoras de semillas se identifican principalmente mediante observaciones de consumo de frutos o mediante capturas con redes de niebla para el análisis posterior de las semillas expulsadas. Sin embargo, estos métodos generalmente requieren muchos días de trabajo de campo para proporcionar una primera idea de qué especies de aves dispersan las semillas de una especie de planta o una comunidad vegetal de interés. Aquí, destacamos las ventajas del análisis de códigos de barras de ADN después de un muestreo de campo rápido para descubrir dispersores de semillas desconocidos. Con muestreo de campo rápido nos referimos a la búsqueda y muestreo de semillas dispersadas por aves durante un período corto de tiempo (de tan sólo unas horas) en lugares donde la probabilidad de deposición de semillas es alta. Esta estrategia de muestreo ‘en un único día’ se basa en una gran ventaja de los códigos de barras de ADN: permiten identificar especies dispersoras durante un período relativamente largo desde que estas defecan o regurgitan las semillas, cubriendo un marco temporal de varias semanas. Mostramos este enfoque metodológico con tres especies de plantas emblemáticas y amenazadas para las cuales hay poca o ninguna información sobre la dispersión de semillas por aves, ya sea para toda su área de distribución o en determinadas poblaciones. El enfoque puede ser rentable y muy valioso para estudios piloto destinados a proporcionar información inicial sobre sistemas poco conocidos, o en lugares donde el trabajo de campo periódico no es factible debido a limitaciones logísticas o de accesibilidad.—González-Varo, J.P., Rumeu, B., Traveset, A. e Illera, J.C. (2022). Identificación de aves dispersoras de semillas mediante muestreo de campo rápido y códigos de barras de ADN. Ardeola, 69: 279-290.

Seed Mucilage Promotes Dispersal of Plantago asiatica Seeds by Facilitating Attachment to Shoes

Understanding the mechanisms underlying seed dispersal is a fundamental issue in plant ecology and vegetation management. Several species demonstrate myxospermy, a phenomenon where the seeds form mucilage after absorbing water. Mucilage is thought to act as a glue, enabling seeds to attach to the external surfaces of dispersing agents. However, there have been no quantitative investigations of the efficacy of this function of seed mucilage. We performed a trampling and walking experiment to investigate the seed dispersal of a perennial herb, Asian plantain (Plantago asiatica L.), which forms polysaccharide mucilage upon hydration. Our experiment showed that: (1) after trampling, more seeds of P. asiatica attached to shoes in wet conditions (after rainfall), in which seed mucilage was created, than in dry conditions (no rainfall); and (2) after walking for 1000 m, more seeds remained attached to shoes in wet conditions than in dry conditions. Our results indicate that mucilage promotes the adherence of seeds to the surface of vectors. We therefore provide the first empirical evidence that seed mucilage facilitates epizoochory and human-mediated dispersal.

Seagrass Connectivity on the West Coast of Africa Supports the Hypothesis of Grazer-Mediated Seed Dispersal

Population connectivity influences the distribution of genetic diversity and divergence along a species range, as the likelihood of extinction or differentiation increases in isolated populations. However, there is still poor understanding of the processes mediating inter-population dispersal in marine species that are sessile and lack planktonic life stages. One such case is the seagrass speciesHalodule wrightii, which produces basal seeds, although detached plants can drift. Along the tropical western coast of Africa, this species occurs in distant discontinuous habitats, raising the question of how interpopulation dispersal is mediated. The species is a key source of ecosystem functions including feeding large migratory grazers. This study aims to infer whether genetic differentiation of the seagrassH. wrightiialong the western coast of Africa supports a hypothesis of predominant transportation of rafting seagrass by ocean currents, versus the hypothesis of biotic vectors of dispersal. Additional hypotheses were addressed concerning range-wide clonality and genetic diversity, assessed with microsatellite markers on populations of the west coast of Africa from Mauritania to Angola. Population genetic diversity and structure were compared with predictions from biophysical models of dispersal by oceanographic currents. The genetic data revealed low divergence among most populations, in strong contrast with predictions of very low probability of connectivity mediated by currents along the western African coastline. Moderate to high genotypic diversity showed important seed recruitment, but genetic and genotypic diversities were lower at range edges. Populations north and south of the equator were differentiated, and remarkably, so were neighboring equatorial populations despite their proximity. These results reveal independent sources of colonization of meadows in these islands, which are major habitat for migratory grazing green turtles, also supporting the hypothesis of biotically mediated seed transport. The importance of seagrass for conservation of endangered macrofauna has been widely reported; here we report evidence supporting the reciprocal role, that macrofauna protection can also plays a role in long-term survival and reproductive success of seagrass.