Long-distance Dispersal Research Articles

Differential Primary Seed and Fruit Dispersal Mechanisms and Dispersal Biomechanics in Invasive Dehiscent and Indehiscent-Fruited Lepidium Species

This study explores primary dispersal, which involves diaspores’ detachment directly from mature plants, and secondary dispersal, which encompasses any further dispersal occurring after the primary dispersal. A comparison of the primary dispersal vectors of the invasive dehiscent fruit producing Lepidium campestre and the indehiscent fruit producing Lepidium draba was conducted. These vectors were examined in relation to the native and introduced distribution ranges of the species, and regarding biomechanical forces required detaching the fruits from mature plants. Our findings reveal that rainfall and animal contact serve as primary dispersal vectors for Lepidium campestre, while animal contact is rarely involved in primary dispersal of Lepidium draba. Primary dispersal is more important for Lepidium campestre than Lepidium draba, which requires significantly greater force for fruit detachment. While previous studies indicate wind and rainfall as major secondary dispersal vectors for Lepidium draba, our results suggest secondary dispersal via mucilage on seeds is more crucial for this species. The strong reliance of Lepidium draba on secondary dispersal, enabling long-distance dispersal, could contribute to its invasion success, linking it to the species’ geographic distribution. Understanding these different dispersal strategies is essential for effective management of invasive species.

Chasing the Rainbow: Decoupled phenotypic and genotypic evolution in New Guinea’s rainbow skinks (Squamata: Scincidae)

With the advent of molecular data, the discovery of cryptic species has become commonplace. New Guinea, a region of high vertebrate biodiversity and complex geological history, has been found to contain immense numbers of cryptic skink species. We present the first molecular phylogenetic analysis of Carlia Gray, 1845, and its sister genus Lygisaurus de Vis, 1884, across mainland New Guinea and the Solomon Islands. We find rainbow skinks exhibit significant genetic divergence with minimal morphological variation and our data suggest the existence of many undescribed species. Due to the morphologically cryptic nature of rainbow skinks, we demonstrate the efficacy of the COI gene as a “barcode” for difficult species determinations. Divergence time and biogeographic analyses support four separate dispersal events from Australia to New Guinea for rainbow skinks from ~10–5 mya, with most groups arriving first in the East Papua Composite Terrane (EPCT) and dispersing from there to other terranes and islands. Exceptions to this pattern were observed in Lygisaurus, which dispersed first to the West Papuan portion of the Craton ~8.4mya, and the island clade of the Carlia fusca group, which dispersed to the Vogelkop peninsula ~4.7mya and from there to many islands.

Phylogenetic origin of dioecious Callicarpa (Lamiaceae) species endemic to the Ogasawara Islands revealed by chloroplast and nuclear whole genome analyses.

Oceanic islands offer excellent opportunities to study the ecology, evolutionary biology, and biogeography of plants. To uncover the genetic basis of various evolutionary trends commonly observed on these islands, the origins and phylogenetic relationships of the species being studied should be understood. Callicarpa glabra, Callicarpa parvifolia, and Callicarpa subpubescens are evergreen woody plants endemic to the Ogasawara Islands, which are remote oceanic islands located off of the Japanese Archipelago. These species are ideal for studying evolutionary changes on oceanic islands because of their adaptive radiation and shift toward dioecious sex expression. We used a phylogenomic perspective to determine the evolutionary relationship of the three species within the genus and infer their colonization time. Based on the analysis of both chloroplast genomes and 86 nuclear single-copy genes, we found that these three species were monophyletic and embedded in a backbone clade that included multiple East Asian species. The phylogenetic tree based on over 10,000 nuclear genes placed the insular species in the East Asian clade, although the topology did not entirely correspond to the chloroplast tree, probably because of incomplete lineage sorting and interspecific hybridization. The three endemic species were estimated to have diverged from continental species approximately three million years ago (Mya). The results of this study suggested that the ancestor of the Ogasawara endemic species originated from long-distance dispersal from East Asia mainland in the late Pliocene, and then progressively speciated within the islands.

Phytolith evidence of agricultural emergence and its dispersal routes in the southeastern mountain area of China

Phytolith evidence of agricultural emergence and its dispersal routes in the southeastern mountain area of China

Comparative phylogeography of four lizard taxa within an oceanic island.

Comparative phylogeography aims to detect common patterns of differentiation among taxa attributed to the same geological or environmental barriers and, thus, find shared drivers of genomic splits and landscape features that explain patterns of occurrence and genetic diversity. Following this approach, this work focuses on four endemic lizard taxa, namely Acanthodactylus schreiberi schreiberi, Ophisops elegans schlueteri, Phoenicolacerta troodica, and Laudakia cypriaca, that co-occur in Cyprus, an isolated island of the Mediterranean. In an attempt to discern possible effects of the geological and ecological history of the region on diversity patterns along the lineages under study, samples were collected from all parts of Cyprus and phylogenetic reconstructions, species delimitation analyses, and biogeographic comparisons were conducted at both genetic and genomic levels (Sanger and ddRAD sequencing data, respectively) for all four taxa. The derived phylogenomic relationships provide evidence of a strong genetic structure within the island that agrees with the geographical origins of each population. A rare case of an island-to-mainland dispersal event is confirmed for one of the focal taxa, making it one of the few documented cases of this type. Estimated diversification times during the Miocene reflect the timing of the first arrival on the island, while further diversification seems to have been strongly affected by the Pleistocene oscillations.

What Do We Know About Non-Native, Invasive, and Transplanted Aquatic Mollusks in South America?

Global awareness of introduced species as one of the primary drivers of biodiversity change—causing environmental impacts, and economic and social effects—emphasizes the need to enhance our understanding of these species. Developing a comprehensive database will enable policymakers to identify global bioinvasion patterns and strengthen their capacity to manage them effectively. Aquatic mollusks play a crucial role in the ecosystems they inhabit, influencing food webs and nutrient cycling, and habitat formation and modification. They are also the dominant group in aquaculture, contributing significantly to the economy while also causing economic losses through macrofouling and posing health risks. Despite their importance, information on the introduction, establishment, and dispersal of mollusk species in South America remains scarce and is often confined to the grey literature. With the aim of organizing, increasing, and strengthening the knowledge of non-native and transplanted mollusks in general and aquatic mollusks in particular, 29 specialists in the introduced mollusks of South America, from seven countries, have been working collaboratively since 2016. Each member contributes expertise, data, and bibliographic resources to build the status of the introduced mollusks in South America and provide critical information to prevent future introductions and transplants. In aquatic environments, 41 non-native mollusk species and 18 transplanted species have been identified. Among them, the bivalve Limnoperna fortunei stands out with the greatest economic effect, while the gastropods Lymnaeidae and Thiaridae represent significant health concerns. Although this research represents a major step forward, it also highlights challenges such as the scarcity of taxonomic studies and the limited investigation of vast areas in South America. The information compiled in this review serves as a resource for researchers, policymakers, and the general public when addressing mollusk bioinvasions in South America.

Insights into the exceptional support phase effect on Ag/Sm2Ce2O7: Modulating Ag distribution and Ag-support interaction to construct reactive soot oxidation catalysts

Developing efficient, cost-effective and robust catalysts for soot combustion is crucial yet challenging. In this study, we fabricated Ag-loaded Sm2Ce2O7 paramorphs catalysts (C-type and Cubic fluorite) via different methods, aiming to improve the distribution and interaction of Ag by modifying the crystalline structures of the supports to enhance oxygen activation. The oxygen vacancy concentration and redox performance of the rare earth C-type catalysts exceeded those of the cubic fluorite ones. In the case of the Ag-assisted catalysts, the Sm2Ce2O7–Ag interface with oxygen vacancies displayed an increased affinity for oxygen. The distribution state of Ag on the catalysts is closely related to the Ag–support interactions and the active sites on the support. Experimental analyses and density functional theory (DFT) calculations have revealed a more even dispersion of the Ag species on the C-type catalyst; differential charge density and Bader charge analysis have confirmed that the Ag loadings can alter the surface charge arrangement, resulting in stronger electronic interactions between Ag and the Sm2Ce2O7-C support. Uniformly dispersed Ag species can effectively promote the activation of gaseous O2 molecules, which is key in the oxidation of soot particles. This approach provides a promising strategy for developing more applicable catalysts for soot combustion.

Apparent survival and population turnover in a long-lived generalist raptor: a comparison of estimation methods

Adult survival and turnover rates are often estimated in long-lived species as the primary drivers of population dynamics. Various methods have been used, yet comparison of estimation methods is seldom undertaken. To address this gap, we used colour-ringing across different age groups, as well as GPS-tracking and genetic analysis of shed feathers, to estimate these critical parameters in a population of the medium-sized bird of prey, the Lesser Spotted Eagle. According to the colour-ringing data, the apparent survival during the first year of life (0.21) was more than four times lower than that of birds older than one year (0.88); the GPS-tracking (0.84) and genetic analysis (0.81) yielded similar survival estimates. All used techniques indicated a stable trend in apparent survival rates. However, population turnover rates derived from genetic feather analysis (0.17–0.43) exceeded expectations based on apparent survival estimates, as well as those derived from colour-rings (0.05–0.17) and GPS-tracking (0.05–0.08). Notably, all markers indicated high site fidelity among adult eagles, with breeding dispersal events being infrequent. Our findings underscore the utility of diverse methods for estimating apparent survival, though the ecological characteristics of the species may influence the efficacy of each method. However, estimates of population turnover rates were notably influenced by the choice of method and should be interpreted cautiously before recommending management actions.

Observation of Tropilaelaps mercedesae (Mesostigmata: Laelapidae) on Western honey bees (Apis mellifera) exiting colonies.

Tropilaelaps mercedesae (Delfinado and Baker) is an emerging parasitic mite that can severely impact the Western honey bee (Apis mellifera L.). While T. mercedesae has been reported to be expanding its geographical range, the routes of inter-colony dispersal between A. mellifera colonies are still largely unknown. In this study, we used funnel traps to collect foraging honey bees exiting their colonies before performing an alcohol wash to collect any phoretic T. mercedesae mites. We found T. mercedesae on exiting adult honey bees; however, they were only detected when a colony had an elevated T. mercedesae brood infestation. We show that T. mercedesae can exit colonies through phoresy on adult A. mellifera which demonstrates the potential of these mites to be spread through the natural movement of A. mellifera honey bees among colonies.

Climate-driven range expansion via long-distance larval dispersal

Climate-driven warming and changes in major ocean currents enable poleward larval transport and range expansions of many marine species. Here, we report the population genetic structure of the gastropod Kelletia kelletii, a commercial fisheries species and subtidal predator with top-down food web effects, whose populations have recently undergone climate-driven northward range expansion. We used reduced representation genomic sequencing (RAD-seq) to genotype 598 adults from 13 locations spanning approximately 800 km across the historical and expanded range of this species. Analyses of 40747 single nucleotide polymorphisms (SNPs) showed evidence for long-distance dispersal of K. kelletii larvae from a central historical range site (Point Loma, CA, USA) hundreds of km into the expanded northern range (Big Creek, CA), which seems most likely to result from transport during an El Niño-Southern Oscillation (ENSO) event rather than consistent on-going gene flow. Furthermore, the high genetic differentiation among some sampled expanded-range populations and their close genetic proximity with distinct populations from the historical range suggested multiple origins of the expanded-range populations. Given that the frequency and magnitude of ENSO events are predicted to increase with climate change, understanding the factors driving changes in population connectivity is crucial for establishing effective management strategies to ensure the persistence of this and other economically and ecologically important species.

Crystal Phase-Dependent Dispersion and Catalysis of the Ag Species Supported on TiO2 for CO Oxidation with Excess Oxygen

Crystal Phase-Dependent Dispersion and Catalysis of the Ag Species Supported on TiO₂ for CO Oxidation with Excess Oxygen

Spontaneous adsorption of iridium chloride complex on oxychloride photocatalysts provides efficient and durable reaction site for water oxidation.

The visible-light-driven O2 evolution on oxychloride photocatalysts, such as Bi4NbO8Cl, was significantly enhanced by stirring in an aqueous solution containing IrCl63- in the dark. Various characterizations indicated that highly dispersed IrOxHyClz-like species spontaneously formed on the oxychloride surface, serving as effective and stable cocatalysts for enhancing O2 evolution.

Ecological and demographic drivers of kin-directed cooperation in a social bird: Insights from a long-term study.

The evolution of sociality is one of the major evolutionary transitions in the history of life and a key step in this transition is the occurrence of kin associations. Yet, the question of what demographic processes and environmental factors generate kin-structured populations and drive kin-directed cooperation remains open. In this review, we synthesise 30 years of studies of the long-tailed tit Aegithalos caudatus, which has a kin-selected cooperative breeding system with redirected help: failed breeders may help to raise offspring of conspecifics, typically relatives, breeding nearby. We describe the use of ecological, demographic, genetic and behavioural approaches to reveal: (a) how kin-structured populations (here 'kin neighbourhoods') arise; (b) why the prevalence of cooperation varies among populations and individuals; and (c) how variation in dispersal and opportunities for cooperation influence individual fitness. The kin neighbourhoods of long-tailed tits arise from three processes. First, natal dispersal is limited and sex-biased so many individuals, especially males, recruit as breeders close to their natal site. Second, neither dispersal nor migration necessarily disrupts kin associations because long-tailed tits often move with close relatives. Third, a small effective population size driven by high nest predation rates enhances within-population relatedness. Together, these processes set the scene for kin-directed helping behaviour by causing spatial clustering of relatives. The prevalence of cooperation within kin neighbourhoods depends on several factors, both at the population-level (annual nest predation rate and length of the breeding season) and individual-level (relatedness, familiarity, sex and condition). However, limited information on prior social association and the reliability of kin discrimination cues hampers our current understanding of individual helping decisions. Finally, variation in dispersal within and between sexes affects the probability of interacting with kin, the likelihood of cooperation, and accrual of the direct and indirect components of inclusive fitness. We use this comprehensive understanding of the factors driving cooperative behaviour in long-tailed tits to highlight gaps in knowledge and suggest future avenues for research in this system, and to make general inferences about the role of dispersal, demography and kinship in social evolution.

Otolith Increments and Elements: Assessing a Recently Discovered Population of Weather Loach

ABSTRACTThe introduction of aquatic non‐native species into novel systems may have negative impacts on native biodiversity. Introduced species can predate native species, compete for resources, transmit diseases, hybridise and degrade habitat. To minimise impacts on aquatic biota, management efforts are needed to reduce invasive species abundance. However, eradication or reduction efforts require information about the source of introductions and the biology and ecology of the organism. Therefore, the objective of this study was to quantify population dynamics, natal origins and dispersal characteristics of the introduced Weather Loach Misgurnus anguillicaudatus, which was recently discovered in Georgia, USA waters. Sagittal otoliths were extracted and aged to determine dynamic rate functions, and we performed microchemical analysis on a subset of otoliths to quantify dispersal and introduction events. Sampled Weather Loach consisted of a wide range of ages and lengths, indicating that natural reproduction and recruitment have been occurring for multiple years. The change in otolith microchemistry seen in some fish reveals that they have dispersed from their introduction or reproduction sites into different areas, while others have likely remained in the same system since hatching. Overall, our findings indicate that the Weather Loach populations in Georgia are disjunct, likely stemming from multiple introductions. These results will be used to develop management strategies as well as aid in the effort to continue and enhance outreach regarding the release of unwanted aquarium fish.

Hot child in the city: Drivers of urban buffelgrass presence in Tucson, Arizona

AbstractInvasive species distributions and ecological impacts in natural ecosystems have been broadly studied, but invasive species urban distributions and impacts on human populations warrant further investigation. Urban areas are highly disturbed environments at high risk of invasion by non‐native species, and urban infrastructure can influence the dispersal and abundance of invasive species. Furthermore, in areas with concentrated human populations, invasive species may pose a risk to human as well as native biota. Here, we examine (1) how high‐traffic roadways and the presence of suitable habitat influence buffelgrass abundance in residential areas and (2) whether buffelgrass differentially invades residential areas across socioeconomic levels and racial diversity indices in Tucson, Arizona. We found that, within residential areas, the presence of vacant lots was positively associated with buffelgrass abundance; however, there was no relationship between other suitable habitat types and buffelgrass abundance. We found no relationship between road type and buffelgrass abundance in residential areas. We found that lower‐income communities were more likely to be invaded by buffelgrass, but there was no relationship between racial diversity index and buffelgrass abundance. Understanding drivers of invasive species presence and abundance in urban areas is necessary to inform urban management strategies to prevent spread to surrounding wildlands.

Extreme migratory connectivity and apparent mirroring of non-breeding grounds conditions in a severely declining breeding population of an Afro-Palearctic migratory bird

Understanding the distribution of breeding populations of migratory animals in the non-breeding period (migratory connectivity) is important for understanding their response to environmental change. High connectivity (low non-breeding population dispersion) may lower resilience to climate change and increase vulnerability to habitat loss within their range. Very high levels of connectivity are reportedly rare, but this conclusion may be limited by methodology. Using multiple tracking methods, we demonstrate extremely high connectivity in a strongly declining, peripheral breeding population of a long-distance migrant, the Common Nightingale in the UK. Non-breeding population dispersion is lower than for previously tracked populations of this and other species and likely lower than can usually be detected by light-level geolocation, the main tracking method for small bodied species. Extremely low levels of population mixing were also detected, so any impacts on this population on the non-breeding grounds are unlikely to be shared with more distant breeding populations, corresponding to the observed patterns of European population change. According to a species distribution model using independent field data, this population’s non-breeding grounds had lower suitability than others and likely declined before the period we were able to assess. These results support hypotheses that climatic and habitat-related deterioration of non-breeding grounds contributes to population declines in peripheral and high-connectivity breeding populations of long-distance migrants, including the one studied here.

Rangr: An R package for mechanistic, spatially explicit simulation of species range dynamics

Abstract Global change driven by human activities is causing profound shifts in species distributions. Understanding the mechanisms that influence these dynamics is crucial for biodiversity management. Several mechanistic, spatially explicit models have been proposed to address this issue, but they do not cover the full range of potential functionalities. We present a new open‐source R package called rangr, which integrates population dynamics and dispersal into a mechanistic virtual species simulator. The package can be used to study the effects of environmental change on population growth and range shifts. It extends the capabilities of previously available simulators by allowing simple and straightforward definition of population dynamics (including positive density dependence), extensive possibilities for defining dispersal kernels and the ability to generate virtual ecologist data. We showcased rangr functionality by simulating the invasion of the collared dove (Streptopelia decaocto). First, we demonstrated how to set up a simulation with different dispersal kernels by investigating the role of long‐distance dispersal events on colonisation outcome. Second, we showed the use of rangr to assess the potential of an Allee effect to impede biological invasion. Finally, we used the virtual ecologist framework to determine the timeframe required to detect the spread of an invasive species. The rangr package, which comes with extensive documentation and vignettes, is easy to set up, flexible, fast, fully configurable and capable of emulating the observation process. These features make rangr particularly well suited to generating data that replicate existing wildlife monitoring programmes.

Ensuring representative sample volume predictions in microplastic monitoring

A large body of literature is available quantifying microplastic contamination in freshwater and marine systems across the globe. “Microplastics” do not represent a single analyte. Rather, they are usually operationally defined based on their size, polymer and shape, dependent on the sample collection method and the analytical range of the measurement technique. In the absence of standardised methods, significant variability and uncertainty remains as to how to compare data from different sources, and so consider exposure correctly. To examine this issue, a previously compiled database containing 1603 marine observations and 208 freshwater observations of microplastic concentrations from across the globe between 1971 and 2020 was analysed. Reported concentrations span nine orders of magnitude. Investigating the relationship between sampling methods and reported concentrations, a striking correlation between smaller sample unit volumes and higher microplastic concentrations was observed. Close to half of the studies reviewed scored poorly in quality scoring protocols according to the sample volume taken. It is critical that sufficient particles are measured in a sample to reduce the errors from random chance. Given the inverse relationship with particle size and abundance, the volume required for a representative sample should be calculated case-by-case, based on what size microplastics are under investigation and where they are being measured. We have developed the Representative Sample Volume Predictor (RSVP) tool, which standardises statistical prediction of sufficient sample volumes, to ensure microplastics are detected with a given level of confidence. Reviewing reports in freshwater, we found ~ 12% of observations reported sample volumes which would have a false negative error rate > 5%. Such sample volumes run the risk of wrongly concluding that microplastics are absent in samples and are not sufficient to be quantitative. The RSVP tool also provides a harmonised Poisson point process estimation of confidence intervals to test whether two observations are likely to be significantly different, even in the absence of replication. In this way, we demonstrate application of the tool to evaluate historic data, but also to assist in new study designs to ensure that environmental microplastic exposure data is relevant and reliable. The tool can also be applied to other data for randomly dispersed events in space or time, and so has potential for transdisciplinary use.Graphical

Dispersal of influenza virus populations within the respiratory tract shapes their evolutionary potential

Viral infections are characterized by dispersal from an initial site to secondary locations within the host. How the resultant spatial heterogeneity shapes within-host genetic diversity and viral evolutionary pathways is poorly understood. Here, we show that virus dispersal within and between the nasal cavity and trachea maintains diversity and is therefore conducive to adaptive evolution, whereas dispersal to the lungs gives rise to population heterogeneity. We infected ferrets either intranasally or by aerosol with a barcoded influenza A/California/07/2009 (H1N1) virus. At 1, 2, or 4 days postinfection, dispersal was assessed by collecting 52 samples from throughout the respiratory tract of each animal. Irrespective of inoculation route, barcode compositions across the nasal turbinates and trachea were similar and highly diverse, revealing little constraint on the establishment of infection in the nasal cavity and descent through the trachea. Conversely, infection of the lungs produced genetically distinct viral populations. Lung populations were pauci-clonal, suggesting that each seeded location received relatively few viral genotypes. While aerosol inoculation gave distinct populations at every lung site sampled, within-host dispersal after intranasal inoculation produced larger patches, indicative of local expansion following seeding of the lungs. Throughout the respiratory tract, barcode diversity declined over time, but new diversity was generated through mutation. De novo variants were often unique to a given location, indicating that localized replication following dispersal resulted in population divergence. In summary, dispersal within the respiratory tract operates differently between regions and contributes to the potential for viral evolution to proceed independently in multiple within-host subpopulations.

Abundance survey of crustacean “y-larvae” (Thecostraca: Facetotecta) over a fringing reef in Okinawa, Japan, with special reference to the two dominant planktotrophic and lecithotrophic naupliar types

Facetotecta, or “y-larvae”, are mysterious planktonic crustaceans that are known only from their larval instars, but which are often assumed to be endoparasitic as adults. Dozens of mostly undescribed forms occur in the shallow-water plankton over a fringing reef at Sesoko Island, Okinawa, Japan. Recently, it has become possible to discriminate the different forms of their nauplius-stage larvae (“y-nauplii”) in a replicable way. A large year-to-year overlap in morphospecies recovered during fieldwork at Sesoko Island in 2018, 2019, and 2023 suggests that a full inventory is close at hand. To date, 49 morphospecies of y-nauplii (8 planktotrophic, 41 lecithotrophic) have been recognized in the area, among which three have been formally described. A detailed analysis of the temporal fluctuations in abundance during October 2023 showed that most morphospecies were rare, but two were particularly common: Type A*, a planktotroph with a long (> 3 weeks) period of naupliar development allowing for long-distance dispersal, and Type AG*, a lecithotroph with a short (3 days) period of development that implies rapid local recolonization. During the survey, both types showed distinct, largely non-overlapping peaks in abundance, related perhaps to their different dispersal/feeding strategies. An examination of the morphology of the swimming/feeding appendages in y-nauplii of Types A* and AG*, together with a mapping of feeding versus non-feeding nauplii on a recent comprehensive phylogeny of Facetotecta, suggests that broader taxonomic coverage of naupliar feeding structures in this group may provide useful information regarding the evolutionary direction of planktotrophy versus lecithotrophy in marine larvae.