Passive Dispersal Research Articles

Darwin Returns to the Galapagos: Genetic and Morphological Analyses Confirm the Presence of Tramea darwini at the Archipelago (Odonata, Libellulidae).

Simple SummaryFlying insects are able to colonize oceanic islands by both active and passive dispersal. Ten species of dragonflies are found in the Galapagos archipelago, located at 900 km from mainland South America. Shortly after the publication of Darwin’s “The Origin of Species”, one of the dragonflies from these islands was named after him as Tramea darwini. However, subsequent studies considered it to belong to another continental species of the same genus known as Tramea cophysa. Here, we studied a series of specimens of Tramea collected in 2018 from the Islands of San Cristobal, Isabela, and Santa Cruz, with the aim of determining their specific identity, through a combination of molecular and morphological analyses. Our results indicate that the Galapagos specimens examined belong to Tramea calverti, another continental species, and not to T. cophysa as previously thought. Following the principle of priority in taxonomic nomenclature, Tramea calverti, which was described in 1910 by Muttkowski, should hereafter be considered a synonym of Tramea darwini, which was described in 1889 by Kirby; hence, the species named after Darwin is to be considered valid, inhabiting both the Galapagos islands and continental America.The status of the Tramea species present in the Galapagos Islands (Odonata, Libellulidae) has been the subject of a long-standing debate among odonatologists. Here, we use molecular and morphological data to analyze a series of specimens from this genus collected in 2018 from the Islands of San Cristobal, Isabela, and Santa Cruz, with the aim of determining their relationship with Tramea calverti Muttkowski and with their currently considered senior synonym T. cophysa Hagen. We combined sequencing of mitochondrial and nuclear DNA with morphological examination of several specimens of Tramea, including representatives of continental T. cophysa and T. calverti. Our molecular analyses place the Tramea from Galapagos in the same clade as T. calverti, with T. cophysa as a closely related species. The morphological analyses found only one consistent difference between T. cophysa and T. calverti: the presence of an accessory lobe in the male vesica spermalis of T. cophysa that is absent in T. calverti and in the Tramea from Galapagos. In agreement with our genetic results, the overall morphological differences documented by us indicate that the Galapagos material examined is conspecific with T. calverti. In light of this, and following the principle of priority in taxonomic nomenclature, Tramea calverti Muttkowski, 1910 should hereafter be considered a junior synonym of Tramea darwini Kirby, 1889.

Effects of anthropogenic pollution and hydrological variation on macroinvertebrates in Mediterranean rivers: A case-study in the upper Tagus river basin (Spain)

Seasonal hydrological variation and chemical pollution represent two main drivers of freshwater biodiversity change in Mediterranean rivers. We investigated to what extent low flow conditions can modify the effects of chemical pollution on macroinvertebrate communities. To that purpose, we selected twelve sampling sites in the upper Tagus river basin (central Spain) having different sources of chemical pollution and levels of seasonal hydrological variation. The sites were classified as natural (high flow variation, low chemical impact), agricultural (high flow variation, high agricultural chemical inputs) and urban (limited flow variation, high urban chemical inputs). In these sites, we measured daily water discharge, nutrients, and contaminant concentrations, and we sampled benthic macroinvertebrates, in spring, summer and autumn. Significant differences related to toxic pressure and nutrient concentrations were observed between the three groups of sites. Seasonal patterns were found for some water quality parameters (e.g. nitrites, ammonia, suspended solids, metal toxicity), particularly in agricultural sites. Taxonomic and functional richness were slightly lower in the polluted sites (agricultural and urban), particularly during low flow periods (summer and early autumn). Functional diversity was significantly lower in sites with seasonal flow variation (agricultural sites) as compared to the more constant ones (urban sites). The frequency of traits such as large size, asexual reproduction, aquatic passive dispersion and the production of cocoons increased in response to pollution during low flow periods. This study shows that the impacts of anthropogenic chemical pollution on taxonomic and functional characteristics of macroinvertebrate communities seem to be larger during low flow periods. Therefore, further studies and monitoring campaigns assessing the effects of chemical pollution within these periods are recommended.

Limnology of rock pools in the river Chenab at Dhoomi, Akhnoor, in Jammu region of the Union Territory of Jammu and Kashmir

Small and temporary freshwater rock pools, compared to lakes, ponds and rivers, have received a very little scientific attention in India. For the present limnological study, six rock pools in the river Chenab at Dhoomi, Akhnoor, were analysed seven times for water quality and fauna during 17-01-2011 to 26-01-2011 and have been described. Among various water parameters depth (6-11 cm), transparency (6-11 cm) and turbidity (1.4-6.88 NTU) recorded a decrease after high record on first observation. Salinity remained constant (0.1 ppt) on all the seven observations. Dissolved oxygen (DO) observed maximum (12.81 mg/l) record on 19-01-2011 and minimum (9.99 mg/l) on 26-01-2011. Chloride (Cl?) was minimum (2.73 mg/l) on 17-01-2011 and 18-01-2011 and maximum (6.81 mg/l) on 24-01-2011. Conductivity (75.50 – 178.8 µS cm?¹), total dissolved solids (TDS) (40.13 – 85.5 mg/l), Biological oxygen demand (BOD) (2.5 – 6.63 mg/l), pH (8.26 – 9.12), carbonate ( CO3-2) (2.31 – 22.84 mg/l), bicarbonate (HCO3-) (29.83 – 71.29 mg/l), calcium (Ca+2) (9.45 – 29.50 mg/l), magnesium (Mg+2) (2.24 – 5.38 mg/l), total hardness (TH) (35.34 – 95.80 mg/l) and sodium (Na+) (0.44 – 1.05 mg/l) showed highest record on last observation. Potassium (K+) (0.60 – 1.70 mg/l) was minimum on 18-01-2011 and maximum on 24-01-2011. Nitrate (NO3?) (0.084-0.373 mg/l), phosphate (PO4³? ) (0.043 – 0.140 mg/l), silicate (SiO4-4) (1.28 – 3.95 mg/l) and sulphate (SO4-2) (4.89 – 7.84 mg/l) observed an irregular pulse. Fauna in these rock pools was represented by zooplankton (passive dispersers) belonging to Protozoa (27 species), Rotifera (3 species), gemmules of Porifera (2 species) and Turbellaria (1 species) only. Zooplanktonic maximum qualitative record was observed on 6th observation and quantitative on 7th observation. In the absence of any earlier study on freshwater rock pools in the Himalayan rivers, present work shall be of great help for future workers.

Understanding macroinvertebrate metacommunity organization using a nested study design across a mountainous river network

Metacommunity ecology highlights the importance of integrating simultaneously environmental filtering and spatial processes, such as mass effects and dispersal limitation, into investigation of community assembly. However, few studies to date have tried to examine mass effects and dispersal limitation as independent ecological mechanisms along with environmental filtering in shaping biological communities in river networks. We examined the relative importance of three factor groups, i.e., environmental variables, within-river spatial factors (indicative of mass effects) and basin identity (referring to dispersal limitation) on a macroinvertebrate metacommunity and nine trait-based deconstructed sub-metacommunities from seven subtropical rivers. We applied redundancy analysis and variance partitioning to reveal the pure and shared effects of the three groups of factors on community variation. Environmental filtering, mass effects and dispersal limitation were all significant mechanisms affecting variation in macroinvertebrate communities, but their relative importance depended on biological traits. Environmental filtering explained more of the variation in the whole metacommunity, tolerant taxa and macroinvertebrate groups with weak dispersal ability (i.e., aquatic dispersal, aerial passive dispersal and large body size). In contrast, mass effects accounted for more variation in the communities of intolerant taxa and macroinvertebrate groups with strong dispersal ability (i.e., aerial active dispersal mode and medium body size). Dispersal limitation was more influential for sub-communities of moderately tolerant taxa and large-sized taxa. Our study highlights that simultaneously accounting for different spatial processes and using a trait-based approach are essential to improve our understanding of community assembly in river networks.

The relative contribution of non-selection and selection processes in marine benthic assemblages

We tested the hypothesis that the ubiquity of marine meiofaunal nematodes and their indiscriminate passive dispersal create assemblages that are less limited by its environment; whereas the relatively smaller population sizes of macrofauna, associated with their ability to track environmental conditions before settlement, renders their distribution more environmentally-restricted. We compared the empirical distribution of macrofauna and nematode species with that of communities simulated under different assumptions of selection (e.g. environmental filtering) and non-selection (e.g. dispersal limitation) processes. Selection processes were the prime driver of both meio- and macrofauna assemblages, with rare species strongly contributing to this component. The total number of species explained by non-selection processes was 27% higher in nematodes than in macrofauna. Our results underline the importance of a species-level approach to determine the contribution of selection and non-selection assembly processes. Moreover, they highlight the important yet overlooked role of dispersal and stochastic processes in determining species dynamics.

Stream Microbial Community Structured by Trace Elements, Headwater Dispersal, and Large Reservoirs in Sub-Alpine and Urban Ecosystems.

Stream bacterioplankton communities, a crucial component of aquatic ecosystems and surface water quality, are shaped by environmental selection (i.e., changes in taxa abundance associated with more or less favorable abiotic conditions) and passive dispersal (i.e., organisms’ abundance and distribution is a function of the movement of the water). These processes are a function of hydrologic conditions such as residence time and water chemistry, which are mediated by human infrastructure. To quantify the role of environmental conditions, dispersal, and human infrastructure (dams) on stream bacterioplankton, we measured bacterioplankton community composition in rivers from sub-alpine to urban environments in three watersheds (Utah, United States) across three seasons. Of the 53 environmental parameters measured (including physicochemical parameters, solute concentrations, and catchment characteristics), trace element concentrations explained the most variability in bacterioplankton community composition using Redundancy Analysis ordination. Trace elements may correlate with bacterioplankton due to the commonality in source of water and microorganisms, and/or environmental selection creating more or less favorable conditions for bacteria. Bacterioplankton community diversity decreased downstream along parts of the stream continuum but was disrupted where large reservoirs increased water residence time by orders of magnitude, potentially indicating a shift in the relative importance of environmental selection and dispersal at these sites. Reservoirs also had substantial effects on community composition, dissimilarity (Bray-Curtis distance) and species interactions as indicated by co-occurrence networks. Communities downstream of reservoirs were enriched with anaerobic Sporichthyaceae, methanotrophic Methylococcaceae, and iron-transforming Acidimicrobiales, suggesting alternative metabolic pathways became active in the hypolimnion of large reservoirs. Our results identify that human activity affects river microbial communities, with potential impacts on water quality through modified biogeochemical cycling.

Is the spread of the alien water boatman Trichocorixa verticalis verticalis (Hemiptera, Corixidae) aided by zoochory and drought resistant eggs?

Abstract Desiccation resistance is a key trait determining the distribution of aquatic insects, their potential for overland dispersal, and survival during drought periods in temporary waterbodies, as well as the spread of invasive species. Passive dispersal by waterbirds is considered to be a key process favouring the spread of invasive species and is more likely to occur for insects with eggs that are resistant to desiccation or gut passage. We investigated the hypothesis that the eggs of the alien boatman Trichocorixa verticalis verticalis are resistant to desiccation and digestion and thus able to disperse via waterbirds. We conducted experiments to test for egg resistance to desiccation in still air and under moving air conditions, to simulate bird flight. Oviposition on greater flamingo (Phoenicopterus roseus) legs and wetland plants was tested in the laboratory and in the field. Resistance of eggs to simulated gut passage was studied, as was the viability of eggs recovered from Eurasian coot (Fulica atra) droppings in the field. Only a fraction of eggs hatched after 8 hr of exposure to still air at 15°C (4% of exposed eggs), and after 2 hr exposure to air flow conditions at 20°C (8%). Oviposition on flamingo legs was confirmed in the laboratory but not in the field. However, oviposition rates were higher on plant stems than on flamingo legs. Digestion simulations showed very low resistance to chemical treatment and no resistance to scarification, and eggs recovered from coot droppings did not hatch. Our experiments demonstrated that T. v. verticalis cannot be considered to have eggs resistant to desiccation or gut passage. However, the dispersal of eggs on legs of flamingos or other waterbirds may occur as rare events. This epizoochory of eggs could potentially contribute to the expansion and gene flow of T. v. verticalis around the Mediterranean region.

The influence of solar natural heating and NOx-O3 photochemistry on flow and reactive pollutant exposure in 2D street canyons

This study incorporates solar radiation model and NOx-O3 photochemistry into computational fluid dynamics (CFD) simulations with the standard k-ε model to quantify the integrated impacts of turbulent mixing, solar heating and chemical processes on vehicular passive (CO) and reactive (NOx, O3) pollutant dispersion within two-dimensional (2D) street canyons. Various street aspect ratios (H/W = 1, 3, 5) and solar-radiative scenarios (LST 0900, 1200, 1500) are considered. The initial source ratio of NO2 to NO is 1:10 and the background O3 concentration is 100 ppb (mole fraction). The reference Reynolds numbers are ~106–107 and Froude number ranges from 0.23 to 1.14. Personal intake fraction (P_IF) and its spatially-averaged values at the leeward-side (⟨P_IF⟩lee), windward-side (⟨P_IF⟩wind) and both street sides (⟨P_IF⟩) are adopted to evaluate pollutant exposure in near-road buildings.As H/W = 1 and 3, the clockwise single vortex is formed under neutral condition. Leeward/ground solar heating at LST 0900/1200 slightly enhance such vortex and reduce ⟨P_IF⟩. However, as H/W = 3, the single dominant vortex is separated into two counter-rotating vortices by windward solar heating at LST 1500, thus this ⟨P_IF⟩wind is significantly larger than the neutral case. As H/W = 5, the lower-level secondary anticlockwise vortex appears under neutral condition inducing much weaker wind and extremely higher pedestrian-level concentration. This two-main-vortex structure is destroyed by leeward/ground heating into single-main-vortex pattern, but dissociates into three counter-rotating vortices by windward heating. These three radiative scenarios raise pedestrian-level velocity in neutral case by about two orders, and reduce overall ⟨P_IF⟩ by two times to one order. For all cases, NO2 exposure is generally about 40%–380% larger than passive CO exposure, which indicates the conversion of NO into NO2 by depleting O3 is dominant in present NOx-O3 titration interactions. Finally, solar heating only raises air temperature by up to 2–3 K and influences chemical rate slightly, thus this impact on reactive pollutant dispersion is less significant than its effect by the enhanced turbulent mixing.

Construction of urban turbulent flow database with wavelet-based compression: A study with large-eddy simulation of flow and dispersion in block-arrayed building group model

Urban Turbulent flow database, which includes accurately simulated velocity field with full spatial distribution and time-dependent dynamics, is beneficial for fast analysis of pollutant dispersion and comprehensive validation. However, the enormous data volume makes storage and sharing difficult. This research investigated the feasibility of constructing a small-sized database by compression. A wavelet-based compression method was selected because of its light calculation burden and independence of time series data. The database of the flow field in urban-like arrayed blocks was obtained by large-eddy simulation, and then the velocity and diffusion coefficient fields were compressed with different error controls to construct databases. The compression ability of the wavelet-based method was evaluated, and it was found that the maximum compression ratio is reached when most information in the wavelet coefficients is discarded. The effects of compression error on both the single snapshot and the time-series results were studied. The applicability of the compressed database was verified by the resimulation of passive scalar dispersion in the flow. According to results, the database with approximately 100-times compression is suitable for such applications as the visualization and dispersion simulation of passive scalars with sufficient accuracy.

Biogeography of land snail genus Acusta (Gastropoda: Camaenidae): Diversification on East Asian islands

East Asia has highly diverse and endemic biota due to its complex geological and climatic history and its diversified topography. The continental and insular distributions of land snail genus Acusta in East Asia provide a good opportunity to compare the evolutionary processes in this group under different biogeographical conditions. In this study, we inferred the evolutionary history of the land snail genus Acusta by a molecular phylogeny and investigated how the palaeogeographic events shaped species diversity and the distribution of the Acusta genus within the island arc. A concatenated dataset generated from sequences of one nuclear (ITS2) and two mitochondrial (16S, COI) gene fragments, include most of nominal taxa of the genus, four related species and one outgroup. We constructed the phylogeny and the evolutionary history of the genus through maximum-likelihood and Bayesian inference methods, using a Bayesian molecular clock and ancestral range estimation. Our results suggested that currently recognized species in Acusta are polyphyletic. The traditionally accepted concept of the affinity of Acusta and Bradybaena is not supported. The hypothesis of colonization via land bridges during the Pleistocene glaciations for the biota of East Asian islands is not supported. Instead, the origin and diversification of the genus Acusta was dated to the late Miocene–Pliocene from an area around North and Northeast China to South China and East Asian islands Three major evolutionary lineages were identified. Two of the major lineages demonstrate distinct evolutionary histories, as sympatric speciation is the major speciation process for the continental clade, while the insular clade originated from founder events. Taiwan functioned as an important source of diversification for species on the East Asian islands possibly through passive dispersal of different mechanisms. The sea level fluctuations caused by the Pleistocene glacial cycles play a role in the subsequent dispersion and diversification of species of the continental clade, such as the more recent range expansion of A. redfieldi from South China to Taiwan and Japan.

Diversity Patterns Associated with Varying Dispersal Capabilities as a Function of Spatial and Local Environmental Variables in Small Wetlands in Forested Ecosystems

The diversity of species on a landscape is a function of the relative contribution of diversity at local sites and species turnover between sites. Diversity partitioning refers to the relative contributions of alpha (local) and beta (species turnover) diversity to gamma (regional/landscape) diversity and can be influenced by the relationship between dispersal capability as well as spatial and local environmental variables. Ecological theory predicts that variation in the distribution of organisms that are strong dispersers will be less influenced by spatial properties such as topography and connectivity of a region and more associated with the local environment. In contrast, the distribution of organisms with limited dispersal capabilities is often dictated by their limited dispersal capabilities. Small and ephemeral wetlands are centers of biodiversity in forested ecosystems. We sampled 41 small and ephemeral wetlands in forested ecosystems six times over a two-year period to determine if three different taxonomic groups differ in patterns of biodiversity on the landscape and/or demonstrate contrasting relationships with local environmental and spatial variables. We focused on aquatic macroinvertebrates (aerial active dispersers consisting predominantly of the class Insecta), amphibians (terrestrial active dispersers), and zooplankton (passive dispersers). We hypothesized that increasing active dispersal capabilities would lead to decreased beta diversity and more influence of local environmental variables on community structure with less influence of spatial variables. Our results revealed that amphibians had very high beta diversity and low alpha diversity when compared to the other two groups. Additionally, aquatic macroinvertebrate community variation was best explained by local environmental variables, whereas amphibian community variation was best explained by spatial variables. Zooplankton did not display any significant relationships to the spatial or local environmental variables that we measured. Our results suggest that amphibians may be particularly vulnerable to losses of wetland habitat in forested ecosystems as they have high beta diversity. Consequently, the loss of individual small wetlands potentially results in local extirpations of amphibian species in forested ecosystems.

The importance of individual movement and feeding behaviour for long-distance seed dispersal by red deer: a data-driven model

BackgroundLong-distance seed dispersal (LDD) has strong impacts on the spatiotemporal dynamics of plants. Large animals are important LDD vectors because they regularly transport seeds of many plant species over long distances. While there is now ample evidence that behaviour varies considerably between individual animals, it is not clear to what extent inter-individual variation in behaviour alters seed dispersal by animals.MethodsWe study how inter-individual variation in the movement and feeding behaviour of one of Europe’s largest herbivores (the red deer, Cervus elaphus) affects internal seed dispersal (endozoochory) of multiple plant species. We combine movement data of 21 individual deer with measurements of seed loads in the dung of the same individuals and with data on gut passage time. These data serve to parameterize a model of passive dispersal that predicts LDD in three orientations (horizontal as well as upward and downward in elevation).With this model we investigate to what extent per-seed probabilities of LDD and seed load vary between individuals and throughout the vegetation period (May–December). Subsequently, we test whether per-seed LDD probability and seed load are positively (or negatively) correlated so that more mobile animals disperse more (or less) seeds. Finally, we examine whether non-random associations between per-seed LDD probability and seed load affect the LDD of individual plant species.ResultsThe studied deer dispersed viable seeds of at least 62 plant species. Deer individuals varied significantly in per-seed LDD probability and seed loads. However, more mobile animals did not disperse more or less seeds than less mobile ones. Plant species also did not differ significantly in the relationship between per-seed LDD probability and seed load. Yet plant species differed in how their seed load was distributed across deer individuals and in time, and this caused their LDD potential to differ more than twofold. For several plant species, we detected non-random associations between per-seed LDD probability and seed load that generally increased LDD potential.ConclusionsInter-individual variation in movement and feeding behaviour means that certain deer are substantially more effective LDD vectors than others. This inter-individual variation reduces the reliability of LDD and increases the sensitivity of LDD to the decline of deer populations. Variation in the dispersal services of individual animals should thus be taken into account in models in order to improve LDD projections.

Environment and Space Rule, but Time Also Matters for the Organization of Tropical Pond Metacommunities

Metacommunities are dynamic systems, but the influence of time independently of environmental change in their configuration has been rarely considered. Temporary ponds are excellent ecosystem models, as they have well-defined boundaries in time and space; their communities are relatively isolated through a landscape matrix, and the progress of time leads to major changes through ecological succession and in habitat suitability related to hydroperiod dynamics. Therefore, strong temporal effects are expected to influence their metacommunity structure. We surveyed 30 temporary ponds along the dry tropical region of western Costa Rica and Nicaragua at three different moments of their hydroperiod: shortly after the infilling of the water bodies, at the middle of the hydroperiod and just before desiccation. We obtained data on 56 environmental variables (including limnological, climatic, landscape, hydrogeomorphological and conservation state), and used geographic coordinates to build spatial variables (Moran Eigenvector Maps). We collected biological samples and estimated the specific abundance of phytoplankton, zooplankton and benthic invertebrates. To evaluate the relative role of environmental, spatial and temporal (sequential sampling season) effects in metacommunity organization of the 646 species found, we used variation partitioning with distance-based redundancy analyses for each group of organisms. We repeated the analyses for selected taxonomic groups, separately for each sampling season, to check how the variance explained by spatial and environmental factors varied between sampling periods. The inclusion of time in the analysis highlighted that pure temporal effects explained part of metacommunity variance in almost every group, being as important as spatial or even environmental effects for some groups of organisms. In contrast to the assumed low environmental constraints in tropical areas (i.e. high and stable temperatures), we found strong environmental effects. Passive dispersers were more influenced by environmental factors than active ones. We also found a positive relationship between the body size of the different groups of organism and the magnitude of the temporal effect, interpreted as related to generation time. Finally, when analyzing each sampling period separately, we found differences in the relative role of environment and space at different sampling periods, showing that snapshot surveys may not be representative of highly dynamic metacommunities.

Host-parasite relationships between seabirds and the haemadipsid leech Chtonobdella palmyrae (Annelida: Clitellata) inhabiting oceanic islands in the Pacific Ocean.

The duognathous haemadipsid leeches of the genus Chtonobdella show a trans-oceanic distribution throughout the Indo-Pacific region. Although passive long-distance dispersal (LDD) of Chtonobdella leeches by birds has been suggested, little is known about the host-parasite relationships between avian hosts and Chtonobdella leeches. In the current study, we investigated Chtonobdella leech infestations of the eyes and other mucus membranes of migratory procellariiform seabirds, Pterodroma hypoleuca and Oceanodroma tristrami, captured at six locations in the Bonin Islands, Honshu and Okinawa Island, Japan. Analyses of the partial sequences of 18S rRNA, 28S rRNA, and mitochondrial cytochrome c oxidase subunit I (COI) and morphological examination of the specimens demonstrated that the Chtonobdella leeches belonged to Chtonobdella palmyrae, which is indigenous to Palmyra Atoll in the Northern Line Islands. A dominant COI sequence type was observed in samples from all six sites; therefore, C. palmyrae almost surely dispersed approximately 1000 km by infesting the eyes and mucus membranes of procellariiform seabirds. The host-parasite relationships between procellariiform seabirds and C. palmyrae provide explicit evidence of the LDD of duognathous haemadipsid leeches. The taxonomic status of Haemadipsa zeylanica ivosimae from the Volcano Islands is also briefly discussed.

Assessing the current state of ecological connectivity in a large marine protected area system.

The establishment of marine protected areas (MPAs) is a critical step in ensuring the continued persistence of marine biodiversity. Although the area protected in MPAs is growing, the movement of individuals (or larvae) among MPAs, termed connectivity, has only recently been included as an objective of many MPAs. As such, assessing connectivity is often neglected or oversimplified in the planning process. For promoting population persistence, it is important to ensure that protected areas in a system are functionally connected through dispersal or adult movement. We devised a multi‐species model of larval dispersal for the Australian marine environment to evaluate how much local scale connectivity is protected in MPAs and determine whether the extensive system of MPAs truly functions as a network. We focused on non‐migratory species with simplified larval behaviors (i.e., passive larval dispersal) (e.g., no explicit vertical migration) as an illustration. Of all the MPAs analyzed (approximately 2.7 million km2), outside the Great Barrier Reef and Ningaloo Reef, <50% of MPAs (46‐80% of total MPA area depending on the species considered) were functionally connected. Our results suggest that Australia's MPA system cannot be referred to as a single network, but rather a collection of numerous smaller networks delineated by natural breaks in the connectivity of reef habitat. Depending on the dispersal capacity of the taxa of interest, there may be between 25 and 47 individual ecological networks distributed across the Australian marine environment. The need to first assess the underlying natural connectivity of a study system prior to implementing new MPAs represents a key research priority for strategically enlarging MPA networks. Our findings highlight the benefits of integrating multi‐species connectivity into conservation planning to identify opportunities to better incorporate connectivity into the design of MPA systems and thus to increase their capacity to support long‐term, sustainable biodiversity outcomes.

Isothermal and non-isothermal flow in street canyons: A review from theoretical, experimental and numerical perspectives

Urban street canyon flows play a central role in microclimate control, from street canyon to neighbourhood and city scale, which affect pollutant dispersion, thermal comfort of residents and building energy consumption for various indoor and outdoor flow conditioning systems. Extensive studies have been devoted to this field, from theoretical modelling to experimental measurements and numerical simulations. While some important characteristics of street canyon flows, such as the presence of a primary standing vortex and the mechanism for its establishment, have been well revealed, a holistic understanding consolidating theoretical, experimental and numerical research has not been achieved. This review is therefore aimed to holistically articulate these approaches and research outcomes in the field. Some critical points overlooked in the literature are identified and commented on. These are: distinguishing gradient and bulk Richardson numbers; identifying dominant similarity characteristic numbers for scaling down models; predicting the condition in which thermal effects come into play; modelling the convective heat transfer in non-equilibrium mixed convection conditions using wall functions; and exploring the influence of neutral and non-neutral urban boundary layers on street canyon flows and associated passive scalar dispersion. The review is concluded with an outlook to most challenging research questions towards understanding of microclimate of full-scale realistic street canyons.

A comprehensive and cost-effective approach for investigating passive dispersal in minute invertebrates with case studies of phytophagous eriophyid mites

Dispersal is a fundamental biological process that operates at different temporal and spatial scales with consequences for individual fitness, population dynamics, population genetics, and species distributions. Studying this process is particularly challenging when the focus is on microscopic organisms that disperse passively, whilst controlling neither the transience nor the settlement phase of their movement. In this work we propose a comprehensive approach for studying passive dispersal of microscopic invertebrates and demonstrate it using wind and phoretic vectors. The protocol includes the construction of versatile, modifiable dispersal tunnels as well as a theoretical framework quantifying the movement of species via wind or vectors, and a hierarchical Bayesian approach appropriate to the structure of the dispersal data. The tunnels were used to investigate the three stages of dispersal (viz., departure, transience, and settlement) of two species of minute, phytophagous eriophyid mites Aceria tosichella and Abacarus hystrix. The proposed devices are inexpensive and easy to construct from readily sourced materials. Possible modifications enable studies of a wide range of mite species and facilitate manipulation of dispersal factors, thus opening a new important area of ecological study for many heretofore understudied species.

Pest survey card on Geosmithia morbida and its vector Pityophthorus juglandis

This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2017-0137) at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for Geosmithia morbida and Pityophthorus juglandis surveys. These are required to design statistically sound and risk-based pest surveys, in line with current international standards.Geosmithia morbida and its vector P. juglandis are clearly defined taxonomic entitiesand the combined activity of the fungus and the insect causes the disease complex thousand canker disease on the plant genera Juglans and Pterocarya. The pest and its vector originate in North America and currently have a restricted distribution in the EU, limited to the northern parts of Italy.However, they are potentially able to become established everywhere in the EU where their host plants occur.Currently, the spread capacity ofP.juglandis is unknown, but the insect vectormay cover large distances by passive dispersal or human-assisted spread. Risk locations include entry points (e.g. seaports, airports), loading stations, storage facilities and wood processing companies that deal withheat-treated wood, bark or woodchips of the genera Juglans and Pterocarya originating from countries where the fungus and its vector occur.Trapping is the recommended method for detecting the vector inthe early stages of an epidemic. Following insect trapping, a specific tree inspection should be carried out, looking for external symptoms(e.g. penetration and exit holes, cankers and wilting). The trapping should start when the mean air temperature exceeds 18°C.Morphological identification of the pathogen and its vector should be performed by experts. Molecular assays are also available for both fungal and vector identification.

Progression du moustique tigre en France : surveillance transfrontalière dans le Grand-Est

Vector of chikungunya, dengue and zika viruses, the Asian tiger mosquito Aedes albopictus is also one of the most invasive species in the world. Due to its both biological (resistant and diapausing eggs) and behavioural (following human in their vehicles) characteristics, the tiger mosquito has quickly colonised the whole World through passive dispersal via international trade and travel.Therefore, the invasive mosquitoes including Ae. albopictus are tracked by entomological surveillances at local, national and international scales. The use of ovitraps and citizen reports allows experts to monitor the evolution of its colonisation. Over the last 30 years, the tiger mosquito has established in Europe and settled in France since 2004. Ten years later, it has been detected in the administrative unit of Bas-Rhin (France) which is part of the Upper Rhine valley, a wider area spanning France, Germany and Switzerland. As no administrative borders can prevent invasive mosquitoes' colonisation, this issue has brought together assets of a European collaboration at a cross border scale. Thereby, the common tri-national surveillance network (Interreg, TIGER) enables the colonisation monitoring of the three invasive mosquito species already detected on both sides of borders: Ae. albopictus, Ae. japonicus and Ae. koreicus. Considering a cross-border area, integrating the European scale for vector monitoring and control is thus a major asset to the issue of arboviruses vectors.

Biogeographic origin and phylogenetic relationships of Mepraia (Hemiptera, Reduviidae) on islands of northern Chile.

Chagas disease is one of the main zoonoses mediated by vectors in America. The etiological agent is the protozoan Trypanosoma cruzi, transmitted mainly by hematophagous insects of the subfamily Triatominae. Mepraia species are triatomines endemic to Chile that play an important role in T. cruzi transmission in the wild cycle and are potential vectors for humans. In addition to the continental distribution, populations of Mepraia genus have been reported inhabiting islands of northern Chile. The presence of individuals of Mepraia in insular areas might be explained through passive dispersion by marine birds or by vicariance of an ancestral widespread population. To clarify the biogeographic origin and phylogenetic relationships of island individuals of Mepraia, mitochondrial COI and cyt b genes were sequenced in individuals from island and continental areas. Gene sequences were used to estimate phylogenetic relationships, divergence dates and migration rates between insular and continental populations. The dates of divergence estimates are congruent with sea level and tectonic changes that originated the islands during Pleistocene. Migration rates suggest symmetric historical island-continent gene flow. We suggest that the origin of island triatomines can be explained by both vicariance and dispersion. Phylogenetic relationships show that individuals from Santa María Island and the continent clustered in a clade different from those previously reported, indicating a new lineage of Mepraia genus. This study will contribute to understand the origin of the T. cruzi infection in coastal islands of northern Chile.