Dispersal Rates Research Articles

Digest: Evolution of redirected help in a viscous population.

When broods fail, parents may assist neighbours' offspring, a behaviour called redirected helping that is observed in many species. Flatrès and Wild (2024) used inclusive fitness models to study this behaviour. They showed that redirected helping can evolve in viscous populations, where individuals stay near their birthplace, increasing relatedness and competition among neighbours, especially when helping costs are low. Life-history traits like survival, dispersal, and brood-failure rates shape this behaviour. Interestingly, survival benefits from helping can outweigh reproductive gains, challenging assumptions and providing fresh insights into cooperative breeding dynamics.

First record of microplastic contamination in adult endemic amazonian anuran species

The microplastics (MPs), due to their high dispersion and bioaccumulation rates, have been identified in various animal groups, such as anuran amphibians during both larval and adult stages. However, current studies on adult anuran amphibians focus on assessing only one exposure route, the digestive system, while other routes remain underestimated. Therefore, this present study aimed to evaluate the degree of contamination in the digestive, respiratory, and integumentary systems, in situ, of two endemic Amazonian adult anuran species (Physalaemus ephippifer and Boana multifasciata). From this, we identified and characterized microplastic particles for each exposure route, assessed the effects of morphometric measures on the total MP contamination level and in the gastrointestinal tract (GIT). Additionally, we determined different contamination indices and how they vary according to species and systems. Based on our data, the digestive and integumentary exposure routes showed the highest contamination levels for both species. Additionally, variations in MP contamination levels indicated that P. ephippifer had a higher level of MP contamination. Thus, this study provides the first evidence of microplastic exposure through respiratory and integumentary routes in adult anurans in situ, and it is the first to identify MP contamination in terrestrial biomonitors in the Amazon.

Pre-exposure of abundant species to disturbance improves resilience in microbial metacommunities.

Understanding factors influencing community resilience to disturbance is critical for mitigating harm at various scales, including harm from medication to gut microbiota and harm from human activity to global biodiversity, yet there is a lack of data from large-scale controlled experiments. Factors expected to boost resilience include prior exposure to the same disturbance and dispersal from undisturbed patches. Here we set up an in vitro system to test the effect of disturbance pre-exposure and dispersal represented by community mixing. We performed a serial passage experiment on a 23-species bacterial model community, varying pre-exposure history and dispersal rate between three metacommunity patches subjected to different levels of disturbance by the antibiotic streptomycin. As expected, pre-exposure caused evolution of resistance, which prevented decrease in species abundance. The more abundant the pre-exposed species had been in the undisturbed community, the less the entire community changed. Pre-exposure of the most dominant species also decreased abundance change in off-target species. In the absence of pre-exposure, increasing dispersal rates caused increasing spread of the disturbance across the metacommunity. However, pre-exposure kept the metacommunity close to the undisturbed state regardless of dispersal rate. Our findings demonstrate that pre-exposure is an important modifier of ecological resilience in a metacommunity setting.

Establishment and range expansion of invasive Cactoblastis cactorum (Lepidoptera: Pyralidae: Phycitinae) in Texas

Abstract Invasive species are a leading cause of global biodiversity decline. Larvae of the cactus moth Cactoblastis cactorum Berg (Lepidoptera: Pyralidae: Phycitinae) consume prickly pear cactus species (Opuntia; Cactaceae) in its native South American range. High host specificity made C. cactorum an appropriate biological control agent of Opuntia species, which have become invasive weeds around the world. This biological control program was successful. Ironically, the success of cactus weed biological control facilitated a series of events which led to C. cactorum invasion of North America where Opuntia diversity is tremendous. In 2017, C. cactorum established along the southeast Texas coast. In 2020, we began monitoring C. cactorum dispersal towards south and south-west Texas with cactus moth pheromone traps. Our objectives were to document the extent of the invasion and calculate dispersal rates towards commercial Opuntia-growing regions in Mexico. There are four overlapping moth flight peaks in Texas. Between 2017 and 2022, the C. cactorum populations invaded over 27,000 km2 in south-east and south-central Texas at a dispersal rate up to 47 km year. Since 2022, this dispersal rate slowed as the moth invasion front came into contact with the Tamaulipan thornscrub region of south Texas where Opuntia density is high and native cactus moth species are attacked by a diverse assemblage of parasitoids. We present data on the density of native cactus moth species in Texas which shows that their density increases west and south-west of the area currently occupied by C. cactorum. These data suggest that apparent competition may be occuring between C. cactorum and native cactus moth species via shared parasitoids. This hypothesis is not mutually exclusive of other biological barriers that may contribute to explaining why the Texas C. cactorum dispersal rate has slowed significantly. We conclude with a discussion about how to leverage these data to support future deployment of C. cactorum biological control agents in Texas.

To stay or to go: resource diversity alters the dispersal behavior of sympatric cryptic marine nematodes.

Animals can use specific environmental cues to make informed decisions about whether and where to disperse. Patch conditions are known to affect the dispersal behavior of animals, but empirical studies investigating the impact of resource diversity on the dispersal of closely related species are largely lacking. In this study, we investigated how food diversity affects the dispersal behavior of three co-occurring cryptic species of the marine bacterivorous nematode complex Litoditis marina (Pm I, Pm III and Pm IV). Using microcosms composed of a local patch (inoculation plate), a connection tube, and a distant patch (dispersal plate), we examined nematode dispersal patterns with bacteria serving as the food source. Food treatments included low-, medium-, and high-diversity bacterial mixtures of 5, 10, and 15 bacterial strains, respectively. Additionally, a single-strain food resource Escherichia coli was used as a control treatment. Both local and distant patches had either identical food treatments ('homogeneous patches') or E. coli in the local patches and more diverse food (low-, medium-, or high-diversity food) in distant patches ('heterogeneous patches'). Our results show that the dispersal behavior of the cryptic species varies depending on food diversity, indicating that L. marina acquire information about their environment when making dispersal decisions. All three cryptic species tend to disperse faster toward food patches that increase fitness. Pm I and Pm IV exhibited faster dispersal toward patches with a more diverse food source, while Pm III showed similar dispersal rates toward E. coli, medium-diversity, and high-diversity food. This indicates that resource diversity can alter the dispersal behavior of cryptic species and may be an important mechanism to achieve species coexistence in the field.

Big-Hearted Invaders: The Impacts of Range Expansion and Parasite Infection on Heart Mass in Cane Toads.

The invasion of cane toads (Rhinella marina) across tropical Australia has resulted in the rapid evolution of traits that enable higher rates of dispersal, and that adapt toads to hot dry climates. In anurans, a larger heart facilitates both locomotor activity and desiccation tolerance. Heart size is also often affected, either directly or indirectly, by parasite infections. To test the effects of invasion history and parasite exposure on heart size, we studied common garden-reared toads whose parents were sourced from diverse locations, and experimentally exposed them to larvae of a nematode lungworm (Rhabdias pseudosphaerocephala). Offspring of invasion-front parents had larger hearts than did conspecifics from long-established populations. Exposure to infective lungworm larvae decreased heart mass in toads from all populations. Our study suggests that cardiovascular function, like other traits, has evolved rapidly during the toad invasion; and that lungworm parasites can modify the cardiovascular function and hence aerobic capacity of their host.

Broad geographic dispersal is not a diversification driver for Emberizoidea.

The movement of species to new geographical areas has been proposed to be crucial for speciation. As such, dispersal has been regarded as a likely explanation for the variation in species richness among clades. The Emberizoidea are a highly diverse Oscine bird clade native to the New World that has been characterized for their ubiquitous distribution both ecologically and geographically, making this group ideal to test how biogeographical dispersal could promote speciation. To do so, we relate dispersal rates with speciation rates of Emberizoidea families using a combination of bioregionalization analysis, ancestral area reconstruction and speciation rate estimation methods. We found that the Emberizoidea superfamily likely arose from a widespread ancestor distributed over the New World, with its range evolution being primarily driven by range contraction and the main cladogenetic events for the clade occurring within bioregions. Moreover, we demonstrate that dispersal rates between bioregions showed no relationship with speciation rates, suggesting that the movement to new geographical spaces is not a driver of speciation in this group. Instead, cladogenetic events within individual bioregions promoted by range stability prove to be an important driver for speciation at broad spatial scales for Emberizoidea families.

Diverse microbiome functions, limited temporal variation and substantial genomic conservation within sedimentary and granite rock deep underground research laboratories

BackgroundUnderground research laboratories (URLs) provide a window on the deep biosphere and enable investigation of potential microbial impacts on nuclear waste, CO2 and H2 stored in the subsurface. We carried out the first multi-year study of groundwater microbiomes sampled from defined intervals between 140 and 400 m below the surface of the Horonobe and Mizunami URLs, Japan.ResultsWe reconstructed draft genomes for > 90% of all organisms detected over a four year period. The Horonobe and Mizunami microbiomes are dissimilar, likely because the Mizunami URL is hosted in granitic rock and the Horonobe URL in sedimentary rock. Despite this, hydrogen metabolism, rubisco-based CO2 fixation, reduction of nitrogen compounds and sulfate reduction are well represented functions in microbiomes from both URLs, although methane metabolism is more prevalent at the organic- and CO2-rich Horonobe URL. High fluid flow zones and proximity to subsurface tunnels select for candidate phyla radiation bacteria in the Mizunami URL. We detected near-identical genotypes for approximately one third of all genomically defined organisms at multiple depths within the Horonobe URL. This cannot be explained by inactivity, as in situ growth was detected for some bacteria, albeit at slow rates. Given the current low hydraulic conductivity and groundwater compositional heterogeneity, ongoing inter-site strain dispersal seems unlikely. Alternatively, the Horonobe URL microbiome homogeneity may be explained by higher groundwater mobility during the last glacial period. Genotypically-defined species closely related to those detected in the URLs were identified in three other subsurface environments in the USA. Thus, dispersal rates between widely separated underground sites may be fast enough relative to mutation rates to have precluded substantial divergence in species composition. Species overlaps between subsurface locations on different continents constrain expectations regarding the scale of global subsurface biodiversity.ConclusionsOur analyses reveal microbiome stability in the sedimentary rocks and surprising microbial community compositional and genotypic overlap over sites separated by hundreds of meters of rock, potentially explained by dispersal via slow groundwater flow or during a prior hydrological regime. Overall, microbiome and geochemical stability over the study period has important implications for underground storage applications.

Allee pits in metapopulations: critical dispersal rates for connectivity to be beneficial

Habitat fragmentation divides populations into smaller subpopulations. At the same time, the Allee effect reduces the growth and thereby the viability of small populations. Hence, habitat fragmentation and the Allee effect can synergistically amplify negative impacts on spatially distributed populations. To support endangered populations, management and conservation strategies aim to improve connectivity between subpopulations by creating corridors and stepping stones, for instance. This study investigates how enhanced connectivity (strength of connections between subpopulations in terms of dispersal rate) influences a fragmented population subject to the Allee effect. Using a generic two-patch discrete-time model with a positively density-dependent growth function, we study the impact of connectivity on the asymptotic total population size through simulations. Due to the Allee effect, low connectivity can lead to a decline in the asymptotic total population size, which we call the Allee pit. However, increased connectivity facilitates the rescue effect, wherein a persistent subpopulation in one patch can save an extinction-prone subpopulation in another patch. We find that for connectivity to benefit the asymptotic total population size, dispersal must be sufficiently large to push the smaller subpopulation above its Allee threshold. If dispersal is below this critical dispersal rate, there remains a detrimental effect on the asymptotic total population size. Therefore, this study implies that conservation strategies should not only aim to increase connectivity in fragmented populations subject to Allee effects but also ensure that the critical dispersal rate is surpassed.

Selective advantage of redirected helping in a viscous population.

When a brood fails, the failed parent can help a neighbor rear its offspring. This behavior is known as redirected helping and occurs in various species. The advantage of redirected helping may seem obvious, provided the individual whose brood fails helps a related neighbor: the helper at least gains indirect fitness by redirecting its parental effort. However, complications arise when considering a viscous population, where individuals remain on or close to their natal site. In such a population, individuals compete with relatives, which dilutes the advantage of helping and may counteract it altogether. This raises a question: when can we expect redirected helping to evolve in a viscous population? We address this question with inclusive fitness models. We find that redirected helping can always be favored in a viscous population, provided the cost is sufficiently low. We also identify life-history features - like survival, dispersal, and brood-failure rate - that promote redirected helping. The effect of these life-history features, in general, depends on which component of fitness (survival or fecundity) benefits from help and how brood failure varies among demes. Unlike previous authors, we find that helping can be more strongly promoted when it provides survival rather than fecundity benefits.

Macro‐evolutionary dynamics dominated by dispersal promote the formation of regional biodiversity hotspot‐insights from hawkmoths (Lepidoptera: Sphingidae) in South China

AbstractAimRapid loss in global insect diversity has generated substantial public worry due to their critical ecological roles. However, there is controversy about the effectiveness of the global‐scale hotspots in guiding the conservation of diversity at the regional scale. Even worse, little is known about the knowledge of insect distributional dynamics in many understudied regions, such as East and Southeast Asia. Here, to guide for setting regional‐scale conservation priorities for insect diversity, we explore hawkmoths (Lepidoptera: Sphingidae) for their distributional dynamics and identify regional hotspots requiring protection.LocationSouth China (including Guangdong, Guangxi, Hainan, Hong Kong and Macau) and northern Vietnam (17°~26.5° N, 102°~117.5° E).MethodsSpecies distribution models were generated for 194 hawkmoth species based on 3597 occurrence records to predict their distributions. We calculated the spatial patterns of taxonomic and phylogenetic diversity and identified regional hotspots. Furthermore, the potential assembly mechanisms underlying insect diversity were explored by analysing the rates of speciation, extinction and dispersal between phyloregions.Results(a) The coastal regions of South China and northern Vietnam represent a regional hotspot of hawkmoths in East and Southeast Asia, with significantly higher α‐diversity than that in inland regions. (b) Dispersal played a more important role than local speciation and extinction in the formation of regional hawkmoth hotspots.Main ConclusionsIn this study, the ‘Out‐of‐the‐tropics model’ can explain the formation of the hawkmoth regional hotspots and the enhanced version of the ‘Pure dispersal model’ can explain the formation of the hotspots in Hainan Island. Compared with the local speciation and extinction, dispersal is the main driving factor that promoted the formation of the regional biodiversity hotspot of hawkmoths in South China. The case of Hainan Island suggests that protection within hotspots needs to account for specific regional macro‐evolutionary dynamics rather than indiscriminate coverage of identified hotspots.

Dispersal induced catastrophic bifurcations, Arnold tongues, shrimp structures, and stock patterns in an ecological system.

This paper presents a comprehensive analysis of a discrete-time predator-prey model within a homogeneous two-patch environment, incorporating both prey and predator dispersal. We consider a logistic growth for both prey and predator species, and the predation process is based on the Holling type-II functional response in the isolated patches. We explore the existence of multiple coexisting equilibria and establish their stability conditions. By independently varying the prey and predator dispersal rates, we discover a sequence of phenomena including bifurcations, quasiperiodicity, and chaos. In addition, we observe a 10-period orbit, each point of the periodic orbit gives birth to a closed invariant curve. Such large number of closed invariant curves are generally not reported in spatially coupled population models. The system exhibits both catastrophic (non-smooth) jumps and smooth transitions in the dynamics whenever a bifurcation occurs. Commonly, dispersal can only destabilize the coexisting equilibrium. However, we found the stabilization of the coexisting equilibrium, which is a rare occurrence. Furthermore, a two-parameter space analysis reveals intricate dynamics when both dispersal rates are varied simultaneously, showcasing complex phenomena and the emergence of organized periodic regimes such as Arnold tongues and shrimp structures. We also investigate the stock pattern of both species with respect to the dispersal. This study enhances the understanding of predator-prey interactions in spatially homogeneous environments, illuminating their intricate and dynamic nature.

Dynamics of R&D Efforts, Patents, Exports and Economic Growth by World Trade Region, 1990-2021

This paper has two objectives. First, to compare the dynamics of R&D/GDP (%), resident patent applications, high-tech exports -VATX- (%), and the innovation and economic growth patterns of countries in North America, the European Union and Asia between 1997 and 2021. Second, to estimate the impact of R&D/GDP and resident and non-resident patent applications on VATX for each selected country through an ARDL model in the period 1997-2016. Results show that countries with more resident patent applications have more VATX. Overall, the effect of the number of resident patent applications and R&D expenditure on VATX depends on the dynamics in each country. Thus, in the United States, Germany, Japan, and China, the effect of the R&D, the number of resident and non- resident patents applied for, on the tendency to VATX is positive, while in the rest of the economies, the results are mixed. Comparing the dynamics of innovation and economic growth between the “old” and “new” members of the European Union, we find evidence of differentiated patterns, with the “old” members’ economic growth is particularly linked to the sustainability of innovative activity, supported by continuous R&D efforts, while among the new members some are beginning to build the virtuous circles that will lead them to sustainable economic growth. The differences are also evident among the USMCA countries, where the United States is the leader and Mexico has dispersion and erratic growth rates, showing that economic growth is not significantly related to innovation. In contrast, in the Southeast Asian region, the dynamics of innovation and GDP grow in a sustained and articulated manner over time.

Estimating dispersal rates and locating genetic ancestors with genome-wide genealogies.

Spatial patterns in genetic diversity are shaped by individuals dispersing from their parents and larger-scale population movements. It has long been appreciated that these patterns of movement shape the underlying genealogies along the genome leading to geographic patterns of isolation-by-distance in contemporary population genetic data. However, extracting the enormous amount of information contained in genealogies along recombining sequences has, until recently, not been computationally feasible. Here, we capitalize on important recent advances in genome-wide gene-genealogy reconstruction and develop methods to use thousands of trees to estimate per-generation dispersal rates and to locate the genetic ancestors of a sample back through time. We take a likelihood approach in continuous space using a simple approximate model (branching Brownian motion) as our prior distribution of spatial genealogies. After testing our method with simulations we apply it to Arabidopsis thaliana. We estimate a dispersal rate of roughly 60 km2/generation, slightly higher across latitude than across longitude, potentially reflecting a northward post-glacial expansion. Locating ancestors allows us to visualize major geographic movements, alternative geographic histories, and admixture. Our method highlights the huge amount of information about past dispersal events and population movements contained in genome-wide genealogies.

Coexistence or extinction: Dynamics of multiple lizard species with competition, dispersal and intraguild predation.

Biological invasions significantly impact native ecosystems, altering ecological processes and community behaviors through predation and competition. The introduction of non-native species can lead to either coexistence or extinction within local habitats. Our research develops a lizard population model that integrates aspects of competition, intraguild predation, and the dispersal behavior of intraguild prey. We analyze the model to determine the existence and stability of various ecological equilibria, uncovering the potential for bistability under certain conditions. By employing the dispersal rate as a bifurcation parameter, we reveal complex bifurcation dynamics associated with the positive equilibrium. Additionally, we conduct a two-parameter bifurcation analysis to investigate the combined impact of dispersal and intraguild predation on ecological structures. Our findings indicate that intraguild predation not only influences the movement patterns of brown anoles but also plays a crucial role in sustaining the coexistence of different lizard species in diverse habitats.

Testing relationships between multiple regional features and biogeographic processes of speciation, extinction, and dispersal.

The spatial and environmental features of regions where clades are evolving are expected to impact biogeographic processes such as speciation, extinction, and dispersal. Any number of regional features (such as elevation, distance, area, etc.) may be directly or indirectly related to these processes. For example, it may be that distances or differences in elevation or both may limit dispersal rates. However, it is difficult to disentangle which features are most strongly related to rates of different processes. Here, we present an extensible Multi-feature Feature-Informed GeoSSE (MultiFIG) model that allows for the simultaneous investigation of any number of regional features. MultiFIG provides a conceptual framework for incorporating large numbers of features of different types, including categorical, quantitative, within-region, and between-region features, along with a mathematical framework for translating those features into biogeographic rates for statistical hypothesis testing. Using traditional Bayesian parameter estimation and reversible-jump Markov chain Monte Carlo, MultiFIG allows for the exploration of models with different numbers and combinations of feature-effect parameters, and generates estimates for the strengths of relationships between each regional feature and core process. We validate this model with a simulation study covering a range of scenarios with different numbers of regions, tree sizes, and feature values. We also demonstrate the application of MultiFIG with an empirical case study of the South American lizard genus Liolaemus, investigating sixteen regional features related to area, distance, and elevation. Our results show two important feature-process relationships: a negative distance/dispersal relationship, and a negative area/extinction relationship. Interestingly, although speciation rates were found to be higher in Andean versus non-Andean regions, the model did not assign significance to Andean- or elevation-related parameters. These results highlight the need to consider multiple regional features in biogeographic hypothesis testing.

Effect of network topology in consumer-resource systems with species’ dispersal and evolution

This paper considers consumer-resource systems, where the consumer moves on a fully-connected patch network and behaves like an agent. Using graph-theoretical method and dynamical systems theory, we show global equilibrium stability in the system. Analysis on the equilibrium demonstrates that when the dispersal rate is small, the effect of network topology is the result of the effect of each path in isolation. It is shown that varying network topology could lead to persistence and/or increase of the consumer. Moreover, agent-based selection on a network would make the network evolve to an evolutionary stable topology, where any small deviation to it will not lead to the increase of species. Our results have potential application in constructing ecological corridors and planning network topology under evolution.

Stochastic model of seed dispersal with homogeneous and non-homogeneous Poisson processes under habitat reduction conditions.

This study presents a stochastic model of seed dispersal based on a branching random walk (BRW) framework, incorporating both homogeneous and non-homogeneous Poisson point processes (PPP). Building on the model introduced by Coletti et al. (2023), we examine the effects of habitat reduction on seed dispersal dynamics. We analyze the phase transition behavior of the BRW model under varying conditions of habitat fragmentation, focusing on how these conditions influence the critical dispersal rate. Specifically, we study a BRW on the real line with a non-homogeneous PPP driven by a log-normal density, constrained between spatial barriers. Our simulations localize the critical dispersal rate with respect to barrier positions and compare this dependence between homogeneous and non-homogeneous models.

Hopf bifurcations for a delayed discrete single population patch model in advective environments

Abstract In this paper, we consider a delayed discrete single population patch model in advective environments. The individuals are subject to both random and directed movements, and there is a net loss of individuals at the downstream end due to the flow into a lake. Choosing time delay as a bifurcation parameter, we show the existence of Hopf bifurcations for the model. In homogeneous non-advective environments, it is well known that the first Hopf bifurcation value is independent of the dispersal rate. In contrast, for homogeneous advective environments, the first Hopf bifurcation value depends on the dispersal rate. Moreover, we show that the first Hopf bifurcation value in advective environments is larger than that in non-advective environments if the dispersal rate is large or small, which suggests that directed movements of the individuals inhibit the occurrence of Hopf bifurcations.

Predictive Value of Tpeak-to-Tend/QT for Early Ventricular Arrhythmias and Arrhythmogenic Death in Patients with Anterior ST Elevation Myocardial Infarction

BackgroundPatients with anterior ST elevation myocardial infarction (STEMI) are vulnerable to life-threatening ventricular arrhythmia and arrhythmic death. This study aimed to investigate the predictive value of Tpeak-to-Tend (TpTe) and TpTe/QT ratio in patients with anterior STEMI on admission for the occurrence of in-hospital life-threatening ventricular arrhythmias and arrhythmic death. MethodsThis observational cross-sectional research was performed on patients with anterior STEMI who showed up within 12 hours of the beginning of symptoms and received the initial percutaneous coronary intervention (pPCI). The primary study endpoints included the assessment of sustained ventricular arrhythmias and all-cause/arrhythmic deaths throughout the hospitalization. Data collection involved clinical history, vital signs monitoring, ECG measurements, LVEF evaluation, and performance of pPCI procedures. ResultsThe studied patients had a mean age of 53 ± 11 years. Patients with arrhythmic events displayed a significant rise in QT dispersion, TpTe, TpTe/QT, and arrhythmic death rates (P < 0.05). A multivariate logistic regression examination revealed that HR (with an OR of 1.037 and a 95% CI of 1.004 to 1.071, P = 0.027), TpTe (with an OR of 1.025 and a 95% CI of 1.004 to 1.047, P = 0.022), and TpTe/QT (with an OR of 5.464 and a 95% CI of 2.027 to 14.726, P = 0.001) were found to be significant predictors of arrhythmic events or mortality. ConclusionIn patients with anterior STEMI, TpTe and TpTe/QT ratio are significant predictors of in-hospital VA and arrhythmic death. Higher TpTe and TpTe/QT values are linked to a higher risk of these occurrences.