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opencc-zeroOct 2020View details →

Genetic structures across a biogeographical barrier reflect dispersal potential of four Southeast Asian mangrove plant species

Aim Biogeographic barriers restrict the movement of individuals, resulting in population divergence, genetic differentiation, endemism and speciation. Yet, some barriers demonstrate unequal effect across species depending on species dispersal, which manifests in varying genetic structure. We test the hypotheses that the genetic structure of four coastal mangrove species would reflect differences in dispersal potential across the Malay Peninsula, a major biogeographic barrier in the Indo-West Pacific region. Location Twelve sites from the east and west coasts of the Malay Peninsula. Taxon Mangrove trees Avicennia alba, Sonneratia alba, Bruguiera gymnorhiza, and Rhizhophora mucronata. Methods For each species, we characterized genetic structure and gene flow using seven to 12 species-specific nuclear microsatellite markers. We tested for east-west genetic differentiation across the peninsula, a stepping-stone migration pattern, and assessed the proportion of recent dispersal and direction of historical migration along the Malacca Strait. Results Significant east-west genetic differentiation across the peninsula was observed in A. alba, S. alba and B. gymnorhiza, and the effect was most pronounced for the two species with lower dispersal potential (A. alba, S. alba). In contrast, the two species with higher dispersal potential (B. gymnorhiza and R. mucronata) exhibited much higher proportion of recent inter-population migration along the Malacca Strait. The signature of historical colonization from refugia in the Andaman Sea (north-to-south migration along the Malacca Strait) predominated for A. alba and S. alba. Historical south-north migration predominated for R. mucronata and B. gymnorhiza. Main conclusions This study is the first to implicate dispersal potential as a causal factor of varying mangrove species genetic structure across a biogeographic barrier. The Malay Peninsula functions as a filter to gene flow rather than a barrier. The genetic structure in mangrove species with a higher dispersal potential is more congruent with contemporary gene flow while that of species with a lower dispersal potential reflects historical processes.Our findings hint at the role of dispersal potential as a predictor of gene flow in mangroves.

opencc-zeroOct 2020View details →

Data from: Dispersal patterns in a medium-density Irish badger population: implications for understanding the dynamics of tuberculosis transmission.

European badgers (Meles meles) are group-living mustelids implicated in the spread of bovine tuberculosis (TB) to cattle and act as a wildlife reservoir for the disease. In badgers, only a minority of individuals disperse from their natal social group. However, dispersal may be extremely important for the spread of TB, as dispersers could act as hubs for disease transmission. We monitored a population of 139 wild badgers over seven years in a medium-density population (1.8 individuals/ km2). GPS-tracking collars were applied to 80 different individuals. Of these, we identified 25 dispersers, 14 of which were wearing collars as they dispersed. This allowed us to record the process of dispersal in much greater detail than ever before. We show that dispersal is an extremely complex process, and measurements of straight-line distance between old and new social groups can severely underestimate how far dispersers travel. Assumptions of straight-line travel can also underestimate direct and indirect interactions and the potential for disease transmission. For example, one female disperser which eventually settled 1.5 km from her natal territory travelled 308 km and passed through 22 different territories during dispersal. Knowledge of badgers'ranging behaviour during dispersal is crucial to understanding the dynamics of TB transmission, and for designing appropriate interventions, such as vaccination.

opencc-by-4.0Oct 2020View details →

Data set accompanying: Topology of the Warm plasma dispersion relation at the second Harmonic Electron Cyclotron Resonance Layer

The Warm Plasma Dispersion Relation, for waves in the electron cyclotron resonance range of frequencies, can be cast into the form of a bi-quadratic equation for $N_\perp$, where the coefficients are a function of $N_\perp^2$ and an iterative procedure is required to obtain a solution. However, this iterative procedure is not well understood and fails to converge towards a solution at the second harmonic resonance layer. In particular at higher densities where the wave can couple to an electron Bernstein wave. This paper focuses on a solution to the poor convergence of the iterative method, enabling determination of the topology of the dispersion relation around the second harmonic using a fully relativistic code for oblique waves. A feed-forward controller is proposed with the ability to adjust the rotation of a step of $N_\perp^2$ within the complex plane, while also limiting the step-size. It is shown that implementation of the controller stabilizes unstable solutions, while improving overall robustness of the iteration. This allows the evaluation of the coupling between the fast extraordinary mode and electron Bernstein waves at the second harmonic electron cyclotron resonance layer, for non-perpendicularly propagating waves.

opencc-by-4.0Oct 2020View details →

Does the spatial sorting of dispersal traits affect the phenotype of the non-dispersing stages of the invasive frog Xenopus laevis through coupling?

Over ten weeks, we surveyed the development of X. laevis tadpoles in the French invasive range by conducting experiments in outdoor mesocosms and in laboratory microcosms, from free-swimming larvae to metamorphosis. We tested the effect of the location of the parental pond in the colonised range (core or periphery) on morphological traits related to dispersal (SVL and hind limb length), time to metamorphosis (development) and survival to metamorphosis. This excel spreadsheet contains the metadata and data spreadsheets used in the analysis. In addition to the first metadata sheet, the file contains nine additional sheets each containing data used in the separate analysis as outlined in the manuscript.

opencc-zeroOct 2020View details →

Strong genetic structure in a widespread estuarine crab: A test of potential versus realized dispersal

Aim: Genetic structure has proven difficult to predict for marine and estuarine species with multi-day pelagic larval durations, since many disperse far less than expected based on passive transport models. In such cases, the gap between potential and realized dispersal may result from larval behaviors that evolved to facilitate retention and settlement in favorable environments. Behavior is predicted to play a particularly key role in structuring truly estuarine species, which often moderate their behavior to remain within their natal estuaries. In such systems, this restricted dispersal may lead to high divergence, local adaptation, and eventual speciation across their range. Here, we test whether a geographically widespread estuarine crab, known to have behavior promoting larval retention, exhibits high population structure despite a 2-4 week larval duration. Location: Atlantic and Gulf Coasts of North America Taxon: White-fingered mud crab, Rhithropanopeus harrisii Methods: Population genomic analyses across nine estuaries from New Hampshire to Louisiana using 12,638 transcriptome-derived SNPs. Results: We found highly differentiated genetic signatures among all nine estuaries, separated by 200-5,000 km of coastline. Estimates of gene flow suggest that migration is low and largely symmetrical between sites. We also observed deep phylogenetic divides corresponding to major biogeographic breaks. Main conclusions: These results indicate substantial and longstanding constraints to dispersal in the species' native range, likely arising from the emergence of geological and oceanographic barriers and sustained by behavior that promotes estuarine retention during larval development. This work supports the idea that larval behavior promoting estuarine retention can be reflected in substantial genetic structure even in species with multi-week pelagic larval durations. Such behavior-restricted dispersal has implications for predicting adaptation and spread in estuarine species, many of which have been introduced outside their native ranges.

opencc-by-4.0Nov 2020View details →

The linear dispersion relation of the electrostatic waves in magnetized anisotropic dysty plasma

The linear and weakly nonlinear dust-ion-acoustic wave propagation obliquely with respect to an external magnetic field is studied in magnetized dusty plasma, which consists of magnetized fluid ions bearing with anisotropic pressure, suprathermal electrons, and static dust grains. In the linear regime, the magnetized dusty plasma supports the propagation of fast dust-ion-cyclotron (EDIC) mode and the slow electrostatic dust-ion-acoustic (DIA) mode.

opencc-zeroDec 2020View details →

Social learning by mate-choice copying increases dispersal and reduces local adaptation

1. In heterogeneous environments, dispersal may be hampered not only by direct costs, but also because immigrants may be locally maladapted. While maladaptation affects both sexes, this cost may be modulated in females if they express mate preferences that are either adaptive or maladaptive in the new local population. 2. Dispersal costs under local adaptation may be mitigated if it is possible to switch to expressing traits of locally adapted residents. In a sexual selection context, immigrant females may learn to mate with locally favoured males. Mate-choice copying is a type of social learning, where individuals, usually females, update their mating preferences after observing others mate. If it allows immigrant females to switch from maladapted to locally adapted preferences, their dispersal costs are mitigated as mate choice helps them create locally adapted offspring. 3. To study if copying can promote the evolution of dispersal, we created an individual-based model to simulate the coevolution of four traits: copying, dispersal, a trait relevant for local adaptation, and female preference. We contrast two scenarios with copying — either unconditional, or conditional such that only dispersers copy — with a control scenario that lacks any copying. 4. We show copying to lead to higher dispersal, especially if copying is conditionally expressed. This leads to an increase in gene flow between patches and, consequently, a decrease in local adaptation and trait-preference correlations. 5. While our study is phrased with female preference as the learned trait, one may generally expect social learning to mitigate dispersal costs, with consequent feedback effects on the spatial dynamics of adaptation.

opencc-zeroDec 2020View details →

Host spatial structure and disperser activity determine mistletoe infection patterns

What processes and factors are responsible for species distribution are long-standing questions in ecology and a key element for conservation and management. Mistletoes provide the opportunity to study a forest species whose occurrence is expected to be constrained by multiple factors as a consequence of their life form. We studied the mistletoe Tristerix corymbosus (Loranthaceae) on its most common hosts species in northwest Patagonia. The seeds of this mistletoe are almost exclusively dispersed by the small arboreal and endemic marsupial Dromiciops gliroides (Microbiotheridae). We assessed the underlying causes of plant spatial patterns through point pattern analysis and we used different variables that characterize the neighborhood around each host to analyze the relative effect of host availability, potential for disperser movement, and canopy light conditions. We found that potential hosts were strongly aggregated and that the three most common host species were distributed independent of each other. Considering all host species together, infected and non-infected host were individually aggregated but segregated from each other. The aggregated pattern of infected hosts could be explained in part by the template of potential hosts distribution, but was subsequently modulated by the activity of the mistletoe disperser. Potential for disperser movement, the proximity to reproductive mistletoes and habitat complexity, increased mistletoe infection probability. However, neighboring host availability decreased mistletoe infection probability, and tree DBH (used as surrogate for light conditions) had no detectable effect. Our results suggested that the distribution of mistletoe infection was determined by the structure of potential host populations and by the marsupial disperser activity. Compared to bird dispersed mistletoes, the scale of the infection was smaller and the proximity to reproductive mistletoes and habitat complexity were important for seed arrival and infection. The interplay between landscape structure and disperser activity determine the spatial structure of mistletoe future generations.

opencc-zeroNov 2021View details →

Weather variation affects the dispersal of grasshoppers beyond their elevational ranges

Understanding how abiotic conditions influence dispersal patterns of organisms is important for understanding the degree to which species can track and persist in the face of changing climate. The goal of this study was to understand how weather conditions (temperature, precipitation and wind patterns) influence the dispersal patterns of multiple non-migratory grasshopper species from lower elevation grassland habitats in which they complete their life-cycles to higher elevations that extend beyond their range limits. The study also explored the role of weather factors (temperature and precipitation) in influencing the population sizes of species found at lower elevations.

opencc-zeroDec 2020View details →

Reconstructing hotspots of genetic diversity from glacial refugia and subsequent dispersal in Italian common toads (Bufo bufo)

Genetic diversity feeds the evolutionary process and allows populations to adapt to environmental changes. However, we still lack a thorough understanding of why hotspots of genetic diversity are so 'hot'. Here, we analysed the relative contribution of bioclimatic stability and genetic admixture between divergent lineages in shaping spatial patterns of genetic diversity in the common toad Bufo bufo along the Italian peninsula. We combined population genetic, phylogeographic and species distribution modelling (SDM) approaches to map ancestral areas, glacial refugia, and secondary contact zones. We consistently identified three phylogeographic lineages, distributed in northern, central and southern Italy. These lineages expanded from their ancestral areas and established secondary contact zones, before the last interglacial. SDM identified widespread glacial refugia in peninsular Italy, sometimes located under the present-day sea-level. Generalized linear models indicated genetic admixture as the only significant predictor of the levels of population genetic diversity. Our results show that glacial refugia contributed to preserving both levels and patterns of genetic diversity across glacial-interglacial cycles, but not to their formation, and highlight a general principle emerging in Mediterranean species: higher levels of genetic diversity mark populations with substantial contributions from multiple genetic lineages, irrespective of the location of glacial refugia.

Data from: Tracking temperate fish reveals their relevance for plant seed dispersal

Seed dispersal is a fundamental process for plant communities, especially now that our changing world demands rapid colonization of new habitats. Long-distance dispersal is especially important for plant population persistence and range expansions. The contribution of fishes to plant seed dispersal in aquatic ecosystems (ichthyochory) has long been overlooked. Although we know fish disperse seeds, it is largely unknown where, when and how far – especially in temperate regions. Here we studied the potential of fish to disperse seeds locally and over long distances, specifically hypothesizing that i) dispersal by fish depends on the season, ii) individual fish contribute differently to seed dispersal, and iii) water regulating structures (barriers) inhibit seed dispersal. We tested our hypotheses by acoustically tracking 71 common carp (Cyprinus carpio) with 21 hydrophones in a 38km-long study system for >2 years in the Netherlands. We calculated potential seed dispersal throughout this system by combining nearly 1.5 million location registrations with experimentally assessed retention times of seeds after ingestion (i.e. time between ingestion and egestion). Seed dispersal on local scales was quantitatively most important during summer and autumn, with high dispersal potential in a range of four kilometres from the location of seed ingestion. Long-distance dispersal up to 16 km was possible at low probabilities in spring. In winter, most seeds were egested within two km. Maximum and median dispersal distances varied widely among individuals, emphasizing variation in effectiveness among individual fish for seed dispersal. Less than two percent of all fish movements reached beyond sluices and weirs, indicating that anthropogenic barriers in freshwater systems strongly reduced the potential of common carp to disperse seeds to these areas. This study shows that common carp can locally disperse plant seeds with high probabilities, and over distances up to 16 km with low probabilities throughout temperate ecosystems. This can contribute to restoration and maintenance of plant community diversity. However, this ecosystem function of fish to plants requires intact fish populations – because not all individual fish contribute equally to dispersal – and unrestricted connectivity throughout aquatic ecosystems.

Data from: Long-term monitoring of seed dispersal by Asian elephants in a Sundaland rainforest

Asian elephants (Elephas maximus) have inhabited almost all forests in tropical Asia until recently, yet little is known about their role in ecological processes, particularly in the Sundaic forests of Southeast Asia. These forests are peculiar in their phenology, with supra-annual and highly irregular episodes of mast fruiting. Here we present a long-term (six-year) monitoring of the seeds dispersed by elephants in dipterocarp forests of northern Peninsular Malaysia. We conducted monthly dung surveys at two mineral licks (11.3 km apart) frequently visited by elephants. Additionally, we recorded haphazard observations of seeds and seedlings in elephant dung at other locations. We recorded a minimum of 48 morphospecies from at least 25 plant families dispersed by elephants. Elephant seed dispersal was very heterogenous in space, with only 30.3 % of the morphospecies dispersed at both sites (Jaccard dissimilarity index = 0.48). Temporally, elephants dispersed seeds in sporadic pulses of abundance and diversity, without any apparent seasonality (seeds appeared in 19.1 % of 1,284 dung piles and 57.1 % of the 63 months in which we found dung) and with long periods without any seed being dispersed. Nearly half (48 %) of the plants dispersed by elephants belong to a megafaunal dispersal syndrome. Our long-term approach allowed us to unravel an important aspect of Asian elephants' role and effectiveness in the seed dispersal cycle. Sundaland's forests are undergoing a rapid loss of their previously common megaherbivores (rhinos and elephants), with profound and long-term consequences for ecosystem functioning.

Synthesis of a novel amphoteric copolymer and its application as a dispersant for coal water slurry preparation

In this work, a novel amphoteric copolymer was synthesized via free radical polymerization, named Poly(sodium p-styrenesulfonate–co-acrylic acid-co-diallyldimethylammonium chloride) (P(SS-co-AA-co-DMDAAC)). Afterwards, P(SS-co-AA-co-DMDAAC) was explored for use as a dispersant in coal water slurry (CWS) preparation. The structure of P(SS-co-AA-co-DMDAAC) was verified by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance (NMR). The synthetic conditions were optimized as the feed ratio of AA to SS was 1:1 (for Yulin coal) or 1.5:1 (for Yili coal), and DMDAAC dosage was 4.0 wt% (for Yulin coal) and 6.0 wt% (for Yili coal) toward total monomers. The performances of P(SS-co-AA-co-DMDAAC) as a dispersant for CWS were evaluated by various technologies, such as apparent viscosity, Zeta potential, static stability and contact angle measurements. The results revealed that the optimized dosage of P(SS-co-AA-co-DMDAAC) in CWS preparation was 0.3 wt% and 0.4 wt% for Yulin coal and Yili coal respectively. In this optimum condition, CWS prepared using P(SS-co-AA-co-DMDAAC) as dispersant showed a typical shear thinning behavior and excellent stability, which are desired in industry. The rheological models also confirmed the pseudo-plastic characteristics of CWS. Finally, as compared to the widespread used anionic dispersant Poly(sodium p-styrenesulfonate) (PSS), P(SS-co-AA-co-DMDAAC) developed in this work exhibited better slurry making performance. Introduction of cationic functional groups promoted the adsorption of dispersant, which further enhanced the electrostatic repulsion among coal particles. Accordingly, the viscosity of CWS decreased and static stability enhanced.

opencc-by-4.0Jul 2020View details →

Supplementary Information for "Resolution and the Detection of Cultural Dispersals: development and application of spatiotemporal methods in Lowland South America"

Data and code to reproduce the analyses in "Resolution and the Detection of Cultural Dispersals: development and application of spatiotemporal methods in Lowland South America"   Abstract Inferring episodes of expansion, admixture, diffusion, and/or migration in prehistory is at present undergoing a resurgence in macro-scale archaeological interpretation. In parallel to this renewed popularity, expanding access to computational tools and datasets has seen the use of aggregated radiocarbon datasets for the study of dispersals also increasing. This paper advocates for developing reflexive practice in the application of radiocarbon dates to prehistoric dispersals, by reflecting on the quality and qualities of the underlying data, particularly chronometric uncertainty, and framing dispersals explicitly in terms of hypothesis testing. This paper draws on cultural expansions within South America and employs two emblematic examples, the Arauquinoid and Tupiguarani traditions, to develop an analytical solution that not only incorporates chronometric uncertainty in bivariate regression but, importantly, tests whether the datasets provide statistically significant evidence for a dispersal process. The analysis, which the paper provides the means to replicate, identifies fundamental issues with resolution and data quality that impede identification of pre-Columbian cultural dispersals through simple spatial gradients of radiocarbon data. The results suggest that reflexivity must be fed back into theoretical frameworks of prehistoric mobility for the study of dispersals, in turn informing the construction of more critical statistical null models. As a first step, alternative models of cultural expansion should be formally considered alongside demographic models.Inferring episodes of expansion, admixture, diffusion, and/or migration in prehistory is at present undergoing a resurgence in macro-scale archaeological interpretation. In parallel to this renewed popularity, expanding access to computational tools and datasets has seen the use of aggregated radiocarbon datasets for the study of dispersals also increasing. This paper advocates for developing reflexive practice in the application of radiocarbon dates to prehistoric dispersals, by reflecting on the quality and qualities of the underlying data, particularly chronometric uncertainty, and framing dispersals explicitly in terms of hypothesis testing. This paper draws on cultural expansions within South America and employs two emblematic examples, the Arauquinoid and Tupiguarani traditions, to develop an analytical solution that not only incorporates chronometric uncertainty in bivariate regression but, importantly, tests whether the datasets provide statistically significant evidence for a dispersal process. The analysis, which the paper provides the means to replicate, identifies fundamental issues with resolution and data quality that impede identification of pre-Columbian cultural dispersals through simple spatial gradients of radiocarbon data. The results suggest that reflexivity must be fed back into theoretical frameworks of prehistoric mobility for the study of dispersals, in turn informing the construction of more critical statistical null models. As a first step, alternative models of cultural expansion should be formally considered alongside demographic models.

Small fish, large river: surprisingly minimal genetic structure in a dispersal-limited, habitat specialist fish

Genetic connectivity is expected to be lower in species with limited dispersal ability and a high degree of habitat specialization (intrinsic factors). Also, gene flow is predicted to be limited by habitat conditions such as physical barriers and geographic distance (extrinsic factors). We investigated the effects of distance, intervening pools, and rapids on gene flow in a species, the Tuxedo Darter (Etheostoma lemniscatum), a habitat specialist that is presumed to be dispersal-limited. We predicted that the interplay between these intrinsic and extrinsic factors would limit dispersal and lead to genetic structure even at the small spatial scale of the species range (a 38.6 km river reach). The simple linear distribution of E. lemniscatum allowed for an ideal test of how these factors acted on gene flow and allowed us to test expectations (e.g., isolation-by-distance) of linearly distributed species. Using 20 microsatellites from 163 individuals collected from 18 habitat patches, we observed low levels of genetic structure that were related to geographic distance and rapids, though these factors were not barriers to gene flow. Pools separating habitat patches did not contribute to any observed genetic structure. Overall, E. lemniscatum maintains gene flow across its range and is comprised of a single population. Due to the linear distribution of the species, a stepping stone model of dispersal best explains the maintenance of gene flow across its small range. In general, our observation of higher than expected connectivity likely stems from an adaptation to disperse due to temporally unstable and patchy habitat.

Analysing landscape effects on dispersal networks and gene flow with genetic graphs

Graph-theoretic approaches have relevant applications in landscape genetic analyses. When species form populations in discrete habitat patches, genetic graphs can be used i) to identify direct dispersal paths followed by propagules or ii) to quantify landscape effects on multigenerational gene flow. However, the influence of their construction parameters remains to be explored. Using a simulation approach, we constructed genetic graphs using several pruning methods (geographical distance thresholds, topological constraints, statistical inference) and genetic distances to weight graph links (FST, DPS, Euclidean genetic distances). We then compared the capacity of these different graphs to i) identify the precise topology of the dispersal network and ii) to infer landscape resistance to gene flow from the relationship between cost-distances and genetic distances. Although not always clear-cut, our results showed that methods based on geographical distance thresholds seem to better identify dispersal networks in most cases. More interestingly, our study demonstrates that a subselection of pairwise distances through graph pruning (thereby reducing the number of data points) can counter-intuitively lead to improved inferences of landscape effects on dispersal. Finally, we showed that genetic distances such as the DPS or Euclidean genetic distances should be preferred over the FST for landscape effect inference as they respond faster to landscape changes.

The combined role of dispersal and niche evolution in the diversification of Neotropical lizards

Ecological requirements and environmental conditions can influence diversification across temporal and spatial scales. Understanding the role of ecological niche evolution under phylogenetic contexts provides insights on speciation mechanisms and possible responses to future climatic change. Large-scale phyloclimatic studies on the megadiverse Neotropics, where biomes with contrasting vegetation types occur in narrow contact, are rare. We integrate ecological and biogeographic data with phylogenetic comparative methods, to investigate the relative roles of biogeographic events and niche divergence and conservatism on the diversification of the lizard genus Kentropyx Spix, 1825 (Squamata: Teiidae), distributed in South American rainforests and savannas. Using five molecular markers, we estimated a dated species tree, which recovered three clades coincident with previously proposed species groups diverging during the mid-Miocene. Biogeography reconstruction indicates a role of successive dispersal events from an ancestral range in the Brazilian Shield and western Amazonia. Ancestral reconstruction of climatic tolerances and niche overlap metrics indicate a trend of conservatism during the diversification of groups from the Amazon Basin and Guiana Shield, and a strong signal of niche divergence in the Brazilian Shield savannas. Our results suggest that climatic-driven divergence at dynamic forest-savanna borders might have resulted in adaptation to new environmental niches, promoting habitat shifts and shaping speciation patterns of Neotropical lizards. Dispersal and ecological divergence could have a more important role in Neotropical diversification than previously thought.

Rwenzori colobus core unit SNA data - association scans between units, simple association index per dyad, male dispersal events, rainfall and food availability

1. Multi-level societies are complex, nested social systems where basic social groups (i.e., core units) associate in a hierarchical manner, allowing animals to adjust their group sizes in response to variables such as food availability, predation, or conspecific threat. These pressures fluctuate over time and examining the extent to which this variation affects the clustering of core units into different tiers may be instrumental in understanding the evolution of multi-level societies. 2. The goal of our study was to determine the degree of temporal variability in inter-unit associations in a multi-level society of Rwenzori Angolan colobus monkey (Colobus angolensis ruwenzorii), and to determine the social and ecological factors that underlie association patterns. The C. a. ruwenzorii multi-level society consists of at least three tiers, with core units clustering into clans that share a home range in a band tier. 3. We performed social network analyses on 21 months of association data from 13 core units (totaling 139 identifiable individuals) at Lake Nabugabo, Uganda. We described the patterns of variation in core-unit associations over time and investigated how changes in rainfall, food availability, and inter-unit dispersals were correlated with these associations over the short-term (month to month) and long-term (year to year). 4. Although clans were relatively stable, larger-scale changes in association patterns included the formation of an all-male unit and the transfer of one core unit between clans (within the band tier). Seasonally, core units associated significantly more when fruit, their preferred food source, was abundant (i.e., social networks were denser and more clustered) and there was no direct effect of rainfall seasonality or young leaf availability. Male dispersals also occurred more during periods of high fruit availability, suggesting that greater band cohesion allowed males to prospect and transfer between core units. Once males transferred, their previous and new units associated significantly more with one another than with other core units for 1-2 months post-dispersal. The dispersal of five males from one core unit to another in a different clan co-occurred with this core unit switching its clan affiliation. 5. By examining temporal shifts in social network structure among core units, this study shows the inter-connected roles that food availability and dispersal have in shaping the C. a. ruwenzorii multi-level social system. Our findings highlight how ecological conditions can drive association patterns, impact interunit relationships, and influence social organization.

Genetic variation in an ephemeral mudflat species: the role of the soil seed bank and dispersal in river and secondary anthropogenic habitats

Many ephemeral mudflat species, which rely on a soil seed bank to build up the next generation, are endangered in their natural habitat due to the widespread regulation of rivers. The aim of the present study was to elucidate the role of the soil seed bank and dispersal for the maintenance of genetic diversity in populations of near-natural river habitats and anthropogenic habitats created by traditional fish farming practices using Cyperus fuscus as a model. Using microsatellite markers, we found no difference in genetic diversity levels between soil seed bank and above-ground population and only moderate differentiation between the two fractions. One possible interpretation is the difference in short-term selection during germination under specific conditions (glasshouse versus field) resulting in an ecological filtering of genotypes out of the reservoir in the soil. River populations harboured significantly more genetic diversity than populations from the anthropogenic pond types. We suggest that altered levels and patterns of dispersal together with stronger selection pressures and historical bottlenecks in anthropogenic habitats are responsible for the observed reduction in genetic diversity. Dispersal is also supposed to largely prohibit genetic structure across Europe, although there is a gradient in private allelic richness from southern Europe and Anatolia (high values) to northern, especially north-western, Europe (low values), which probably relates to postglacial expansion out of southern and/or eastern refugia.

The role of evolutionary time, diversification rates and dispersal in determining the global diversity of a large radiation of passerine birds

Aim: Variation in species diversity among different geographic areas may result from differences in speciation and extinction rates, immigration and time for diversification. An area with high species diversity may be the result of a high net diversification rate, multiple immigration events from adjacent regions,anda long time available for the accumulation of species (know as the "time-for-speciation effect"). Here, we examine the relative importance of the three aforementionedprocesses in shaping the geographic diversity patterns of a large radiation of passerine birds. Location: Global Time period: Early Miocene to present Major taxa studied: Babblers (Aves: Passeriformes) Methods: Using a comprehensive phylogeny of extant species (~90% sampled) and distributions of the world's babblers, we reconstructed their biogeographic history and analysed the diversification dynamics. We examined how species richness correlates with the timing of regional colonization, the number of immigration events and the rate of speciation within all 13 geographic distribution regions. Results: We found thatbabblers likely originated in the Sino-Himalayan Mountains (SHM) in the early Miocene, suggesting a long time for diversification and species accumulation within the SHM. Regression analyses showed the regional diversity of babblers can be well explained by the timing of the first colonization within of these areas, while differences in rates of speciation or immigration have far weaker effects. Nonetheless, the rapid speciation of Zosteropsduring the Pleistocene has accounted for the increased diversification and accumulation of species in the oceanic islands. Main conclusions: Our results suggest that the global diversity patterns of babblers have predominantly been shaped by the time-for-speciation effect. Our findings also support an origin centred in tropical and subtropical parts of the SHM, with a cradle of recent diversification in the oceanic islands of the Indo-Pacific region, which provides new insights into the generation of global biodiversity hotspots.