Articles de revues : « Dispersal event »

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Hooker, J. J. « A two-phase Mammalian Dispersal Event across the Paleocene–Eocene transition ». Newsletters on Stratigraphy 48, n^o 2 (1 avril 2015) : 201–20. http://dx.doi.org/10.1127/nos/2015/0060.

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McClenaghan, M. B., et R. N. W. DiLabio. « Ice-flow history and glacial dispersal patterns, southeastern Cape Breton Island, Nova Scotia : implications for mineral exploration ». Canadian Journal of Earth Sciences 33, n^o 2 (1 février 1996) : 351–62. http://dx.doi.org/10.1139/e96-026.

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Regional till sampling and stratigraphic studies were completed in southeastern Cape Breton Island, Nova Scotia, in 1990 and 1991 to document the directions and distances that successive ice-flow events have dispersed material and to document regional till geochemical patterns to aid mineral exploration in this heavily drift-covered area. Three major Wisconsinan ice-flow events affected the area: an early eastward flow, followed by a northeastward flow, and finally a southward flow. The shape and magnitude of dispersal trains in the area are the net result of the three ice-flow events, which are variable from north to south. In the north, the northeast ice flow was the dominant erosive and depositional event, producing a large northeast-trending drumlin field. Salmon River porphyry clasts and Pb- and Zn-rich till from the Yava Pb mine were dispersed more than 15 km to the northeast. In the south, eastward ice flow was the dominant erosive and depositional event, producing large east-trending till ridges. Dispersal in this area is difficult to detect because exotic red silty till in the giant till ridges masks underlying mineralized bedrock and dilutes the locally derived glacial debris. Many precious and base metal anomalies and dispersal trains were identified in the regional till samples, several of which are related to unknown mineralized sources.

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Iannucci, Alessio, et Raffaele Sardella. « What Does the “Elephant-Equus” Event Mean Today ? Reflections on Mammal Dispersal Events around the Pliocene-Pleistocene Boundary and the Flexible Ambiguity of Biochronology ». Quaternary 6, n^o 1 (28 février 2023) : 16. http://dx.doi.org/10.3390/quat6010016.

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The dispersal of primitive elephantines and monodactyl equids in Eurasia has long been regarded as representative of a substantial turnover in mammal faunas, denoting the spread of open environments linked to the onset of cold and dry conditions in the Northern Hemisphere. During the 1980s, this event was named the “Elephant-Equus event” and it was correlated with the Gauss-Matuyama reversal, today corresponding to the Pliocene-Pleistocene transition and the beginning of the Quaternary, dated at ~2.6 Ma. Therefore, the Elephant-Equus event became a concept of prominent biochronological and paleoecological significance, especially in western Europe. Yet, uncertainties surrounding the taxonomy and chronology of early “elephant” and “Equus”, as well as conceptual differences in adopting (or understanding) the Elephant-Equus event as an intercontinental dispersal event or as a stratigraphic datum, engendered ambiguity and debate. Here, we provide a succinct review of the Elephant-Equus event, considering separately the available evidence on the “elephant” and the “Equus”. Elephantines dispersed out of Africa during the Pliocene (Piacenzian). Their earliest calibrated occurrences from eastern Europe date at ~3.2 Ma and they are usually referred to Mammuthus rumanus, although the allocation of several samples to this species is tentative. Available dating constraints for other localities do not resolve whether the dispersal of Mammuthus was synchronous across Eurasia, but this possibility cannot be ruled out. The spread of Mammuthus was part of an intercontinental faunal exchange between Africa and Eurasia that occurred during the Piacenzian, but in this scenario, Mammuthus is quite unique in being the only genus of African origin dispersing to western Eurasia. The arrival of monodactyl equids from North America coincides with the Pliocene-Pleistocene transition, with several occurrences dated or calibrated at ~2.6 Ma and no compelling evidence prior to this age. In Europe, early monodactyl equids are often aligned to Equus livenzovensis, but the material from the type locality of this species is chronologically time-averaged and taxonomically heterogeneous, and western European samples are seldom abundant or informative. Regardless, this does not diminish the biochronological significance of the “Equus event”. Indeed, while the term “Elephant-Equus event” should no longer be used, as the appearance of elephantines in the European fossil record markedly precedes that of monodactyl equids, we endorse the use of the “Equus event” as a valid alternative to refer to the intercontinental dispersal event that characterizes the middle Villafranchian faunal turnover, epitomized by but not limited to monodactyl equids.

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Vahedian, Amin, Xun Zhou, Ling Tong, W. Nick Street et Yanhua Li. « Predicting Urban Dispersal Events : A Two-Stage Framework through Deep Survival Analysis on Mobility Data ». Proceedings of the AAAI Conference on Artificial Intelligence 33 (17 juillet 2019) : 5199–206. http://dx.doi.org/10.1609/aaai.v33i01.33015199.

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Urban dispersal events are processes where an unusually large number of people leave the same area in a short period. Early prediction of dispersal events is important in mitigating congestion and safety risks and making better dispatching decisions for taxi and ride-sharing fleets. Existing work mostly focuses on predicting taxi demand in the near future by learning patterns from historical data. However, they fail in case of abnormality because dispersal events with abnormally high demand are non-repetitive and violate common assumptions such as smoothness in demand change over time. Instead, in this paper we argue that dispersal events follow a complex pattern of trips and other related features in the past, which can be used to predict such events. Therefore, we formulate the dispersal event prediction problem as a survival analysis problem. We propose a two-stage framework (DILSA), where a deep learning model combined with survival analysis is developed to predict the probability of a dispersal event and its demand volume. We conduct extensive case studies and experiments on the NYC Yellow taxi dataset from 20142016. Results show that DILSA can predict events in the next 5 hours with F1-score of 0:7 and with average time error of 18 minutes. It is orders of magnitude better than the state-of-the-art deep learning approaches for taxi demand prediction.

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Vidal, Nicolas, Anna Azvolinsky, Corinne Cruaud et S. Blair Hedges. « Origin of tropical American burrowing reptiles by transatlantic rafting ». Biology Letters 4, n^o 1 (11 décembre 2007) : 115–18. http://dx.doi.org/10.1098/rsbl.2007.0531.

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Populations of terrestrial or freshwater taxa that are separated by oceans can be explained by either oceanic dispersal or fragmentation of a previously contiguous land mass. Amphisbaenians, the worm lizards (approx. 165 species), are small squamate reptiles that are uniquely adapted to a burrowing lifestyle and inhabit Africa, South America, Caribbean Islands, North America, Europe and the Middle East. All but a few species are limbless and they rarely leave their subterranean burrows. Given their peculiar habits, the distribution of amphisbaenians has been assumed to be primarily the result of two land-mass fragmentation events: the split of the supercontinent Pangaea starting 200 Myr ago, separating species on the northern land mass (Laurasia) from those on the southern land mass (Gondwana), and the split of South America from Africa 100 Myr ago. Here we show with molecular evidence that oceanic dispersal—on floating islands—played a more prominent role, and that amphisbaenians crossed the Atlantic Ocean in the Eocene (40 Myr ago) resulting in a tropical American radiation representing one-half of all known amphisbaenian species. Until now, only four or five transatlantic dispersal events were known in terrestrial vertebrates. Significantly, this is the first such dispersal event to involve a group that burrows, an unexpected lifestyle for an oceanic disperser.

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Magalhaes, Ivan L. F., Adalberto J. Santos et Martín J. Ramírez. « Incorporating Topological and Age Uncertainty into Event-Based Biogeography of Sand Spiders Supports Paleo-Islands in Galapagos and Ancient Connections among Neotropical Dry Forests ». Diversity 13, n^o 9 (31 août 2021) : 418. http://dx.doi.org/10.3390/d13090418.

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Event-based biogeographic methods, such as dispersal-extinction-cladogenesis, have become increasingly popular for attempting to reconstruct the biogeographic history of organisms. Such methods employ distributional data of sampled species and a dated phylogenetic tree to estimate ancestral distribution ranges. Because the input tree is often a single consensus tree, uncertainty in topology and age estimates are rarely accounted for, even when they may affect the outcome of biogeographic estimates. Even when such uncertainties are taken into account for estimates of ancestral ranges, they are usually ignored when researchers compare competing biogeographic hypotheses. We explore the effect of incorporating this uncertainty in a biogeographic analysis of the 21 species of sand spiders (Sicariidae: Sicarius) from Neotropical xeric biomes, based on a total-evidence phylogeny including a complete sampling of the genus. Using a custom R script, we account for uncertainty in ages and topology by estimating ancestral ranges over a sample of trees from the posterior distribution of a Bayesian analysis, and for uncertainty in biogeographic estimates by using stochastic maps. This approach allows for counting biogeographic events such as dispersal among areas, counting lineages through time per area, and testing biogeographic hypotheses, while not overestimating the confidence in a single topology. Including uncertainty in ages indicates that Sicarius dispersed to the Galapagos Islands when the archipelago was formed by paleo-islands that are now submerged; model comparison strongly favors a scenario where dispersal took place before the current islands emerged. We also investigated past connections among currently disjunct Neotropical dry forests; failing to account for topological uncertainty underestimates possible connections among the Caatinga and Andean dry forests in favor of connections among Caatinga and Caribbean + Mesoamerican dry forests. Additionally, we find that biogeographic models including a founder-event speciation parameter (“+J”) are more prone to suffer from the overconfidence effects of estimating ancestral ranges using a single topology. This effect is alleviated by incorporating topological and age uncertainty while estimating stochastic maps, increasing the similarity in the inference of biogeographic events between models with or without a founder-event speciation parameter. We argue that incorporating phylogenetic uncertainty in biogeographic hypothesis-testing is valuable and should be a commonplace approach in the presence of rogue taxa or wide confidence intervals in age estimates, and especially when using models including founder-event speciation.

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Mai-Prochnow, Anne, Jeremy S. Webb, Belinda C. Ferrari et Staffan Kjelleberg. « Ecological Advantages of Autolysis during the Development and Dispersal of Pseudoalteromonas tunicata Biofilms ». Applied and Environmental Microbiology 72, n^o 8 (août 2006) : 5414–20. http://dx.doi.org/10.1128/aem.00546-06.

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ABSTRACT In the ubiquitous marine bacterium Pseudoalteromonas tunicata, subpopulations of cells are killed by the production of an autocidal protein, AlpP, during biofilm development. Our data demonstrate an involvement of this process in two parameters, dispersal and phenotypic diversification, which are of importance for the ecology of this organism and for its survival within the environment. Cell death in P. tunicata wild-type biofilms led to a major reproducible dispersal event after 192 h of biofilm development. The dispersal was not observed with a ΔAlpP mutant strain. Using flow cytometry and the fluorescent dye DiBAC4(3), we also show that P. tunicata wild-type cells that disperse from biofilms have enhanced metabolic activity compared to those cells that disperse from ΔAlpP mutant biofilms, possibly due to nutrients released from dead cells. Furthermore, we report that there was considerable phenotypic variation among cells dispersing from wild-type biofilms but not from the ΔAlpP mutant. Wild-type cells that dispersed from biofilms showed significantly increased variations in growth, motility, and biofilm formation, which may be important for successful colonization of new surfaces. These findings suggest for the first time that the autocidal events mediated by an antibacterial protein can confer ecological advantages to the species by generating a metabolically active and phenotypically diverse subpopulation of dispersal cells.

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James, Trevor K., Michael R. Trolove et Claire A. Dowsett. « Roadside mowing spreads yellow bristle grass (Setaria pumila) seeds further than by natural dispersal ». New Zealand Plant Protection 72 (22 juillet 2019) : 153–57. http://dx.doi.org/10.30843/nzpp.2019.72.246.

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Yellow bristle grass is a highly invasive annual C4 pasture weed that has spread rapidly through many New Zealand dairying regions via seed dispersal. Seven trials were conducted on roadsides infested with yellow bristle grass to evaluate natural and mower-assisted dispersal. To trap seeds, yellow sticky traps were laid out at various intervals both perpendicular to and parallel to the road. Traps were in place for 24 h in the four natural dispersal trials but only for the event in the mowing trials. Seeds on the retrieved traps were counted and the seeds caught in the mower estimated. For natural dispersal, 90% of seeds fell within 0.5 m. When mown, 90% of the seeds fell within 2 metres in the direction of mowing and 80% within 20 cm in the perpendicular direction. More importantly, a small percentage of dispersed seeds were caught in the mower and presumably could subsequently fall off anywhere. Mowing mature yellow bristle grass on the roadside will result in accelerating seed dispersal along the roadside for many metres and potentially many kilometres.

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Skjelseth, Sigrun, Thor Harald Ringsby, Jarle Tufto, Henrik Jensen et Bernt-Erik Sæther. « Dispersal of introduced house sparrows Passer domesticus : an experiment ». Proceedings of the Royal Society B : Biological Sciences 274, n^o 1619 (8 mai 2007) : 1763–71. http://dx.doi.org/10.1098/rspb.2007.0338.

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An important issue concerning the introduction of non-indigenous organisms into local populations is the potential of the introduced individuals to spread and interfere both demographically and genetically with the local population. Accordingly, the potential of spatial dispersal among introduced individuals compared with local individuals is a key parameter to understand the spatial and temporal dynamics of populations after an introduction event. In addition, if the variance in dispersal rate and distance is linked to individual characteristics, this may further affect the population dynamics. We conducted a large-scale experiment where we introduced 123 house sparrows from a distant population into 18 local populations without changing population density or sex ratio. Introduced individuals dispersed more frequently and over longer distances than residents. Furthermore, females had higher probability of dispersal than males. In females, there was also a positive relationship between the wing length and the probability of dispersal and dispersal distance. These results suggest that the distribution and frequency of introduced individuals may be predicted by their sex ratio as well as their phenotypic characteristics.

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Martínez, Isabel, et Fernando González-Taboada. « Seed dispersal patterns in a temperate forest during a mast event : performance of alternative dispersal kernels ». Oecologia 159, n^o 2 (19 novembre 2008) : 389–400. http://dx.doi.org/10.1007/s00442-008-1218-4.

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Parada, Gloria M., Florence Tellier et Enrique A. Martínez. « Spore dispersal in the intertidal kelp Lessonia spicata : macrochallenges for the harvested Lessonia species complex at microscales of space and time ». Botanica Marina 59, n^o 4 (29 juillet 2016) : 283–89. http://dx.doi.org/10.1515/bot-2016-0034.

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Abstract The intertidal coast of Chile has two cryptic kelp species, Lessonia spicata and L. berteroana, which share closely situated, but not overlapping, high-energy habitats. Their populations recover slowly after major disturbances and massive mortalities, suggesting that dispersal from remnant populations is strongly limited. This low dispersal is also a factor that probably favours the speciation process. Understanding the limiting factors for spore dispersal is crucial. Here we evaluated 1. spore dispersal and spore dilution over distance, 2. if submersion in calm waters for a specific period of time is needed for the settlement of spores before exposure to water movement, and 3. duration of spore attachment ability. Results were consistent with the hypothesis of low-distance dispersal of spores: stained-spore dilution was high at short spatial scales (<4 m); spores settled quickly (1–2 min) even under constant water movement, but they lost the ability to attach rapidly (≤16 h). Water motion did not affect spore attachment to the substratum, a fact probably resulting from an adaptation to high energy intertidal habitats. The very low dispersal range of the spores may explain the strong genetic differentiation at small spatial scales, the speciation event that occurred within the Lessonia species complex and the slow recovery of L. berteroana after massive mortalities occurring with the 1982/1983 El Niño Southern oscillation event.

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Yenish, Joseph P., Thomas A. Fry, Beverly R. Durgan et Donald L. Wyse. « Tillage Effects on Seed Distribution and Common Milkweed (Asclepias syriaca) Establishment ». Weed Science 44, n^o 4 (décembre 1996) : 815–20. http://dx.doi.org/10.1017/s0043174500094765.

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Soil profile distribution of a single simulated seed dispersal event after tillage followed a nonlinear model. Approximately 40% of recovered simulated seed were found within 4 cm of the surface following chisel plowing and disking, and density declined steadily with depth to 20 cm. Moldboard plowing placed 50 to 60% of simulated seed to a depth of 11 to 16 cm. Simulated seed were evenly distributed to 8 cm depth by disking and did not differ regardless of whether plots were chisel or moldboard plowed prior to seed dispersal. More than 90% of seed remained within 2 cm of the surface with no-tillage. Simulated seed distribution was the same after a tillage rotation of chisel plowing, disking, moldboard plowing, and disking regardless if the dispersal event occurred prior to chisel or moldboard plowing. Two years of the tillage rotation and two dispersal events resulted in a distribution pattern greatly influenced by the most recent major tillage of chisel or moldboard plowing. Seedling emergence of common milkweed averaged 80% for seed buried 0.5 to 4 cm deep and emergence was negligible for seed on the surface or buried 7 cm in soil in pots in a growth chamber.

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Bock, C. H., P. E. Parker et T. R. Gottwald. « Effect of Simulated Wind-Driven Rain on Duration and Distance of Dispersal of Xanthomonas axonopodis pv. citri from Canker-Infected Citrus Trees ». Plant Disease 89, n^o 1 (janvier 2005) : 71–80. http://dx.doi.org/10.1094/pd-89-0071.

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Dynamics of dispersal of the bacteria that causes citrus canker (Xanthomonas axonopodis pv. citri) were assessed in simulated wind-driven rain splash. The wind/rain-splash events were simulated using electric blowers to generate turbulent wind (15 to 20 m s-1) and sprayer nozzles to produce water droplets entrained in the wind flow. The splash was blown at an inoculum source of canker-infected trees 1 m downwind. The splash downwind of the source of the infected trees was collected by vertical panel samplers and funnel samplers. The duration over which bacteria were dispersed in spray was assessed in continuous wind at intervals from 0 to 52 h after commencing the simulated rain splash event. In one experiment on 11 February 2003, a total of 1.48 × 106 bacteria were collected by panels 1 m downwind from the inoculum source during the first 10 min of dispersal, but the numbers declined to 3.60 × 105 bacteria after 1 h and ranged between 1.42 × 105 and 1.93 × 104 up to 52 h. In a more detailed study (15 July 2003) of dispersal duration over 4 h, the greatest quantity of bacteria collected by panel samplers were dispersed in the first 5-min period (1.01 × 108 bacteria collected). By 10 min after initiation of dispersal, approximately one-third (3.09 × 107 bacteria collected) of the initial number was being dispersed, and by the end of the first hour, only one-tenth (1.31 × 107 bacteria collected) of the initial quantity was dispersed. Funnel samplers placed at ground level under the trees showed a similar trend. The distance to which bacteria were dispersed in wind-blown splash was also tested under simulated conditions: on 18 September 2003, bacteria were collected by panel samplers at all distances sampled (1, 2, 4, 6, 8, 10, and 12 m) with the greatest number of bacteria deposited at 1 m (4.93 × 106 bacteria collected), while 2.22 × 103 bacteria were deposited over a 10-min period 12 m from the inoculum source. Wind speed declined from 19.5 m s-1 upwind of the trees to 2.8 m s-1 1 m downwind, and by 4 m downwind from the inoculum source, movement was similar to the surrounding air. The data on duration and distance of dispersal were best described by power law regression models compared to exponential models. Citrus canker is readily dispersed in wind-driven rain and is dispersed in large quantities immediately after the stimulus occurs, upon which wind-driven splash can disperse inoculum over a prolonged period and over a substantial distance.

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Wohletz, K. H., et R. Raymond. « Atmospheric dust dispersal analyzed by granulometry of the Misers Gold Event ». Journal of Geophysical Research : Solid Earth 98, B1 (10 janvier 1993) : 557–66. http://dx.doi.org/10.1029/92jb01888.

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Magill, J., D. Hamilton, K. Lützenkirchen, M. Tufan, G. Tamborini, W. Wagner, V. Berthou et A. von Zweidorf. « Consequences of a Radiological Dispersal Event with Nuclear and Radioactive Sources ». Science & ; Global Security 15, n^o 2 (23 octobre 2007) : 107–32. http://dx.doi.org/10.1080/08929880701609162.

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Rowe, Timothy B., Hans-Dieter Sues et Robert R. Reisz. « Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon ». Proceedings of the Royal Society B : Biological Sciences 278, n^o 1708 (6 octobre 2010) : 1044–53. http://dx.doi.org/10.1098/rspb.2010.1867.

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Sauropodomorph dinosaurs originated in the Southern Hemisphere in the Middle or Late Triassic and are commonly portrayed as spreading rapidly to all corners of Pangaea as part of a uniform Late Triassic to Early Jurassic cosmopolitan dinosaur fauna. Under this model, dispersal allegedly inhibited dinosaurian diversification, while vicariance and local extinction enhanced it. However, apomorphy-based analyses of the known fossil record indicate that sauropodomorphs were absent in North America until the Early Jurassic, reframing the temporal context of their arrival. We describe a new taxon from the Kayenta Formation of Arizona that comprises the third diagnosable sauropodomorph from the Early Jurassic of North America. We analysed its relationships to test whether sauropodomorphs reached North America in a single sweepstakes event or in separate dispersals. Our finding of separate arrivals by all three taxa suggests dispersal as a chief factor in dinosaurian diversification during at least the early Mesozoic. It questions whether a ‘cosmopolitan’ dinosaur fauna ever existed, and corroborates that vicariance, extinction and dispersal did not operate uniformly in time or under uniform conditions during the Mesozoic. Their relative importance is best measured in narrow time slices and circumscribed geographical regions.

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Cordo, C. A., C. I. Mónaco, R. Altamirano, A. E. Perelló, S. Larrán, N. I. Kripelz et M. R. Simón. « Weather Conditions Associated with the Release and Dispersal of Zymoseptoria tritici Spores in the Argentine Pampas Region ». International Journal of Agronomy 2017 (2017) : 1–13. http://dx.doi.org/10.1155/2017/1468580.

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The abundance of Zymoseptoria tritici ascospores and conidia in a field was examined throughout two one-year periods (1998-1999 and 1999-2000) establishing the relationship between spore release and weather variables. Radiation, temperature, intensity of rainfall, and relative humidity significantly affected the dispersal of ascospores and pycnidiospores of this pathogen. Spore traps collected both types of spores, at weekly intervals, at two different stages of the wheat crop (vegetative and wheat stubble stages) and different distances from the sources. Ascospores were the predominant sources of inoculum in the field. The numbers of ascospores and pycnidiospores declined with the increase of distance from the sources. The release of pycnidiospores was associated with the increase in rainfall intensity 7 days before the released event and the increase in radiation 60 days before the same event. Relative humidity 3 and 15 days before the release event was positively correlated with ascospores release and negatively correlated with radiation and temperature in all the sampling interval. Also for the first time, a positive correlation between radiation and pycnidiospores dispersal is reported. Understanding the relationship between environment conditions and spores dispersal event could improve the control strategies of the disease.

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Aravind, N. A., K. N. Ganeshaiah et R. Uma Shaanker. « Indian monsoons shape dispersal phenology of plants ». Biology Letters 9, n^o 6 (23 décembre 2013) : 20130675. http://dx.doi.org/10.1098/rsbl.2013.0675.

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The Indian monsoons are a major seasonal climatic event over the Indian subcontinent, heralding the arrival of the wet season. Many features of life, biological and cultural, are intimately synchronized to this seasonality. In this paper, we show that the Indian monsoons might have played an important role in shaping the fruiting time and hence dispersal phenology of plant species in the subcontinent.

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Weeks, Brian C., et Santiago Claramunt. « Dispersal has inhibited avian diversification in Australasian archipelagoes ». Proceedings of the Royal Society B : Biological Sciences 281, n^o 1791 (22 septembre 2014) : 20141257. http://dx.doi.org/10.1098/rspb.2014.1257.

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Different models of speciation predict contrasting patterns in the relationship between the dispersal ability of lineages and their diversification rates. This relationship is expected to be negative in isolation-limited models and positive in founder-event models. In addition, the combination of negative and positive effects of dispersal on speciation can result in higher diversification rates at intermediate levels of dispersal ability. Using molecular phylogenies to estimate diversification rates, and wing morphology to estimate dispersal ability, we analysed the influence of dispersal on diversification in the avifauna of Australasian archipelagoes. Contrary to expectations given the fragmented nature of island systems, the relationship between dispersal ability and diversification rate was monotonically negative. While multiple mechanisms could generate this pattern, they all share a phase of range expansion that is decoupled from speciation.

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Grobler, G. C., A. D. S. Bastos, C. T. Chimimba et S. L. Chown. « Inter-island dispersal of flightless Bothrometopus huntleyi (Coleoptera : Curculionidae) from the sub-Antarctic Prince Edward Island archipelago ». Antarctic Science 23, n^o 3 (25 février 2011) : 225–34. http://dx.doi.org/10.1017/s0954102011000113.

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AbstractBothrometopus huntleyi is a flightless weevil endemic to the volcanically-formed sub-Antarctic Prince Edward Islands archipelago that arose approximately 0.5 million years ago (m.y.a.). Since emergence, a series of volcanic and glaciation events have occurred on Marion Island, whilst Prince Edward Island, the second island constituting the archipelago, has remained largely unaffected by glaciation. Cytochrome oxidase I gene analyses indicate that major historical dispersal events in this species are linked to the geologically discrete histories of these islands and underlie the high haplotype diversity (0.995) recovered for the Prince Edward Islands archipelago. The estimated time to haplotype coalescence of ∼ 0.723 m.y.a. is in keeping with estimated dates of island emergence, and the majority of individuals appear to have descended from a relict, high-altitude population that is still present on Marion Island. The first major inter-island dispersal event occurred ∼ 0.507 m.y.a., coinciding with the oldest dated rocks on Marion Island. Apart from this early inter-island colonization, only one other between-island dispersal event was detected. The genetically discrete B. huntleyi complexes on each of the islands of the Prince Edward Islands archipelago together with the low levels of inter-island gene flow reaffirm the need to control alien invasive mice, which are restricted to Marion Island, and which prey on this weevil species.

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Ziegler, Amanda F., Lisa Hahn-Woernle, Brian Powell et Craig R. Smith. « Larval Dispersal Modeling Suggests Limited Ecological Connectivity Between Fjords on the West Antarctic Peninsula ». Integrative and Comparative Biology 60, n^o 6 (3 juillet 2020) : 1369–85. http://dx.doi.org/10.1093/icb/icaa094.

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Synopsis Larval dispersal is a key process for community assembly and population maintenance in the marine environment, yet it is extremely difficult to measure at ecologically relevant spatio-temporal scales. We used a high-resolution hydrodynamic model and particle-tracking model to explore the dispersal of simulated larvae in a hydrographically complex region of fjords on the West Antarctic Peninsula. Modeled larvae represented two end members of dispersal potential observed in Antarctic benthos resulting from differing developmental periods and swimming behavior. For simulations of low dispersing larvae (pre-competency period = 8 days, settlement period = 15 days, swimming downward) self-recruitment within fjords was important, with no larval settlement occurring in adjacent fjords <50 km apart. For simulations of highly dispersing organisms (pre-competency period = 35–120 days, settlement period = 30–115 days, no swimming behavior), dispersal between fjords occurred when larvae were in the water column for at least 35 days, but settlement was rarely successful even for larvae spending up to 150 days in the plankton. The lack of ecological connectivity between fjords within a single spawning event suggests that these fjords harbor ecologically distinct populations in which self-recruitment may maintain populations, and genetic connectivity between fjords is likely achieved through stepping-stone dispersal. Export of larvae from natal fjord populations to the broader shelf region (>100 km distance) occurred within surface layers (<100 m depth) and was enhanced by episodic katabatic wind events that may be common in glaciomarine fjords worldwide.

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Dytham, Calvin. « Evolved dispersal strategies at range margins ». Proceedings of the Royal Society B : Biological Sciences 276, n^o 1661 (20 février 2009) : 1407–13. http://dx.doi.org/10.1098/rspb.2008.1535.

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Dispersal is a key component of a species's ecology and will be under different selection pressures in different parts of the range. For example, a long-distance dispersal strategy suitable for continuous habitat at the range core might not be favoured at the margin, where the habitat is sparse. Using a spatially explicit, individual-based, evolutionary simulation model, the dispersal strategies of an organism that has only one dispersal event in its lifetime, such as a plant or sessile animal, are considered. Within the model, removing habitat, increasing habitat turnover, increasing the cost of dispersal, reducing habitat quality or altering vital rates imposes range limits. In most cases, there is a clear change in the dispersal strategies across the range, although increasing death rate towards the margin has little impact on evolved dispersal strategy across the range. Habitat turnover, reduced birth rate and reduced habitat quality all increase evolved dispersal distances at the margin, while increased cost of dispersal and reduced habitat density lead to lower evolved dispersal distances at the margins. As climate change shifts suitable habitat poleward, species ranges will also start to shift, and it will be the dispersal capabilities of marginal populations, rather than core populations, that will influence the rate of range shifting.

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Solem, Øyvind, Richard D. Hedger, Henning A. Urke, Torstein Kristensen, Finn Økland, Eva M. Ulvan et Ingebrigt Uglem. « Movements and dispersal of farmed Atlantic salmon following a simulated-escape event ». Environmental Biology of Fishes 96, n^o 8 (29 septembre 2012) : 927–39. http://dx.doi.org/10.1007/s10641-012-0088-0.

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Kondo, H. « (P1-19) Disaster Medical System in APEC Japan 2010 ». Prehospital and Disaster Medicine 26, S1 (mai 2011) : s105. http://dx.doi.org/10.1017/s1049023x11003517.

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Background and MethodThe preparedness for mass casualty is needed in political event. We have the experience to build up the disaster medical system in G8 summit in Okinawa and Hokkaido. But these two areas were resort area which had little population. This time Japan hosted APEC JAPAN 2010 which held in Yokohama City. We reported disaster medical system for this event in big city.ResultWe mobilized DMAT from 21 hospitals whole Japan. We set 11 teams in Yokohama city, 10 teams in 2 Airports. DMAT inspected rerated disaster base hospitals. These hospitals made the plan for receive mass casualty included the victims by CBRNE event and had the exercise. They set up the decontamination system during APEC leader's week. We also have the contingency plan to coordinate with fire department. This contingency plan included transportation plan for hospitals and coordination plan in site. In transportation plan, sever casualty transported dispersal for hospital in Yokohama within 25. For over 25, sever casualty transported intensive for 4 hospitals in Yokohama. After stabilization treatment in these hospitals, the casualty transported dispersal from these hospitals to outside of Yokohama. In coordinate plan in site included job description in command and control, decontamination and medical relief post.DiscussionWe established disaster medical system for APEC JAPAN 2010. This event hold in Yokohama City had the big population. Compare with former G8 summit, medical system put importance in mass casualty event. As a result, non mass casualty event happened. But this preparedness will contribute not only future same kind events but also accidental mass casualty event such as train accident.

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Costa, Wilson. « A new genus of miniature cynolebiasine from the Atlantic Forest and alternative biogeographical explanations for seasonal killifish distribution patterns in South America (Cyprinodontiformes : Rivulidae) ». Vertebrate Zoology 64, n^o 1 (30 avril 2014) : 23–33. http://dx.doi.org/10.3897/vz.64.e31460.

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The analysis of 78 morphological characters for 16 species representing all the lineages of the tribe Cynopoecilini and three out-groups, indicates that the incertae sedis miniature species ‘Leptolebias’ leitaoi Cruz & Peixoto is the sister group of a clade comprising the genera Leptolebias, Campellolebias, and Cynopoecilus, consequently recognised as the only member of a new genus. Mucurilebias gen. nov. is diagnosed by seven autapomorphies: eye occupying great part of head side, low number of caudal-fin rays (21), distal portion of epural much broader than distal portion of parhypural, an oblique red bar through opercle in both sexes, isthmus bright red in males, a white stripe on the distal margin of the dorsal fin in males, and a red stripe on the distal margin of the anal fin in males. Mucurilebias leitaoi is an endangered seasonal species endemic to the Mucuri river basin. The biogeographical analysis of genera of the subfamily Cynolebiasinae using a dispersal-vicariance, event-based parsimony approach indicates that distribution of South American killifishes may be broadly shaped by dispersal events. The analysis supports south-eastern Brazilian coastal plains as the centre of dispersal for cynolebiasine killifishes. Alternative biogeographical explanations are compared and possible dispersal routes and means of dispersal are discussed.

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Ponniah, Mark, et Jane M. Hughes. « The evolution of Queensland spiny mountain crayfish of the genus Euastacus. II. Investigating simultaneous vicariance with intraspecific genetic data ». Marine and Freshwater Research 57, n^o 3 (2006) : 349. http://dx.doi.org/10.1071/mf05172.

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Phylogenetic evidence suggested that the Queensland Euastacus diversified through ‘simultaneous vicariance’, where the range of a widespread ancestral Euastacus receded to tops of mountains with the Pliocene warming of the continent and subsequent isolation lead to speciation. Implicit in the simultaneous vicariance hypothesis are three postulates on ancestral history: (1) warm temperatures were effective barriers to ancestral gene flow; (2) the ancestral Euastacus had an extensive contiguous distribution; and (3) there was a single vicariant event associated with Pliocene warming. It is argued that if there was interspecific diversification due to simultaneous vicariance then, within extant species, there are three predictions on current population structure. First, lowland areas, even those connected by streams, would be barriers to contemporary dispersal. Second, there would be contemporary dispersal between catchments covered by mesic rainforests. Third, there would have been recent Pleistocene intraspecific vicariant events. The population structure of E. robertsi, E. fleckeri, E. hystricosus and E. sulcatus was investigated with mtDNA and allozymes and it was found that the intraspecific data were consistent with these predictions. Furthermore, the Euastacus underwent limited range expansions during the cooler Pleistocene glacial cycles, and it is hypothesised that during cooler glacial periods, lowlands were still effective barriers to dispersal because of increased Pleistocene aridity.

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Mondal, S. N., T. R. Gottwald et L. W. Timmer. « Environmental Factors Affecting the Release and Dispersal of Ascospores of Mycosphaerella citri ». Phytopathology® 93, n^o 8 (août 2003) : 1031–36. http://dx.doi.org/10.1094/phyto.2003.93.8.1031.

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Greasy spot, caused by Mycosphaerella citri, produces a leaf spot disease affecting all citrus species in Florida and the Caribbean Basin. M. citri produces pseudothecia and ascospores, which are considered the principal source of inoculum, in decomposing leaves on the grove floor. In studies using a computer-controlled environmental chamber, a single rain event triggered release of most mature ascospores beginning 30 to 60 min after the rain event. Additional rain events did not bring about further release. High relative humidity without rain triggered release of low numbers of ascospores, but vibration and red/infrared irradiation had little or no effect on ascospore release. After three to four cycles of wetting and drying of leaves, all pseudothecia had matured and released their ascospores. In the field, ascospores were detectable starting about 2 h after the beginning of a rain or irrigation and most ascospores were released within 16 h. Ascospore release was greatest following rain events and somewhat less following irrigations, and low numbers of ascospores were detectable on days without precipitation. Ascospore numbers declined linearly with horizontal distance from the source and as a function of the logarithm of ascospore numbers with vertical distance. Low numbers of ascospores were detected 7.5 m above the ground and 90 m downwind from the grove. Ascospore release can be advanced by irrigating frequently during dry, nonconducive conditions to stimulate ascospore release when environmental conditions are unfavorable for infection, but the eventual effects on disease severity are uncertain.

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McGrath, Guy, Simon J. More et Ronan O’Neill. « Hypothetical route of the introduction of Schmallenberg virus into Ireland using two complementary analyses ». Veterinary Record 182, n^o 8 (7 décembre 2017) : 226. http://dx.doi.org/10.1136/vr.104302.

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Ireland lost its official freedom from Schmallenberg virus (SBV) in October 2012. The route of introduction is uncertain, with long-distance displacement of infected Culicoides, biting midges, by suitable wind flows considered to be the most likely source. The authors investigated the potential introduction of SBV into Ireland through a Culicoides incursion event in the summer of 2012. They conducted SBV serology on archived bovine sera to identify the prospective dispersal window, then used atmospheric dispersion modelling during periods around this window to identify environmental conditions the authors considered suitable for atmospheric dispersal of Culicoides from potential infected source locations across Southern England. The authors believe that there was one plausible window over the summer of 2012, on August 10–11, based on suitable meteorological conditions. They conclude that a potential long-range transportation event of Culicoides appears to have occurred successfully only once during the 2012 vector competent season. If these incursion events remain at a low frequency, meteorological modelling has the potential to contribute cost-effectively to the alert and response systems for vectorborne diseases in the future.

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Batista, Romina, Urban Olsson, Tobias Andermann, Alexandre Aleixo, Camila Cherem Ribas et Alexandre Antonelli. « Phylogenomics and biogeography of the world's thrushes (Aves, Turdus ) : new evidence for a more parsimonious evolutionary history ». Proceedings of the Royal Society B : Biological Sciences 287, n^o 1919 (22 janvier 2020) : 20192400. http://dx.doi.org/10.1098/rspb.2019.2400.

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To elucidate the relationships and spatial range evolution across the world of the bird genus Turdus (Aves), we produced a large genomic dataset comprising ca 2 million nucleotides for ca 100 samples representing 53 species, including over 2000 loci. We estimated time-calibrated maximum-likelihood and multispecies coalescent phylogenies and carried out biogeographic analyses. Our results indicate that there have been considerably fewer trans-oceanic dispersals within the genus Turdus than previously suggested, such that the Palaearctic clade did not originate in America and the African clade was not involved in the colonization of the Americas. Instead, our findings suggest that dispersal from the Western Palaearctic via the Antilles to the Neotropics might have occurred in a single event, giving rise to the rich Neotropical diversity of Turdus observed today, with no reverse dispersals to the Palaearctic or Africa. Our large multilocus dataset, combined with dense species-level sampling and analysed under probabilistic methods, brings important insights into historical biogeography and systematics, even in a scenario of fast and spatially complex diversification.

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Jordano, Pedro, Pierre-Michel Forget, Joanna E. Lambert, Katrin Böhning-Gaese, Anna Traveset et S. Joseph Wright. « Frugivores and seed dispersal : mechanisms and consequences for biodiversity of a key ecological interaction ». Biology Letters 7, n^o 3 (17 novembre 2010) : 321–23. http://dx.doi.org/10.1098/rsbl.2010.0986.

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The 5th Symposium on Frugivores and Seed Dispersal, held in Montpellier (France), 13–18 June 2010, brought together more than 220 researchers exemplifying a wide diversity of approaches to the study of frugivory and dispersal of seeds. Following Ted Fleming and Alejandro Estrada's initiative in 1985, this event was a celebration of the 25th anniversary of the first meeting in Veracruz, Mexico. Frugivory and seed dispersal are active research areas that have diversified in multiple directions since 1985 to include evolution (e.g. phylogenetic diversity and dispersal adaptations), physiology (e.g. sensory cues and digestion), landscape ecology (movement patterns), molecular ecology (e.g. gene flow, genetic diversity and structure), community ecology (e.g. mutualistic interaction networks) and conservation biology (effects of hunting, fragmentation, invasion and extinction), among others. This meeting provided an opportunity to assess conceptual and methodological progress, to present ever more sophisticated insights into frugivory in animals and dispersal patterns in plants, and to report the advances made in examining the mechanisms and consequences of seed dispersal for plants and frugivores.

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Borz�e, A., Y. Yi, D. Andersen, K. Kim, K. S. Moon, J. J. Kim, T. W. Kim et Y. Jang. « First dispersal event of a reintroduced Asiatic black bear (Ursus thibetanus) in Korea ». Russian Journal of Theriology 18, n^o 1 (28 juin 2019) : 51–55. http://dx.doi.org/10.15298/rusjtheriol.18.1.06.

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Elcock, Deborah, Gladys A. Klemic et Anibal L. Taboas. « Establishing Remediation Levels in Response to a Radiological Dispersal Event (or “Dirty Bomb”) ». Environmental Science & ; Technology 38, n^o 9 (mai 2004) : 2505–12. http://dx.doi.org/10.1021/es034894+.

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Kraft, Petr, Josef Pšenička, Jakub Sakala et Jiří Frýda. « Initial plant diversification and dispersal event in upper Silurian of the Prague Basin ». Palaeogeography, Palaeoclimatology, Palaeoecology 514 (janvier 2019) : 144–55. http://dx.doi.org/10.1016/j.palaeo.2018.09.034.

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Severns, Paul M. « Dispersal Kernel Type Highly Influences Projected Relationships for Plant Disease Epidemic Severity When Outbreak and At-Risk Populations Differ in Susceptibility ». Life 12, n^o 11 (28 octobre 2022) : 1727. http://dx.doi.org/10.3390/life12111727.

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In silico study of biologically invading organisms provide a means to evaluate the complex and potentially cryptic factors that can influence invasion success in scenarios where empirical studies would be difficult, if not impossible, to conduct. I used a disease event simulation program to evaluate whether the two most frequently used types of plant pathogen dispersal kernels for epidemiological projections would provide complementary or divergent projections of epidemic severity when the hosts in a disease outbreak differed from the hosts in the at-risk population in the degree of susceptibility. Exponential dispersal kernel simulations of wheat stripe rust (Pucciniastriiformis var trittici) predicted a relatively strong and dominant influence of the at-risk population on the end epidemic severity regardless of outbreak disease levels. Simulations using a modified power law dispersal kernel gave projections that varied depending on the amount of disease in the outbreak and some interactions were counter-intuitive and opposite of the exponential dispersal kernel projections. Although relatively straightforward, the disease spread simulations in the present study strongly suggest that a more biologically accurate dispersal kernel generates complexity that would not be revealed by an exponential dispersal gradient and that selecting a less accurate dispersal kernel may obscure important interactions during biological invasions.

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Klaus, Kristina V., et Nicholas J. Matzke. « Statistical Comparison of Trait-Dependent Biogeographical Models Indicates That Podocarpaceae Dispersal Is Influenced by Both Seed Cone Traits and Geographical Distance ». Systematic Biology 69, n^o 1 (17 mai 2019) : 61–75. http://dx.doi.org/10.1093/sysbio/syz034.

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Abstract The ability of lineages to disperse long distances over evolutionary timescales may be influenced by the gain or loss of traits adapted to enhance local, ecological dispersal. For example, some species in the southern conifer family Podocarpaceae have fleshy cones that encourage bird dispersal, but it is unknown how this trait has influenced the clade’s historical biogeography, or its importance compared with other predictors of dispersal such as the geographic distance between regions. We answer these questions quantitatively by using a dated phylogeny of 197 species of southern conifers (Podocarpaceae and their sister family Araucariaceae) to statistically compare standard, trait-independent biogeography models with new BioGeoBEARS models where an evolving trait can influence dispersal probability, and trait history, biogeographical history, and model parameters are jointly inferred. We validate the method with simulation-inference experiments. Comparing all models, those that include trait-dependent dispersal accrue 87.5% of the corrected Akaike Information Criterion (AICc) model weight. Averaged across all models, lineages with nonfleshy cones had a dispersal probability multiplier of 0.49 compared with lineages with fleshy cones. Distance is included as a predictor of dispersal in all credible models (100% model weight). However, models with changing geography earned only 22.0% of the model weight, and models submerging New Caledonia/New Zealand earned only 0.01%. The importance of traits and distance suggests that long-distance dispersal over macroevolutionary timespans should not be thought of as a highly unpredictable chance event. Instead, long-distance dispersal can be modeled, allowing statistical model comparison to quantify support for different hypotheses.

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Linder, H. Peter. « Rytidosperma vickeryae — a new danthonioid grass from Kosciuszko (New South Wales, Australia) : Morphology, phylogeny and biogeography ». Australian Systematic Botany 12, n^o 5 (1999) : 743. http://dx.doi.org/10.1071/sb97046.

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Rytidosperma vickeryae, a new species of danthonioid grass, is described, and detailed information on the morphology, anatomy, cytology and embryology of the species is provided. The phylogenetic relationships among the Australasian species of Rytidosperma s.s. are analysed, by parsimony-based methods. The new species is shown to be the sister species of R. thomsonii from New Zealand. The phytogeographical implications of this are analysed, by area-optimisation methods as well as methods which search for area relationships. This suggests that the Australasian species of Rytidosperma radiated from an ancestral area in Tasmania, followed by dispersal to New Zealand, and repeated dispersal northwards to Kosciuszko and New Guinea. R. vickeryae appears to have originated as the result of a dispersal event from New Zealand to Kosciuszko.

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Barraud, Nicolas, David Schleheck, Janosch Klebensberger, Jeremy S. Webb, Daniel J. Hassett, Scott A. Rice et Staffan Kjelleberg. « Nitric Oxide Signaling in Pseudomonas aeruginosa Biofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-GMP Levels, and Enhanced Dispersal ». Journal of Bacteriology 191, n^o 23 (2 octobre 2009) : 7333–42. http://dx.doi.org/10.1128/jb.00975-09.

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ABSTRACT Bacteria in biofilms often undergo active dispersal events and revert to a free-swimming, planktonic state to complete the biofilm life cycle. The signaling molecule nitric oxide (NO) was previously found to trigger biofilm dispersal in the opportunistic pathogen Pseudomonas aeruginosa at low, nontoxic concentrations (N. Barraud, D. J. Hassett, S. H. Hwang, S. A. Rice, S. Kjelleberg, and J. S. Webb, J. Bacteriol. 188:7344-7353, 2006). NO was further shown to increase cell motility and susceptibility to antimicrobials. Recently, numerous studies revealed that increased degradation of the secondary messenger cyclic di-GMP (c-di-GMP) by specific phosphodiesterases (PDEs) triggers a planktonic mode of growth in eubacteria. In this study, the potential link between NO and c-di-GMP signaling was investigated by performing (i) PDE inhibitor studies, (ii) enzymatic assays to measure PDE activity, and (iii) direct quantification of intracellular c-di-GMP levels. The results suggest a role for c-di-GMP signaling in triggering the biofilm dispersal event induced by NO, as dispersal requires PDE activity and addition of NO stimulates PDE and induces the concomitant decrease in intracellular c-di-GMP levels in P. aeruginosa. Furthermore, gene expression studies indicated global responses to low, nontoxic levels of NO in P. aeruginosa biofilms, including upregulation of genes involved in motility and energy metabolism and downregulation of adhesins and virulence factors. Finally, site-directed mutagenesis of candidate genes and physiological characterization of the corresponding mutant strains uncovered that the chemotaxis transducer BdlA is involved in the biofilm dispersal response induced by NO.

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Spahic, Darko, et Tivadar Gaudenyi. « 60 years of the Serbo-Macedonian Unit concept : From Cadomian towards alpine tectonic frameworks ». Annales g?ologiques de la Peninsule balkanique 81, n^o 1 (2020) : 41–66. http://dx.doi.org/10.2298/gabp191018004s.

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The study represents a summary of the hitherto tectonic concepts revolving around a peri-Gondwanan fragment referred to as the Serbo- Macedonian Unit. The Serbo-Macedonian Unit as a gneiss-dominated basement segment is positioned in the proximity of the Baltican craton (peri-Moesian realm). This area represents a repository of the transferred broadly similar thus highly complex, elongated polycrystalline vestiges of the Pan-African inheritance. This peculiar far-travelled composite crustal fragment of north Gondwana is amalgamated on top of the Supragetic unit during the late Variscan peri-Moesian amalgamation. However, the original early Pa - leozoic tectonostratigraphic configuration of these three intimate green schistand medium- to high-grade gneiss-amphibolite basement vestiges (Serbo-Ma - cedonian/Supragetic and Getic) is further perplexed by the presence of poorly documented pre-Variscan (Ordovician?) lithospheric-scale event. The Pan-African to Lower Paleozoic subduction/magmatic arc stage led to the amalgamation, breakup and dispersal of a cluster of peri-Gondwanan continental and oceanic terranes. Breakup and dispersal from the northern shore of the Gondwanan active margin triggered the development of the Paleozoic deep-marine sedimentary cover (?Kucaj unit? or Getic unit). To make matter more complex, prior the Lower Paleozoic terrane agglomeration and sub - sequent dispersal, it appears that a Lower Paleozoic geodynamic linkage is additionally marked by the poorly investigated cross-lithospheric event. This event connects the outboard oceanic Supragetic/?Kucaj? succession with a segment of the former north Gondwanan protobasin (juvenile Serbo-Ma - cedonian Unit).

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Smith, PhD, David A., Daniel T. Holt, PhD et Audeen Fentiman, PhD. « A conceptual model for determining the level of impact from a radiological dispersal event ». Journal of Emergency Management 8, n^o 1 (1 janvier 2010) : 25–36. http://dx.doi.org/10.5055/jem.2010.0002.

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Nowak, M. D., B. C. Haller et A. D. Yoder. « The founding of Mauritian endemic coffee trees by a synchronous long-distance dispersal event ». Journal of Evolutionary Biology 27, n^o 6 (3 mai 2014) : 1229–39. http://dx.doi.org/10.1111/jeb.12396.

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Vogt, Kati, Leonid Rasran et Kai Jensen. « Seed deposition in drift lines during an extreme flooding event — Evidence for hydrochorous dispersal ? » Basic and Applied Ecology 7, n^o 5 (septembre 2006) : 422–32. http://dx.doi.org/10.1016/j.baae.2006.05.007.

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Preuss, Sonja, Åsa Berggren et Anna Cassel-Lundhagen. « Genetic patterns reveal an old introduction event and dispersal limitations despite rapid distribution expansion ». Biological Invasions 17, n^o 10 (18 juin 2015) : 2851–62. http://dx.doi.org/10.1007/s10530-015-0915-2.

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Zhang, Jin Xiu, W. G. Dilantha Fernando et Allen G. Xue. « Daily and seasonal spore dispersal by Mycosphaerella pinodes and development of mycosphaerella blight of field pea ». Canadian Journal of Botany 83, n^o 3 (1 mars 2005) : 302–10. http://dx.doi.org/10.1139/b05-003.

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Daily and seasonal spore dispersal of Mycosphaerella pinodes (Berk & Bloxam) Vestergren and the relationship of spore dispersal to distance and disease severity were investigated in a pea field in western Canada during two consecutive years. Most ascospores were released in response to rain events, during the first 2327 d after the inoculum source area was infested with naturally diseased pea residue, whereas most pycnidiospores were trapped during the first 20 d. For both ascospores and pycnidiospores, the highest peaks of spore release occurred during the first 1420 d after infestation. Few spores were trapped after day 27 after infestation. Daily peaks of ascospore and pycnidiospore release occurred between 1700 and 0400 hours. Most ascospores were released 12 d after a rain event and the largest peak appeared the first day after rain. In contrast, most pycnidiospores were released on the same day as rain occurred or the following day. The release of both spore types was associated with rainfall events ≥2 mm during the first 27 d after infestation but not with rainfall events after 27 d. Ascospore density was negatively correlated with distance from the inoculum source (r ≤ 0.92) and positively related to the disease severity (r ≥ 0.92). Disease severity decreased with increasing distance from the inoculum source. The patterns of spore dispersal associated with rain events have practical applications in the disease forecasting and spraying of chemicals to control the disease.Key words: field pea, mycosphaerella blight, rainfall, spore release.

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Bona, Paula, Martín D. Ezcurra, Francisco Barrios et María V. Fernandez Blanco. « A new Palaeocene crocodylian from southern Argentina sheds light on the early history of caimanines ». Proceedings of the Royal Society B : Biological Sciences 285, n^o 1885 (22 août 2018) : 20180843. http://dx.doi.org/10.1098/rspb.2018.0843.

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Caimanines are crocodylians currently restricted to South and Central America and the oldest members are from lower Palaeocene localities of the Salamanca Formation (Chubut Province, Argentina). We report here a new caimanine from this same unit represented by a skull roof and partial braincase. Its phylogenetic relationships were explored in a cladistic analysis using standard characters and a morphogeometric two-dimensional configuration of the skull roof. The phylogenetic results were used for an event-based supermodel quantitative palaeobiogeographic analysis. The new species is recovered as the most basal member of the South American caimanines, and the Cretaceous North American lineage ‘ Brachychampsa and related forms' as the most basal Caimaninae. The biogeographic results estimated north-central North America as the ancestral area of Caimaninae, showing that the Cretaceous and Palaeocene species of the group were more widespread than thought and became regionally extinct in North America around the Cretaceous–Palaeocene boundary. A dispersal event from north-central North America during the middle Late Cretaceous explains the arrival of the group to South America. The Palaeogene assemblage of Patagonian crocodylians is composed of three lineages of caimanines as a consequence of independent dispersal events that occurred between North and South America and within South America around the Cretaceous–Palaeogene boundary.

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Bacon, Christine D., Daniele Silvestro, Carlos Jaramillo, Brian Tilston Smith, Prosanta Chakrabarty et Alexandre Antonelli. « Biological evidence supports an early and complex emergence of the Isthmus of Panama ». Proceedings of the National Academy of Sciences 112, n^o 19 (27 avril 2015) : 6110–15. http://dx.doi.org/10.1073/pnas.1423853112.

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The linking of North and South America by the Isthmus of Panama had major impacts on global climate, oceanic and atmospheric currents, and biodiversity, yet the timing of this critical event remains contentious. The Isthmus is traditionally understood to have fully closed by ca. 3.5 million years ago (Ma), and this date has been used as a benchmark for oceanographic, climatic, and evolutionary research, but recent evidence suggests a more complex geological formation. Here, we analyze both molecular and fossil data to evaluate the tempo of biotic exchange across the Americas in light of geological evidence. We demonstrate significant waves of dispersal of terrestrial organisms at approximately ca. 20 and 6 Ma and corresponding events separating marine organisms in the Atlantic and Pacific oceans at ca. 23 and 7 Ma. The direction of dispersal and their rates were symmetrical until the last ca. 6 Ma, when northern migration of South American lineages increased significantly. Variability among taxa in their timing of dispersal or vicariance across the Isthmus is not explained by the ecological factors tested in these analyses, including biome type, dispersal ability, and elevation preference. Migration was therefore not generally regulated by intrinsic traits but more likely reflects the presence of emergent terrain several millions of years earlier than commonly assumed. These results indicate that the dramatic biotic turnover associated with the Great American Biotic Interchange was a long and complex process that began as early as the Oligocene–Miocene transition.

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Perdomo, Giselle, Paul Sunnucks et Ross M. Thompson. « The role of temperature and dispersal in moss-microarthropod community assembly after a catastrophic event ». Philosophical Transactions of the Royal Society B : Biological Sciences 367, n^o 1605 (5 novembre 2012) : 3042–49. http://dx.doi.org/10.1098/rstb.2012.0241.

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There is a clear crisis in the maintenance of biodiversity. It has been generated by a multitude of factors, notably habitat loss, now compounded by the effects of climate change. Predicted changes in climate include increased severity and frequency of extreme climatic events. To manage landscapes, an understanding of the processes that allow recovery from these extreme events is required. Understanding these landscape-scale processes of community assembly and disassembly is hindered by the large scales at which they operate. Model systems provide a means of studying landscape scale processes at tractable scales. Here, we assess the combined effects of temperature and habitat-patch isolation on assembly of naturally diverse moss microarthropod communities after a high-temperature event. We show that community assembly depends on temperature and on degree of habitat isolation. Heated communities were heavily dominated in abundance by two species, one of them relatively large. The resulting size-structure is unlike that seen in the field. Community composition in habitat fragments appears also to have been influenced by the source pool of recolonizing fauna. Our results highlight the value of dispersal in disturbed landscapes and the potential for habitat connectivity to buffer communities from the effects of climate change.

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Osborne, OE, PD O’Hara, S. Whelan, P. Zandbergen, SA Hatch et KH Elliott. « Breeding seabirds increase foraging range in response to an extreme marine heatwave ». Marine Ecology Progress Series 646 (30 juillet 2020) : 161–73. http://dx.doi.org/10.3354/meps13392.

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Marine heatwaves are increasing in frequency and can disrupt marine ecosystems non-linearly. In this study, we examined the effect of the North Pacific warming event of 2014, the largest long-term sea surface anomaly on record, on black-legged kittiwake Rissa tridactyla foraging trips before, during, and after the event. We assessed foraging trip characteristics (trip distance and duration), the dispersal of foraging locations, and the persistence of foraging areas within and among years. Foraging trip characteristics, foraging area size, and location varied from year to year. Kittiwake foraging was more dispersed, direct, and farther from the colony in years immediately after and during the warming event. A third of the foraging area used pre-heatwave (2012) was important in subsequent years, which indicates that this area was, and may still be, a perennial foraging hot spot. During the chick-rearing stage, black-legged kittiwakes increased their speed and reduced the proportion of resting compared to the incubation stage. We conclude that marine heatwaves may have a strong impact on seabird foraging, extending foraging ranges, and that those impacts may be nonlinear with a strong lag.

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Li, Mimi, Jianhua Li, Jinhuo Jiang, Chengxin Fu et Walter Judd. « Phylogenetics and Biogeography of Pieris (Lyonieae, Ericaceae) Inferred from Sequences of Nuclear and Chloroplast Genomes ». Systematic Botany 34, n^o 3 (1 juillet 2009) : 553–60. http://dx.doi.org/10.1600/036364409789271272.

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Pieris is an eastern Asian (EA)-eastern North American (NA) disjunct genus with P. cubensis in the West Indies (WI). In this study, we inferred interspecific relationships using nucleotide sequences of the internal and external transcribed spacer regions of nuclear ribosomal DNA and chloroplast genome (matK, trnL-F, and psbA-trnH). Pieris nana was sister to the rest of Pieris, i.e. Pieris subg. Pieris. The species of subg. Pieris diverged consecutively in the order of Pieris cubensis, P. swinhoei, P. floribunda, P. phillyreifolia, and P. formosa plus P. japonica. Neither section Phillyreoides nor section Pieris was monophyletic, and P. phillyreifolia of NA was more closely related to two of the EA species (P. formosa and P. japonica) than to the other NA species (P. floribunda). Morphological characters, such as inflorescence position, testa cell shape, and placenta attachment, used to define the sections were homoplasious. Dispersal and vicariance analyses suggested that ancestral populations of Pieris were widespread in the composite area of EA, NA, and WI, and two dispersal events may have occurred from the New World to the Old World. Pieris cubensis may have originated as the result of a dispersal event from the composite area of NA and EA during the early diversification of Pieris in the late Eocene.

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Tay, Mei Lin, Heidi M. Meudt, Philip J. Garnock-Jones et Peter A. Ritchie. « DNA sequences from three genomes reveal multiple long-distance dispersals and non-monophyly of sections in Australasian Plantago (Plantaginaceae) ». Australian Systematic Botany 23, n^o 1 (2010) : 47. http://dx.doi.org/10.1071/sb09040.

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We examined the geographic origins and taxonomic placements of New Zealand and Australian Plantago (Plantaginaceae) by using molecular phylogenetic data. Plantago comprises over 200 species distributed worldwide. Analyses of three markers from the nuclear (ITS), chloroplast (ndhF–rpl32) and mitochondrial (coxI) genomes showed that the New Zealand species form three distinct, well supported clades that are not each others’ closest relatives, and were each derived relative to the sampled Australian species. Therefore, at least three long-distance directional dispersal events into New Zealand can be inferred for Plantago, likely from Australian ancestors. This result differs from the biogeographic pattern often reported for New Zealand plant genera of a single dispersal event followed by rapid radiation, and may be attributed to ready biotic dispersal of mucilaginous seeds and habitat similarities of the Australasian species. Molecular dating placed the arrival time and diversification of the New Zealand species between 2.291 and 0.5 million years ago, which coincides with the geological dates for the uplift of mountain ranges in New Zealand. The mitochondrial DNA substitution rate of the Australasian clade relative to the rest of the genus is discussed, as well as implications of the non-monophyly of sections Oliganthos, Mesembrynia and Plantago within subgenus Plantago.

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Tay, Mei Lin, Heidi M. Meudt, Philip J. Garnock-Jones et Peter A. Ritchie. « Erratum to : DNA sequences from three genomes reveal multiple long-distance dispersals and non-monophyly of sections in Australasian Plantago (Plantaginaceae) ». Australian Systematic Botany 23, n^o 4 (2010) : 306. http://dx.doi.org/10.1071/sb09040_er.

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We examined the geographic origins and taxonomic placements of New Zealand and Australian Plantago (Plantaginaceae) by using molecular phylogenetic data. Plantago comprises over 200 species distributed worldwide. Analyses of three markers from the nuclear (ITS), chloroplast (ndhF?rpl32) and mitochondrial (coxI) genomes showed that the New Zealand species form three distinct, well supported clades that are not each others' closest relatives, and were each derived relative to the sampled Australian species. Therefore, at least three long-distance directional dispersal events into New Zealand can be inferred for Plantago, likely from Australian ancestors. This result differs from the biogeographic pattern often reported for New Zealand plant genera of a single dispersal event followed by rapid radiation, and may be attributed to ready biotic dispersal of mucilaginous seeds and habitat similarities of the Australasian species. Molecular dating placed the arrival time and diversification of the New Zealand species between 2.291 and 0.5�million years ago, which coincides with the geological dates for the uplift of mountain ranges in New Zealand. The mitochondrial DNA substitution rate of the Australasian clade relative to the rest of the genus is discussed, as well as implications of the non-monophyly of sections Oliganthos, Mesembrynia and Plantago within subgenus Plantago.

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