Explore the vast range of titles available.

Aim: To test competing hypotheses about the timing and extent of Holocene landscape opening using pollen-based quantitative land-cover estimates. Location: Dove Lake, Tasmanian Wilderness World Heritage Area, Australia. Methods: Fossil pollen data were incorporated into pollen dispersal models and corrected for differences in pollen productivity among key plant taxa. Mechanistic models (REVEALS-Regional Estimates of VEgetation Abundance from Large Sites) employing different models for pollen dispersal (Gaussian plume and Lagrangian stochastic models) were evaluated and applied in the Southern Hemisphere for the first time. Results: Validation of the REVEALS model with vegetation cover data suggests an overall better performance of the Lagrangian stochastic model. Regional land-cover estimates for forest and non-forest plant taxa show persistent landscape openness throughout the Holocene (average landscape openness similar to 50%). Gymnoschoenus sphaerocephalus, an indicator of moorland vegetation, shows higher values during the early Holocene (11.7-9 ka) and declines slightly through the mid-Holocene (9-4.5 ka) during a phase of partial landscape afforestation. Rain forest cover reduced (from similar to 40% to similar to 20%) during the period between 4.2-3.5 ka. Main conclusions: Pollen percentages severely under-represent landscape openness in western Tasmania and this bias has fostered an over-estimation of Holocene forest cover from pollen data. Treeless vegetation dominated Holocene landscapes of the Dove Lake area, allowing us to reject models of landscape evolution that invoke late-Holocene replacement of a rain forest-dominated landscape by moorland. Instead, we confirm a model of Late Pleistocene inheritance of open vegetation. Rapid forest decline occurred after c.4 ka, likely in response to regional moisture decline.

Question: The prominent role of wind dispersal in alpine habitats has been recognized early but has rarely been quantified. The aim of this study is to compare wind dispersal under alpine and lowland conditions and to analyse whether differences are caused by species traits, e.g. terminal velocity of seeds (Vterm) or weather conditions. Location and Methods: We characterized wind dispersal potential of >1100 Central European species using measured Vterm. To quantify the habitat effect on wind dispersal, we measured meteorological key-parameters and simulated dispersal distance spectra of nine selected species under typical alpine conditions (foreland of the Scaletta-glacier, Switzerland) and typical lowland conditions (grassland in Bad Lippspringe, Germany). Results: Lowland species had higher Vterm compared to alpine species. However, this difference is absent when only species of species of open habitats are concerned. The meteorological measurements showed that the alpine habitat was mainly characterized by higher frequency and strength of updrafts. The simulations showed that under alpine conditions long distance dispersal occurred much more frequent. Conclusions: More than 50 % of the alpine species have a fair chance to be dispersed by wind over long distances, while this proportion is less than 25 % for species from open habitats in the lowland. The more prominent role of wind dispersal in alpine habitats is mainly a result of differences in environmental conditions, namely more intense vertical turbulence in the alpine habitat, and does not result from prominent differences in plant traits, namely Vterm, between alpine and lowland species. Nomenclature: Wisskirchen & Haeupler (1998).

AIM: Dioscorea (Dioscoreaceae) is a predominantly pantropical genus (< 600 species) that includes the third most important tropical tuber crop and species of pharmacological value. Fossil records from both the Northern and Southern Hemispheres were used to test hypotheses about the origin of the genus Dioscorea, and to examine potential macroevolutionary processes that led to its current distribution. LOCATION: Pantropical distribution. METHODS: Divergence times were estimated using the most comprehensive phylogeny of the group published to date based on plastid sequences and fossil calibrations, applying a relaxed‐clock model approach. Ancestral areas and range shifts were reconstructed using time‐stratified likelihood‐based models, reflecting past continental connectivity and biogeographical models incorporating the spatial range of fossils. RESULTS: Fossil‐informed biogeographical analysis supported colonization of the Nearctic by ancient yam lineages from the western Palaearctic and subsequent migration to the South. Most of the pantropical South American, African and Southeast Asian lineages experienced a relatively recent diversification in the Oligocene–Miocene. Long‐distance dispersals were inferred for the colonizations of the New World, Africa and Madagascar. MAIN CONCLUSIONS: Dioscorea likely originated between the Late Cretaceous and the Early Eocene in the Laurasian Palaearctic, followed by possible dispersal to South America via the Eocene North Atlantic Land Bridge.

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.

1. In plants, long-distance dispersal (LDD) is a widespread phenomenon of great importance, especially in spatial dynamics such as in metapopulations, invasions and migration. Much has become known about the mechanisms underlying LDD by wind, but selective release mechanisms have received little attention. Recent papers call for particular effort in clarification of the seed release stage of the dispersal process, which is our aim here. 2. We studied non-random seed release at a range of spatial scales, from the individual plant to species' spatial dynamics. We did this by combining wind tunnel experiments, field trap data and simulation and analytical models, using two common wind-dispersed heathland plants (Calluna vulgaris and Erica cinerea) as study species. 3. In both species, seed release from the plant increases with increasing wind velocity. There is a minimum release threshold, above which the probability of seed release increases with increasing wind velocity. The drag caused by the wind is the motive force for seed release. 4. Simulations of seed dispersal with non-random seed release match measured dispersal kernels better, especially in the tails, than 'conventional' simulations with random seed release. Seed release during gusts gives the most realistic kernel. This result matches previous findings that seeds are released primarily at the start of gusts and during turbulent wind flow. 5. Dispersal kernels assuming non-random seed release had large impacts on analytically modelled population migration rates. Wavespeeds assuming seed release during gusts were, on average, more than double those assuming random seed release. Increases in wavespeeds under different seed release assumptions were due mostly to increases in the tail of the dispersal kernel. 6. Synthesis. This study shows how the small-scale process of a seed being released from the plant could affect the large-scale spatial dynamics of plant species in landscapes. The mechanism of non-random seed release, i.e., seed release during gusts, is an important mechanism for attaining LDD by wind. As such, non-random seed release influences landscape-scale species dynamics such as invasions and migration.

The objective of most pest management programs is to \"control\" the pest species. However, optimal control of local abundance and population growth may require different management strategies than optimal control of spatial spread. We use coupled demographic—dispersal models to address the relative importance of different management approaches to these two main control objectives for the invasive thistle Carduus nutans. The models are parameterized with data from thistle populations in the native (France) and invaded ranges (Australia and New Zealand). We assess a wide range of commonly used management strategies for their absolute and relative impacts on population growth and spread in both invaded-range scenarios. The projected population growth rate in New Zealand is more than twice that in Australia, while the spread rate is more than four times the Australian value. In general, spread and growth are both most strongly affected by the same life cycle transitions; however, in a few cases certain vital rates disproportionately affect either spread or growth. The transition that represents the contribution of large rosettes in one year to the number of large rosettes in the following year (the large rosette—large rosette transition) in Australia is dominated by reproduction (rather than survival) and hence is relatively more important to spread than to population growth. In New Zealand, the small rosette—small rosette transition is also predominantly dispersal-related. However, establishment of small plants from the seed bank contributes more to population growth than spread, as no dispersal is involved. The fine-resolution vital-rate-based modeling approach allows us to identify potentially novel optimal management strategies: approaches that reduce microsite availability show promise for reducing both population growth and spread, while strategies that affect dispersal parameters will affect spread. Additionally, the relative ranking of some biocontrol agents shifts depending on whether control of population growth or population spread is the desired outcome and therefore could alter which of the agents are preferred for release in a new area. The possibility of differences in ranked agent effectiveness has been predicted theoretically, but never before demonstrated using field data.

Aim: We sought to illuminate the history of the arachnid orders Schizomida and Uropygi, neither of which have previously been subjected to global molecular phylogenetic and biogeographical analyses. Location: Specimens used in this study were collected in all major tropical and subtropical areas where they are presently found, including the Americas, Africa, Australia and the Indo-Pacific region. Methods: From field-collected specimens, we sequenced two nuclear and two mitochondrial markers, combined these with publicly available data, and conducted multi-gene phylogenetic analyses on 240 Schizomida, 24 Uropygi and 12 other arachnid outgroups. Schizomid specimens included one specimen from the small family Protoschizomidae; other schizomid specimens were in Hubbardiidae, subfamily Hubbardiinae, which holds 289 of the order's 305 named species. We inferred ancestral areas using the Dispersal-Extinction-Cladogenesis model of range evolution, and we used fossil calibrations to estimate divergence times. Results: We recovered monophyletic Schizomida and Uropygi as each other's sister group, forming the clade Thelyphonida, and terminals from the New World were usually positioned as the earliest diverging lineages. The ancestral area for schizomids reconstructed unambiguously to the region comprised of Mexico, Southern California and Florida (the xeric New World subtropics). Optimal trees suggested a single colonization of the Indo-Pacific in both orders, although this did not receive bootstrap support. Molecular dating gave an Upper Carboniferous origin for each order, and a mid-Cretaceous expansion of Schizomida, including the origin and initial diversification of those in the Indo-Pacific. Main conclusions: Ancestral area reconstructions, molecular dating and fossil evidence all support an Upper Carboniferous, tropical Pangean origin for Thelyphonida, Schizomida and perhaps Uropygi. Much of this region became unsuitable habitat for these arachnids during the breakup of Pangea, but they persisted in the area that is now Meso- and South America. From there they then expanded to the Indo-Pacific, where schizomids today display an idiosyncratic combination of microendemism and long-range dispersal.

Seed dispersal studies have primarily relied on prediction model methods, which limit clarity regarding how variables affect movement direction. Suggestions for improvement are limited to specific domains due to the lack of quantitative evaluation of the comprehensive scope of the basic steps, from explaining seed dispersal to its application in related fields. This study aimed to reconsider the classification of seed movement mechanisms, identify research trends from an integrated perspective, and discuss the current implications and improvement measures. The data included 240 studies related to seed dispersal across the observation, generalization, and application phases. By classifying the mechanisms based on the direction of movement, the main variables affecting movement due to gravity or wind can be clearly distinguished. Although seed dispersal models assume gravity as the core principle, only 12.91% of the studies addressed terminal velocity, and a mere 1.25% measured the diaspore area, both of which are essential for accurate prediction. In addition, attempts to utilize seed dispersal for natural regeneration were relatively frequent (14.58%), but they remained at the empirical model stage, relying on data collected in the field, and thus lacked connection with models developed in previous studies. The requirements for enhancing the field usability of seed dispersal based on the current review include (1) improving the data collection system for securing primary data, (2) collecting sufficient field data, and (3) developing a unified model that can be applied to various conditions and species.

Dispersal influences ecological dynamics, evolution, biogeography, and biodiversity conservation, but models of larval dispersal in marine organisms make simplifying assumptions that are likely to approximate poorly the temporal dynamics of larval survival and capacity for settlement. In particular, larval mortality rates are typically assumed to be constant throughout larval life; and all larvae are frequently assumed to acquire and lose competence at the same time. To improve upon these assumptions, we here develop simple models of dispersal potential that incorporate rates of mortality, and acquisition and loss of settlement competence. We fit these models to empirical competence and survival data for five scleractinian coral species, to test the models' ability to characterize empirical survival and competence patterns, and to estimate the dispersal potential implied by those patterns. The models fit the data well, incorporating qualitative features of competence and survival that traditional approaches to modeling dispersal do not, with important implications for dispersal potential. Most notably, there was high within-cohort variation in the duration of the competent period in all species, and this variation increases both self-recruitment and long-distance dispersal compared with models assuming a fixed competent period. These findings help to explain the seeming paradox of high genetic population structure, coupled with large geographic range size, observed in many coral species. More broadly, our approach offers a way to parsimoniously account for variation in competence dynamics in dispersal models, a phenomenon that our results suggest has important effects on patterns of connectivity in marine metapopulations.

Plant establishment patterns suggest that ectomycorrhizal fungal (EMF) inoculant is not found ubiquitously. The role of animal vectors dispersing viable EMF spores is well documented. Here we investigate the role of wind in basidiospore dispersal for six EMF species, Inocybe lacera, Laccaria laccata, Lactarius rufus, Suillus brevipes, Suillus tomentosus and Thelephora americana. Basidiospores adhered to microscope slides placed on three 60 cm transects radiating from sporocarps. Morphological characteristics of species as well as average basidiospore volume were recorded. Number of basidiospores was quantified at specific distances to produce actual dispersal gradients. We found a negative exponential decay model using characteristics for each species fit the field data well. The 95% modeled downwind dispersal distance of basidiospores was calculated for each species. The 95% modeled downwind dispersal distance increased with increasing cap height and decreasing basidiospore volume for the species sampled, with 95% of basidiospores predicted to fall within 58 cm of the cap. Differences in anatomical characteristics of EMF species influence how far basidiospores are dispersed by wind. We discuss the role of wind dispersal leading to patterns of EMF establishment during primary succession.