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Palms are ubiquitous as landscaping plants in many urban areas. Dispersed by frugivorous birds and often tolerated as self-seeded plants by the property owners, Phoenix canariensis (Canary Islands date palms) and two species of fan palms (Washingtonia robusta and Washingtonia filifera) in particular, have become established in many urban spaces. This paper examines the establishment of such self-seeded palms as epiphytic growth in crooks and branch scars of suburban street trees. Given the limited nutrient availability and the restricted space for rootmass development, these palms undergo a natural bonsai process. Some palms have persisted for over a decade without reaching sexual maturity. While the epiphytic growth demonstrates the palms' further dispersal capability, it does not appear to increase their potential invasiveness into new areas of land.
Semi-dry grasslands were once widely distributed communities, but today they represent some of the most vulnerable habitats in Central Europe. European and national legislation and non-governmental organizations have managed to protect some of the remaining fragments. However, despite their status as Natura 2000 habitats, they are often endangered due to improper management, fragmentation and edge effects from adjacent croplands. By using a sample of 44 semi-dry hay meadows in the south-eastern Alpine Foreland of Styria, we investigated how species-richness and trait composition of semi-dry grassland species respond to variation in patch size, connectivity, abiotic site factors and management regimes. We used linear regression models to identify the most important drivers for richness of typical semi-dry grassland species and thus conservation value. The number of typical semi-dry grassland species was highest in well-connected fragments, i.e. units that shared two or more borders with neighbouring species-rich grasslands. Furthermore, large semi-dry grasslands (> 8000 m²) had highest numbers of semi-dry grassland species and highest relevance for conservation; no difference was found among smaller fragment sizes. Unregular management was associated with increased presence of competitive species which replaced stress-tolerant specialists. Our study indicates that under eutrophication, small fragment size and isolation, only large semi-dry grasslands can sustain a high number of species with high conservation value. The conservation value of smaller semi-dry grassland fragments could be improved by buffer zones, adapted mowing treatments and periodical sheep grazing.
When based on phylogenetic proposals, biogeographic historic narratives have a great interest for hypothesizing paths of origin of the current biodiversity. Among the many questions that remain unsolved about psocids, the distribution of Thyrsophorini represents still a remarkable enigma. This tribe had been considered as exclusively Neotropical, until the description of Thyrsopsocopsis thorntoni Mockford, 2004, from Vietnam. Three hypotheses have been proposed to explain this atypical distribution, recurring to dispersal, vicariance and morphological parallelism between lineages, but the lack of evidence has not allowed a unique support. Here, we describe a new Neotropical species of Thyrsopsocopsis, and also attempt to test the three biogeographical hypotheses in a phylogenetic context. In our analyses, the position of Cycetes (Cycetini) and Thyrsopsocopsis among Thyrsophorini psocids is well resolved, suggesting a dispersal event from the Neotropics for both genera.
In the present study the population genetic structure of the terrestrial snail Pomatias elegans was related to habitat structure on a microspatial scale. The genetic variability of 1607 individuals from 51 sampling sites in five different populations in Provence, France, was studied with an allozyme marker using population genetic methods, Mantel tests and spatial autocorrelation techniques were applied to different connectivity networks accounting for the structural features of the landscape. It is suggested that the population structure is, to a large extent, a function of the habitat quality, quantified as population density, and of the spatial arrangement of the habitat in the landscape and not of the geographical distance per se. In fragmented habitats, random genetic drift was the prevailing force for sampling sites separated by a few hundred meters.
In zwei Landschaftsausschnitten im nördlichen Teil des Kreises Herzogtum-Lauenburg (Gesamtfläche von 19.142 ha) wurde die Waldvegetation auf der Basis eines selbst entwickelten Schlüssels kartiert. Mit Hilfe eines Geographischen Informationssystems (GIS) wurde die Vegetationskartierung mit Karten der historischen Waldbedeckung (Kurhannoversche Landesaufnahme von 1777, Varendorfsche Karte des Herzogtum Holstein von 1789-1796) sowie mit der geologischen Übersichtskarte verschnitten, um Aussagen über die Waldentwicklung in den letzten 250 Jahren an Standorten mit unterschiedlichem geologischen Ausgangsmaterial (Jungmoräne, Sander) treffen zu können. Darüber hinaus wurde in den Wäldern des Untersuchungsgebietes das Vorkommen von insgesamt 33 seltenen Waldgefäßpflanzenarten kartiert und mit Angaben für den Zeitraum 1960 bis 1985 verglichen.
Mit 5.550 ha (29 %) Waldbedeckung ist das Untersuchungsgebiet für Schleswig-Holstein relativ waldreich. Die besseren Böden der Grund- und Endmoräne tragen allerdings nur mit 9 %, die vergleichsweise nährstoffarmen, sauren Böden der Sanderflächen mit 19 % zur Waldfläche bei. Ein Vergleich der Waldkartierung mit den Angaben zur Bewaldung in den historischen Karten zeigt, dass seit Ende des 18. Jahrhunderts die Waldfläche insgesamt um 636 ha (13 %) zugenommen hat. Auf den Böden der Grund- und Endmoräne übersteigen Rodungsmaßnahmen allerdings bei weitem die Aufforstung (Bilanz: - 544 ha). Im Bereich der Sander führt insbesondere die Aufforstung von ehemaligen Heideflächen, Ackern und Viehtriften mit Nadelholz zu einer Waldvermehrung um 1.198 ha. Die anhand ihrer Frequenz im Verbreitungsatlas der Flora von Schleswig-Holstein ausgewählten seltenen Waldgefäßpflanzenarten haben ihren Verbreitungsschwerpunkt an den nährstoffreichen und feuchten Standorten der Jungmoräne und hier vor allem im Stellario-Alnetum (Alno-Ulmion) und Hordelymo-Fagetum (Galio-Fagion). Auffällig ist die enge Bindung dieser Arten an Standorte mit kontinuierlicher Waldbedeckung. Nur 12 der 72 Standorte, an denen mindestens eine der seltenen Arten gefunden wurde, sind eindeutig Neuaufforstungen von landwirtschaftlichen Flächen. - Ein Vergleich der Vorkommen der seltenen Arten mit Fundangaben im Verbreitungsatlas lässt einen starken Rückgang vieler dieser Arten vermuten. Die Gründe hierfür werden diskutiert.
Aim
How species respond to climate change is influenced by their sensitivity to climatic conditions (i.e. their climatic niche) and aspects of their adaptive capacity (e.g. their dispersal ability and ecological niche). To date, it is largely unknown whether and how species’ sensitivity to climate change and their adaptive capacity covary. However, understanding this relationship is important to predict the potential consequences of a changing climate for species assemblages. Here, we test how species’ sensitivity to climate change and trait-based measures of their ecological adaptive capacity (i) vary along a broad elevational gradient and (ii) covary across a large number of bird species.
Location
A Neotropical elevational gradient (300–3600 m.a.s.l.) in the Manú Biosphere Reserve, south-east Peru.
Methods
We focus on 215 frugivorous bird species along a Neotropical elevational gradient. We approximate species’ sensitivity to climate change by their climatic niche breadth, based on species occurrences across South America and bioclimatic variables. In addition, we use a trait-based approach to estimate the dispersal ability of species (approximated by their wing pointedness), their dietary niche breadth (approximated by bill width) and their habitat niche breadth (the number of used habitat classes).
Results
We found that (i) species’ climatic niche breadth increased with elevation, while their trait-based dispersal ability and dietary niche breadth decreased with elevation, and (ii) sensitivity to climate change and trait-based adaptive capacity were not related across species.
Main conclusions
These results suggest different mechanisms of how species in lowland and highland assemblages might respond to climate change. The independent variation of species’ sensitivity to climate change and their trait-based adaptive capacity suggests that accounting for both dimensions will improve assessments of species’ susceptibility to climate change and potential impacts of climate change on diverse species assemblages.
Primary determinants of communities in deadwood vary among taxa but are regionally consistent
(2020)
The evolutionary split between gymnosperms and angiosperms has far‐reaching implications for the current communities colonizing trees. The inherent characteristics of dead wood include its role as a spatially scattered habitat of plant tissue, transient in time. Thus, local assemblages in deadwood forming a food web in a necrobiome should be affected not only by dispersal ability but also by host tree identity, the decay stage and local abiotic conditions. However, experiments simultaneously manipulating these potential community drivers in deadwood are lacking. To disentangle the importance of spatial distance and microclimate, as well as host identity and decay stage as drivers of local assemblages, we conducted two consecutive experiments, a 2‐tree species and 6‐tree species experiment with 80 and 72 tree logs, respectively, located in canopy openings and under closed canopies of a montane and a lowland forest. We sampled saproxylic beetles, spiders, fungi and bacterial assemblages from logs. Variation partitioning for community metrics based on a unified framework of Hill numbers showed consistent results for both studies: host identity was most important for sporocarp‐detected fungal assemblages, decay stage and host tree for DNA‐detected fungal assemblages, microclimate and decay stage for beetles and spiders and decay stage for bacteria. Spatial distance was of minor importance for most taxa but showed the strongest effects for arthropods. The contrasting patterns among the taxa highlight the need for multi‐taxon analyses in identifying the importance of abiotic and biotic drivers of community composition. Moreover, the consistent finding of microclimate as the primary driver for saproxylic beetles compared to host identity shows, for the first time that existing evolutionary host adaptions can be outcompeted by local climate conditions in deadwood.
The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θ) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample.
Despite being generally distributed and common on Cuba, Hispaniola, and in south Florida, species of Pyrgus Hübner (Lepidoptera: Hesperiidae), commonly known as checkered skippers, are very poorly known from The Bahamas. Previous records indicated the presence only of Pyrgus oileus (Linnaeus, 1767), just from Great Inagua Island, although its status on that island remains unclear. Herein we document P. oileus for the first time from Grand Bahama Island, suggesting an independent dispersal of this species to the northern Bahamas from south Florida. Furthermore, we document Pyrgus albescens Plötz, 1884 from Grand Bahama and Abaco islands, representing the first Caribbean records for this rapidly dispersing species. We suggest that both P. oileus and P. albescens arrived on Grand Bahama sometime between 2010 and 2014, most likely from south Florida, and that P. albescens has subsequently dispersed to Abaco. Careful study of Pyrgus species in The Bahamas is needed to document future colonization events.
Einige Flechten sind im Verlauf der letzten Jahre deutlich häufiger geworden oder haben sogar ihr Areal ausgedehnt. Die Ausbreitung einiger hemerophiler Flechten in Mecklenburg-Vorpommern wird nachfolgend diskutiert. Anisomeridium nyssaegenum, Strangospora moriformis und Thellomma ocellatum sind neu für Mecklenburg-Vorpommern.