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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.
Islands are particularly noteworthy for global conservation because of the high number of species they host, the high levels of species endemism, and the large number and proportion of species at risk of extinction. Much of the conservation threat on islands is from invasive species. Whilst biosecurity is an increasing focus of attention for authorities globally, species are continuing to establish in new locations outside of their native ranges. Among invasive species, ants are a prominent taxon, especially on islands. Over the past decade, following the detection of one of the world’s worst invasive ant species, African big-headed ant Pheidole megacephala, the environmental management authority on world-heritage-listed Lord Howe Island has focused attention on invasive ants. This detection influenced the creation of biosecurity measures to prevent further incursions of exotic species, particularly ants. Despite these efforts, over the following decade numerous ant species were collected on the island for the first time, indicating a serious biosecurity problem. Here, we investigate the chronosequence of ant introductions to Lord Howe Island to quantify the extent and nature of the island’s ant biosecurity problem. A total of 45 species have been collected on the island and of these, 12 are considered to be endemic, and a further seven are possibly native. Nineteen of the 26 introduced species (42% of the total fauna and 73% of the introduced fauna) were only found for the first time in the last 15 years. All but two of the species that are not native to Lord Howe Island are native to the Australian mainland, indicating that the biosecurity threat comes from the transport of goods from the Australian mainland. We suggest that the pattern of accelerating ant species accumulation on Lord Howe Island is probably not an isolated phenomenon, and that it is probably occurring on most islands globally that are habitable by ants and visited by people.
We argue that human-mediated invasions are part of the spectrum of species movements, not a unique phenomenon, because species self-dispersing into novel environments are subject to the same barriers of survival, reproduction, dispersal and further range expansion as those assisted by people. Species changing their distributions by human-mediated and non-human mediated modes should be of identical scientific interest to invasion ecology and ecology. Distinctions between human-mediated invasions and natural colonisations are very valid for management and policy, but we argue that these are value-laden distinctions and not necessarily an appropriate division for science, which instead should focus on distinctions based on processes and mechanisms. We propose an all-encompassing framework of species range expansion. This does not detract from the importance of invasion biology as a discipline, but instead will help bring together research being conducted on multiple taxa, and by multiple disciplines, including epidemiology, that are often focused on an identical phenomenon: colonisation.
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.
Die vorliegende Arbeit beschreibt das Lebensstrategien-Gefüge in der Anthyllis cytisoides-Gesellschaft, einer mesomediterranen Ersatzgesellschaft auf aufgelassenen Ackerflächen, die heute stark beweidet werden. Grundlage der Analyse sind pflanzensoziologische Aufnahmen aus dem südostspanischen Trockengebiet. Für die Gewichtung der Lebensstrategien wurde der mittlere Gruppenmengenanteil herangezogen. In der Anthyllis cytisoides-Gesellschaft dominieren Ausdauernde mit Fern- und Nahausbreitung, mit generativem Reproduktionsverhalten und Kurzlebige mit Fern- und Nahausbreitung, mit generativem Reproduktionsverhalten. Auffallend ist die starke Gewichtung der generativen Reproduktion und das polychore Ausbreitungsverhalten der Diasporen vieler Arten. Die Variabilität und Tendenz zur Risikoverteilung der Ausbreitung und Reproduktion veranschaulicht die klonal wachsende Art Anthyllis cytisoides. Ihre akantho-/sakkophoren Diasporen werden zum einen zoochor über größere Entfernungen transportiert, zum anderen durch den Wind verweht. Ihr Flugvermögen ist jedoch trotz des Lufteinschlusses und der hohen Expositionshöhe gering. Die harte, impermeable Fruchthülle, die den Samen umgibt, verhindert eine Massenkeimung der Diasporen unter ungünstigen Habitatbedingungen. Für die Diasporen zahlreicher Arten der Anthyllis cytisoides-Gesellschaft wurde eine Verschleppung durch Ernteameisen nachgewiesen. Davor geschützt sind viele Arten, die ihre Diasporen während des Sommers in einer am Sproß verbleibenden Diasporenbank lagern. Die Produktion schleimbildender oder sich einbohrender Diasporen sind weitere signifikante Mechanismen, die die sekundäre Verfrachtung von Diasporen verhindern. Die Ersatzgesellschaft ist ökologisch bedeutsam, da Anthyllis cytisoides in der Lage ist, nährstoffverarmte Böden zu besiedeln und Luftstickstoff zu fixieren. Im Rahmen von Anpflanzungsmaßnahmen kann sie einen bedeutenden Beitrag leisten, um der zunehmenden Erosion und Desertifikation entgegenzuwirken.
Bostrichidae (Coleoptera) are a family of beetles with specialized xylophagous feeding habits that allow consumption of dry woody plant tissues. Bostrichids are often polyphagous and therefore pose a significant threat to many agricultural and forestry products, particularly in tropical regions. Bostrichids are commonly detected in solid wood packaging material at in ternational ports of entry. Notably, Sinoxylon anale Lesne has been intercepted in wood crates and pallets worldwide and has now become established in Brazil. This paper reports the first documented establishment of S. anale in Brazil, being found both in domestic wood pallets and within native forest and monoculture. The origin of these populations remains uncertain, but introductions through infested wood packaging at ports of entry is a likely scenario. Similarly, the exact time of establishment is unknown. Given that S. anale adults are attracted to light and ethanol, trapping using light or ethanol could be used in monitoring surveys. This species typically infests dead or decaying woody material, and therefore does not pose a direct threat to healthy, live trees. Although more common in tropical regions, S. anale has exhibited some adaptability to temperate climates, which may allow it to spread across the tropical and subtropical regions of Brazil and potentially to other parts of South America.
ZooBank registration. urn:lsid:zoobank.org:pub:9B47075B-AC63-4AA4-AFB6-E2689346CC11
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.
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.
Aim: Biological invasions are likely determined by species dispersal strategies as well as environmental characteristics of a recipient region, especially climate and human impact. However, the contribution of climatic factors, human impact, and dispersal strategies in driving invasion processes is still controversial and not well embedded in the existing theoretical considerations. Here, we study how climate, species dispersal strategies, and human impact determine plant invasion processes on islands distributed in all major oceans in the context of directional ecological filtering.
Location: Six mountainous, tropical, and subtropical islands in three major oceans: Island of Hawai'i and Maui (Pacific), Tenerife and La Palma (Atlantic), and La Réunion and Socotra (Indian Ocean).
Taxon: Vascular Plants.
Methods: We recorded 360 non-native species in 218 plots along roadside elevational transects covering the major temperature, precipitation and human impact (i.e., road density) gradients of the islands. We collected dispersal strategies for a majority of the recorded species and calculated the environmental niche per species using a hypervolume approach.
Results: Non-native species’ generalism (i.e., mean community niche width) increased with precipitation, elevation and human impact but showed no relationship with temperature. Increasing precipitation led to environmental filtering of non-native species resulting in more generalist species under high precipitation conditions. We found no directional filtering for temperature but an optimum range of most species between 10 and 20°C. Niche widths of non-native species increased with the prevalence of certain dispersal strategies, particularly anemochory and anthropochory.
Main conclusions: Plant invasion on tropical and subtropical islands seems to be mainly driven by precipitation and human impact, while temperature seems to be of little importance. Furthermore, anemochory and anthropochory are dispersal strategies associated with large niche widths of non-native species. Our study allows a more detailed look at the mechanisms behind directional ecological filtering of non-native plant species in non-temperature-limited ecosystems.
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.