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Aim: Much of what is known about invasion biology is based on research conducted in North America and Europe, leading to limitations and potential biases in our knowledge. We address these limitations by conducting a systematic review to assess the literature on ecological studies of two major tropical and subtropical invasive plant species, Ageratina adenophora and Chromolaena odorata. Our goals were to: (1) collect the literature on the invasion biology of these species by broadly searching five databases (one international and four regional); (2) determine limitations to the international literature available in the ISI Web of Science (WOS); (3) quantitatively summarize the scope of the invasion literature on the two species; and (4) propose future studies based on what we found. Location: Global. Methods: Using specific search terms, we searched the literature for A. adenophora and C. odorata in the ISI WOS, Chinese National Knowledge Infrastructure (CNKI), Indian Journals, Nepal Journals Online and African Journals Online (AJOL). We extracted information on journal titles, publication years, study area locations, habitats investigated and study focus. Results: We found 101 papers for A. adenophora and 61 papers for C. odorata, published from 1987 to 2015. A high percentage of the studies were conducted in China, western and southern Africa, and India. Studies from WOS most frequently focused on the mechanism of invasion, while studies from CNKI and AJOL focused on the impacts of the invader. Main conclusions: Web of Science is not sufficient for generalizing about the invasion biology literature, particularly if the goal is a comprehensive assessment that includes areas other than North America, Hawaii, Europe, Australia, South Africa and New Zealand. In future systematic reviews, other databases should be used if possible, including those in languages other than English. For future research, several research areas should be studied more thoroughly for A. adenophora and C. odorata invasions, including possible multiple factors responsible for invasion, and impacts of co-occurring invasive species. [ABSTRACT FROM AUTHOR]

Aim: Vegetation structure is a key determinant of animal diversity and species distributions. The introduction of Light Detection and Ranging (LiDAR) has enabled the collection of massive amounts of point cloud data for quantifying habitat structure at fine resolution. Here, we review the current use of LiDAR‐derived vegetation metrics in diversity and distribution research of birds, a key group for understanding animal–habitat relationships. Location: Global. Methods: We review 50 relevant papers and quantify where, in which habitats, at which spatial scales and with what kind of LiDAR data current studies make use of LiDAR metrics. We also harmonize and categorize LiDAR metrics and quantify their current use and effectiveness. Results: Most studies have been conducted at local extents in temperate forests of North America and Europe. Rasterization is currently the main method to derive LiDAR metrics, usually from airborne laser scanning data with low point densities (<10 points/m2) and small footprints (<1 m diameter). Our metric harmonization suggests that 40% of the currently used metric names are redundant. A categorization scheme allowed to group all metric names into 18 out of 24 theoretically possible classes, defined by vegetation part (total vegetation, single trees, canopy, understorey, and other single layers as well as multi‐layer) and structural type (cover, height, horizontal variability and vertical variability). Metrics related to canopy cover, canopy height and canopy vertical variability are currently most often used, but not always effective. Main conclusions: Light Detection and Ranging metrics play an important role in understanding animal space use. Our review and the developed categorization scheme may facilitate future studies in the selection, prioritization and ecological interpretation of LiDAR metrics. The increasing availability of airborne and spaceborne LiDAR data and the development of voxel‐based and object‐based approaches will further allow novel ecological applications, also for open habitats and other vertebrate and invertebrate taxa. [ABSTRACT FROM AUTHOR]

The mysid crustacean Hemimysis anomala (‘bloody-red shrimp’) is one of the most recent participants in the invasion of European inland waters by Ponto-Caspian species. Recently the species also became established in England and the Laurentian Great Lakes of North America. Using information from mitochondrial cytochrome oxidase I (COI) gene sequences, we traced the invasion pathways of H. anomala; the inferences were enabled by the observed phylogeographical subdivision among the source area populations in the estuaries of the Ponto-Caspian basin. The data distinguish two routes to northern and western Europe used by distinct lineages. One route has been to and through the Baltic Sea and further to the Rhine delta, probably from a population intentionally introduced to a Lithuanian water reservoir from the lower Dnieper River (NW Black Sea area) in 1960. The other lineage is derived from the Danube delta and has spread across the continent up the Danube River and further through the Main–Danube canal down to the Rhine River delta. Only the Danube lineage was found in England and in North America. The two lineages appear to have met secondarily and are now found intermixed at several sites in NW Europe, including the Rhine and waters linked with the man-made Mittellandkanal that interconnects the Rhine and Baltic drainage systems. [ABSTRACT FROM AUTHOR]

Knowing the origin of invasive taxa, whether multiple introductions have occurred, and levels of genetic variation relative to the native range, is vital to conducting rigorous tests of hypotheses to explain biological invasions. We explore phylogeographical relationships of two Eurasian knapweed taxa that are invasive in North America, Centaurea diffusa and C. stoebe micranthos (Asteraceae), using chloroplast DNA intron sequences. We also gathered data from C. stoebe stoebe, hybrids between C. diffusa and C. stoebe stoebe ( C. x psammogena), and three other species in the genus. We sequenced 213 individuals from Eurasia and North America, and found 22 haplotypes. Centaurea diffusa has lower haplotype diversity and allelic richness in the introduced range relative to the native range. Even with reduced variation, the data suggest at least two introductions of C. diffusa. There is a trend towards reduced variation in C. stoebe micranthos, but it is not significant. One of the haplotypes found in North American C. stoebe micranthos matches a haplotype from a taxon other than C. stoebe micranthos in Europe. This suggests introgression of the chloroplast between taxa, or possibly the invasion of another Centaurea taxon into North America. Additionally, C. diffusa, C. stoebe micranthos, and C. stoebe stoebe share several haplotypes, including their most common haplotype. This suggests ongoing hybridization between the species or incomplete segregation. These data can guide further exploration for the origins of these species, and point out locations within the introduced range with unique and diverse genetic makeup. [ABSTRACT FROM AUTHOR]

Abstract. Distributions of species along a freshwater habitat gradient, ranging from ephemeral pools with few predators to permanent lakes with fish, have been used to infer how predation establishes trade-offs that promote ecological specialization. Larval anurans are said to support the trade-off model, but there are few comparable and quantitative habitat data available to assess this claim. I performed a survey of field biologists to evaluate the habitats of similar sets of species in the northern parts of Europe (40 respondents and 12 species) and eastern North America (30 respondents and 8 species), using a standard set of criteria. For six European species I also had quantitative field sampling data, and found close agreement between survey results and predator densities experienced by tadpoles in the field. Distributions of most species were restricted to only part of the habitat gradient, as expected under the trade-off model. The survey confirmed reports that North Ameri-can Rana species replace one another along the gradient, but this was not true in Europe. European Rana were no different from the North American species in their seasonal and geographical overlap, so the absence of habitat partitioning in European Rana may result from interactions with other species or the special impact of glaciation in Europe. Habitats were unrelated to evolutionary relationships among species, suggesting that changes in habitat evolve quickly. The survey approach was useful for comparing distributions of species, and for generating hypotheses about evolutionary responses to habitat gradients. [ABSTRACT FROM AUTHOR]