How much of the invader's genetic variability can slip between our fingers? A case study of secondary dispersal of Poa annua on King George Island (Antarctica)

We studied an invasion of Poa annua on King George Island (Maritime Antarctic). The remoteness of this location, its geographic isolation, and its limited human traffic provided an opportunity to trace the history of an invasion of the species. Poa annua was recorded for the first time at H. Arctowski Polish Antarctic Station in the austral summer of 1985/6. In 2008/9, the species was observed in a new locality at the Ecology Glacier Forefield (1.5 km from “Arctowski”). We used AFLP to analyze the genetic differences among three populations of P. annua: the two mentioned above (Station and Forefield) and the putative origin of the introduction, Warsaw (Poland). There was 38% genetic variance among the populations. Pairwise Ф_PT was 0.498 between the Forefield and Warsaw populations and 0.283 between Warsaw and Station. There were 15 unique bands in the Warsaw population (frequency from 6% to 100%) and one in the Station/Forefield populations (which appears in all analyzed individuals from both populations). The Δ(K) parameter indicated two groups of samples: Warsaw/Station and Forefield. As indicated by Fu's Fs statistics and an analysis of mismatch distribution, the Forefield population underwent a bottleneck and/or founder effect. The Forefield population was likely introduced by secondary dispersal from the Station population.     

The “Trojan horse” strategy: Seed fungal endophyte symbiosis helps to explain the invasion success of the grass,Poa annua,in Maritime Antarctica

Aim

Poa annua L. (annual bluegrass) is presently the sole invasive vascular plant species to have successfully established in Maritime Antarctica, where it poses a significant conservation threat to native plant species. However, the reasons for its success in the region have yet to be established. Here, we determined whether the invasiveness of P. annua, and its competitiveness with the native Antarctic hairgrass Deschampsia antarctica, is influenced by symbioses formed with seed fungal endophytes, and whether plants derived from seeds from four global regions differ in their performance.

Locations

Four regions (Maritime Antarctica, sub-Antarctica, South America and Europe).

Methods

Endophyte frequency was measured in P. annua seeds collected from the four regions. The germination, survival, biomass accumulation, flowering and competitiveness with D. antarctica of P. annua plants grown from endophyte-uncolonised and uncolonised seeds was determined in the laboratory. The effects of endophytes on P. annua seed germination and survival and seedling osmoprotection were also assessed in the Maritime Antarctic natural environment using locally-sourced seeds.

Results

Endophytes were at least twice as frequent in seeds from Maritime Antarctica than in those from other regions. A higher proportion of endophyte-colonized seeds germinated and survived than did uncolonised seeds, but only when they originated from Maritime Antarctica. Seed endophytes increased the competitiveness of P. annua with D. antarctica, but only for plants grown from Maritime Antarctic seeds. In the field, endophyte-colonized seeds from Maritime Antarctica germinated and survived more frequently than uncolonised seeds, and osmoprotection was higher in seedlings grown from colonized seed.

Main Conclusions

The findings indicate beneficial effects of seed endophytes on invasion-related traits of P. annua, such as survival, germination success and flowering. Together with vegetative and reproductive traits facilitating the colonization process, the seed-fungal endophyte symbiosis can be invoked as an important factor explaining the invasiveness of P. annua in Maritime Antarctica.     

From pole to pole: the potential for the Arctic seastar Asterias amurensis to invade a warming Southern Ocean

Due to climatic warming, Asterias amurensis, a keystone boreal predatory seastar that has established extensive invasive populations in southern Australia, is a potential high‐risk invader of the sub‐Antarctic and Antarctic. To assess the potential range expansion of A. amurensis to the Southern Ocean as it warms, we investigated the bioclimatic envelope of the adult and larval life stages. We analysed the distribution of adult A. amurensis with respect to present‐day and future climate scenarios using habitat temperature data to construct species distribution models (SDMs). To integrate the physiological response of the dispersive phase, we determined the thermal envelope of larval development to assess their performance in present‐day and future thermal regimes and the potential for success of A. amurensis in poleward latitudes. The SDM indicated that the thermal ‘niche’ of the adult stage correlates with a 0–17 °C and 1–22.5 °C range, in winter and summer, respectively. As the ocean warms, the range of A. amurensis in Australia will contract, while more southern latitudes will have conditions favourable for range expansion. Successful fertilization occurred from 3 to 23.8 °C. By day 12, development to the early larval stage was successful from 5.5 to 18 °C. Although embryos were able to reach the blastula stage at 2 °C, they had arrested development and high mortality. The optimal thermal range for survival of pelagic stages was 3.5–19.2 °C with a lower and upper critical limit of 2.6 and 20.3 °C, respectively. Our data predict that A. amurensis faces demise in its current invasive range while more favourable conditions at higher latitudes would facilitate invasion of both larval and adult stages to the Southern Ocean. Our results show that vigilance is needed to reduce the risk that this ecologically important Arctic carnivore may invade the Southern Ocean and Antarctica.     

Extinction and recolonization of maritime Antarctica in the limpet Nacella concinna (Strebel, 1908) during the last glacial cycle: toward a model of Quaternary biogeography in shallow Antarctic invertebrates

Quaternary glaciations in Antarctica drastically modified geographical ranges and population sizes of marine benthic invertebrates and thus affected the amount and distribution of intraspecific genetic variation. Here, we present new genetic information in the Antarctic limpet Nacella concinna, a dominant Antarctic benthic species along shallow ice‐free rocky ecosystems. We examined the patterns of genetic diversity and structure in this broadcast spawner along maritime Antarctica and from the peri‐Antarctic island of South Georgia. Genetic analyses showed that N. concinna represents a single panmictic unit in maritime Antarctic. Low levels of genetic diversity characterized this population; its median‐joining haplotype network revealed a typical star‐like topology with a short genealogy and a dominant haplotype broadly distributed. As previously reported with nuclear markers, we detected significant genetic differentiation between South Georgia Island and maritime Antarctica populations. Higher levels of genetic diversity, a more expanded genealogy and the presence of more private haplotypes support the hypothesis of glacial persistence in this peri‐Antarctic island. Bayesian Skyline plot and mismatch distribution analyses recognized an older demographic history in South Georgia. Approximate Bayesian computations did not support the persistence of N. concinna along maritime Antarctica during the last glacial period, but indicated the resilience of the species in peri‐Antarctic refugia (South Georgia Island). We proposed a model of Quaternary Biogeography for Antarctic marine benthic invertebrates with shallow and narrow bathymetric ranges including (i) extinction of maritime Antarctic populations during glacial periods; (ii) persistence of populations in peri‐Antarctic refugia; and (iii) recolonization of maritime Antarctica following the deglaciation process.     

Spatial analysis of Listronotus maculicollis immature stages demonstrates strong associations with conspecifics and turfgrass damage but not with optimal hosts on golf course fairways

For insects that develop on few hosts and/or have immobile immature stages, optimal oviposition theory suggests that females should seek high‐quality hosts that maximize larval development and reduce competition from conspecifics. However, there is a growing amount of evidence that suggests female choice may often be at odds with their offspring's development. Listronotus maculicollis (Kirby) (Coleoptera: Curculionidae) is a serious pest of golf course turfgrass in eastern North America. The weevil develops on few hosts and demonstrates improved fitness traits when developing on Poa annua L. (Poaceae). However, previous population studies observed either weak or no correlations between the spatial dispersion of larval populations and P. annua in the field. In this study, populations on three golf course fairways were monitored over a 4‐year period (2009–2012) to determine whether the lack of spatial associations between preferred hosts and immatures was a result of spatial scale or the density and distribution of conspecifics. Spatial Analysis by Distance IndicEs (SADIE) was used to characterize the spatial dispersion of populations of individual stages (larvae and pupae), P. annua, and turfgrass damage. Life stages were aggregated in each observation, independent of population density or the spatial dispersion of hosts. The distribution of consecutive and non‐consecutive immature stages was found to be correlated in all years, suggesting that females do not avoid patches already occupied by conspecific eggs. Surprisingly, significant spatial associations were not found between larvae and P. annua when the host plant was relatively abundant. Hence, multiple mechanisms may drive L. maculicollis oviposition site‐selection behavior, and a flexible strategy may allow the weevil to persist in areas where P. annua is not the dominant species. Future studies are required to determine what other factors (e.g., natural enemy‐free space, egg or time limitations) influence oviposition behavior.     

The effect of nitrate-nitrogen supply on bacteria and bacterial-feeding fauna in the rhizosphere of different grass species

Summary Microbial growth in the rhizosphere is affected by the release of organic material from roots, so differences in carbon budgets between plants may affect their rhizosphere biology. This was tested by sampling populations of bacteria and bacteriophagous fauna from the rhizosphere of Lolium perenne, Festuca arundinacea, Poa annua, and Poa pratensis, under conditions of high and low nitrate availability. Concentrations of soluble phenolics and lignin varied considerably between the species but were not related to differences in rhizosphere biology. L. perenne and F. arundinacea supported fewer bacteria than the Poa species. There was no significant rhizosphere effect on the groups of protozoa. The major indicators of rhizosphere productivity were the bacterial-feeding nematodes (mainly Acrobeloides spp.), and there was a large positive effect of added nitrate. Nematode biomass was significantly lower in the rhizosphere of the slow-growing P. pratensis compared with the fast-growing P. annua, indicating that the differential allocation of carbon has affects on rhizosphere biology. A large rhizosphere effect on enchytraeid worms was also observed, and their potential importance in the rhizosphere is discussed.     

Phylogeography of the poison frog Mantella viridis (Amphibia: Mantellidae) reveals chromatic and genetic differentiation across ecotones in northern Madagascar

Mantella viridis is a threatened poison frog species endemic to the ecologically very heterogeneous northern region of Madagascar. The existence of several colour morphs within M. viridis and its very low genetic differentiation to the allopatrically distributed Mantella ebenaui raise questions about the processes driving the differentiation between these poison frog populations and about their taxonomic status. Using a DNA fragment of 476 nucleotides of the mitochondrial cytochrome b gene from 240 individuals of this species complex, we investigated the genetic variability of all known colour morphs of M. viridis, sampling this species throughout its known range, as well as several populations of M. ebenaui. Our genetic results confirm that M. viridis and M. ebenaui are closely related but reveal that no haplotype sharing occurs between these two taxa. Further, our molecular analyses provided evidence for barriers to gene flow among some of the colour morphs. Estimates of overlap of bioclimatic envelopes as assessed by ecological niche modelling also suggest a distinct bioclimatic niche of some of the lineages studied.     

Introduced plants on Kilimanjaro: tourism and its impact

Kilimanjaro, a world heritage site and an icon of global change, not only suffers from climatic alterations but also is undergoing a drastic socio-economic upheaval. A strong increase of tourism enhances the risk of introducing alien plant species in particular in the upper zones of Kilimanjaro. One such species is Poa annua L., a cosmopolitan weed of European origin on roadsides and pastures. The aim of this study is to document its distribution, the speed of its propagation and risks for the indigenous vegetation of Kilimanjaro, and to compare the findings with other introduced species on this mountain. Based on a complete survey of the vegetation of Kilimanjaro with about 1,500 vegetation plots, plant communities invaded by Poa annua are determined. As with most of the other neophytes on Kilimanjaro, Poa annua invades only anthropogenic vegetation but not undisturbed natural vegetation. Similar to the situation in middle Europe, this neophyte is on Kilimanjaro a constituent of the vegetation of trampled ground, occurring between about 1,600 and 4,000 m asl along climbing routes or their vicinity. On a newly opened climbing route a rapid invasion (5.6 km in 3 months) was observed, which makes it likely that Poa annua spread on Kilimanjaro during the last 30 years in parallel to the increase of the climbing tourism. Although Poa annua is still in the stage of propagation, an invasion of natural vegetation types seems to be unlikely.     

Warmer and less variable temperatures favour an accelerated plant phenology of two invasive weeds across sub‐Antarctic Macquarie Island

The great plasticity and diverse reproductive strategies of invasive alien plants are widely assumed to contribute to invasion success, even in extreme areas, often displacing native species. In this context, climate change creates new opportunities for biological invasions. Environmental variability and global warming are two of the climatic processes that may promote invasiveness, since alien species modulate their phenology to succeed under these circumstances. We monitored the phenological development (phenological stage advancement) of the two main invasive alien species: Poa annua L. and Cerastium fontanum Baumg. in the sub‐Antarctic Macquarie Island during the austral summer period along an altitudinal gradient. We found that higher temperatures lead to increased plant height and accelerated phenological development than lower temperatures in P. annua but found no direct evidence of the latter in C. fontanum. However, increased temperature variability negatively affected the phenological development of both species. Interestingly, despite their different reproductive strategy (rapid and impromptu in P. annua, and more synchronic and gradual in C. fontanum), both species prolifically succeeded in producing seeds at all sites showing the great acclimation of these two alien species even in limiting conditions. Since both alien species in Macquarie Island showed larger size and faster phenology at lower altitudes (i.e. milder conditions), this would indicate a great influence of ameliorating abiotic extremes on alien plant invasive capabilities at environmental extremes. Thus, our results warn of the increasing capabilities under climatic warming scenarios for alien plants to reproduce even at such remote ranges. This highlights the need to reinforce calls for special attention to prevent the spread of these kinds of species to other similar sub‐polar areas, where intensive post‐introduction management may be difficult or expensive.     

Precipitation of the warmest quarter and temperature of the warmest month are key to understanding the effect of climate change on plant species diversity in Southern African savannah

In this study, we test for the key bioclimatic variables that significantly explain the current distribution of plant species richness in a southern African ecosystem as a preamble to predicting plant species richness under a changed climate. We used 54,000 records of georeferenced plant species data to calculate species richness and spatially interpolated climate data to derive nineteen bioclimatic variables. Next, we determined the key bioclimatic variables explaining variation in species richness across Zimbabwe using regression analysis. Our results show that two bioclimatic variables, that is, precipitation of the warmest quarter (R² = 0.92, P < 0.001) and temperature of the warmest month (R² = 0.67, P < 0.001) significantly explain variation in plant species richness. In addition, results of bioclimatic modelling using future climate change projections show a reduction in the current bio‐climatically suitable area that supports high plant species richness. However, in high‐altitude areas, plant richness is less sensitive to climate change while low‐altitude areas show high sensitivity. Our results have important implications to biodiversity conservation in areas sensitive to climate change; for example, high‐altitude areas are likely to continue being biodiversity hotspots, as such future conservation efforts should be concentrated in these areas.     

Niche Conservatism and Future Changes in the Potential Area Coverage of Arundina graminifolia,an Invasive Orchid Species from Southeast Asia

The Asian orchid, Arundina graminifolia, has been introduced to many locations over the last 50 yr, predominantly in South and Central America. A list of localities of A. graminifolia was compiled and used to model potential climatic niches based on the maximum entropy method. The differences are presented between niches occupied by native and invasive populations of A. graminifolia, and possible changes in the potential range of the species are discussed on the basis of various climate change scenarios. The coverage of habitats suitable for A. graminifolia will be reduced under future climate changes scenarios. The created niche distribution models indicated a more significant reduction in the potential ecological niches of the studied species in its invasive range. Nevertheless, areas with potentially suitable bioclimatic conditions for A. graminifolia should be monitored to prevent future uncontrolled invasion of the orchid into new habitats and to study its impact on the local ecosystems, as vast areas of its potential niche in the Americas are still unoccupied.     

Isolating the role of soil resources,defoliation, and interspecific competition on early establishment of the late successional bunchgrass Festuca campestris

Native grasslands are valued for biodiversity and supporting dormant season grazing, but are prone to invasion. In western Canada, revegetation of Festuca campestris grasslands may be hindered by Poa pratensis, an invasive grass. To determine the competitive interaction of these species during establishment, two greenhouse experiments were conducted where F. campestris seedlings were planted in monocultures or mixtures with P. pratensis. The first experiment used equal‐aged (3‐month old) seedlings of both species, while the second experiment used unequal‐aged seedlings (4‐month‐old F. campestris and 2‐month‐old P. pratensis). Seedling performance was measured in response to manipulations of water and nitrogen, defoliation, and plant neighbor. While water and nitrogen reduced the biomass and vegetative reproduction (tillering) of F. campestris, exposure to P. pratensis most strongly limited the growth of F. campestris seedlings regardless of other treatments. More frequent and consistent decreases in F. campestris due to P. pratensis were observed in older F. campestris seedlings than younger seedlings. Defoliation also reduced the growth of F. campestris, and the added presence of P. pratensis during defoliation further enhanced these reductions in younger, equal‐aged bunchgrass seedlings. Overall, these results suggest that when restoring native F. campestris grasslands, early establishment may be improved by reducing the negative impacts of P. pratensis, and avoiding severe defoliation.     

Spatial structure of the soil seed bank of Poa annua L.—alien species in the Antarctica

Poa annua L. (annual bluegrass) is the only non–native flowering plant species that has successfully established a breeding population in the maritime Antarctic and has been shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic population of this species is the formation of distinct dense clumps—tussocks. In the temperate zone the species is only loosely tufted. We focused on the characteristics of seed deposition associated with the tussocks and some aspects of the spatial heterogeneity of the soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is highly associated with the presence of tussocks. Seeds are deposited underneath the tussock rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive the Antarctic winter and readily germinate under optimal conditions.     

Hybridization of Southern Hemisphere blue whale subspecies and a sympatric area off Antarctica: impacts of whaling or climate change?

Understanding the degree of genetic exchange between subspecies and populations is vital for the appropriate management of endangered species. Blue whales (Balaenoptera musculus) have two recognized Southern Hemisphere subspecies that show differences in geographic distribution, morphology, vocalizations and genetics. During the austral summer feeding season, the Antarctic blue whale (B. m. intermedia) is found in polar waters and the pygmy blue whale (B. m. brevicauda) in temperate waters. Here, we genetically analyzed samples collected during the feeding season to report on several cases of hybridization between the two recognized blue whale Southern Hemisphere subspecies in a previously unconfirmed sympatric area off Antarctica. This means the pygmy blue whales using waters off Antarctica may migrate and then breed during the austral winter with the Antarctic subspecies. Alternatively, the subspecies may interbreed off Antarctica outside the expected austral winter breeding season. The genetically estimated recent migration rates from the pygmy to Antarctic subspecies were greater than estimates of evolutionary migration rates and previous estimates based on morphology of whaling catches. This discrepancy may be due to differences in the methods or an increase in the proportion of pygmy blue whales off Antarctica within the last four decades. Potential causes for the latter are whaling, anthropogenic climate change or a combination of these and may have led to hybridization between the subspecies. Our findings challenge the current knowledge about the breeding behaviour of the world's largest animal and provide key information that can be incorporated into management and conservation practices for this endangered species.     

Global realized niche divergence in the African clawed frog Xenopus laevis

Although of crucial importance for invasion biology and impact assessments of climate change, it remains widely unknown how species cope with and adapt to environmental conditions beyond their currently realized climatic niches (i.e., those climatic conditions existing populations are exposed to). The African clawed frog Xenopus laevis, native to southern Africa, has established numerous invasive populations on multiple continents making it a pertinent model organism to study environmental niche dynamics. In this study, we assess whether the realized niches of the invasive populations in Europe, South, and North America represent subsets of the species’ realized niche in its native distributional range or if niche shifts are traceable. If shifts are traceable, we ask whether the realized niches of invasive populations still contain signatures of the niche of source populations what could indicate local adaptations. Univariate comparisons among bioclimatic conditions at native and invaded ranges revealed the invasive populations to be nested within the variable range of the native population. However, at the same time, invasive populations are well differentiated in multidimensional niche space as quantified via n‐dimensional hypervolumes. The most deviant invasive population are those from Europe. Our results suggest varying degrees of realized niche shifts, which are mainly driven by temperature related variables. The crosswise projection of the hypervolumes that were trained in invaded ranges revealed the south‐western Cape region as likely area of origin for all invasive populations, which is largely congruent with DNA sequence data and suggests a gradual exploration of novel climate space in invasive populations.     

Climatic niche of the Saker Falcon Falco cherrug: predicted new areas to direct population surveys in Central Asia

Accurate species distribution data across remote and extensive geographical areas are difficult to obtain. Here, we use bioclimatic envelope models to determine climatic constraints on the distribution of the migratory Saker Falcon Falco cherrug to identify areas in data-deficient regions that may contain unidentified populations. Sakers live at low densities across large ranges in remote regions, making distribution status difficult to assess. Using presence-background data and eight bioclimatic variables within a species distribution modelling framework, we applied MaxEnt to construct models for both breeding and wintering ranges. Occurrence data were spatially filtered and climatic variables tested for multicollinearity before selecting best fit models using the Akaike information criterion by tuning MaxEnt parameters. Model predictive performance tested using the continuous Boyce index (B) was high for both breeding (B_TEST = 0.921) and wintering models (B_TEST = 0.735), with low omission rates and minimal overfitting. The Saker climatic niche was defined by precipitation in the warmest quarter in the breeding range model, and mean temperature in the wettest quarter in the wintering range model. Our models accurately predicted areas of highest climate suitability and defined the climatic constraints on a wide-ranging rare species, suggesting that climate is a key determinant of Saker distribution across macro-scales. We recommend targeted population surveys for the Saker based on model predictions to areas of highest climatic suitability in key regions with distribution knowledge gaps, in particular the Qinghai-Tibet plateau in western China. Further applications of our models could identify protected areas and reintroduction sites, inform development conflicts, and assess the impact of climate change on distributions.     

Poa pratensis L., current status of the longest-established non-native vascular plant in the Antarctic

A single colony of the non-native grass Poa pratensis L., which was introduced inadvertently to Cierva Point, Antarctic Peninsula, during the 1954–1955 season, was still present during a survey in February 2012, making it the longest surviving non-native vascular plant colony known in Antarctica. Since 1991, the grass cover has roughly tripled in size, with an annual increase in area of approximately 0.016 m², and an estimated maximum radial growth rate of 1.43 cm y^?1. However, it remains restricted to the original site of introduction and its immediate surroundings (c. 1 m²). Annual flowering of the plants occurred during the 2010/2011 and 2011/2012 seasons; however, there has been no seed production and only incomplete development of the sexual structures. Current environmental conditions, including low temperatures, may inhibit sexual reproduction. Lack of effective vegetative dispersal may be influenced by the low level of human activity at the site, which limits opportunities for human-mediated dispersal. Although P. pratensis has existed at Cierva Point for almost 60 years, it has not yet become invasive. Scenarios for the potential future development of the species in Antarctica and the associated negative impacts upon the native vegetation from competition are discussed in the context of regional climate change. Finally, we describe the environmental risk presented by P. pratensis and argue that this non-native species should be eradicated as soon as possible in accordance with the Protocol on Environmental Protection to the Antarctic Treaty.     

Evidence of ecological niche shift in Rhododendron ponticum (L.) in Britain: Hybridization as a possible cause of rapid niche expansion

Biological invasions threaten global biodiversity and natural resources. Anticipating future invasions is central to strategies for combating the spread of invasive species. Ecological niche models are thus increasingly used to predict potential distribution of invasive species. In this study, we compare ecological niches of Rhododendron ponticum in its native (Iberian Peninsula) and invasive (Britain) ranges. Here, we test the conservation of ecological niche between invasive and native populations of R. ponticum using principal component analysis, niche dynamics analysis, and MaxEnt‐based reciprocal niche modeling. We show that niche overlap between native and invasive populations is very low, leading us to the conclusion that the two niches are not equivalent and are dissimilar. We conclude that R. ponticum occupies novel environmental conditions in Britain. However, the evidence of niche shift presented in this study should be treated with caution because of nonanalogue climatic conditions between native and invasive ranges and a small population size in the native range. We then frame our results in the context of contradicting genetic evidence on possible hybridization of this invasive species in Britain. We argue that the existing contradictory studies on whether hybridization caused niche shift in R. ponticum are not sufficient to prove or disprove this hypothesis. However, we present a series of theoretical arguments which indicate that hybridization is a likely cause of the observed niche expansion of R. ponticum in Britain.     

Ovipositional preferences and larval survival of annual bluegrass weevil,Listronotus maculicollis,on Poa annua and selected bentgrasses (Agrostis spp.)

The annual bluegrass weevil (ABW), Listronotus maculicollis Kirby (Coleoptera: Curculionidae), is a serious and expanding pest of short‐cut turfgrass on golf courses in eastern North America. Increasing problems with the development of insecticide resistance in this pest highlights the need for more sustainable management approaches. Plant resistance is one of the most promising alternative strategies. Bentgrasses are the dominant grass species on golf course fairways, tees, and putting greens in the areas affected by ABW. But Poa annua L. (Poaceae), a highly invasive weed, often constitutes a large percentage of turf stands in short‐mown golf courses and is thought to be particularly susceptible to ABW. We studied resistance to ABW in four cultivars of creeping bentgrass, Agrostis stolonifera L., and two cultivars each of colonial bentgrass, Agrostis capillaris L., and velvet bentgrass, Agrostis canina L. (Poaceae), in comparison with P. annua by addressing the three major components of resistance: antixenosis (adult ovipositional and feeding preferences), antibiosis (larval survival and growth), and grass tolerance (grass damage). Our findings suggest that antixenosis/non‐preference is at least partially involved in bentgrass resistance to ABW. Even though oviposition was observed in all tested grasses, females laid significantly fewer eggs in Agrostis spp. than in P. annua. Compared to P. annua, Agrostis spp. were also less suitable for larval development with lower numbers of ABW immatures recovered and larvae weighing less and being less advanced in development. Resistance levels to ABW larvae varied significantly among Agrostis spp. and cultivars. Agrostis canina was least preferred by females for oviposition and A. stolonifera was the least suitable for larval survival and development. Agrostis spp., especially A. stolonifera, were more tolerant to ABW feeding than P. annua. Our findings suggest that reduction in P. annua and replacement with Agrostis spp., especially A. stolonifera, wherever feasible should be integral to more sustainable approaches to ABW management.     

Pupilla pratensis (Gastropoda: Pupillidae) in the Czech Republic and Slovakia and its distinction from P. muscorum and P. alpicola based on multidimensional analysis of shell measurements

Pupilla pratensis (Clessin, 1871) was recently confirmed as a distinct species based on morphological, ecological and molecular evidence. The main purpose of this study is to publish the first reliable data on the occurrence of P. pratensis in the Czech Republic and Slovakia. The second goal is to analyse conchometry of P. pratensis, P. muscorum (L., 1758), and P. alpicola (Charpentier, 1837) to find out whether it is possible to reliably distinguish these species solely based on shell measurements. For multidimensional analysis of shell measurement variation we used principal components analysis (PCA). We documented six populations of P. pratensis in the Czech Republic and one in SW Slovakia. The revision of voucher material showed that all previously reported records of P. alpicola from the Czech Republic belonged in fact to P. pratensis. This requires the exclusion of P. alpicola from the list of Czech molluscs. Based on multidimensional analysis of shell measurements it was possible to distinguish P. pratensis from P. muscorum with no overlapping specimens. Pupilla alpicola was almost completely different from P. muscorum with only few overlapping specimens, contrary to P. pratensis which was mostly impossible to distinguish from P. alpicola based on analysed shell measurements. Shell width was the best single shell measurement for distinguishing P. pratensis and P. muscorum. Shell measurements of two Swedish populations of P. pratensis did not differ from shell variation of Czech and Slovak populations. However, Scandinavian populations displayed some differences from central European populations in apertural barriers which are discussed in detail. Czech and Slovak populations of P. pratensis occurred in calcium-rich fen meadows which perfectly matches with site characteristics reported from Scandinavia. We assume that the observed morphometric differences between P. pratensis and P. muscorum can be useful for distinguishing the species also outside the Czech territory and for palaeoecological studies where only empty shells are available. Since these species occupy ecologically different habitats their reliable identification in fossil material can improve the reconstructions of past environments.