Ecological impacts of non-indigenous invasive fungi as forest pathogens

Non-indigenous pathogenic fungi increasingly threaten North American tree species. Ecosystems may be fundamentally changed when abundant tree species are functionally eliminated, as occurred with American chestnut (Castanea dentata (Marsh.) Borkh.). Conversely, changes may be more subtle but still significant and long lasting when populations are lost, or all trees in the larger size classes are killed. Proposed approaches for characterizing the magnitude of ecological impacts use characteristics of both the non-indigenous pathogen and the host species. Impacts are most significant when highly successful invading pathogens attack foundation species, setting in motion a long-lasting cascade of effects on the host and associated species. Such impacts have generally not been well documented at the ecosystem level. Several North American forest tree species have been functionally eliminated or severely reduced by non-indigenous pathogens. Historical invasions, such as that of chestnut blight (Cryphonectria parasitica (Murr.) Bar), caused very significant ecological impacts that will never be completely understood because of lack of quantitative data. Beech bark disease, caused by a combination of an introduced scale insect (Cryptococcus fagisuga Lindinger) and a fungus (Neonectria faginata (Lohman et al.) Castl. & Rossman), is still advancing and provides opportunities for studying ecosystem-level impacts when a major tree species is removed or markedly reduced in abundance from the overstorey. Butternut canker, caused by the fungus, Sirococcus clavigignenti-juglandacearum N.B. Nair, Kostichka & Kuntz, has spread throughout the host range, endangering species’ survival. Other non-indigenous invasive fungi such as Cronartium ribicola J.C. Fisch and Phytophthora lateralis Tucker & Milbrath continue to move into new populations, causing high mortality and associated restructuring of these ecosystems. Global trade and environmental change trends will ensure new challenges by non-indigenous fungal pathogens, presenting an urgent need for improved understanding of long-term impacts across ecological systems.     

Citizen monitoring of invasive species: wing morphometry as a tool for detection of alien Tetropium species

The increasing threat of alien wood‐boring insect has resulted in the initiation of large‐scale monitoring programmes. These programmes are most often based on pheromone‐bailed traps, which allow the early detection and monitoring of invasive species. This approach is expensive because it entails the processing and accurate identification of large numbers of specimens. One of the most often suggested solutions to this problem is citizen participation in the monitoring of invasive species. Such an approach has the potential for reducing costs as well as providing data from a larger number of sites. However, citizens vary in taxonomic expertise and experience which can result in identification errors. This may be particularly important in the case of wood borers which include many morphologically similar species. In this study, we develop and discuss a semi‐automated method of identifying four morphologically similar and invasive Tetropium spp. wood borers as a potential tool for citizen‐based monitoring programmes. Identification is based on wing measurements and requires neither specialist knowledge nor expensive equipment. The method correctly identified the species of Tetropium with an error ranging from 1.3% for T. fuscum to 7.5% for T. cinnamopterum. We found that experience level of the individual user was not essential for correct identification; on average, inexperienced volunteers correctly identified the Tetropium species in 93% of cases. Further development of this method may be a significant step to overcoming the taxonomical impediment to citizen monitoring of taxonomically challenging groups of insects.     

Morphology and ontogeny of Tetmemena pustulata indica nov. subspec. (Ciliophora,Hypotricha), from the Thane Creek,Mumbai, India

The morphology and ontogenesis of a novel stylonychid ciliate, Tetmemena pustulata indica nov. subspec., were investigated using live observation and protargol preparation. The new subspecies was isolated from a water sample collected from the Thane Creek, Mumbai, India. At first glance, T. pustulata indica looked very similar in morphology and ontogenesis to the well-known Tetmemena pustulata, however, on detailed investigation some non-overlapping features in the ciliature were identified, i.e., the numbers of cirri in marginal rows, adoral membranelles, and bristles in dorsal kineties. These morphometric differences justified the separation at subspecies level. Furthermore, the resting cysts are different, i.e., with smooth external layer in T. pustulata indica whereas spinous in the nominotypical subspecies T. pustulata pustulata. The Venezuelan population of T. pustulata described by Foissner corresponds very well with the Indian population in the ciliature; however, the information on the resting cyst is lacking for the former. Our study presents an example of a cyst subspecies among hypotrich ciliates, and thus extends the concept which has been mainly reported for spathidiids.     

Modelling invasive alien species distributions from digital biodiversity atlases. Model upscaling as a means of reconciling data at different scales

Aim

There is a wealth of information on species occurrences in biodiversity data banks, albeit presence‐only, biased and scarce at fine resolutions. Moreover, fine‐resolution species maps are required in biodiversity conservation. New techniques for dealing with this kind of data have been reported to perform well. These fine‐resolution maps would be more robust if they could explain data at coarser resolutions at which species distributions are well represented. We present a new methodology for testing this hypothesis and apply it to invasive alien species (IAS).

Location

Catalonia, Spain.

Methods

We used species presence records from the Biodiversity data bank of Catalonia to model the distribution of ten IAS which, according to some recent studies, achieve their maximum distribution in the study area. To overcome problems inherent with the data, we prepared different correction treatments: three for dealing with bias and five for autocorrelation. We used the MaxEnt algorithm to generate models at 1‐km resolution for each species and treatment. Acceptable models were upscaled to 10 km and validated against independent 10 km occurrence data.

Results

Of a total of 150 models, 20 gave acceptable results at 1‐km resolution and 12 passed the cross‐scale validation test. No apparent pattern emerged, which could serve as a guide on modelling. Only four species gave models that also explained the distribution at the coarser scale.

Main conclusions

Although some techniques may apparently deliver good distribution maps for species with scarce and biased data, they need to be taken with caution. When good independent data at a coarser scale are available, cross‐scale validation can help to produce more reliable and robust maps. When no independent data are available for validation, however, new data gathering field surveys may be the only option if reliable fine‐scale resolution maps are needed.     

The Hoosier cavefish,a new and endangered species (Amblyopsidae,Amblyopsis) from the caves of southern Indiana

We describe a new species of amblyopsid cavefish (Percopsiformes: Amblyopsidae) in the genus Amblyopsis from subterranean habitats of southern Indiana, USA. The Hoosier Cavefish, Amblyopsis hoosieri sp. n., is distinguished from A. spelaea, its only congener, based on genetic, geographic, and morphological evidence. Several morphological features distinguish the new species, including a much plumper, Bibendum-like wrinkled body with rounded fins, and the absence of a premature stop codon in the gene rhodopsin. This is the first new cavefish species described from the United States in 40 years and exemplifies how molecular data can alert us to the presence of otherwise cryptic biodiversity.     

成都市外来入侵植物种类特征及区系分析

【目的】全面掌握成都市外来入侵植物的种类特征、起源、区系成分和危害情况等特征,为相关部门制定管理策略和及早采取应对措施提供依据。【方法】以实地调查为主,结合标本及文献研究的方式获得成都市外来入侵植物的种类和分布信息,根据其在野外的生长和分布状况进行评估及划分危害等级,并进行植物区系分析。【结果】成都市现有外来入侵植物158种(亚种、变种),隶属42个科110个属,其中种类最多的3个科分别是菊科(36种)、豆科(17种)及禾本科(13种),合计占比41.77%;种类最多的属是苋属(8种),占比5.06%。原产地分析结果表明,有101种来自美洲地区,占比63.92%。从危害等级分析来看,其中19种为恶性入侵种(1级),32种为严重入侵种(2级),20种为局部入侵种(3级),41种为一般入侵种(4级)以及46种为有待观察种(5级)。植物区系分析结果显示,成都市外来入侵植物属的分布类型主要为泛热带分布、热带亚洲及热带美洲间断分布和世界分布。【结论】成都市地区的外来入侵植物种类明显增多,扩散趋势已加剧。根据上述入侵现状,本文对成都市地区防范外来植物入侵提出了以下4点防控建议:建立外来入侵植物风险评价体系,开展防控和利用技术研发,谨慎引种以及加强科普教育。     

DNA barcoding as a tool for early warning and monitoring alien duckweeds (Lemna sp.pl.): the case of Central Italy

Aquatic habitats are vulnerable to the invasion of alien species, so early warning protocols are necessary for eradication. The presence in Italy of two alien duckweeds in freshwaters has been documented: Lemna minuta, that showed high invasivity, and L. valdiviana, still confined to south Lazio. These two species may be mistaken for each other and for the domestic L. minor and L. gibba due to morphological variation. Here, we assess the applicability of DNA barcoding as a complement to morphological analysis for monitoring the spread of alien Lemna. We chose two chloroplast genome sequences for their ability to discriminate all Lemna species: the 5’ intron of the trnK gene and the matK gene. Among 48 samples of Lemna collected at 20 sites in Central Italy, 20 were identified as L. minor, 19 as L. minuta, five as L. trisulca and four as L. gibba. L. minuta was present at most sampling sites; in particular, at six locations of Lake Trasimeno, eight L. minuta samples were found. We demonstrate that DNA sequence analyses with cost-effective barcoding techniques can effectively support expert efforts in species determination for an early alert system of invasive Lemna species.     

Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems

Biological invasions cause ecological and economic impacts across the globe. However, it is unclear whether there are strong patterns in terms of their major effects, how the vulnerability of different ecosystems varies and which ecosystem services are at greatest risk. We present a global meta-analysis of 199 articles reporting 1041 field studies that in total describe the impacts of 135 alien plant taxa on resident species, communities and ecosystems. Across studies, alien plants had a significant effect in 11 of 24 different types of impact assessed. The magnitude and direction of the impact varied both within and between different types of impact. On average, abundance and diversity of the resident species decreased in invaded sites, whereas primary production and several ecosystem processes were enhanced. While alien N-fixing species had greater impacts on N-cycling variables, they did not consistently affect other impact types. The magnitude of the impacts was not significantly different between island and mainland ecosystems. Overall, alien species impacts are heterogeneous and not unidirectional even within particular impact types. Our analysis also reveals that by the time changes in nutrient cycling are detected, major impacts on plant species and communities are likely to have already occurred.     

Neuronal types in the spinal dorsal gray of the turtle Chrysemys d'orbigny: a Golgi study

At thoracic and lumbar levels the spinal dorsal gray of young specimens of the turtle Chrysemys d'orbigny consists of a cell-free neuropil and an aggregation of perikarya termed here the lateral column of the dorsal horn (LCDH). Nerve cell clusters also occur in the dorsal commissure. The main neuropil area can be divided into a thin superficial layer containing some myelinated fibers (neuropil area Ib) and a compact core composed of unmyelinated axon terminals, dendritic branches, and thin glial processes (neuropil area II). A looser neuropil area is located at the horn base (neuropil area III). The so-called marginal zone of de Lange represents a fourth synaptic field termed here neuropil area Ia. The LCDH consists of neurons of different size and shape. Two peculiar nerve cell types have been recognized in the dorsal horn: giant and bitufted neurons. The former exhibits a large dendritic arbor, which after passing through neuropil areas II and Ib projects into neuropil area Ia and the adjacent white matter. Most frequently Golgi-stained giant neurons have perikarya and dendritic domains on the same side (ipsilateral giant neurons). There are also heterolateral giant neurons whose dendritic branches invade the opposite horn. Bitufted neurons are characterized by the presence of two main dendritic shafts connecting neuropil area II of both dorsal horns. At neuropil levels the major dendritic branches ramify profusely giving rise to short tortuous terminal processes. Perikarya of bitufted neurons occur in the dorsal commissure. The LCDH also contains many small and medium-sized neurons. These are oriented in two main directions: parallel or radial with respect to the dorsal horn surface. The population of horizontally oriented neurons comprises two subtypes termed here alpha and beta. Radially oriented neurons are pleomorphic, defying precise, unequivocal classification.