Kamil Najberek

Alien cyanobacteria: an unsolved part of the “expansion and evolution” jigsaw puzzle?

Abstract Some algal species have extended their native range. Problems in settling on a proper definition of ‘alien’ for microorganisms have made it difficult to unequivocally assess whether their spread was natural or resulted from human intervention. As direct evidence seems to be virtually non-existent, the only option is to rely on circumstantial evidence. In this paper, we discuss the expansion routes of three cyanobacteria species: Cylindrospermopsis raciborskii, Raphidiopsis mediterranea and Cuspidothrix issatschenkoi. We analyse the information available for these species, which are commonly regarded as alien, in order to establish the context in which the migration and evolution of these microorganisms should be understood, so that a proper assessment of their geographic expansion can be made. A more complete picture of the expansion and evolution of microorganisms must combine many types of information, including the history of local expansions, ecological ranges, and data from studies in morphology, ecology, genetics and paleolimnology.

Towards clarifying the presence of alien algae in inland waters — can we predict places of their occurrence?

Small algae are the trophic basis in both marine and freshwater ecosystems. The identification of tiny microorganisms and place of their origin is laborious but necessary. This paper consists of a literature review of 17 species of planktonic algae, with a discussion of taxonomic problems. We also clarify whether these 17 species are non-native, invasive or cryptogenic species, with an indication whether they had been recognised as ‘alien’ in Europe. According to our observations, areas colonized by small and alien algal species, were anthropogenically altered. There were: systems with heated waters (‘heated islands’), which imitated tropical conditions; highly eutrophic to hypereutrophic water ecosystems, easily colonized by alien species, fishponds with intense fish cultivation, where alien species of fish are/had been introduced, which carried also other alien organisms; and inland water ecosystems with high salinity or high conductivity e.g. pits inundated by mine waters, imitating sea or brackish conditions acting as hubs of migration of alien species adapted to brackish or saline waters. We have prepared a map showing areas inhabited by alien species, both of documented places and hypothetical ones, where we would expect alien species to occur.

Alien Parasites May Survive Even if Their Original Hosts Do Not.

In their assessment of the role of parasites as drivers and passengers of biological invasions, Blackburn and Ewen (2016) argue that the average success of alien parasites is likely to be lower than for their hosts because they will not become aliens if their hosts fail to establish following arrival to new areas. This is certainly true if the hosts die already during their transport to new areas. However, if they manage to reach them but fail to establish, they still give the parasites they carry a chance to survive. The basic prerequisite of this scenario is spillover of parasites to new local hosts. In order to survive, it would seem that the parasites must find a new host before the original ones die out, but the complex life cycles of some parasites include free-living larvae, eggs, or resting stages that may survive long enough after their alien hosts’ extinction to allow them to find and acclimate to new ones. Some parasites may also be less susceptible to factors that are fatal to their hosts. For instance, internal parasites of warm-blooded tropical taxa may find equally suitable conditions inside new hosts living in cooler climates. The chances for alien parasites may also be higher because the establishment success of some of them is less affected by propagule pressure than it is for their hosts: asexual reproduction is more common among parasites than among their hosts, or male and female parasites may occur in the same host individual. The paucity of supportive examples for these scenarios is due in part to the fact that the chances of finding them are inversely related to the period of time in which the alien hosts managed to survive after introduction, and this time may be too short for their presence to be detected. This holds true particularly if such unsuccessful aliens are introduced unintentionally. The temporary occurrence of such species belonging to understudied taxonomic groups, or introduced in undersampled areas or habitats, is likely to remain unnoticed. When it comes the introductions dating back centuries, our knowledge will remain incomplete even if those introductions were intentional and successful. A spectacular example of an alien parasite’s survival long after its original host had died out is the discovery of the North American liver fluke (Fascioloides magna), recorded in southwestern Poland around 1930 and then in 1953 (Demiaszkiewicz et al. 2015). The parasite was found in the red deer (Cervus elaphus) in an area where the North American wapiti (Cervus canadensis) had been introduced in 1850. As there is no further information on the local wapiti population, they must certainly have died out quickly, so the first record of the parasite they brought in was about 80 years after that failure to establish. It took another 60 years to rediscover F. magna in that same area in 2015 (Demiaszkiewicz et al. 2015). The risk of new parasite invasions may be underestimated even if the transient occurrence of their hosts is well documented, such as in the case of escapes (or releases) of alien companion animals. While records of some of them have become so common that they stopped drawing anyPublished online: May 19, 2016

An invertebrate harmfulness scale for research on plant pest diversity and impacts

ABSTRACT Traditional methods of quantifying the harmful effects of invertebrates on plants require time-consuming identification of large numbers of individuals at species level. Collected specimens usually are killed; this may be unacceptable for some strictly protected species and may bias the results of subsequent surveys at the same site. We developed a “harmfulness scale” for quick, non-invasive assessment of invertebrate impacts on plants, and used the scale to test differences in invertebrate attack on species of Balsaminaceae, Polygonaceae and Asteraceae growing in lowland and mountains in Poland. In 2010–2011, we recorded 9190 invertebrates and identified them in situ to family or superfamily level. Among them were 7593 pests, accounting for 82.6% of all recorded organisms. Pests were three times more numerous in the mountains than in the lowland. Balsaminaceae were most heavily attacked by pests (92.9% of all organisms detected on them). Aphidoideae were the most numerous pests. This method can help reduce the costs and labour required for this type of research, facilitating progress in theoretical biology and in the development of practical phytosanitary measures.

The seeds of success: release from fungal attack on seeds may influence the invasiveness of alien Impatiens

Although closely related, Impatiens glandulifera and Impatiens balfourii differ in their invasiveness in Europe; only the former is highly invasive there. Following the assumptions of the enemy release hypothesis (ERH), we tested whether these differences may be explained by the levels of seed infestation by pathogenic fungi. Using seeds collected along the Swiss-Italian border, we recorded four true pathogens of seeds: Fusarium culmorum, F. oxysporum, F. sporotrichoides, and Giberella avenacea. In Italy the seeds of I. balfourii were infected by fungal pathogens more often than those of I. glandulifera, while in Switzerland both species were under the same level of pressure. However, the overall differences in pathogen abundance were consistent with the ERH: seeds of the more invasive species were attacked less. This could be a result of differences between the communities of fungal pathogens attacking the seeds of both species in each country. The number of colonies of secondary pathogens (Cladosporium cladosporioides, Alternaria alternata) correlated negatively with the number of colonies of true pathogens; we suggest that the secondary pathogens may have prevented the occurrence of the true pathogens. The reason for the between-country differences in the fungal pathogen communities is unclear. A possible explanation is that Italy and Switzerland differ in their road and green-area maintenance work schemes, which may have influenced pathogen pressure on seeds. This study is one of the few that offers results indicating that release from enemies may be crucial to the invasion success of plants as early as the seed stage.