Selection of preadapted populations allowed Senecio inaequidens to invade Central Europe

Invasive species often evolve rapidly in response to the novel biotic and abiotic conditions in their introduced range. Such adaptive evolutionary changes might play an important role in the success of some invasive species. Here, we investigated whether introduced European populations of the South African ragwort Senecio inaequidens (Asteraceae) have genetically diverged from native populations. We carried out a greenhouse experiment where 12 South African and 11 European populations were for several months grown at two levels of nutrient availability, as well as in the presence or absence of a generalist insect herbivore. We found that, in contrast to a current hypothesis, plants from introduced populations had a significantly lower reproductive output, but higher allocation to root biomass, and they were more tolerant to insect herbivory. Moreover, introduced populations were less genetically variable, but displayed greater plasticity in response to fertilization. Finally, introduced populations were phenotypically most similar to a subset of native populations from mountainous regions in southern Africa. Taking into account the species' likely history of introduction, our data support the idea that the invasion success of Senecio inaequidens in Central Europe is based on selective introduction of specific preadapted and plastic genotypes rather than on adaptive evolution in the introduced range.

Diversity versus disparity and the role of ecological opportunity in a continental bird radiation

Aim The Neotropical parrots (Arini) are an unusually diverse group which colonized South America in the Oligocene. The newly invaded Neotropics may have functioned as an underused adaptive zone and provided novel ecological opportunities that facilitated diversification. Alternatively, diversification may have been driven by ecological changes caused by Andean uplift and/or climate change from the Miocene onwards. Our aim was to find out whether Arini diversified in a classical adaptive radiation after their colonization of South America, or whether their diversification occurred later and was influenced by more recent environmental change. Location Neotropics. Methods We generated a time-calibrated phylogeny of more than 80% of all Arini species in order to analyse lineage diversification. This chronogram was also used as the basis for the reconstruction of morphological evolution within Arini using a multivariate ratio analysis of three size measurements. Results We found a concentration of size evolution and partitioning of size niches in the early history of Arini consistent with the process of adaptive radia- tion, but there were no signs of an early burst of speciation or a decrease in speci- ation rates through time. Although we detected no overall temporal shifts in diversification rates, we discovered two young, unexpectedly species-rich clades. Main conclusions Arini show signs of an early adaptive radiation, but we found no evidence of the slowdown in speciation rate generally considered a feature of island or lake radiations. Historical processes and environmental change from the Miocene onwards may have kept diversification rates roughly constant ever since the colonization of the Neotropics. Thus, Arini may not yet have reached equilibrium diversity. The lack of diversity-dependent speciation might be a general feature of adaptive radiations on a continental scale, and diversification processes on continents might therefore not be as ecologically limited as in isolated lakes or on oceanic islands.

The Evolution of Totalitarianism: From Stalin to Putin

The Soviet Union is commonly cited as "totalitarian." But just how totalitarian was the Soviet Union? The modern Russian Federation? There is an ongoing debate in Georgia about the Soviet past, the role of Stalin in Georgian history, an importance of Soviet legacies in shaping the nationalist discourse after independence and etc. Various roundtables and conferences reflecting on the historical, political and sociological contexts of the Soviet occupation are held in Georgian academic institutions and universities. On a discursive level, it is taken as a given that the „Evil Empire‟ was indeed totalitarian – brutally repressive, all-encompassing, and terrorizing. The term "totalitarian" embodies a multitude of concepts which we will try to discuss in a historical perspective, testing the extent of applicability and relevance of this term to modern-day Russia.

Endovascular Treatment of Acute Stroke: Evolution and Selection of Techniques and Instruments Based on Thrombus Imaging.

Mechanical thrombectomy provides higher recanalization rates than intravenous or intra-arterial thrombolysis. Finally this has been shown to translate into improved clinical outcome in six multicentric randomized controlled trials. However, within cohorts the clinical outcomes may vary, depending on the endovascular techniques applied. Systems aiming mainly for thrombus fragmentation and lacking a protection against distal embolization have shown disappointing results when compared to recent stent-retriever studies or even to historical data on local arterial fibrinolysis. Procedure-related embolic events are usually graded as adverse events in interventional neuroradiology. In stroke, however, the clinical consequences of secondary emboli have so far mostly been neglected and attributed to progression of the stroke itself. We summarize the evolution of instruments and techniques for endovascular, image-guided, microneurosurgical recanalization in acute stroke, and discuss how to avoid procedure-related embolic complications.

Rapid divergence in physiological and life-history traits between northern and southern populations of the British introduced neo-species, Senecio squalidus

Alien plants provide a unique opportunity to study evolution in novel environments, but relatively little is known about the extent to which they become locally adapted to different environments across their new range. Here, we compare northern and southern populations of the introduced species Senecio squalidus in Britain; S. squalidus has been in southern Britain for approximately 200 years and reached Scotland only about 50 years ago. We conducted common garden experiments at sites in the north and south of the species’ range in Britain. We also conducted glasshouse and growth chamber experiments to test the hypothesis that southern genotypes flower later, are more drought-tolerant, germinate and establish better at warmer temperatures, and are less sensitive to cold stress than their more northern counterparts. Results from the common garden experiments are largely consistent with the hypothesis of rapid adaptive divergence of populations of the species within the introduced range, with genotypes typically showing a home-site advantage. Results from the glasshouse and growth chamber experiments demonstrate adaptive divergence in ability to tolerate drought stress and high temperatures, as well as in phenology. In particular, southern genotypes were more tolerant of dry conditions and high temperatures and they flowered later than northern genotypes. Our results show that rapid local adaptation can occur in alien species, and they have implications for our understanding of the ecological genetics of range expansion of introduced weeds.

Referential hierarchies: A new look at some historical and typological patterns

This paper proposes a diachronic typology for the various patterns that have been referred to as Hierarchical Alignment or Inverse Alignment. Previous typological studies have tried to explain such patterns as grammatical reflections of a universal Referential Hierarchy, in which first person outranks second person outranks third person and humans outrank other animates outrank inanimates. However, our study shows that most of the formal properties of hierarchy-sensitive constructions are essentially predictable from their historical sources. We have identified three sources for hierarchical person marking, three for direction marking, two for obviative case marking, and one for hierarchical constituent ordering. These sources suggest that there is more than one explanation for hierarchical alignment: one is consistent with Givón’s claim that hierarchical patterns are a grammaticalization of generic topicality; another is consistent with DeLancey’s claim that hierarchies reflect the deictic distinction between present (1/2) and distant (3) participants; another is simply a new manifestation of a common asymmetrical pattern, the use of zero marking for third persons. More importantly, the evolution of hierarchical grammatical patterns does not reflect a consistent universal ranking of participants – at least in those cases where we can see (or infer) historical stages in the evolution of these properties, different historical stages appear to reflect different hierarchical rankings of participants, especially first and second person. This leads us to conclude that the diversity of hierarchical patterns is an artifact of grammatical change, and that in general, the presence of hierarchical patterns in synchronic grammars is not somehow conditioned by some more general universal hierarchy.