Child and adult construal of restrictive relative clauses: Knowledge of grammar and differential effects of syntactic context

We report four act-out experiments testing the sensitivity of adults and three- to five-year-old children to the distinction between restrictive and non-restrictive relative clauses in English. Specifically, we test knowledge of the fact that restrictive relative clauses cannot modify a proper name head, and of the fact that relatives introduced by that (as opposed to a wh-pronoun) are obligatorily restrictive. Both children and adults show knowledge of these properties. No support was found for the hypothesis that children extend the block on proper name heads to wh-relatives. Both children and adults are sensitive to the syntactic context (double object vs. existential) in which the relative clause is embedded. However, adults differ from children in four respects. First, in the double object context, adults are more likely than children to commit the error of construing a that relative as referring to a proper name head. Second, the effect of syntactic context on selection of a head is larger for adults than for children. Third, for adults, but not for children, the effect of syntactic context interacts with the type of relative clause. Fourth, adults, but not children, are influenced by whether they hear the existential context before the double object context. We propose that by three to four years of age children have acquired an adult-like grammar of relative clauses, and that the differences we see in child and adult performance can be attributed to that grammar in combination with a mature (adult) or immature (child) sentence processing capacity

Allium therinanthum (Amaryllidaceae), a new species from Israel

Allium therinanthum, a new species of A. sect. Codonoprasum, is described and illustrated from southern Mt. Hermon (Israel). It is a late-flowering diploid species (2n = 16), growing on calcareous substrates of the mountain belt. It is a narrowly distributed geophyte, showing morphological relationships mainly with A. tardiflorum, a typical autumnal species also occurring in Israel within the pinewoods of Mt. Carmel. The morphology, karyology, leaf anatomy, ecology, conservation status and taxonomical relations are examined for both species. A taxonomic comparison with the most allied late flowering species of the sect. Codonoprasum is provided

Climate and socio-economic factors explain differences between observed and expected naturalization patterns of European plants around the world

Aim The number of naturalized (i.e. established) alien species has increased rapidly over recent centuries. Given the differences in environmental tolerances among species, little is known about what factors determine the extent to which the observed size of the naturalized range of a species and hence the extent to which the observed richness of naturalized species of a region approach their full potential. Here, we asked which region- and species-specific characteristics explain differences between observed and expected naturalizations. Location Global. Time period Present. Major taxa studied Vascular plants. Methods We determined the observed naturalized distribution outside Europe for 1,485 species endemic to Europe using the Global Naturalized Alien Flora (GloNAF) database and their expected distributions outside Europe using species distribution models. First, we investigated which of seven socio-economic factors related to introduction pathways, anthropogenic pressures and inventory effort best explained the differences between observed and expected naturalized European floras. Second, we examined whether distributional features, economic use and functional traits explain the extent to which species have filled their expected ranges outside Europe. Results In terms of suitable area, more than 95% of expected naturalizations of European plants were not yet observed. Species were naturalized in only 4.2% of their suitable regions outside of Europe (range filling) and in 0.4% of their unsuitable regions (range expansion). Anthropogenic habitat disturbance primarily explained the difference between observed and expected naturalized European floras, as did the number of treaties relevant to invasive species. Species of ornamental and economic value and with large specific leaf area performed better at filling and expanding beyond their expected range. Main conclusions The naturalization of alien plant species is explained by climate matching but also by the regional level of human development, the introduction pressure associated with the ornamental and economic values of the species and their adaptation to disturbed environments