No abstract

Erysimum includes 150–350 species distributed in the Northern Hemisphere, with Eurasia being the centre of greatest diversity. It is well known for its taxonomic complexity as a result of overlapping morphological characters. We present the first densely sampled phylogenetic analysis of Erysimum using internal transcribed spacer (ITS) DNA sequences from c. 85% of the species (117 for the first time), representing the full range of morphological variation and geographical distribution. We used several approaches to reconstruct phylogenetic relationships, dating of diversification and patterns of evolution of morphological characters in the genus. Ancestral‐state reconstructions of four morphological diagnostic characters were performed using maximum parsimony, maximum likelihood and Bayesian methods. Our phylogenetic framework strongly supports the monophyly of Erysimum and recovers some well‐supported clades that are geographically, rather than morphologically, correlated. Our study confirms the placement of Erysimum in lineage I and reveals two Malcolmia spp. (M. maritima and M. orsiniana) as its sister taxa. The results suggest that the biennial duration and caespitose habit (vs. annual or perennial duration and herbaceous or woody habit) and large, yellow, glabrous (vs. small, non‐yellow, pubescent) petals are ancestral in Erysimum. The ancestral‐state reconstruction results show that annual vs. perennial and woody vs. herbaceous features have been independently derived several times. The dating analyses suggest an early radiation of Erysimum during the late Pliocene or early Pleistocene. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175, 497–522.

No abstract

Various disturbances affect the vegetation in rural areas. However, the responses of plant communities to multiple disturbances have rarely been studied. We investigated the vegetation of a rural landscape in northeast Iran. We established 42 study sites in three land use types using a stratified‐random design: ungrazed abandoned croplands (UACs), grazed abandoned croplands (GACs), and grazed field margins (GFMs). The species richness and canopy cover for all vascular plants and influential disturbances (i.e., grazing, degraded/nondegraded status, distance to the main road, and distance to active cropland) were recorded at each site. We compared multiple facets of the plant communities among land use types. The results showed that there were significant differences among the species compositions of the land use types, with therophytes dominating in all three. Alien species were found in the three land use types, particularly in UACs. GFMs had the highest number of native species. There were no significant differences in the species or phylogenetic diversities among the land use types. Grazing and distance to active cropland were identified as significant factors determining the native species structure in the area, whereas grazing was the only significant factor determining the alien species structure. There was a significant correlation between the native and alien species structure. Our results imply that grazing disperses native and alien plant propagules simultaneously. Neither grazing nor non‐grazing improved biodiversity in the abandoned croplands. The restoration of this landscape requires a community‐specific plan. GFMs are native plant islands that should be prioritized in restoration.