Search

Cuscuta gronovii species complex (sensu lato, s.l.) is a North American group of species that belong to C. sect. Oxycarpae of subgenus Grammica. Members of C. gronovii s.l. are often associated with riparian or wet habitats, and their delimitation has been problematic historically. DNA sequences from multiple plastid and nuclear ribosomal non-coding regions were used to reconstruct evolutionary relationships among taxa. Molecular phylogeny supported the resurrection of C. saururi, a taxon that has been treated either as C. gronovii var. latiflora or a nomenclatural synonym of C. gronovii var. gronovii. Cuscuta saururi was inferred to be sister to C. cephalanthi, but the relationships among the rest of taxa, although forming a clade with moderate support, remained largely unresolved. Thus, the species limits of C. gronovii s.l. aggregate were also comprehensively investigated through a morphometric study. Plants with 4-merous flowers from New Brunswick and Nova Scotia, Canada, which were previously thought to be C. cephalanthi, were described as a new species, C. acadiana. Cuscuta acadiana, although fertile and producing abundant seeds, is unusual in that the majority of its pollen grains intergrade from zonocolpate, syncolpate, or pantocolpate, with variously shaped or twisted ectoapertures. Cuscuta gronovii var. calyptrata, a widely accepted but virtually unknown taxon, was typified and included in all the analyses. Cuscuta umbrosa was treated as a variety of C. gronovii (var. curta), and C. rostrata was maintained as a species. An identification key, detailed descriptions, illustrations, and a summary of geographical distribution, ecology, and conservation status were provided for all the members of C. gronovii s.l. The only taxon of this species complex found to be weedy, especially in cranberries, was C. gronovii var. gronovii. [ABSTRACT FROM AUTHOR]

The biodiversity–ecosystem function hypothesis postulates that higher biodiversity is correlated with faster ecosystem process rates and increased ecosystem stability in fluctuating environments. Exhibiting high spatiotemporal habitat diversity, floodplains are highly productive ecosystems, supporting communities that are naturally resilient and highly diverse.We examined linkages among floodplain wetland habitats, invertebrate communities and their associated traits, and ecosystem function across 60 sites within the floodplain wetlands of the lower Wolastoq | Saint John River, New Brunswick, using structural equation modelling and Threshold Indicator Taxa ANalysis.We identified key environmental filters structuring invertebrate communities, by linking increased niche differentiation through shoreline change, flood pulse dynamics, and macrophyte bed complexity with increased taxa and functional diversity.Examination of traits linked to ecosystem functions revealed that more resilient wetlands with balance between primary productivity and decomposition as carbon sources were associated with greater functional evenness and richness, while habitat patches with elevated decomposition rates had lower functional richness, reflecting a simplified, more disturbed habitat.While our more complex overarching SEM model was ultimately compromised by an overspecified number of pathways, our results nevertheless are indicative of a divergence between wetland and riverine ecosystems in their relationships linking biodiversity and ecosystem function, illustrating how to define ecosystem health in wetland habitats, and demonstrating how critical functions support healthy wetland habitats by providing increased resilience to disturbance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]