Annual developmental events in biological systems are dependent, in part, on environmental conditions and can be valuable bio-indicators of environmental change. Many studies have been done on the effects of temperatu...Annual developmental events in biological systems are dependent, in part, on environmental conditions and can be valuable bio-indicators of environmental change. Many studies have been done on the effects of temperature and photoperiod on phenophases, but fewer have explored the consequences of nutrient availability in terrestrial ecosystems on forest phenology. Here we examined phenological phenomena at a long-term experimental forested watershed subjected to decadal-scale ecosystem acidification and nitrogen (N) enrichment. Phenophases of Acer rubrum, Acer saccharum, and Picea rubens in both watersheds were observed throughout the 2010 growing season and included bud burst, flowering (A. rubrum), leaf or needle emergence and unfolding, leaf senescence (Acer spp.), and leaf fall (Acer spp). Clear species-specific phenological patterns were observed, but no treatment effects were evident. Chemical phenology of canopy tree foliage was also examined on a monthly basis from May through October 2010. Nitrogen was the only element that was significantly higher in the WB watershed for all species, although not all months showed significant differences. Other treatment differences in elemental composition of foliage are discussed. Foliar N and P concentrations decreased in all species throughout the growing season, while foliar Ca, K, and Al concentrations increased or were constant. This study found clear species-specific patterns of morphological and chemical phenology with time, but did not show evidence for visible alterations in seasonal development as a result of ecosystem acidification and N enrichment. Treatment effects on chemical phenology, as applied here, showed some responses and warrant further consideration for application to coupled chemical-biological indicators of a changing chemical and physical climate.展开更多
Land plants and algae form a supergroup, the Archaeplastida, believed to be monophyletic. We report the results of an analysis of the phylogeny of putative globins in the currently available genomes to bacterial and o...Land plants and algae form a supergroup, the Archaeplastida, believed to be monophyletic. We report the results of an analysis of the phylogeny of putative globins in the currently available genomes to bacterial and other eu- karyote hemoglobins （Hbs）. Archaeplastida genomes have 3/3 and 2/2 Hbs, with the land plant genomes having group 2 2/ 2 Hbs, except for the unexpected occurrence of two group 1 2/2 Hbs in Ricinus communis. Bayesian analysis shows that plant 3/3 Hbs are related to vertebrate neuroglobins and bacterial flavohemoglobins （FHbs）. We sought to define the bacterial groups, whose ancestors shared the precursors of Archaeplastida Hbs, via Bayesian and neighbor-joining anal- yses based on COBALTalignment of representative sets of bacterial 3/3 FHb-like globins and group I and 2 2/2 Hbs with the corresponding Archaeplastida Hbs. The results suggest that the Archaeplastida 3/3 and group 1 2/2 Hbs could have orig- inated from the horizontal gene transfers （HGTs） that accompanied the two generally accepted endosymbioses of a pro- teobacterium and a cyanobacterium with a eukaryote ancestor. In contrast, the origin of the group 2 212 Hbs unexpectedly appears to involve HGT from a bacterium ancestral to Chloroflexi, Deinococcales, Bacilli, and Actinomycetes. Furthermore, although intron positions and phases are mostly conserved among the land plant 3/3 and 2/2 globin genes, introns are absent in the algal 3/3 genes and intron positions and phases are highly variable in their 2/2 genes. Thus, introns are irrelevant to globin evolution in Archaeplastida.展开更多
文摘Annual developmental events in biological systems are dependent, in part, on environmental conditions and can be valuable bio-indicators of environmental change. Many studies have been done on the effects of temperature and photoperiod on phenophases, but fewer have explored the consequences of nutrient availability in terrestrial ecosystems on forest phenology. Here we examined phenological phenomena at a long-term experimental forested watershed subjected to decadal-scale ecosystem acidification and nitrogen (N) enrichment. Phenophases of Acer rubrum, Acer saccharum, and Picea rubens in both watersheds were observed throughout the 2010 growing season and included bud burst, flowering (A. rubrum), leaf or needle emergence and unfolding, leaf senescence (Acer spp.), and leaf fall (Acer spp). Clear species-specific phenological patterns were observed, but no treatment effects were evident. Chemical phenology of canopy tree foliage was also examined on a monthly basis from May through October 2010. Nitrogen was the only element that was significantly higher in the WB watershed for all species, although not all months showed significant differences. Other treatment differences in elemental composition of foliage are discussed. Foliar N and P concentrations decreased in all species throughout the growing season, while foliar Ca, K, and Al concentrations increased or were constant. This study found clear species-specific patterns of morphological and chemical phenology with time, but did not show evidence for visible alterations in seasonal development as a result of ecosystem acidification and N enrichment. Treatment effects on chemical phenology, as applied here, showed some responses and warrant further consideration for application to coupled chemical-biological indicators of a changing chemical and physical climate.
文摘Land plants and algae form a supergroup, the Archaeplastida, believed to be monophyletic. We report the results of an analysis of the phylogeny of putative globins in the currently available genomes to bacterial and other eu- karyote hemoglobins （Hbs）. Archaeplastida genomes have 3/3 and 2/2 Hbs, with the land plant genomes having group 2 2/ 2 Hbs, except for the unexpected occurrence of two group 1 2/2 Hbs in Ricinus communis. Bayesian analysis shows that plant 3/3 Hbs are related to vertebrate neuroglobins and bacterial flavohemoglobins （FHbs）. We sought to define the bacterial groups, whose ancestors shared the precursors of Archaeplastida Hbs, via Bayesian and neighbor-joining anal- yses based on COBALTalignment of representative sets of bacterial 3/3 FHb-like globins and group I and 2 2/2 Hbs with the corresponding Archaeplastida Hbs. The results suggest that the Archaeplastida 3/3 and group 1 2/2 Hbs could have orig- inated from the horizontal gene transfers （HGTs） that accompanied the two generally accepted endosymbioses of a pro- teobacterium and a cyanobacterium with a eukaryote ancestor. In contrast, the origin of the group 2 212 Hbs unexpectedly appears to involve HGT from a bacterium ancestral to Chloroflexi, Deinococcales, Bacilli, and Actinomycetes. Furthermore, although intron positions and phases are mostly conserved among the land plant 3/3 and 2/2 globin genes, introns are absent in the algal 3/3 genes and intron positions and phases are highly variable in their 2/2 genes. Thus, introns are irrelevant to globin evolution in Archaeplastida.
