Edward Hitchcock’s Pre-Darwinian (1840) “Tree of Life”

The “tree of life” iconography, representing the history of life, dates from at least the latter half of the 18th century, but evolution as the mechanism providing this bifurcating history of life did not appear until the early 19th century. There was also a shift from the straight line, scala naturae view of change in nature to a more bifurcating or tree-like view. Throughout the 19th century authors presented tree-like diagrams, some regarding the Deity as the mechanism of change while others argued for evolution. Straight-line or anagenetic evolution and bifurcating or cladogenetic evolution are known in biology today, but are often misrepresented in popular culture, especially with anagenesis being confounded with scala naturae. Although well known in the mid 19th century, the geologist Edward Hitchcock has been forgotten as an early, if not the first author to publish a paleontologically based “tree of life” beginning in 1840 in the first edition of his popular general geology text Elementary Geology. At least 31 editions were published and those between 1840 and 1859 had this “paleontological chart” showing two trees, one for fossil and living plants and another for animals set within a context of geological time. Although the chart did not vary in later editions, the text explaining the chart did change to reflect newer ideas in paleontology and geology. Whereas Lamarck, Chambers, Bronn, Darwin, and Haeckel saw some form of transmutation as the mechanism that created their “trees of life,” Hitchcock, like his contemporaries Agassiz and Miller, who also produced “trees of life,” saw a deity as the agent of change. Through each edition of his book Hitchcock denounced the newer transmutationist hypotheses of Lamarck, then Chambers, and finally Darwin in an 1860 edition that no longer presented his tree-like “paleontological chart.”     

Seasonal changes in the response of winter wheat to elevated atmospheric CO2 concentration grown in Open-Top Chambers and field tracking enclosures

Winter wheat was grown at ambient and elevated (ambient plus 350 μL L^–1) CO₂ concentrations in open top chambers and in field-tracking sun-lit climatized enclosures (elevated is 718 μL L^–1). There was no significant effect of CO₂ concentration on sheath, leaf and root biomass and leaf area in the early spring (January to April). 24-h canopy CO₂ exchange rate (CCER) was not significantly affected either. However, elevated CO₂ concentration increased CCER at midday, decreased evapotranspiration rate and increased instantaneous water-use-efficiency during early spring. Leaf, sheath and root nitrogen concentration per unit dry weight decreased and nonstructural carbohydrate concentration increased under elevated CO₂, and N-uptake per unit ground area decreased significantly (– 22%) towards the end of this period. These results contrast with results from the final harvest, when grain yield and biomass were increased by 19% under elevated CO₂. N concentration per dry weight was reduced by 5%, but N-uptake per unit ground area was significantly higher (+ 11%) for the elevated CO₂ treatment. 24-h and midday-CCER increased significantly more in late spring (period of 21 April to 30 May) (respectively by + 40% and 53%) than in the early spring (respectively 5% and 19%) in response to elevated CO₂. Midday evapotranspiration rate was reduced less by elevated CO₂ in the late spring (– 13%) than in early spring (– 21%). The CO₂ response of midday and 24-h CCER decreased again (+ 27% and + 23% resp.) towards the end of the growing season. We conclude that the low response to CO₂ concentration during the early spring was associated with a growth-restriction, caused by low temperature and irradiance levels. The reduction of nitrogen concentration, the increase of nonstructural carbohydrate, and the lower evapotranspiration indicated that CO₂ did have an effect towards the end of early spring, but not on biomass accumulation. Regression analysis showed that both irradiance and temperature affected the response to CO₂.     

Bayesian calibration method used to elucidate carbon turnover in forest on drained organic soil

Depending on the balance between sink and source processes for C, drained organic forest soil ecosystems can be in balance or act as net sinks or sources of CO₂ to the atmosphere. In order to study the effect of groundwater level and soil temperature on C-flux, the CoupModel was calibrated (climate data, groundwater levels, soil CO₂ flux, net ecosystem fluxes of CO₂-exchange, sensible heat flux and latent heat flux, forest production etc.) for a drained forest in Sweden. Bayesian calibration techniques were used to elucidate how different parameters and variables were interlinked in C-circulation. The calibrated model reproduced abiotic and biotic variables reasonably well except for root respiration, which was largely underestimated. Bayesian calibration reduced the uncertainties in the model and highlighted the fact that calibrations should be performed with a high number of parameters instead of specific parameter values.     

Nest architecture of the ant <Emphasis Type="Italic">Formica pallidefulva</Emphasis>: structure,costs and rules of excavation

Summary The architecture of underground ant nests was studied in the ant Formica pallidefulva. These ants build shallow (30–45 cm deep) nests, which consist of more or less vertical shafts that bear chambers. Shafts are modular units of nest growth; nests are enlarged by adding more shafts or extending previously existing ones. The nests are top-heavy, their volume declining exponentially with depth. The total volume of the nest is strongly correlated with the number of worker occupying the nest (R² = 0.87). Some of the rules and templates used by workers for nest construction were determined: (a) chambers are formed in the direction of the tunnels leading up to them, (b) the amount of soil excavated per unit time increases with soil temperature and moisture content. The amount of time and energy required to construct a typical nest were approximated using digging ability parameters determined in the lab. We estimate that if a colony was to move twice a year, it would expend around 20% of its energy intake and at least 6% of its worker time on nest excavation.Received 16 December 2002; revised 10 July 2003; accepted 23 July 2003.     

Suppression of the Root-knot Nematode Meloidogyne javanica by Alginate Pellets Containing the Nematophagous Fungi Hirsutella rhossiliensis , Monacrosporium cionopagum and M. ellipsosporum

The endoparasitic fungus Hirsutella rhossiliensis and the nematode-trapping fungi Monacrosporium cionopagum and M. ellipsosporum were formulated as hyphae in alginate pellets. In a soil microcosm experiment, dried pellets of all three fungi decreased the invasion of cabbage seedlings by the root-knot nematode Meloidogyne javanica when juvenile nematodes were placed 2 cm from roots; M. cionopagum was more effective than the other two fungi, reducing nematode invasion by 40-95% with 0.24-0.94 pellets cm - 3 of soil. In a field microplot experiment, in which neither H. rhossiliensis nor M. ellipsosporum suppressed nematodes, 0.5 pellets of M. cionopagum cm - 3 of soil suppressed M. javanica invasion of tomato seedlings by 73%. In a second microplot experiment with only M. cionopagum , again at 0.5 pellets cm - 3 of soil, the fungus suppressed the invasion of tomato seedlings whether the pellets were added 0, 5 or 14 days before planting; the population density of M. cionopagum increased to nearly 3000 propagules g - 1 of soil by day 8 and then declined to less than 300 by day 22. Enchytraeid worms were observed in and around damaged and apparently destroyed pellets in both microplot experiments. Whether enchytraeids consumed the fungi or otherwise affected biological control requires additional research.     

冬小麦气孔臭氧通量拟合及通量产量关系的比较分析

基于田间原位开顶箱(Open-Top Chambers,OTCs)实验,研究了不同浓度臭氧(O3)处理下(自然大气处理,AA;箱内大气处理,NF;箱内低浓度O3处理,NF+40 nL/L;箱内中等浓度O3处理,NF+80 nL/L;箱内高浓度O3处理,NF+120 nL/L),冬小麦(Triticum aestivum L.)旗叶气孔运动对不同环境因子的响应,并通过剂量反应分析,比较了冬小麦产量损失与累积气孔O3吸收通量(AFstX)和累积O3暴露浓度(AOT40和SUM06)的相关性差异。结果表明:冬小麦旗叶气孔运动的光饱和点和最适温度分别约为400μmol.m-.2s-1和27℃,水汽压差、土壤含水量和O3剂量的气孔限制临界值分别约为1.4 kPa、-100 kPa和20μL.L-.1h-1,超过此临界值时,气孔导度会明显下降。利用Jarvis气孔导度模型对冬小麦旗叶气孔导度和气孔O3吸收通量进行了预测,结果表明Jarvis模型解释了冬小麦实测气孔导度60%的变异性。由于不同时期植物体气孔导度的差异,冬小麦旗叶生长期内累积气孔O3吸收通量(AFstX)呈非线性增加趋势。O3吸收速率临界值(X)为4 nmol.m-.2s-1时,累积O3吸收通量(AFst4)与冬小麦产量的相关性最高(R2=0.76),该数值介于O3暴露指标AOT40和SUM06的剂量反应决定系数(0.74和0.81)之间。与O3浓度指标(AOT40和SUM06)相比,O3通量指标(AFstX)在本试验冬小麦产量损失评价中未表现出明显优势。     

Schistosoma mansoni: Adult worm chemoattraction,with and without barriers

Heterosexual and homosexual chemoattraction studies were done with 8- to 12-week-old Schistosoma mansoni adults in linear chambers containing Earle's saline, in the absence and presence of both perforated and unperforated dialysis sac chimney barriers. In the absence of barriers attraction was seen in all heterosexual and homosexual combinations. After 90 min of observation at 37 C, organisms maintained at 4 or 37 C for at least 1 hr prior to the assay showed heterosexual attraction similar to those used immediately after perfusion. There was significantly more heterosexual attraction between worms from same than different pairs. In the presence of perforated barriers the greatest attraction was heterosexual, with males moving toward females; heterosexual attraction with females moving toward males was approximately equal to homosexual female attraction, and male homosexual attraction was not seen. In the presence of unperforated barriers the greatest attraction of females toward males occurred during the first 0.5 hr; within 3 to 4 hr females were no longer significantly attracted to males. However, after 0.5 hr males were more significantly attracted to females in unperforated than perforated chimneys. These studies demonstrate that adult schistosomes attract each other in vitro, and that there is a chemical basis for this attraction.