Climate and the evolution of brachycephalization

Significant associations of cranial shape for 82 ethnic groups and seven climate variables are described. Variation among current populations is partially attributed to cold adaptation throughout the Pleistocene. Application of data files tabulated by the authors is described for a number of problems. Temporal distribution of 115 specimens indicates a geometric trend (CI = 76.7-1.96 log time X 10(3) ). Cranial indices are summarized within alternative taxonomic models and between climatic ecotypes. Evidence supports the hypothesis of cold adaptation among "Classic" Neandertals. Limitations of the thermodynamic model are discussed. It is probable that a decrease of the cranial index occurs from the Middle to Upper Paleolithic. During the Holocene, the index increases under all climatic conditions.     

Adaptation to salinity inHordeum jubatum L. populations studied using reciprocal transplants

Tillers and seedlings ofHordeum jubatum L. from three sites with contrasting salinity regimes in central Saskatchewan, Canada were reciprocally transplanted in order to examine the tolerance of populations of this species to salinity and related habitat factors. Survival, growth and fecundity of the three populations were controlled more by transplant site characteristics than by genetic differences, i.e. differences among populations at a site tended to be smaller than differences among sites. Survival, growth and reproduction of all three populations were best at the non-saline site. The population originating at the non-saline site showed the poorest growth in the two saline habitats, but still had substantial salt tolerance. Fecundity was greatest when the populations were grow at their site of origin.     

Genetic and Pathogenic Characterization of Different Stagonospora sp. Isolated from Bindweed

Genetic variation among 38 isolates of Stagonospora sp. and 10 isolates of Septoria sp. from bindweed was studied using (a) restriction fragment length plymorphism (RFLP) analysis of the internal transcribed spacer (ITS) region, and (b) random amplified polymorphic DNA (RAPD) PCR analysis. RFLP analysis revealed three types of fragment patterns among the isolates. A total of 26 distinct groups, based on common fragment patterns, were identified using cluster analysis of the RAPD-PCR data. When the grouping results of the two methods were compared, the fragment pattern types and clusters were generally in agreement. The degree of pathogenicity of six genetically characterized isolates of Stagonospora sp. was assessed on three ecotypes of field bindweed (Convolvulus arvensis). Disease symptoms were observed with all isolates on all ecotypes, but only Stagonospora convolvuli strain LA39, a potential biocontrol agent, showed a high degree of pathogenicity on all ecotypes. A mixture of two Stagonospora sp. enhanced the mean necrotic leaf area on bindweed from 33.9 and 39.0% (when applied alone) to 64.9% applied together at the same final concentration of 5 X 106 spores ml -1 . Molecular methods were used to identify the two pathogens. Both were present on the same plant when applied together, but never found in the same lesion.     

Intraspecific variation in the response of Themeda triandra to defoliation: the effect of time of recovery and growth rates on compensatory growth

Summary The response to a single defoliation was studied on three clones of Themeda triandra collected in the short, mid, and tall grassland regions of the Serengeti National Park (Tanzania). These sites represent a gradient of decreasing grazing intensity. Growth, allocation pattern, and several morphometric traits were monitored during an 80-day period. Clipped plants of the short and medium clones fully compensated for the reduction of biomass, while plants of the tall clone showed overcompensation. During the first two weeks after clipping, clipped plants showed lower relative growth rates than unclipped ones, whereas the opposite was observed later on. Clipped plants compensated for the removal of leaf area by producing new leaves with lower specific weights and higher nitrogen content. They also produced more, smaller tillers. Although clipped plants mobilized nonstructural carbohydrates from roots and crowns, this did not account for a significant amount of growth. Relative growth rates of unclipped plants of the short clone were higher. The relative growth rate of the short clone diminished less after clipping, but also exhibited the lowest increase later. The tall clone was the most negatively affected early, but showed the highest compensation later. Compared to the other clones, the short ecotype showed many of the characteristics that defoliation induced in each individual of any clone: higher allocation to leaf area production, higher relative growth rate, higher number but smaller size of tillers, and lower leaf specific weights.     

Environmental control of clonal growth in Carex nigra: What can be masked under the name Carex nigra subsp. juncella in the Czech Republic?

Carex nigra plants forming elevated dense tussocks are often named C. nigra subsp. juncella, as opposed to rhizomatous C. nigra subsp. nigra. It is uncertain, however, whether the cespitose growth form is a hereditary trait useful for definition of the distinct taxon or a site modification of little taxonomic value. We used vegetation analyses (phytosociological relevés) to reveal main patterns in ecological demands of the cespitose C. nigra plants in the Czech Republic, and three cultivation experiments to assess changes in clonal growth of C. nigra under various environmental conditions. In the field the cespitose C. nigra plants were typically found in abandoned wet meadows near open water, whereas the rhizomatous morphotypes frequently occurred also in regularly mown wet meadows and in peat bogs. The cespitose growth form disappeared in the cultivations, and the rhizome system responded plastically to immediate environmental stimuli. Number of rhizome branches and mean rhizome length decreased after defoliation of aboveground parts and denudation of belowground parts, whereas increased due to inundation. In the population from a cold site in high altitude (Modrava, Šumava Mts.), however, the originally cespitose plants repeatedly produced shorter and less numerous rhizome branches than the rhizomatous plants cultivated in the same conditions. This suggests ecotypic (genetic) differentiation in some populations of C. nigra, driven by environmental selection for more compact growth form in climatically severe sites. The cespitose C. nigra plants thus arise polytopically, by different mechanisms. The growth form itself therefore cannot serve as the character reliably delimiting C. nigra subsp. juncella as the distinct taxon.     

Heat induced changes in protein expression profiles of Norway spruce (Picea abies) ecotypes from different elevations

Although tree species typically exhibit low genetic differentiation between populations, ecotypes adapted to different environmental conditions can vary in their capacity to withstand and recover from environmental stresses like heat stress. Two month old seedlings of a Picea abies ecotype adapted to high elevation showed lower level of thermotolerance and higher level of tolerance to oxidative stress relative to a low elevation ecotype. Protein expression patterns following exposure to severe heat stress of the two ecotypes were compared by means of 2-DE. Several proteins exhibiting ecotype and tissue specific expression were identified by MS/MS. Among them, small heat shock proteins of the HSP 20 family and proteins involved in protection from oxidative stress displayed qualitative and quantitative differences in expression between the ecotypes correlated with the observed phenotypic differences. On the basis of these results, it can be speculated that the observed interpopulation polymorphism of protein regulation in response to heat stress could underlie their different capacities to withstand and recover from heat stress. These local adaptations are potentially relevant for the species adaptation to the conditions predicted by the current models for climate change.     

Genetic structure among and within populations of the serpentine endemic Heteropappus hispidus ssp. leptocladus (Compositae)

Heteropappus hispidus ssp. leptocladus is an edaphic endemic taxon that is confined to serpentine and limestone-derived soils and is allopatrically distributed in three regions of western Japan. In this study, we attempted to detect genomic signatures of seven H. hispidus ssp. leptocladus populations along with eight other subspecies populations using eight nuclear microsatellite loci. The Mantel test supported an isolation by distance model across all H. hispidus populations, thus implying the possibility of parallel evolution for each subspecies. Results from AMOVA recognized relatively larger differentiations in geographic distribution compared to intraspecific taxonomy. Relationships indicated by neighbor-joining phylogenetic tree analysis and population structure generally did not reflect an intraspecific taxonomy. Populations from limestone-derived soil harbored a homogeneous genetic structure with neighboring populations from serpentine-derived soils. These results suggest that the edaphic ecotype may have derived allopatrically while a lack of edaphic constraint existed between serpentine and limestone soils.     

两种生态型榕树的叶绿素含量、荧光特性和叶片气体交换日变化的比较研究

比较盆栽 生榕树和两栖型树的形态差异、叶片叶绿素含量、叶绿素荧光特性和气体交换的日变化。两栖型榕树具有较发达的气生根和水生不定根,叶片比陆生榕树宽,并有向中生性 倾向,陆生榕树的叶绿素含量比两栖榕树高,净光合速率略高于水培两栖型榕树,但明显高于土培两栖型榕树,蒸腾速率以水培两栖型树最高,陆生榕树次之,土培两栖型榕树最低,线性回归分析表明,三者的叶片气孔导度与净光合速率变化均呈正相关,气孔导度的变化     

大蒜品种生态型性状指标分析

在用１２个生态性状对大蒜生态型进行数量分类的基础上,采用主成分分析和判别分析的方法,分析了区分不同生态型的性状指标,主成分分析表明,越冬期叶片生长量。叶片受冻比率和秋,春播叶片数差比（Ｘ９）在各生态型中比较稳定,可做为区分各生态型的代表性状,判别分析筛选出抽薹指数和Ｘ９为判别各生态型的性状,用这２个性状建立的分类函数回判后,判准率为９３．２％,研究结果还表明Ｘ９在生型型分类中有重要意义。     

河西走廊不同生态型芦苇核酸代谢季节动态研究

分布在甘肃河西走廊的４ 种生态型芦苇（Ｐｈｒａｇｍ ｉｔｅｓｃｏｍ ｍ ｕｎｉｓＴｒｉｎ．）的核酸代谢季节变化有差异。盐化草甸芦苇ＲＮＡ 含量持续增加,ＤＮＡ 含量相对稳定,其它３ 种生态型芦苇的ＲＮＡ 和ＤＮＡ 含量以５月份为最高。过渡带芦苇的ＲＮＡ 含量、沼泽芦苇及沙丘芦苇的ＤＮＡ含量９ 月份略有增高。盐化草甸芦苇与过渡带芦苇的ＤＮａｓｅ和ＲＮａｓｅ的活性７ 月份最高,沼泽芦苇与沙丘芦苇的ＤＮａｓｅ和ＲＮａｓｅ活性５—９ 月份呈增高趋势。盐化草甸芦苇的ＤＮＡ 和ＲＮＡ 合成活性不断升高,过渡带芦苇和沼泽芦苇的ＤＮＡ 和ＲＮＡ 合成活性及沙丘芦苇的ＲＮＡ 合成活性５—９月份均降低,仅沙丘芦苇的ＤＮＡ合成活性增强。ＲＮＡ 聚丙烯酰胺梯度凝胶电泳分析结果表明,４ 种生态型芦苇均含有２５Ｓ、２３Ｓ、１８Ｓ、１６Ｓ大分子量ｒＲＮＡ 和小分子量５．８Ｓ、５Ｓ、４．５ＳｒＲＮＡ 及４ＳｔＲＮＡ。大分子量ＲＮＡ 的含量高于小分子量ＲＮＡ 含量。不同生态型及同一生态型芦苇的不同发育时期,相同的ＲＮＡ 组分含量各不相同。且发育过程中２３Ｓ、１８Ｓ、１６ＳｒＲＮＡ 在不同月份发生不同程度的降解。由此,我们认为,核酸代谢的差异性是４ 种生态型由生长转入衰