Development and testing of novel chloroplast microsatellite markers for Lolium perenne and other grasses (Poaceae) from de novo sequencing and in silico sequences

Twelve primers to amplify microsatellite markers from the chloroplast genome of Lolium perenne were designed and optimized using de novo sequencing and in silico sequences. With one exception, each locus was polymorphic with a range from two to nine alleles in L. perenne. The newly developed primer pairs cross‐amplified in different species of Lolium and in 50 other grass species representing nine grass subfamilies.     

Plastid genome sequencing,comparative genomics,and phylogenomics:Current status and prospects

More than 190 plastid genomes have been completely sequenced during the past two decades due to advances in DNA sequencing technologies.Based on this unprecedented abundance of data,extensive genomic changes have been revealed in the plastid genomes.Inversion is the most common mechanism that leads to gene order changes.Several inversion events have been recognized as informative phylogenetic markers,such as a 30-kb inversion found in all living vascular plants minus lycopsids and two short inversions putat...     

Phylogenetics of early branching eudicots: Comparing phylogenetic signal across plastid introns, spacers, and genes

Recent phylogenetic analyses revealed a grade with Ranunculales,Sabiales,Proteales,Trochodendrales,and Buxales as first branching eudicots,with the respective positions of Proteales and Sabiales still ...     

Madagascar's grasses and grasslands: anthropogenic or natural?

Grasses, by their high productivity even under very low pCO₂, their ability to survive repeated burning and to tolerate long dry seasons, have transformed the terrestrial biomes in the Neogene and Quaternary. The expansion of grasslands at the cost of biodiverse forest biomes in Madagascar is often postulated as a consequence of the Holocene settlement of the island by humans. However, we show that the Malagasy grass flora has many indications of being ancient with a long local evolutionary history, much predating the Holocene arrival of humans. First, the level of endemism in the Madagascar grass flora is well above the global average for large islands. Second, a survey of many of the more diverse areas indicates that there is a very high spatial and ecological turnover in the grass flora, indicating a high degree of niche specialization. We also find some evidence that there are both recently disturbed and natural stable grasslands: phylogenetic community assembly indicates that recently severely disturbed grasslands are phylogenetically clustered, whereas more undisturbed grasslands tend to be phylogenetically more evenly distributed. From this evidence, it is likely that grass communities existed in Madagascar long before human arrival and so were determined by climate, natural grazing and other natural factors. Humans introduced zebu cattle farming and increased fire frequency, and may have triggered an expansion of the grasslands. Grasses probably played the same role in the modification of the Malagasy environments as elsewhere in the tropics.     

Conservation of genetic diversity in the endangered plant Eriogonum ovalifolium var. vineum (Polygonaceae)

The purpose of his research was to describethe organization of genetic variation in thefederally endangered plant taxon Eriogonumovalifolium var. vineum using allozymes. Such information can help prioritize sites andmanagement choices for capturing andmaintaining genetic variation and can reducethe number of populations necessary to committo conservation, thus reducing costs andconflicts with competing land uses. Information on genetic diversity patterns alsoprovides insight into evolutionary anddemographic history of a taxon which canprovide means to assess future risk of erosionof diversity. Similar to other Eriogonumovalifolium varieties, E. ovalifoliumvar. vineum is diverse atboth the taxon (proportion of polymorphic loci[P] = 0.55 and alleles per locus [A] =5.45 [SD = 2.5]) and population (P = 0.56 [SD =0.11] and A = 2.68 [SD = 0.35]) levels. Gene diversity (H _e) withinpopulations averaged 0.19 (SD = 0.03). Wefound some evidence for limited clonalreproduction within populations. Populationswere moderately differentiated from one another(_S = 0.14) and showed moderatedeviations from Hardy-Weinberg equilibriumwithin populations (f = 0.14 and F =0.19). Mean Nei's genetic distance (D)among all pairs of populations was 0.02. Populations with high levels of multiplemeasures of genetic diversity, high levels ofdifferentiation, and low levels of apparentinbreeding are suggested as conservationpriorities.     

戴云山物种多样性与系统发育多样性海拔梯度分布格局及驱动因子

生物多样性的海拔分布格局是生态学研究的热点。海拔作为综合性因子驱动着植物群落的物种、系统发育与功能多样性的空间分布。以戴云山南坡900-1600 m森林植物群落为研究对象,探讨物种多样性、系统发育指数与环境驱动因子的相互关系以及环境因子在群落构建与多样性维持中的重要意义。结果表明：（1）森林植物群落的系统发育多样性与物种多样性沿海拔均呈现中间高度膨胀格局。（2）物种多样性Margalef指数、Shannon-Wiener指数与系统发育多样性指数呈显著正相关,表明物种多样性越高,系统发育多样性也越高。Shannon-Wiener指数与物种多样性指数（Margalef、Pielou、Simpson指数）、系统发育多样性及系统发育结构都存在显著相关性,一定程度上Shannon-Wiener指数可以代替其他指数。Pielou指数、Simpson指数、Shannon-Wiener指数与系统发育结构NRI （Net relatedness index）指数、NTI （Net nearest taxa index）指数存在显著正相关,表明群落优势度、均匀度与系统发育结构相关性较强。（3）土壤全磷含量是影响系统发育多样性和物种多样性的主要驱动因子,土壤含水量是影响Shannon-Wiener、Pielou、Simpson指数的最显著因子,海拔是影响群落系统发育结构的主要因素。海拔是影响系统发育结构变化的主要环境因子,而土壤因子是影响物种多样性与系统发育多样性的主要因素,进一步验证了物种多样性与系统发育多样性的高度相关,结果旨在揭示物种群落空间分布规律。