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91.
92.
We reassess the phylogenetic relationships of genera of hemiphractine hylid frogs (Marsupial Treefrogs) and discuss the evolution of several distinctive characters within this group using parsimony analysis. Fifty-one morphological and life-history characters were sampled from two species of Cryptobatrachus , three species of Flectonotus , 17 species of Gastrotheca , all five species of Hemiphractus , and one species of Stefania as the ingroup and three hyline, one phyllomedusine, and one pelodryadine species as outgroups. Our results support the mon-ophyly of Flectonotus, Cryptobatrachus , and Hemiphractus. Gastrotheca is paraphyletic with respect to Hemiphractus , dorsal pouches were lost in the ancestor of Hemiphractus. Direct development is a synapomorphy for Hemiphractinae and tadpoles were regained independently several times. These results stand in stark contrast to the prevailing paradigm regarding marsupial frog relationships.  相似文献   
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94.
The number of eggs produced by Triatoma infestans is determined by the amount of blood ingested; the formation of one egg requires 16 mg blood. An exogenous supply of juvenile hormone, provided by the implantation of extra corpora aliata, increases egg production per unit of blood ingested. The corpus allatum is therefore implicated in the relationship between nutrition and fecundity. The rhythm of egg production is regulated by the nutritional state of the adult female: when the females are fed at frequent intervals, egg production becomes regular and continuous. This calls into question previous interpretations of egg-laying rhythms in the Triatominae as cyclic.  相似文献   
95.
The species related to Vriesea paraibica (Bromeliaceae, Tillandsioideae) have controversial taxonomic limits. For several decades, this group has been identified in herbarium collections as V. × morreniana, an artificial hybrid that does not grow in natural habitats. The aim of this study was to assess the morphological variation in the V. paraibica complex through morphometric analyses of natural populations. Two sets of analyses were performed: the first involved six natural populations (G1) and the second was carried out on taxa that emerged from the first analysis, but using material from herbarium collections (G2). Univariate ANOVA was used, as well as discriminant analysis of 16 morphometric variables in G1 and 18 in G2. The results of the analyses of the two groups were similar and led to the selection of diagnostic traits of four species. Lengths of the lower and median floral bracts were significant for the separation of red and yellow floral bracts. Vriesea paraibica and V. interrogatoria have red bracts; these two species are differentiated by the widths of the lower and median portions of the inflorescence and by scape length. These structures are larger in the former and smaller in the latter. Of the species with yellow floral bracts, V. eltoniana is distinguished by longer leaf blades and scapes and V. flava is characterized by its shorter sepal lengths. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 163–181.  相似文献   
96.
水生植物作为水生生态系统的主体, 对发挥水生生态系统的自维持、自循环功能有重要作用。研究通过相关资料的查阅, 建立上海地区乡土水生植物名录, 并对其科属组成、区系特征、生活型、生长型等进行统计分析。结果表明上海地区乡土水生植物共计35 科83 属160 种(含变种), 单属科、单种属的比例较高, 均达65%以上; 植物区系组成丰富、成分复杂, 以热带成分占优势, 达64.6%; 生活型以挺水植物为主, 沉水植物次之, 浮水植物最少; 生长型类型丰富, 以草本型、禾草型居多, 20 种生长型可进一步归为表征相似生态学特征和功能地位的6 个生长型组。在水生态恢复与水景观建设中, 仅有68.8%的景观水体有水生植物应用,且应用种类在2 种以下的占79.2%。乡土水生植物应用不足, 一半以上为观赏性强的外来物种, 应用频率较高的为挺水植物, 对具有良好净化效果的沉水植物重视不够。因此, 在水生态恢复与水景观建设中, 建议加强乡土水生植物资源的繁育栽培, 在充分利用乡土水生植物资源配置群落的基础上, 根据水质的富营养及基底状况, 通过不同生长型组水生植物的应用, 构建沉水-浮水-挺水植物群落复合体, 并通过近自然型护岸的营造, 形成水生-湿生复合生态系统。运用植被工程学的原理和方法, 采用生态浮岛、生态沉岛等技术营造水生植被, 将强人工化的水景观建成具生命的水生生态系统。    相似文献   
97.
A new species of Sabellaria is described from the southeast coast of Brazil and compared with related species known from South or North America.  相似文献   
98.
99.
Aquatic plant invasions are often associated with long‐distance dispersal of vegetative propagules and prolific clonal reproduction. These reproductive features combined with genetic bottlenecks have the potential to severely limit genetic diversity in invasive populations. To investigate this question we conducted a global scale population genetic survey using amplified fragment length polymorphism markers of the world’s most successful aquatic plant invader –Eichhornia crassipes (water hyacinth). We sampled 1140 ramets from 54 populations from the native (South America) and introduced range (Asia, Africa, Europe, North America, Central America and the Caribbean). Although we detected 49 clones, introduced populations exhibited very low genetic diversity and little differentiation compared with those from the native range, and ~80% of introduced populations were composed of a single clone. A widespread clone (‘W’) detected in two Peruvian populations accounted for 70.9% of the individuals sampled and dominated in 74.5% of the introduced populations. However, samples from Bangladesh and Indonesia were composed of different genotypes, implicating multiple introductions to the introduced range. Nine of 47 introduced populations contained clonal diversity suggesting that sexual recruitment occurs in some invasive sites where environmental conditions favour seedling establishment. The global patterns of genetic diversity in E. crassipes likely result from severe genetic bottlenecks during colonization and prolific clonal propagation. The prevalence of the ‘W’ genotype throughout the invasive range may be explained by stochastic sampling, or possibly because of pre‐adaptation of the ‘W’ genotype to tolerate low temperatures.  相似文献   
100.
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