Phenological and chemical differences among hybrid poplar clones (Salicaceae) varying in resistance to Cryptorhynchus lapathi (L.) (Coleoptera: Curculionidae)

Hybrid poplars with Populus maximowiczii parentage have demonstrated antixenotic resistance against adult poplar-and-willow borers, Cryptorhynchus lapathi (L.) (Coleoptera: Curculionidae), in the summer, and antibiosis against C. lapathi larvae in the spring. We examined phenological and biochemical differences among hybrid poplars with and without P. maximowiczii parentage that are resistant and susceptible, respectively, to C. lapathi, to test the hypotheses that resistance was due to physical hydraulic forces, inadequate nutrition, or abundant secondary metabolites. The hybrids with P. maximowiczii parentage flushed earlier than susceptible hybrids, but no differences were found between hybrids with respect to sap flow or bark moisture content that could explain larval mortality in the spring. Similarly, constitutive levels of nutritive compounds (sitosterol, nitrogen, linoleic and linolenic acids, and carbohydrates) were lower or not different in the most susceptible hybrid TN 302-9. Thus, all hybrids appear to be nutritionally sound. TN 302-9 contained the highest constitutive levels of condensed tannins and catechin, but overall phenolic glycoside levels (salicin and salicortin) were similar among all hybrids, with the exception of one sampling date; however, this difference would not likely explain resistance. Neither induced or constitutive polyphenol oxidase (PPO) activity nor induced levels of secondary metabolites could explain resistance. Thus, we conclude hybrids that contain P. maximowiczii parentage have a novel mechanism for resistance.     

High Resolution Melting (HRM) analysis in eggplant (Solanum melongena L.): A tool for microsatellite genotyping and molecular characterization of a Greek Genebank collection

The conservation and characterization of eggplant (Solanum melongena L.) genetic resources in germplasm banks has been the basis of their use in breeding projects, which has resulted in the development of new cultivars. High Resolution Melting (HRM) analysis, combined with eight microsatellite markers, has been integrated in order to facilitate the molecular identification and characterization of the eggplant germplasm, collected from the National Genebank Collection of Greece. The eight microsatellite loci used were highly informative and generated sixty three HRM profiles, which were sufficient to discriminate all eggplant landraces and cultivars studied, highlighting its potential use for cultivar genotyping. The thirty six eggplant genotypes were classified into four clusters. Hence, this assay provided a fast, cost-effective and closed-tube microsatellite genotyping method, well suited for molecular characterization of eggplant cultivars.     

The biflagellate spermatozoa of Colostethus marchesianus (Melin, 1941) (Anura, Dendrobatidae) from the type locality and of Colostethus sp. (aff. Marchesianus.) from a different locality: A scanning and transmission electron microscopy analysis

Scanning and transmission electron microscopy and fluorochrome staining with DAPI were used to study the spermatozoa of Colostethus marchesianus from the type locality and Colostethus sp. (aff. marchesianus) from a different locality. The sperm cell of these species resembles those of most neobatrachian species, except for the presence of two complete flagella, a character previously described only for four unrelated anuran species belonging to the families Leptodactylidae, Rhacophoridae and Dendrobatidae. Although very similar, the spermatozoa described here showed slight differences in the length of their nucleus, in the extent of the subacrosomal cone over the nucleus, and in the curvature of the axial fiber seen in cross section. The absence of a juxtaxonemal fiber and the presence of a comma shaped axial fiber seem to be common characteristics of dendrobatid spermatozoa. The minor differences found in our study may indicate that the taxa studied here are distinct species. The evolutionary significance of spermatozoa biflagellarity is still unclear, although the presence of this trait in unrelated groups suggests independent origins.     

Isozyme markers and volatiles in Tunisian Rosmarinus officinalis L. (Lamiaceae): A comparative analysis of population structure

Genetic and essential oil variations from 14 Tunisian natural populations of Rosmarinus officinalis L. were assessed using eight isozymes and 25 terpenoids. Isozymes were revealed by 13% gel electrophoresis. Volatiles were analysed by GC and GC–MS. Populations were collected from different regions belonging to sub-humid, upper semi-arid and upper arid bioclimates.     

Shoaling preferences of two common killifish (Fundulus heteroclitus and F. diaphanus) in the laboratory and in the field: A new analysis of heterospecific shoaling

Heterospecific grouping behavior of mummichogs (Fundulus heteroclitus) and banded killifish (Fundulus diaphanus) was analyzed in the laboratory and in a freshwater tidal marsh in Cremona, Maryland. Several parameters of wild, intact shoals were measured, including species composition, body length, parasite load, gender, and any physical abnormalities. Fish collected were used for laboratory analysis of shoaling preferences. When size was equal, banded killifish and mummichogs preferred conspecific shoals to heterospecific shoals, consisting of mummichogs, banded killifish, and sheepshead minnows (Cyprinodon variegates). Shoal collection from the field resulted in mixed species shoals with individuals predominantly unaffected by parasites or other physical abnormalities. Size appeared to be a sorting mechanism. A temporal shift in lengths was evident. Initial shoals caught contained significantly smaller fish compared to the final shoals caught. Results are compared with previous studies on heterospecific shoaling in killifish and new characteristics of heterospecific shoals inhabiting freshwater tidal marshes are discussed.     

基于成本收益分析的生境网络优化——以苏锡常地区白鹭为例

引入经济学成本收益分析方法对于生境网络优化保护具有重要现实意义。以苏锡常地区白鹭生境网络优化为例,通过分别构建研究区生境网络保护成本与提升收益测算体系、模拟多种情景和优化方案、成本收益分析的方法,实现了满足不同约束条件的优化方案。结果表明:(1)最大收益累积情景下的方案在总收益最高的基础上,实现了保护总成本较低的目的;最佳效益累积情景下的方案在研究区土地资源有限和保护总成本最低的基础上,实现了优化成效最佳的目的;(2)最佳效益累积情景下的方案在实现成本最低的基础上,兼顾到了优化成效的最大化,适宜于土地资源稀缺且城市化快速发展地区;(3)有限效益累积情景作为最佳效益累积情景的基本模式,其优化方案在一定范围内可以兼顾到成本较低和成效较高。将经济学与生态学相结合的网络优化方法,综合考虑了研究区的生态、经济和社会等现实因素,极大的提高了网络优化方案操作的可行性,其思路和方法拓展了网络优化研究视角。但诸多实现因素也决定了成本与收益体系的构建还处于不断完善之中。     

Maintenance of the shore-level size gradient in the marine snail Tegula funebralis (A. Adams): Importance of behavioral responses to light and sea star predators

The intertidal gastropod, Tegula funebralis (A. Adams) exhibits a shore-level size gradient with mean shell size increasing in a down-shore direction. Snails transferred to zones where they do not usually occur migrated back towards their original zone, thus re-establishing a size gradient and implying differential movement among size classes. Both large (≥2.1 cm shell width) and small (≤ 1.77 cm) snails were photonegative on a horizontal surface and geonegative in the laboratory; there were no statistical differences between size classes. Light, however, inhibited upward, or caused downward, movement of large snails on vertical surfaces. Small snails were unaffected, ranging higher on illuminated vertical surfaces than large snails. Both sizes exhibited similar distributions in the dark. In an experimental chamber providing both emersed and immersed surfaces, T. funebralis established vertical size gradients when the chamber was illuminated from above. It is suggested that light is an important factor in the formation and maintenance of Tegula's shore-level size gradient.In response to water-borne chemicals derived from the sea star Pisaster ochraceus (Brandt), large snails moved up vertical surfaces in greater proportion than small. In response to contact with the predator, large snails moved away faster than small and individuals collected from crevices in the field moved away slower than those collected from open rock faces. Although predation may select for a size gradient in Tegulafunebralis, it is unlikely that responses to predatory sea stars directly and proximally cause or maintain them over the short term.     

基于网络效能分析的生境网络构建与优化——以苏锡常地区白鹭为例

从网络效能分析出发研究生境网络优化具有重要意义。以快速城市化苏锡常地区为小尺度研究区、苏锡常及周边15个城市为大尺度泛研究区、白鹭为焦点物种,通过采用引入并构建网络效能概念框架、识别和构建不同尺度生境网络、调整网络结构和转换网络结构特性相结合的方法,实现了跨尺度下白鹭生境网络优化。结果表明:1)依据大尺度迁移网络完善小尺度生境网络得到的方案一和改变方案一网络特性得到的方案二均是现状生境网络的优化方案;2)方案二与方案一相比,在平均路径长度值增加、聚类系数值减少、节点度概率分布幂次关系拟合度提高,即小世界特性减弱、无标度特性增强的基础上,测度网络连接度的α、β、γ指数值得到增加,同时新增生境节点和迁移廊道数量更少,具有更好的优化成效;3)从网络效能分析出发,有益于提高生境网络跨尺度下优化方案的可行性,其分析思路既丰富了网络优化的方法论研究,也为提高上位与下位规划空间契合度的实践提供了理论支持。但从网络效能概念框架看,如网络层级分析、其他尺度情景研究、网络质量测度指标等方面还亟待丰富与完善。