AFLP fingerprinting of Anchusa (Boraginaceae) in the Corso-Sardinian system: Genetic diversity, population differentiation and conservation priorities in an insular endemic group threatened with extinction

Although several plants endemic to Corsica and Sardinia are included in various redlists, no attempts have been made to analyse their genetic diversity with molecular techniques. Genus Anchusa occurs with seven taxa in either mountain or coastal habitats of the two islands, but the very restricted range and low population size pose these endemisms in a very precarious conservation status. Highly variable markers (AFLP) were therefore used to analyse the patterns and levels of genetic diversity in a sample of 11 populations from the entire range of the group.Results indicate the separation between a mountain genic pool including Anchusa formosa, Anchusa capellii and Anchusa montelinasana, and four groups of coastal accessions. In spite of small size, mountain taxa show low interpopulation differentiation (F_st = 0.02) and relatively high intrapopulation genetic variation (0.365), while coastal accessions showed on average a stronger differentiation (mean F_st = 0.20) and a lower diversity (0.281), possibly due to higher rates of inbreeding. The particularly low levels of variation found in A. sardoa, A. littorea and A. crispa ssp. maritima from the Coghinas bay are likely due to a historical decrease of populations and to bottleneck events caused by loss of habitat and natural stochastic factors on sand dune ecosystems. While habitat maintenance and regulation of grazing by domestic herbivores should be sufficient to ensure the persistence of the mountain endemics, additional actions of in situ and ex situ conservation are needed for the critically endangered coastal species A. sardoa and A. littorea. A. crispa showed a relatively high variation, especially on Corsica. No correlation between population size and genetic variation was found in the latter species, highlighting the importance of the small patches for its conservation. Also, the genetic separation between subspecies crispa and maritima stresses the need of keeping them distinct in redlists and conservation actions on Sardinia.     

基于SSR标记的苜蓿种质资源遗传多样性与群体结构分析

种质资源遗传多样性和群体结构的分析是进行复杂性状关联分析的前提条件.从140对SSR引物中筛选到16对多态性引物,对82份苜蓿(Medicago spp.)材料进行遗传多样性与群体结构分析.结果表明;16对SSR引物共检测出190个等位变异,平均11.88个;多态性比率66.67％～100％,平均为83.05％;基因多样性为0.1447～0.3637,平均为0.2577;PIC为0.0079～0.9432,平均为0.5501.群体结构分析表明,当K=5时△K最大,即82份苜蓿材料可划分为5个类群,其中75.61％的种质遗传组分相对比较单一,24.39％的种质遗传背景比较复杂.苜蓿种质资源遗传多样性丰富,群体结构的划分与种质的来源不完全相关.     

籼稻栽培品种中淀粉合成相关基因的遗传变异和群体结构分析

选用34个淀粉合成相关基因分子标记对87份来自不同国家和地区的籼稻栽培品种进行遗传变异和群体结构分析.结果表明,34对引物共检测到80个等位变异,平均每个位点含2.35个等位基因,品种间等位基因变异范围2～6;Shannon's信息指数变幅为0.303 ～0.796,平均为0.539;多态信息含量(PIC)的变幅为0.084～0.658,平均0.295;遗传相似系数变幅为0.265 ～0.990,表明淀粉合成相关基因在品种间存在遗传差异,但不同品种间等位基因的变异频率不同.87份籼稻品种可以分成3个类群,类群内品种遗传背景比较相似,类群间品种遗传背景差异明显,其中,39.1％的籼稻品种遗传组分单一,而遗传背景复杂的籼稻品种达到60.9％.该研究可为水稻淀粉品质的遗传改良提供依据,并为后续淀粉品质性状的关联分析奠定基础.     

The Machine Recognition for Population Feature of Wheat Images Based on BP Neural Network

Recognition and analysis of dynamic information about population images during wheat growth periods can be taken for the base of quantitative diagnosis for wheat growth. A recognition system based on self-learning BP neural network for feature data of wheat population images, such as total green areas and leaves areas was designed in this paper. In addition, some techniques to create favorable conditions for image recognition was discussed, which were as follows: (1) The method of collecting images by a digital camera and assistant equipment under natural conditions in fields. (2) An algorithm of pixei labeling was used to segment image and extract feature. (3)A high pass filter based on Laplacian was used to strengthen image information. The results showed that the ANN system was availability for image recognition of wheat population feature.     

新疆昌吉州波斑鸨分布与数量考察初报

本文报道了波斑鸨（Ｏｔｉｓｕｎｄｕｌａｔａ＝Ｕｎｄｕｌａｔａｕｎｄｕｌａｔａ）在新疆昌吉州境内的分布和种群数量。昌吉州为我国波斑鸨的主要繁殖地，繁殖区由三片不连续的地区组成，总面积约１３４００ｋｍ２，界于Ｅ８８°３０’－９１°１５’，Ｎ４３°５７’－４５°之间。据１２条样带统计结果，平均栖息密度为０．０３２±０．００８２只／ｋｍ２，种群数量为４２８．８±１００．８８只，即３１９—５３９只。     

退化草地群落演替趋向研究进展

草地群落的退化演替以植物个体、种群与群落层次上植物的动态以及土壤理化性状的改变等现象为表征。主要从植物个体形态特征、草地退化模式、草地土壤养分变化等方面对退化的响应,探讨了草地退化演替的特征和趋势,建议今后对草地的退化演替机理、放牧生态学、恢复生态学、界面生态学及草地的价值评估等方面进行更深入的研究。     

中国黑琴鸡东部分布区资源现状及巢址生境评价

应用截线法、访问法、交尾地调查相结合的方法对我国黑琴鸡东部分布区资源现状进行了调查,并对该分布区巢址的林型、食物丰富度、隐蔽级、干扰级、距水源距离、坡向、坡位、坡度、巢位、海拔高度共10项生境因子进行分析.结果显示:我国东部分布区黑琴鸡种群数量为(24 785±2 737)只.河北围场县塞罕坝林区种群密度最高,达到(7.28±0.875)只/km2,内蒙古红花尔基林区种群密度次之,为(5.347±0.645)只/km2,河北木兰围场林区种群密度第三,为(3.94±0.474)只/km2.在该分布区中,影响巢址选择的生境因子主要有距水源距离、食物丰富度、隐蔽级、林型、坡向和干扰级,其中塞罕坝林区、红花尔基林区和木兰围场林区是黑琴鸡巢址选择的最佳生境.     

Ecologically and evolutionarily sustainable fishing of the pikeperch Sander lucioperca: Lake Oulujärvi as an example

Due to the multitude of participants and a diverse range of fishing gear used freshwater fisheries are often managed using minimum size limits (MSL) rather than regulations of total fishing effort. However, a concern has arisen whether attempts to improve ecological sustainability of fisheries by increasing MSLs would induce undesired adaptations to selective fishing. We examined the ecological and evolutionary impacts of varying fishing mortality rates under varying MSLs, with and without stockings, in an age-, size-, and maturity-structured evolutionary model which was parameterized for the Lake Oulujärvi pikeperch, Sander lucioperca. We found that at the current level of harvesting (fishing mortality rate, F = 0.7) and stockings (430 000 year⁻¹), and under the assumption of strongly density-dependent growth, the nation-wide MSL of 370 mm maximizes theoretical biomass yield in a deterministic model but does not prevent severe recruitment overfishing under further increased fishing pressures or stochasticity in recruitment success. The recently imposed, local MSL of 450 mm better ensures stable yields, and even increases them if individual growth is density-independent, but further increase of MSL to 500 mm would already reduce yield especially if there was discard mortality for undersized fish. Given density-dependent growth, equal survival between wild and stocked fish, and sustainable fishing mortality rate, stockings do not increase yield or significantly improve the stability of yields. Evolutionarily stable size at maturation decreases under strong fishing mortality, but increased MSLs reduce the magnitude of this undesired effect. Negatively size-dependent natural mortality was found to have a positive effect on the otherwise negative selection for length-at-age. Increased MSLs also reduce the total selection for decreased length-at-age. Our results support the intentions to increase MSLs in order to improve both ecological and evolutionary sustainability of recreational fisheries.     

Altitudinal and longitudinal variations in Pinus brutia (Ten.) of Crete Island,Greece: some needle,cone and seed traits under natural habitats

Four populations representing the entire natural distribution range of Pinus brutia (Ten.) in Crete (Greece) were sampled to determine: (1) Altitudinal variation within populations of Lassithi, Vorizia, Koustagerako, and Samaria, and; (2) Longitudinal variation among the four populations, based on morphological and anatomical differences in cone, needle and seed characteristics. Samples were collected from 10 trees per altitude, at three altitudes in each population. A total of 12 morphological and anatomical traits from needles, cones and seeds were analyzed to assess the altitudinal and longitudinal variations of the species in the island. The number of teeth per cm showed significant (P<0.01) differences between altitudes in Samaria, Vorizia and Lassithi, while needle length, width and the number of resin canals showed significant differences (P<0.01) between altitudes in Koustagerako. Cone width showed patterns of variation along the altitudinal gradient in Koustagerako, Samaria and Vorizia. Most traits had their highest means at the middle altitudes (650masl) in all the four populations. Overall, no clear altitudinal differentiation was detected, probably due to high rate of gene flow. Longitudinal variability showed a clear pattern of differentiation along the east–west climatic gradient. Needle length, width, sheath length, number of teeth per cm and the number of resin canals were the most useful traits for determining the climatic gradient clines.     

Estimates of minimum viable population sizes for vertebrates and factors influencing those estimates

Population size is a major determinant of extinction risk. However, controversy remains as to how large populations need to be to ensure persistence. It is generally believed that minimum viable population sizes (MVPs) would be highly specific, depending on the environmental and life history characteristics of the species. We used population viability analysis to estimate MVPs for 102 species. We define a minimum viable population size as one with a 99% probability of persistence for 40 generations. The models are comprehensive and include age-structure, catastrophes, demographic stochasticity, environmental stochasticity, and inbreeding depression. The mean and median estimates of MVP were 7316 and 5816 adults, respectively. This is slightly larger than, but in general agreement with, previous estimates of MVP. MVPs did not differ significantly among major taxa, or with latitude or trophic level, but were negatively correlated with population growth rate and positively correlated with the length of the study used to parameterize the model. A doubling of study duration increased the estimated MVP by approximately 67%. The increase in extinction risk is associated with greater temporal variation in population size for models built from longer data sets. Short-term studies consistently underestimate the true variances for demographic parameters in populations. Thus, the lack of long-term studies for endangered species leads to widespread underestimation of extinction risk. The results of our simulations suggest that conservation programs, for wild populations, need to be designed to conserve habitat capable of supporting approximately 7000 adult vertebrates in order to ensure long-term persistence.