海南岛海菖蒲种群克隆多样性和遗传结构

海草是生长在潮间带和潮下带的单子叶植物,由海草植物组成的海草床是生态系统服务价值最高的生态系统之一.然而,近几十年人类活动干扰、全球气候变化等因素导致海草床衰退严重.海菖蒲是分布于热带、体型最大的雌雄异株海草,我国位于该物种的分布北缘,本文对其克隆多样性和遗传结构进行研究,以期为该海草的保护提供参考.采用4对多态微卫星标记对采自海南岛4个地点的现存海菖蒲种群的样品进行基因型分型.结果表明:海菖蒲种群克隆多样性和遗传多样性较低,这与所研究种群处于分布区北缘有关;种群间遗传分化值范围较大(0.073~0.309),这可能是由于分布于不同港湾的种群间距离范围较大以及局域绝灭/再拓殖的遗传漂变效应所致;各种群未发现近期经历种群瓶颈的信号,很可能是由于种群内遗传多样性已经很低,种群减小未能导致遗传多样性明显降低.根据种群遗传特征,提出了重点保护种群的建议,鉴于目前我国海菖蒲等海草快速衰退的局面,应强化海草保护并实施海草床生态恢复.     

Methane emissions along a salt marsh salinity gradient

The seasonal flux of methane to the atmosphere was measured at three salt marsh sites along a tidal creek. Average soil salinities at the sites ranged from 5 to 17 ppt and fluxes ranged from below detection limits (less than 0.3 mgCH₄ m^-2 d^-1) to 259 mgCH₄ m^-2 d^-1. Annual flux to the atmosphere was 5.6 gCH₄ m^-2 from the most saline site, 22.4 gCH₄ m^-2 from the intermediate site, and 18.2 gCH₄ m^-2 from the freshest of the three sites. Regression of the amount of methane in the soil with flux indicates that changes in this soil methane can account for 64% of the observed variation in flux. Data on pore water distributions of sulfate suggests that the activity of sulfate reducing bacteria is a primary control on methane flux in these transitional environments. Results indicate that relatively high emissions of methane from salt marshes can occur at soil salinities up to approximately 13 ppt. When these data are combined with other tidal marsh studies, annual CH₄ flux to the atmosphere shows a strong negative correlation with the long term average soil salinity over a range from essentially fresh water to 26 ppt.     

不同发育时间的互花米草盐沼对大型底栖动物群落的影响

2004-2006年对长江口崇明东滩湿地芦苇(Phragmites australis)盐沼和不同发育时间的互花米草(Spartina alterniflora)盐沼的大型底栖动物群落特征进行分析研究.结果表明:互花米草盐沼发育初期,大型底栖动物群落以腹足类为主,物种丰富度(D=2.18)和多样性(H′=2.19)均低于芦苇盐沼(D=2.61, H′=2.29);随着时间的推移,互花米草与本地生物逐渐形成互动和稳定的格局,大型底栖动物群落组成中多毛类的种类逐渐上升(由3种变为6种),物种数和物种丰富度也上升,从而逐步形成新的大型底栖动物群落,物种丰富度(D=2.70)和多样性(H′=2.48)逐渐上升并高于芦苇盐沼(D=2.19, H′=2.09);从大型底栖动物群落的重新形成到稳定阶段,需要若干年的时间.     

艾纳香野生种群克隆多样性及克隆结构研究

艾纳香是具有克隆生长习性的多年生宿根性草本植物,其广布于中国南部,为了更有效地保护和合理利用艾纳香资源,本文利用RAPD分子标记技术,对4个野生艾纳香种群进行了克隆结构和克隆多样性(单克隆种群或多克隆种群)进行了初步研究。结果表明:(1)10对10bp随机引物共检测到70条谱带,其中多态带为60条,占85.71%,检测到64个基因型,且全部为局限基因型;(2)与Ellstrand Roose(1987)总结的克隆多样性平均值(PD=0.17,D=0.62)相比艾纳香的种群克隆多样性水平稍高,Simpson指数平均为0.973,基因型比率PD平均为0.800;(3)遗传一致度和遗传距离分析表明,4个艾纳香野生种群被分成两组,一组是海南的所有种群,另外一组是云南类群。     

Temporal patterns in shore fly (Diptera, Ephydridae) community structure in a salt marsh habitat

Abstract.  1. An ecological investigation of the shore fly community was carried out in a salt marsh in Novosedly in the Czech Republic.
2. Sampling was carried out in 1997 and 1999 at approximately 14-day intervals during the seasonally active period, using yellow water traps.
3. Altogether 14 374 specimens of the family Ephydridae were collected (6040 in 1997 and 8334 in 1999), belonging to 48 shore fly species (37 in 1997 and 41 in 1999).
4. Community structure, species richness, species diversity, evenness, and seasonal and inter-annual changes were studied. The species richness, species diversity, and evenness of the shore fly community in 1999 were higher than in 1997 but inter-annual difference in species diversity was not statistically significant. Paracoenia fumosa , Scatella tenuicosta , and Hydrellia albilabris were found to be the most abundant species in both study years.
5. Seasonal patterns and phenology of the most abundant species are discussed. Hydrellia albilabris showed similar seasonal distribution of abundance in 1997 and 1999, whereas seasonal distribution of P. fumosa and S. tenuicosta varied between the study years. Paracoenia fumosa , Hydrellia griseola , H. albilabris , Scatella paludum , S. tenuicosta , and Philotelma defecta were found to occur throughout the whole observation period from March until November while Notiphila cinerea , Hydrellia ischiaca , and Psilopa nigritella appeared in a limited period only.     

黔西北地区不同演替阶段植物群落结构与物种多样性特征

该文采用"空间代替时间"的方法,研究了贵州省威宁县喀斯特地区植被演替过程中的群落结构、物种组成、生活型谱和物种多样性的变化规律。结果表明:(1)该调查共记录到种子植物174种,隶属于52科117属,物种分布较多的有菊科、蔷薇科、禾本科、杜鹃花科、小檗科、唇形科、蓼科。(2)随着植被的正向演替,物种丰富度逐渐增加,群落结构趋于复杂,高位芽植物所占比例逐渐增大。(3)随着植被的恢复,群落层次分化逐渐明显,大径级植株所占比例呈现增加趋势。(4)随着植被的恢复,群落各层次的ShannonWiener多样性指数(H)、Simpson多样性指数(DS)、均匀度指数(J)和Margalef丰富度指数(DM)逐渐增加;不同演替阶段植物群落之间的Srensen相似系数呈现先上升后下降的趋势,Cody指数则表现为逐渐增加的趋势。黔西北地区不同演替阶段植物群落结构和物种多样性不同,建群种和关键种发生了明显变化,不同演替阶段植物群落结构和物种多样性的研究对喀斯特地区植被演替规律的认识和生态恢复具有重要意义。     

Unexpectedly high clonal diversity of two salt marsh perennials across a severe environmental gradient

In salt marsh habitats, noted for their extreme environments, a widely held assumption is that a few large clones dominate plant populations. Using a large number of polymorphic genetic markers, we were able to test this assumption for two salt marsh plants known to span extreme salinity gradients. For both species, clonal diversity was surprisingly high across populations: Simpson's diversity indices were 0.96 and 0.99. Although clonal diversity was high, there was no pattern of association between specific clones or alleles with salt microhabitat. Our findings suggest that sexual reproduction and recruitment from seeds may have been generally underappreciated as an important ecological force in the salt marsh. Furthermore, clonal diversity has implications for conservation and restoration of these critical coastal habitats, particularly with regard to buffering environmental change or disease. Recent studies also suggest that high levels of intraspecific diversity can affect a variety of community and ecosystem processes.     

不同年龄巴山木竹种群克隆结构

很多竹类植物是典型的克隆植物,也是大熊猫的食物。研究典型竹子种群克隆结构的形成和发展对竹林的生产和抚育具有理论和实践意义,可为预测该竹林群落的演替趋势和大熊猫保护提供科学依据。利用SSR标记研究不同年龄A(7龄)、B(30龄)和C(60龄)巴山木竹种群的克隆结构和多样性,探讨小尺度范围内不同年龄巴山木竹种群的克隆结构及斑块的建立和发展。8对SSR引物共扩增出了118个位点,3个种群样地的256个样本共检测到了49个克隆(基因型),A、B和C种群分别检测出31、10个和8个克隆。随着种群年龄的增长,巴山木竹克隆面积增加,克隆数量减少;A和B样地各克隆分布格局为团块状,而C样地克隆既有团块状又有离散状。这一结果显示出在幼苗定居的初期,基株可能以短距离的克隆延伸为主从而呈现出团块状;而随着年龄的增长,克隆面积不断扩大,当复轴混生型的巴山木竹克隆受到强大的压迫时,基株可能会进行较多的单轴和长距离克隆延伸,呈现出离散状。Mantel检测和空间自相关分析都支持3个样地在小尺度范围内存在明显的克隆空间遗传结构。3个样地在10 m等级下显著的正相关空间遗传结构距离为3.1、28、48 m,X-轴截距为9.051、30.698和50.536,空间自相关系数的范围分别为0.1—0.167、0.008—0.703和0.006—0.735。由此可推断,随着年龄的增长,巴山木竹克隆斑块的规模在不断地扩大,同一克隆的分株数量增加,在均匀取样情况下,正相关空间遗传结构距离范围内取到具有相同基因型的可能性越大。A、B和C 3样地的基因型比率(G/N)为1、0.14和0.055,Simpson多样性指数(D)分别为1、0.876和0.744。这说明巴山木竹幼苗期基因型比例远远高于成年的竹林,随着年龄的增长巴山木竹克隆多样性虽有所降低,但由于有性繁殖的作用仍然保持了较高的多样性。聚类和主坐标分析均表明总体上各样地的克隆被聚为一类,但不同样地少数克隆的基因型有重叠和聚集,可推断出不同巴山木竹种群之间可能存在着基因流动和近似的克隆起源。     

Biodiversity in different successional stages of Mediterranean enclaves distributed along Sinop Peninsula (Turkey)

The aim of this research was to evaluate plant diversity and the relationships between the distribution of Raunkiaer life forms and community structure, and species richness, at different successional stages in communities of Quercus ilex L., Erica arborea L. and Sarcopoterium spinosum (L.) Spach., distributed as enclaves in Sinop Province. Permanent sample plots were selected to determine plant diversity. The cover percentage of each plant species was recorded monthly during two vegetation periods. Raunkiaer life forms, and the Shannon–Wiener, Evenness, Simpson and Margalef indexes were determined. Twenty-three species in Quercus ilex, 96 species in Erica arborea, and 148 species in Sarcopoterium spinosum were identified. Hemicryptophyte dominancy was observed followed by phanerophytes in the Q. ilex community, and therophyte and hemicryptophyte dominancy in the E. arborea and S. spinosum communities, respectively. It was determined that the S. spinosum community was the most heterogeneous community while the Q. ilex community was more uniform than other communities. The variation in diversity indexes, homogeneity, and composition of life forms among communities adopting a similar climatic environment could result from a differentiation of environmental factors, which impact on community structuring, from biotic to abiotic at different successional stages of Mediterranean communities.     

Effects of impounding coastal salt marsh for mosquito control on microcrustacean populations

Populations of microcrustaceans were studied for 24 months in two New Jersey high salt marsh impoundments, and in three separate 14 month studies of high salt marsh pools in northeastern Massachusetts.In Massachusetts high marsh pools, dominants were all harpacticoids: Amphiascus pallidus, Cletocamptus deitersi, Harpacticus chelifer, Mesochra lilljeborgii, Metis jousseaumei, and Nitokra lacustris. The cyclopoids Apocyclops spartinus, Halicyclops sp. and the calanoid Eurytemora affinis were also numerically important. While there was extensive overlap, dominants varied to some extent from year to year and among the three studies. The New Jersey saline impoundment fauna showed extreme dominance (low equitability) in the first summer, somewhat less in the second and much less in the third. Total microcrustacean densities also declined each year. Variation in Apocyclops spartinus densities was the major factor, as this species comprised in three consecutive summers, 95, 85 and 51% of the total zooplankton at one station. Diversity as species richness was highest in a New Jersey freshwater impoundment which compared well with South Carolina salt marsh values. Impoundment diversity which was very low, and comparable with that found in a New Jersey Spartina patens marsh, increased each year becoming progressively more like that found in the Massachusetts pools.Vegetation changed significantly in the New Jersey impoundments over the three years. Spartina patens died-off in the first summer, while S. alterniflora gradually declined each year. A visit to the site twenty years later showed all emergent vegetation to be gone. These successional zooplankton and vegetation changes, together with the possible consequences of interrupted marsh-bay exchanges should be considered before undertaking any coastal mosquito control involving permanent flooding.     

Biological consequences of ice rafting in a New England salt marsh community

Ice rafting of salt marsh peat is a recurrent phenomenon in north temperate regions. This process was simulated in a northern New England salt marsh to test several hypotheses concerning the effects of peat transport from high to low intertidal heights on the growth and mortality of key sessile organisms: the ribbed mussel Geukensia demissa (Dillwyn), the fucoid alga Fucus vesiculosus L. var. spiralis (Farlow) and the cordgrass Spartina alterniflora (Loisel.). Growth rates increased when Geukensia and Fucus were transported to the lower intertidal; however, Spartina died when similarly transported. Predation pressure (primarily from Carcinus maenus L.) on Geukensia was greater when it was rafted to the lower intertidal zone than in the upper intertidal habitat and was size specific; mussels >3.5cm reached a size-escape from crab predation.A winter survey of dislodged mussels revealed that 72% of the mussels collected were dead and 86% had been overgrown by large Fucus plants, >2.5 × the natural frequency of Fucus overgrowth (32%). In marsh habitats where hard substratum is rare, 91% of the Fucus were growing on Geukensia. A dislodgement experiment showed that a significantly greater percentage of Geukensia was dislodged after ice-out when Fucus was attached to the shell than those mussels without Fucus overgrowth. In the spring, a population survey conducted in the salt marsh examined densities, biomass and population structure of Geukensia, as well as densities, percent cover and biomass of Fucus. Values obtained in the foremarsh were compared to those from the peat islands recently rafted to the tidal flats. Both biomass and densities of Geukensia were similar in the two areas; however, the size-frequency distributions of the mussels were different. Since fewer large mussels, Fucus and Fucus-overgrown mussels were found on the newly transported peat islands, this pattern appears to reflect dislodgement of larger Geukensia by attached algae during ice transport. Two ice-related sources of mortality were identified for Geukensia: (1) Fucus overgrowth acted as a vector for mussel dislodgement and was an indirect source of mortality; and (2) ice crushing was a direct source of mortality for non-overgrown mussels.     

Genetic diversity and population structure of Elytrigia pycnantha (Godr.) (Triticeae) in Mont Saint-Michel Bay using microsatellite markers

During the last decade, an invasive wheatgrass species (Elytrigia pycnantha) has colonized the low salt marshes of the Mont Saint Michel Bay resulting in an accelerated change in the vegetation. This study was conducted using microgeographical genetic diversity in order to understand the genetic structure of this invasive and clonal species. Genetic variation and population structure of fifteen populations collected in high and low marsh habitats around the Bay were analyzed using five microsatellite loci. Because E. pycnantha is an allohexaploid, the application of standard genetic diversity statistics was not possible; we chose to summarize genetic diversity using statistics calculated from banding phenotypes. The mean number of alleles per locus was 10.2, the mean number of different alleles per sample was 6.87. The mean number of allelic phenotypes across all populations was 7.21. The mean value of genetic diversity for the species, calculated as the average number of alleles by which pairs of individuals differ, was H's = 1.91 and H't = 2.04. Little genetic differentiation among populations was detected (0.067). The association between pairwise genetic differentiation and geographic distances exhibited no evidence for isolation by distance. A geographical pattern of population differentiation, where a single population GI was clearly separated from the remaining population groups (considered as a metapopulation), was revealed by principal component analysis (PCA), and we propose that this is because GI represents a new genotype.     

崇明东滩自然保护区盐沼植被的时空动态

盐沼植被是滩涂湿地的重要组成部分,其动态变化直接影响着湿地的生态服务功能和价值。通过对1998~2005年间4景不同时相的LandsatTM遥感影像的解译分析,结合历史资料数据和近年来的现场调查,分析了崇明东滩鸟类自然保护区自建立以来,盐沼植被的时空演替动态过程。结果显示,随着滩涂的淤涨,东滩盐沼植被的面积从1998年的2478.32hm2增加到2005年的4687.74hm2,而互花米草(Spartina alterniflora)自人为引入至2005年,其面积已增加到1283.4hm2,其增加速率显著高于土著种芦苇(Phragmites australis)和海三棱藨草(Scirpus mariqueter),并且已在东滩保护区相当区域内形成单优势种群落。受1998年和2001年两次高滩围垦和互花米草入侵影响,崇明东滩的芦苇群落面积大大减少,虽随着滩涂的淤涨,芦苇群落的面积逐年有所增加,但增加的速度缓慢。互花米草有着更广的生态幅和竞争优势,是滩涂中扩散最快的植被,而淤涨型滩涂为其提供了可扩张的空生态位,如不加以控制和治理,其快速扩散将会对崇明东滩保护区的生态系统造成更大的威胁和影响。     

Root dynamics in a salt marsh over three consecutive years

The minirhizotron technique has been used to study root development in a salt marsh in the western part of the Nationalpark Niedersächsisches Wattenmeer during a three-year period. The objective of our study was to evaluate root depth distribution and seasonal changes in growth activities of natural plant root systems. Root number was counted at monthly intervals in the top soil layer (0–0.2 m) for every 2 cm soil depth. The number of roots was regarded as an easily detectable parameter reflecting root growth and decay.In general, highest rooting intensity was found in the soil's subsurface layer (0–0.08 m). The number of roots significantly decreased in deeper horizons of the soil. There was also a significant increase and decrease in the number of roots in the course of a year. The highest rooting intensity was found in late winter to early spring, which substantially decreased towards mid summer when the plants were in their reproductive phase. The data indicate that there is a clear seasonal pattern of root growth of salt marsh species.     

Estimation of primary production using five different methods in a Spartina alterniflora salt marsh

The aboveground production of Spartina alterniflora in a salt marsh in Barataria Bay, Louisiana, USA was estimated using five different harvest methods: peak standing crop (PSC), Milner-Hughes, Smalley, Wiegert-Evans, and Lomnicki et al., and a non-destructive method based on measurement of stem density and longevity. Annual production estimates were 831 ± 41, 831 ± 62, 1231 ± 252, 1873 ± 147 and 1437 ± 96 g dry wt m^–2 for each method, respectively. The average longevity of individually tagged young shoots was 5.2 ± 0.2 months, equivalent to an annual turnover rate of 2.3 crops per year. Among the five methods, Wiegert-Evans and Lomnicki et al. were considered more accurate than the other three because they corrected for mortality losses between sampling times. The Lomnicki et al. method was preferred over the Wiegert-Evans method because of its greater simplicity.     

Diversity and composition of macroinvertebrate communities in a rare inland salt marsh

Inland salt marshes are rare habitats in the Great Lakes region of North America, formed on salt deposits from the Silurian period. These patchy habitats are abiotically stressful for the freshwater invertebrates that live there, and provide an opportunity to study the relationship between stress and diversity. We used morphological and COI metabarcoding data to assess changes in diversity and composition across both space (a transect from the salt seep to an adjacent freshwater area) and time (three sampling seasons). Richness was significantly lower at the seep site with both datatypes, while metabarcoding data additionally showed reduced richness at the freshwater transect end, consistent with a pattern where intermediate levels of stress show higher diversity. We found complementary, rather than redundant, patterns of community composition using the two datatypes: not all taxa were equally sequenced with the metabarcoding protocol. We identified taxa that are abundant at the salt seep of the marsh, including biting midges (Culicoides) and ostracods (Heterocypris). We conclude that (as found in other studies) molecular and morphological work should be used in tandem to identify the biodiversity in this rare habitat. Additionally, salinity may be a driver of community membership in this system, though further ecological research is needed to rule out alternate hypotheses.     

贵州省普定县不同植被演替阶段的物种组成与群落结构特征

通过对贵州省普定县喀斯特地区不同植被演替阶段群落的调查, 研究了植被演替过程中群落物种组成和群落结构的变化。结果表明, 该地区的植被主要处于5个演替阶段, 即次生乔木林、乔灌过渡林、藤刺灌丛、稀灌草丛以及火烧干扰后的蕨类植物群落。本次调查共记录到植物365种, 隶属89科218属。其中, 蕨类植物31种, 隶属14科23属; 种子植物334种, 隶属75科195属。物种分布较多的科主要有蔷薇科、菊科、禾本科、百合科、忍冬科、唇形科、莎草科、樟科、葡萄科和水龙骨科。随着正向演替的推进, 物种丰富度增加, 群落结构趋于复杂化。藤刺灌丛与乔灌过渡林群落层次不明显, 次生乔木林分层明显。从藤刺灌丛向次生乔木林演替的过程中, 小径级个体所占比例明显降低, 高于1.3 m植物的总密度、乔木密度和藤本密度都先升高后降低, 而灌木密度呈逐渐降低的趋势。对喀斯特地区植被的恢复提出了参考措施。