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51.
We investigated the morphology, morphogenesis and small subunit rRNA gene-based phylogeny of three marine urostylids, Uncinata gigantea Bullington, 1940 Bullington, W. E. (1940). Some ciliates from Tortugas. Papers from the Tortugas Laboratory, 32, 179221. [Google Scholar], Holosticha heterofoissneri Hu & Song, 2001 Hu, X., & Song, W. (2001). Morphology and morphogenesis of Holosticha heterofoissneri n. sp. from the Yellow Sea, China (Ciliophora, Hypotrichida). Hydrobiologia, 448, 171179. doi:10.1023/A:1017553406031.[Crossref], [Web of Science ®] [Google Scholar], and Holosticha cf. heterofoissneri. The dorsal morphogenesis of Uncinata gigantea shows de novo formation of two groups of anlagen near the marginal rows. Holosticha cf. heterofoissneri demonstrates fragmentation of the first dorsal kinety anlage as in Holosticha heterofoissneri. Our population of H. heterofoissneri corresponds well with previously described populations in terms of its general morphology and ciliary pattern. Uncinata gigantea can be recognized by its large and highly contractile body, yellowish to brownish cell colour, two types of cortical granules, and 20–30 transversely oriented and densely arranged cirri in the left marginal row, which often overlie the buccal vertex. Based on the new data, especially infraciliature, the genus Uncinata is here redefined. Both the morphology and phylogenetic analyses suggest that the genus Uncinata should be classified within the family Urostylidae. In addition, both morphological and morphogenetic data suggest that Holosticha bradburyae Gong et al., 2001 Gong, J., Song, W., Hu, X., Ma, H., & Zhu, M. (2001). Morphology and infraciliature of Holosticha bradburyae n. sp. (Ciliophora, Hypotrichida) from the Yellow Sea, China. Hydrobiologia, 464, 6369. doi:10.1023/A:1013901621439.[Crossref], [Web of Science ®] [Google Scholar] should be transferred to Uncinata as U. bradburyae (Gong et al., 2001 Gong, J., Song, W., Hu, X., Ma, H., & Zhu, M. (2001). Morphology and infraciliature of Holosticha bradburyae n. sp. (Ciliophora, Hypotrichida) from the Yellow Sea, China. Hydrobiologia, 464, 6369. doi:10.1023/A:1013901621439.[Crossref], [Web of Science ®] [Google Scholar]) comb. nov., due to its possession of a characteristically prominent beak-like, leftwards curved projection and the developmental mode of the dorsal kineties. This assignment is supported by the phylogenetic analyses, which placed Uncinata gigantea in a clade with U. bradburyae (Gong et al., 2001 Gong, J., Song, W., Hu, X., Ma, H., & Zhu, M. (2001). Morphology and infraciliature of Holosticha bradburyae n. sp. (Ciliophora, Hypotrichida) from the Yellow Sea, China. Hydrobiologia, 464, 6369. doi:10.1023/A:1013901621439.[Crossref], [Web of Science ®] [Google Scholar]) comb. nov., and revealed only 1.13% (19 bp) difference in their SSU-rDNA gene sequence.  相似文献   
52.
Modena, founded by the Romans (183 BC), has always been conditioned by water in all its urban history. In the city, numerous archaeobotanical investigations have been carried out in order to reconstruct the natural landscape and human–environment interactions over time. During these investigations, four archaeological sites (two Roman and two medieval) have revealed deposits with a marked character of palaeobiocoenosis, largely resulting from the natural environment surrounding the sites, due to natural “seed rain”. These deposits are characterized by widespread evidence of plants related to water, constituting a valuable archive to investigate habitats which currently have become very rare and threatened, if they have not completely disappeared. The present paper aims to reveal the peculiarities of the Roman/medieval archaeocarpological floristic lists (through a comparison with the flora over the last two centuries in the area of Modena) and highlight the possible causes explaining the presence or the demise of several taxa, considering also the palaeoecological reconstruction of the environment in which they have been found.  相似文献   
53.
ABSTRACT

Palynological investigations in the garden of the “Casa delle Nozze di Ercole ed Ebe“ in Pompeii revealed the presence of Vitis and Citrus. Citrus has often been said to be cultivated in Roman times, but no plant remains have ever confirmed this hypothesis as regards Pompeii. In this paper, we give evidence for an early cultivation of this plant in a garden. Analyses revealed that, as already observed in other gardens, the ground was covered by herbs which were the same as those found in ancient and contemporary meadows of the Vesuvian area.  相似文献   
54.
Phenotypic integration and plasticity are central to our understanding of how complex phenotypic traits evolve. Evolutionary change in complex quantitative traits can be predicted using the multivariate breeders’ equation, but such predictions are only accurate if the matrices involved are stable over evolutionary time. Recent study, however, suggests that these matrices are temporally plastic, spatially variable and themselves evolvable. The data available on phenotypic variance‐covariance matrix ( P ) stability are sparse, and largely focused on morphological traits. Here, we compared P for the structure of the complex sexual advertisement call of six divergent allopatric populations of the Australian black field cricket, Teleogryllus commodus. We measured a subset of calls from wild‐caught crickets from each of the populations and then a second subset after rearing crickets under common‐garden conditions for three generations. In a second experiment, crickets from each population were reared in the laboratory on high‐ and low‐nutrient diets and their calls recorded. In both experiments, we estimated P for call traits and used multiple methods to compare them statistically (Flury hierarchy, geometric subspace comparisons and random skewers). Despite considerable variation in means and variances of individual call traits, the structure of P was largely conserved among populations, across generations and between our rearing diets. Our finding that P remains largely stable, among populations and between environmental conditions, suggests that selection has preserved the structure of call traits in order that they can function as an integrated unit.  相似文献   
55.
Altitudinal gradients offer valuable study systems to investigate how adaptive genetic diversity is distributed within and between natural populations and which factors promote or prevent adaptive differentiation. The environmental clines along altitudinal gradients tend to be steep relative to the dispersal distance of many organisms, providing an opportunity to study the joint effects of divergent natural selection and gene flow. Temperature is one variable showing consistent altitudinal changes, and altitudinal gradients can therefore provide spatial surrogates for some of the changes anticipated under climate change. Here, we investigate the extent and patterns of adaptive divergence in animal populations along altitudinal gradients by surveying the literature for (i) studies on phenotypic variation assessed under common garden or reciprocal transplant designs and (ii) studies looking for signatures of divergent selection at the molecular level. Phenotypic data show that significant between‐population differences are common and taxonomically widespread, involving traits such as mass, wing size, tolerance to thermal extremes and melanization. Several lines of evidence suggest that some of the observed differences are adaptively relevant, but rigorous tests of local adaptation or the link between specific phenotypes and fitness are sorely lacking. Evidence for a role of altitudinal adaptation also exists for a number of candidate genes, most prominently haemoglobin, and for anonymous molecular markers. Novel genomic approaches may provide valuable tools for studying adaptive diversity, also in species that are not amenable to experimentation.  相似文献   
56.
滇西北高原湿地景观变化与人为、自然因子的相关性   总被引:4,自引:0,他引:4  
人为活动的干扰与自然因子的变化共同作用于湿地生态系统,但两者对湿地生态系统作用的贡献率存在差异,目前尚缺乏进一步的研究。本研究基于面向对象分割和目视解译相结合的技术方法,研究了滇西北高原典型湿地纳帕海汇水区内28年来(1987—2015年)的湿地类型、分布及其空间格局的变化特征,并探讨其与当地人为活动的干扰(主要社会经济发展指标)、自然因子(主要气候因子)之间的相互关系。结果表明:(1)湿地总面积共计减少2456.46 hm~2,其中,原生沼泽、沼泽化草甸和草甸面积分别减少了1152.07,1257.72,202.74 hm~2,湖泊面积增加了156.07 hm~2;(2)湿地景观多样性发生显著变化,其中,斑块数量(NP)由1987年的221增加到2005年的299,随后减少到2015年的260;香农多样性指数(SHDI)由1987年的1.81增加到1999年的1.84,随后减少到2015年的1.75;聚集度指数(contagion index)由1987年的52.82减少到1999年的52.02,随后增加到2015年的53.49;(3)湿地分布面积和香农多样性指数与第一、二、三产业值,以及年均温度呈负相关,与降水量呈正相关;斑块数量、聚集度指数均与第一、二、三产业值,以及年均温度呈正相关,与降水量呈负相关;(4)社会经济发展主要指标对湿地面积和景观多样性指数变化的解释度为63.50%,气候因子对其的解释度为36.50%。整体上,人为活动的干扰是导致该区域湿地不断萎缩、景观多样性改变的关键驱动力。减缓人为活动对湿地生态系统的过度影响,是当地保护湿地资源、维护湿地生态功能的关键。  相似文献   
57.
邓晔也  王春连 《生态学报》2019,39(16):5988-6000
城市湿地公园是城市水环境保护和市民活动的共同载体。如何达到保护城市水环境和满足使用者社会需求的平衡是本研究的关键问题。以景观绩效评价为基础,对宜昌运河公园的社会绩效进行了详细量化,并在调查结果上分析研究了影响城市湿地公园使用者评价的原因,以及在城市湿地公园内使用者的行为偏好和季节变化下使用者满意度和行为模式的变化情况,并提出了设计建议。结果表明,城市湿地公园的水环境治理目标与城市居民的公园服务需求是统一的。但是在公园生态和社会效益之间还是存在着冲突关系,如湿地面积和活动空间面积的权衡,消减河流污染物和维持公园水景质量的权衡以及湿地生境冬季景观效果不佳降低使用者满意度的情况。  相似文献   
58.
雄安新区白洋淀生态属性辨析及生态修复保护研究   总被引:6,自引:0,他引:6  
刘俊国  赵丹丹  叶斌 《生态学报》2019,39(9):3019-3025
湿地是自然界生物多样性最丰富的生态系统之一,与社会发展和人类福祉息息相关。近年来,由于全球气候变化和人类活动的过度干扰,湿地正面临着面积萎缩、功能减弱、多样性降低等诸多问题,湿地退化已经成为制约区域可持续性发展的重大阻碍。伴随着生态文明建设逐渐成为中国特色社会主义建设的重要支柱,湿地生态修复工作得到前所未有的制度保障。深入剖析湿地属性,结合政策保障,有针对性的提出湿地保护与修复的治理措施,对区域的生态环境建设和可持续性发展具有重要意义。选择国家级新区-雄安新区的水命脉-白洋淀湿地为研究对象,在深入剖析其生态属性和已存在的生态问题的基础上,结合生态修复的原则、方法和步骤,提出生态修复与保护的可行性策略。研究结果表明,白洋淀本质是典型的湖泊湿地,同时兼具沼泽湿地特征,由于人类活动的剧烈干扰,白洋淀有向沼泽湿地逆向演替的变化趋势。湿地内存在面积萎缩、水资源量短缺、水环境污染问题突出及生物多样性减少等生态问题。本研究建议:为顺利建设雄安新区,首先,白洋淀湿地在算清"水账"、"污账"和"生态账"的前提下,进一步加强流域水资源调配,科学确定白洋淀湿地最佳水位,恢复淀区水量;其次,通过使用清洁生产技术和限制高排污企业建设等措施,加强污染防治,恢复湿地水质;最后,依据生态承载力理论,划分白洋淀流域的生态功能红线、环境质量红线和资源利用红线等国家生态保护红线体系,为尽快恢复湿地结构与功能提供制度保障。  相似文献   
59.
采用静态箱-气相色谱法,于2016年6—11月连续观测辽河口芦苇湿地、翅碱蓬湿地和裸滩湿地的CH_4排放速率,同时测定温度、氧化还原电位(Eh)、pH值和电导率(EC)等相关环境因子的动态变化。结果表明,3种类型湿地的CH_4排放具有明显的季节变化特征,均呈先上升后下降趋势。芦苇湿地、翅碱蓬湿地(涨潮前)和裸滩湿地(涨潮前)CH_4排放通量变化范围分别为0.447—10.40、0.045—0.509 mg m~(-2) h~(-1)和0.016—0.593 mg m~(-2) h~(-1),观测期内排放通量均值相应为(3.699±3.679)、(0.165±0.156) mg m~(-2) h~(-1)和(0.198±0.191) mg m~(-2) h~(-1),不同类型湿地之间差异显著(P0.01),芦苇湿地裸滩湿地(涨潮前)翅碱蓬湿地(涨潮前)。涨潮过程中,翅碱蓬湿地和裸滩湿地的排放速率分别变化在0.009—0.353 mg m~(-2) h~(-1)和0.018—0.335 mg m~(-2) h~(-1),观测期间其排放速率均值分别为(0.119±0.132) mg m~(-2) h~(-1)和(0.131±0.103) mg m~(-2) h~(-1),明显低于涨潮前(P0.01)。不同湿地类型间CH_4排放通量与电导率(EC)呈显著负相关(P0.01)。研究结果表明,潮汐和电导率均为影响辽河口不同类型湿地中CH_4排放的关键因子。  相似文献   
60.
该研究以中国古老月季品种‘月月粉’(Rosa chinensis‘Old Blush’)为试材,根据拟南芥和草莓FT/TFL1基因家族成员的保守结构域设计引物,对‘月月粉’基因组DNA进行克隆和测序,结合数据库序列和双单倍体基因组信息进行序列比对,结果共获得了8条月季的FT/TFL1基因家族序列,且8条序列分别注释为2个FT基因(RcFT1和RcFT2)、1个BFT基因(RcBFT)、1个ATC基因(RcATC)、2个MFT基因(RcMFT1和RcMFT2)和2个PEBP基因(PEBP1和PEBP2);进化树分析结果将这8个基因分为3个亚组;结构分析显示8个基因的内含子为1~5个不等。qRT-PCR分析显示,RcFT1、RcPEBP、RcMFT1、RcMFT2和RcBFT在‘月月粉’的叶片中表达量最高,茎尖中次之;RcFT2在茎尖中的表达最高,叶片中次之;RcATC在茎尖中的表达量高于其他组织;除RcPEBP在根组织中有表达外,其他基因在根组织中几乎没有检测到。进一步表达分析显示,RcFT1和RcFT2在‘无刺光叶蔷薇’(R.wichuriana‘Basye’s Thornless')生殖生长期的叶片、茎尖中的表达量显著高于营养生长期。研究推测,具有连续开花性状的中国古老月季‘月月粉’可能具有多个开花时间(FT)基因位点,FT有可能可以作为月季生殖转换的标记基因。  相似文献   
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