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91.
Junjie Wang Chao Li Jiaqi Chen Jujing Wang Jinjin Jin Shuying Jiang Luobin Yan HungDu Lin Jun Zhao 《Ecology and evolution》2021,11(18):12583
Geological events, landscape features, and climate fluctuations have shaped the distribution of genetic diversity and evolutionary history in freshwater fish, but little attention has been paid to that around the Gulf of Tonkin; therefore, we investigated the phylogeographic structure of the dwarf snakehead (Channa gachua) on Hainan Island and mainland China, as well as two populations in Vietnam. We attempted to elucidate the origins of freshwater fish in South Hainan by incorporating genetic data from DNA markers on both the mitochondrial cytochrome b gene (cyt b) and the nuclear recombination‐activating gene 1 (RAG‐1). Mitochondrial phylogenetic analysis identified two major lineages (lineages A and B), which may represent separate species. Divergence data suggested that C. gachua populations diverged between 0.516 and 2.376 myr. The divergence of the two cryptic species is congruent with sea‐level rise, which subsequently isolated Hainan from the mainland. During the Pleistocene glaciations, the entire region of the Gulf of Tonkin and the Qiongzhou Strait became part of the coastal plain of the Asian continent, which might have resulted in the current distribution patterns and dispersal routes of C. gachua populations. The formation of three sublineages in lineage A indicated that the Gulf of Tonkin was a geographical barrier between Hainan Island and mainland China but not between Vietnam and Hainan Island. The results of this study may help to elucidate the origins of freshwater fish in South Hainan and the phylogeographic structure of C. gachua. 相似文献
92.
93.
Hybrids between native white-spotted charr Salvelinus leucomaenis and non-native brown trout Salmo trutta were identified in streams of Hokkaido, Japan, using both appearance and genetic characters. The DNA analyses indicated that the specimens were hybrids between female S. leucomaenis and male S. trutta . Occurrence of such hybrids implies increased mating opportunities between these species in wild streams. 相似文献
94.
缅甸英雄岛始新世-上新世浮游有孔虫及其古环境意义 总被引:1,自引:0,他引:1
英雄岛位于印度洋缅甸西海岸,前人在该区所做的工作较少,生物地层研究程度较低.围绕该区石油勘探的进行,作者分析了RM19-3-1井的29件钻井岩屑样品,根据所含浮游有孔虫识别出7次有孔虫生物事件.考虑到研究区处于低纬度地区,故采用Bolli和Saunders(1985)的分带标准建立了7个浮游有孔虫化石带:P12-P17带;P18/19-P21/N2带;P22/N3带,N4-N7带;N8-N10带;N11-N14带和N15-N20?带,其延限时代为始新世-上新世.根据所含有孔虫动物群的演替规律,可将研究区的沉积环境变化由下而上划分为6个阶段,总体具有大陆架-陆坡的沉积环境特征. 相似文献
95.
96.
人工林对海南鹦哥岭鸟类多样性的影响 总被引:1,自引:0,他引:1
为了解在天然林中所种植的人工林对鹦哥岭鸟类多样性的影响,于2005年10月~2006年4月,分别采用样带法和雾网法,对海南鹦哥岭的原生林、次生林、人工林及其林缘的鸟类多样性进行了比较研究.野外记录到鸟类102种,其中栗腹矶鸫Monticola rufiventris、橙胸姬鹟Ficedula strophiata和黄雀Carduelis spinus 3种为海南鸟类新纪录.与原生林和次生林相比,人工林及其林缘的鸟类多样性很低,其中人工林最低.人工林不仅对鹦哥岭自然保护区的鸟类多样性具有非常大的负面影响,而且由于人工林的种植使天然林破碎化而产生的林缘与天然林林缘不同,鸟类多样性较低. 相似文献
97.
Non-permineralized or mummified ancient wood found within proglacial soil near the ad Astra Ice Cap (81°N, 76°W), Ellesmere
Island, Canada was investigated to ascertain the identification of the trees, current morphological and chemical characteristics
of the woods and the fungi within them. These woods, identified as Betula, Larix, Picea and Pinus, were found with varying states of physical and chemical degradation. Modern microbial decomposition caused by soft rot fungi
was evident and rDNA sequencing of fungi obtained from the samples revealed several species including Cadophora sp., Exophiala sp., Phialocephala sp., as well as others. Analytical 13C-labeled tetramethylammonium hydroxide thermochemolysis showed the lignin from the ancient wood was in a high degree of preservation
with minor side chain alteration and little to no demethylation or ring hydroxylation. The exposure of these ancient woods
to the young soils, where woody debris is not usually prevalent, provides carbon and nutrients into the polar environment
that are captured and utilized by unique decay fungi at this Arctic site. 相似文献
98.
Michaela Aschan Oleg V. Karamushko Ingvar Byrkjedal Rupert Wienerroither Igor V. Borkin Jørgen S. Christiansen 《Polar Biology》2009,32(7):963-970
The Arctogadus glacialis is endemic to the Arctic Ocean and its apparently disjunct circumpolar distribution range from the Siberian coast through
the Chukchi Sea and the Canadian Arctic to the shelf off NE Greenland. Records of A. glacialis are scarce in the European Arctic and here we present all available and reliable records of the species in the area. Altogether,
296 specimens of A. glacialis are reported from 53 positions in the European Arctic during the period 1976–2008. The specimens were registered off Iceland
and the Jan Mayen Island, northwest and northeast of Svalbard, northeast in the Barents Sea, and south and east off Franz
Josef Land. The additional records show that A. glacialis display a circumpolar and more continuous distribution than described before. In the European Arctic, A. glacialis has been caught at 155–741 m depth with the highest abundance at 300–400 m. We therefore suggest that A. glacialis is more associated to the continental shelves surrounding the Arctic Ocean than previously thought. The length–weight relation
of A. glacialis is similar across the European Arctic. 相似文献
99.
A new diatom genus, Olifantiella gen. nov., has been discovered from the coral reefs of Réunion Island (Western Indian Ocean). This monospecific genus belonging to the Biraphidineae, contains a small, marine taxon, Olifantiella mascarenica sp. nov., which shows close structural similarity with the recently described genus Labellicula Van de Vijver & Lange-Bertalot, but with significant differences: (i) the presence of a remarkable internal tubular process – the buciniportula; (ii) the easily identifiable external funnel-shaped opening of this process; (iii) the design of the external raphe endings; (iv) the general shape of the frustules; and (v) a lateral void and elevated crest. The buciniportula, associated with the other characters, is apparently new, and allows the establishment of a new genus. The morphology of this genus is compared with that of related genera, such as Luticola , Diadesmis , Labellicula, Brachysira , Neidium and Nupela , with some comments on the contribution of scanning electron microscopy towards distinguishing new genera, and the possible superabundance of these new entities, particularly of small diatoms. 相似文献
100.
Pisonia grandis monocultures limit the spread of an invasive ant—a case of carbohydrate quality? 总被引:2,自引:0,他引:2
The mechanisms by which invasive species are able to spread into and dominate natural communities are poorly understood and
remain a focus of invasion research. In this quest, studying invasions that are limited by a controlling factor will be more
informative than will studies documenting unabated spread and impacts. Some ant species are very successful invaders, and
research demonstrating abiotic and biotic factors limiting their success has aided the understanding of invasion ecology.
We report here a study showing the highly invasive African big headed ant Pheidole megacephala having a novel distribution on coral cays within Australia’s Great Barrier Reef. These patterns displayed a clear limitation
of its distribution with monocultures of the tree Pisonia grandis. This distribution was contrary to the known environmental limitations of the ant, and the limitation could not be associated
with an underlying abiotic determinant of the vegetation type. We present these distributional patterns, and following consideration
of all known biotic and abiotic limitations of ant invasions we discuss the potential that the peculiar ecophysiology of P. grandis is the causal factor. Specifically, we suggest that the quality of carbohydrate supply to ants is a limitation to invasive
spread in much the same way that carbohydrate quantity is known to affect ant population densities in other ecosystems. 相似文献