Microbial diversity and structure in the gastrointestinal tracts of two stranded short-finned pilot whales(Globicephala macrorhynchus)and a pygmy sperm whale(Kogia breviceps)

Information on the gut microbiome composition of different mammals could provide novel insights into the evolution of mammals and succession of microbial communities in different hosts.However,there is limited information on the gut microbiome composition of marine mammals,especially cetaceans because of sampling constraints.In this study,we investigated the diversity and composition of microbial communities in the stomach,midgut,and hindgut of 2 stranded short-finned pilot whales(Globicephala macrorhynchus)and hindgut of a stranded pygmy sperm whale(Kogia breviceps)by using 16S rRNA gene amplicon sequencing technology.On the basis of the 50 most abundant operational taxonomic units,principal coordinate analysis,and non-metric multidimensional scaling analysis,we confirmed that the gut microbial communities of the 3 whales were different.Our results revealed that the gut microbiome of 1 stranded short-finned pilot whale GM16 was dominated by Firmicutes(mainly Clostridium)and Fusobacteria;whereas that of the other pilot whale GM19 was composed of Gammaproteobacteria and Bacteroidetes(mainly Vibrio and Bacteroides,respectively),probably caused by intestinal disease and antibiotic treatment.The gut microbiome of the pygmy sperm whale was dominated by Firmicutes and Bacteroidetes.Moreover,different gastrointestinal tract regions harbored different microbial community structures.To our knowledge,this is the first report of the gut microbiome of short-finned pilot whales,and our findings will expand our current knowledge on microbial diversity and composition in the gastrointestinal tract of cetaceans.

小抹香鲸回声定位信号高指向性发声机理

齿鲸回声定位信号具有高频高指向性特性,使其能够精确感知水中目标,是现代声纳模仿的对象。本文通过分析小抹香鲸Kogia breviceps头部的几何结构与组织特性,采用双曲正割折射率材料模拟声速连续变化的额隆,并利用双曲正割折射率材料的最外侧声线轨迹对额隆的轮廓进行建模。在频域与时域两种模式下,应用有限元方法对仿真模型的远场指向性展开了分析,结果表明,点源经过具有双曲正割梯度折射率的额隆后在开口处形成了平面波,即额隆起到了准直的作用。通过对远场声压值分区域相关性分析表明,额隆的准直作用是形成较窄主瓣的主要原因,气囊和头骨则主要起到抑制旁瓣的作用。

制造奴隶的母蚁

在蚂蚁界生活的某些角落里，充满一侵袭、凶杀和“人质”扣押。这种激烈争斗乃是群居寄生的一种形态。

大而显著的苞片影响了笋兰的繁殖成功

在被子植物中,多样的花部特征是为了适应各种选择压力和生态功能。到目前为止,对兰科植物花部特征的生态功能研究主要集中在唇瓣,而从未有对苞片的研究。本研究以一种熊蜂授粉并且提供花蜜报酬的地生或附生兰科植物笋兰(Thunia alba)为研究材料,其大而显著形似舟状的苞片包裹着花蜜距和花梗。我们猜想显著的大苞片能够保护蜜距,抵御盗蜜者。为了验证这一假设,我们通过实验去除苞片,记录传粉者和盗蜜者访花行为的变化,并评估了它们对笋兰繁殖成功的影响。研究结果表明,当苞片被去除后,唯一的传粉者短头熊蜂(Bombus breviceps)转变为盗蜜者,并且被盗蜜的花的比例也显著增加。无论是花苞片被去除的处理组还是未处理的对照组,笋兰都是受传粉者限制的。去除苞片对传粉者的访花频率并没有影响,但是显著降低了笋兰雄性和雌性的繁殖成功率。本研究表明,在复杂的授粉限制的环境压力下,大而显著的苞片可以防止花被盗蜜者盗蜜从而提高笋兰的整体适合度。