Why cuckoos remove host eggs: Biting eggs facilitates faster parasitic egg‐laying

Brood parasitism by cuckoos relies on manipulating hosts to raise their offspring and has evolved stunning adaptations to aid in their deception. The fact that cuckoos usually but not always, remove one or two host eggs while laying their eggs has been a longstanding focus of intensive research. However, the benefit of this behavior remains elusive. Moreover, the recently proposed help delivery hypothesis, predicting that egg removal by cuckoos may decrease the egg‐laying duration in the parasitism process caused by biting action, lacks experimental verification. Therefore, in this study, we examined the effects of egg removal/biting on the egg‐laying speed in the common cuckoo (Cuculus canorus) to experimentally test this hypothesis. We compared the duration of cuckoo egg‐laying in empty nests, nests with host eggs, and nests with artificial blue stick models to test whether cuckoos biting an egg/stick can significantly hasten the egg‐laying speed than no biting action. Our results showed that biting an egg or an object is associated with cuckoos laying approximately 37% faster than when they do not bite an egg or an object. This study provides the first experimental evidence for the help delivery hypothesis and demonstrates that when cuckoos bite eggs or other objects in the nest, they lay eggs more quickly and thereby avoid suffering the hosts' injurious attack

Regional Geological Survey of Hanggai, Xianxia and Chuancun, Zhejiang Province in China

This Open Access book introduces readers to the regional geology of Hanggai, Xianxia and Chuancun, the area between China's northern Zhejiang Province and southern Anhui Province and explores the strata, magmatic rocks and tectonic structures in 1:50,000 scale geological maps. Based on studies of multiple stratigraphic divisions, the standard stratigraphic section of the upper Ordovician Hirnantian in the lower Yangtze region is established, revealing for the first time numerous “Burgess Shale-type” sponge fossils in Hirnantian strata and identifying 10 grapholite fossil belts and various fossil categories, including chitin, trilobites, gastropods, brachiopods, and cephalopods. Moreover, the book identifies for the first time Late Ordovician volcanic events in northern Zhejiang province. The work represents a major contribution to research on Paleozoic strata in the Lower Yangtze region, and sheds new light on understanding the Hirnantian glacial event and biological extinction event in South China by providing a high-precision time scale. In addition, the book opens an important avenue for future research on sponge evolution after the Cambrian life explosion. As such, it offers a unique and valuable asset for researchers and graduate students alike

Umpolung Reactivity of Indole through Gold Catalysis

The 3-position of indole is highly electron rich and typically functions as the primary nucleophilic site that reacts with a large array of electrophiles, thereby leading to various functionalized indoles. [1] The reversal of this prime reactivity, that is, making the 3-position of indole electrophilic, would be of significant synthetic utility and provide a complementary strategy to access derivatives [2] otherwise difficult to prepare conventionally. This umpolung [3] reactivity of indole has, however, only been realized in a limited number of cases. [4] For the past few years we have engaged in extensive studies of gold-catalyzed intra- [5] and intermolecular [6] alkyne oxidations using oxygen-delivering oxidants, [7] wherein reac- tive a -oxo gold carbene intermediates are presumably generated [8] and responsible for the diverse reaction out- comes. Lately we extended this strategy to the use of nitrene precursors as oxidants, thus providing access to reactive a - imino gold carbenes (Scheme 1a); [9] however, the chemistry has so far been limited to ynamides, [10] which are activated alkynes. In our effort to expand the scope of this type of gold- catalyzed nitrene transfer, [11] we decided to use an azido group as a nitrene precursor, a choice that was inspired by previous studies of gold- [12] and platinum-catalyzed [13] pyrrole synthesis. We reasoned that closely and rigidly positioned C C bonds in ortho -azidoarylalkynes might facilitate an intramolecular nitrene transfer from the azido group. Importantly, the thus- formed gold carbene B would serve as an electrophilic indole equivalent, as depicted in its resonance form C , thereby realizing umpolung reactivity of the 3-position of indole (Scheme 1b)

Green economic efficiency in the Yangtze River Delta: spatiotemporal evolution and influencing factors

Based on economic-social-resource-environment perspective, which people’s welfare was considered compared with the traditional perspective, using SSU and PP model, spatial analysis method, spatial econometric model to study green economy efficiency (GRE) of 26 Cities in the Yangtze River Delta from 2005 to 2015. The results show the following: Corrected GRE is markedly lower than conventional efficiency; Stage characteristics are obvious of GRE. An overall spatial pattern has emerged of lower efficiency in the east and higher efficiency in the west, and exist clear signs of spatial agglomeration. The spatial Dubin model has abetter fitting effect. The biggest direct effect on local green economic efficiency and spatial spillover effects on nearby areas is proportion of tertiary industry

Egg rejection and egg recognition mechanism in a Chinese Azure-winged Magpie (Cyanopica cyanus) population

Recognition and rejection of foreign eggs are effective defense of hosts against brood parasitism. However, brood parasitism can impose various selection pressures on different geographic populations of the same host species. In a multiple cuckoo system in China, Azure-winged Magpies (Cyanopica cyanus) are parasitized by both Indian Cuckoos (Cuculus micropterus) and Asian Koels (Eudynamys scolopaceus). In this study, egg recognition ability and recognition mechanism of the Azure-winged Magpie were investigated using a population in Fusong, southeastern Jilin, China. The results showed that 55.6% (20/36) of the Azure-winged Magpies correctly rejected quail (Coturnix japonica) eggs in their nests, while 13.9% (5/36) of the individuals experienced rejection costs by wrongly rejecting their own eggs. Azure-winged Magpies could accurately reject the experimental eggs when the number of such eggs in the nests was the same as that of the magpie eggs. However, Azure-winged Magpies do not recognize and reject conspecific eggs (0/28). The present study indicates that the Azure-winged Magpie has moderate egg recognition ability toward non-mimetic quail eggs and shows a true recognition mechanism with rejecting foreign eggs by accurately recognizing their own eggs. However, they cannot recognize conspecific eggs

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Au-catalyzed synthesis of 2-alkylindoles from N-arylhydroxylamines and terminal alkynes

The first gold-catalyzed addition of N-arylhydroxylamines to aliphatic terminal alkynes is developed to access O-alkenyl-N-arylhydroxylamines, which undergo facile in situ sequential 3,3-rearrangements and cyclodehydrations to afford 2-alkylindoles with regiospecificity and under exceptionally mild reaction conditions

Data from: How cuckoos find and choose host nests for parasitism

How cuckoos find the nests of their hosts and choose nests with respect to egg phenotype for parasitism is a long-standing puzzle that has so far not been solved. We recently developed an experimental design to shed light on this mystery by studying the egg-laying behavior of common cuckoos (Cuculus canorus) in nests of its Oriental reed warbler (Acrocephalus orientalis) host. Our results showed that common cuckoos only parasitized host nests with host activities but ignored the egg phenotypes in the nests. Furthermore, cuckoos distinguished between nest types of black-browed reed warbler (Acrocephalus bistrigiceps) and Oriential reed warbler and chose to parasitize the latter. This study provides strong evidence for host activities being a prime factor affecting cuckoo parasitism. Cuckoos must first locate the general site of host nests from activities by the host and then target the nests for parasitism. These observations reject the optimal egg-laying hypothesis stating that cuckoos are capable of choosing to lay eggs in host nests with visually matching egg phenotypes. Therefore, our studies challenge the idea that cuckoos recognize eggs that match their own

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Value Assessment of Artificial Wetland Derived from Mining Subsided Lake: A Case Study of Jiuli Lake Wetland in Xuzhou

Mining subsided lakes are major obstacles for ecological restoration and resource reuse in mining regions. Transforming mining subsided lakes into artificial wetlands is an ecological restoration approach that has been attempted in China in recent years, but a value assessment of the approach still needs systematic research. This paper considers Jiuli Lake wetland, an artificial wetland derived from restoration of a mining subsided lake in plain area, as a case study. A value assessment model for the artificial wetland was established based on cost–benefit analysis by means of field monitoring, social surveys, GIS geostatistics, raster calculation methods, etc. Empirical analysis and calculations were performed on the case study region. The following conclusions were drawn: (1) after ecological restoration, ecosystem services of Jiuli Lake wetland which has become a national level wetland park yield positive values; (2) the improved environment of the Jiuli Lake wetland has a spillover effect on the price of surrounding land, resulting in land price appreciation; (3) using GIS geostatistics and raster calculation methods, the impact range, strength, and value of the spillover effect can be explicitly measured; (4) through the establishment of a value assessment model of the artificial wetland, incomes of the ecological restoration was found to be sufficient to cover the implementation costs, which provides a research foundation for economic feasibility of ecological restoration of mining subsided lakes