The fifteenth- and twentieth-century colonization of the Basin of Mexico by the Great-tailed Grackle (Quiscalus mexicanus)

Historical evidence indicates that Great‐tailed Grackles colonized the Basin of Mexico from the Gulf Coast lowlands in the fifteenth century. They were probably assisted by an intentional introduction, but colonization succeeded because of anthropogenic habitat alterations over the previous two centuries. During the Colonial period, grackles withdrew from the Basin, only to recolonize it in recent decades. This withdrawal was also due probably to changes in land use, including drainage of much of the water from the Basin's lakes.     

Climatic sensitivity of species’ vegetative and reproductive phenology in a Hawaiian montane wet forest

Understanding how tropical tree phenology (i.e., the timing and amount of seed and leaf production) responds to climate is vital for predicting how climate change may alter ecological functioning of tropical forests. We examined the effects of temperature, rainfall, and photosynthetically active radiation (PAR) on seed phenology of four dominant species and community-level leaf phenology in a montane wet forest on the island of Hawaiʻi using monthly data collected over ~ 6 years. We expected that species phenologies would be better explained by variation in temperature and PAR than rainfall because rainfall at this site is not limiting. The best-fit model for all four species included temperature, rainfall, and PAR. For three species, including two foundational species of Hawaiian forests (Acacia koa and Metrosideros polymorpha), seed production declined with increasing maximum temperatures and increased with rainfall. Relationships with PAR were the most variable across all four species. Community-level leaf litterfall decreased with minimum temperatures, increased with rainfall, and showed a peak at PAR of ~ 400 μmol/m²s⁻¹. There was considerable variation in monthly seed and leaf production not explained by climatic factors, and there was some evidence for a mediating effect of daylength. Thus, the impact of future climate change on this forest will depend on how climate change interacts with other factors such as daylength, biotic, and/or evolutionary constraints. Our results nonetheless provide insight into how climate change may affect different species in unique ways with potential consequences for shifts in species distributions and community composition.     

Multiculturalism in crisis: A postmodern perspective on Canada

Using a modified postmodern perspective, Canada's policy of multiculturalism and the emphasis upon ‘unity within diversity’ are related to the theme of globalization and the development of ‘a new world order’. It is argued that Canada is not unique in its efforts to come to terms with the contradictions and conflicts generated by postindustrialism and the realignment of superpowers. Questions of identity, collective self‐determination and the problematic relation between universalism and particularism, in relation to sovereignty, legitimacy, human rights and participation are explored.     

Characterization of tubule and monomer derived from VP4 protein of infectious bursal disease virus

The VP4 protein of infectious bursal disease virus (IBDV) is a serine protease that processes the polyprotein for viral assembly. VP4 has been found to associate primarily with type II IBDV tubules that are 24 nm in diameter. In this study, a chimeric VP4, assigned as HS1VP4, was constructed with a VP4-autocleavage site inserted between the N-terminal His-tag and the VP4 sequence. The results showed that the VP4 forms tubules after the self-cleavage of HS1VP4 when expressed in Escherichia coli. Furthermore, a deletion of 28 amino acids at the C-terminus of VP4 resulted in monomers and dimers instead of tubule formation; mutants of S652A and K692A at active site destroyed the activity. The endopeptidase activity of these monomers and dimers was approximately 12.5 times higher than that of VP4 tubules. Additionally, the formation of tubules inhibited VP4 protease activity, as demonstrated through in vitro assays. The production and characterization of monomers or dimers that have greater endopeptidase activity and protease activity than tubules can provide further insight into VP4 tubule assembly and the regulation of VP4 activity in host cells; this insight will facilitate the development of new anti-IBDV strategies.     

Spatial evaluation of the ecological importance based on GIS for environmental management: A case study in Xingguo county of China

How to assort with the relationship between the urban construction and the maintenance of ecological security is a hot issue during the process of urbanization. The purpose of this study is to identify the key ecological land maintaining ecological security and to put forward some measures for environmental management. Based on the GIS technology, from the view of water security, biodiversity conservation, disaster protection, natural recreation security, and human disturbance, an integrated index is put forward to evaluate the ecological importance of regional space. Then, a GIS-based approach for evaluating ecological importance was created, with Xingguo county of China as a case study. The results show that the area of core eco-space in the study area accounts for 30% of the total area. These areas mainly consist of the core areas of regional river systems, wetlands, nature reserves, forest parks, and scenic spots and the endangered and protected zone of geological hazards. According to the spatial characteristics of ecological importance for different regions, this study proposes some zoning regulations and measures for environmental management.