Avian brood parasitism is a model system for studies of coevolution and ecological interactions between parasites and their hosts. However, recent work may have led to misconceptions concerning the Brown-headed Cowbir...Avian brood parasitism is a model system for studies of coevolution and ecological interactions between parasites and their hosts. However, recent work may have led to misconceptions concerning the Brown-headed Cowbird (Molothrus ater), the most widely studied brood parasitic bird in the world, and its effects on host species. Potential misconceptions about this species that could affect management issues are as follows: cowbird populations are increasing; cowbirds are relatively new to North America; recently exposed hosts are defenseless against parasitism; cowbirds have caused widespread declines of songbirds; and cowbird control is always effective in increasing the size of endangered host populations. Potential coevolutionary misconceptions are that cowbirds are typically 'host tolerant'; cowbirds evict host nestmates; and the mafia effect is widespread. It is important to clarify these issues because such misconceptions could hinder our understanding of parasite-host interactions, and thus obscure the direction of basic research and of management efforts taken to limit cowbird impacts on endangered species. We discuss these issues and suggest future research directions to enhance our understanding of this fascinating species.展开更多
Under the highly competitive market economy management system, economic management of Chinese enterprises tends to be diversity. With the continuous development of market economy, enterprises need choose the appropria...Under the highly competitive market economy management system, economic management of Chinese enterprises tends to be diversity. With the continuous development of market economy, enterprises need choose the appropriate management methods according to the actual situation, which is to help enterprises to survive in the highly competitive environment. However, due to a variety of external factors, economic management situation is not optimistic. And it increases their sense of crisis. This article will make a systematic analysis of management strategies as the point of the enterprise management mode and innovation strategy under market economy.展开更多
文摘Avian brood parasitism is a model system for studies of coevolution and ecological interactions between parasites and their hosts. However, recent work may have led to misconceptions concerning the Brown-headed Cowbird (Molothrus ater), the most widely studied brood parasitic bird in the world, and its effects on host species. Potential misconceptions about this species that could affect management issues are as follows: cowbird populations are increasing; cowbirds are relatively new to North America; recently exposed hosts are defenseless against parasitism; cowbirds have caused widespread declines of songbirds; and cowbird control is always effective in increasing the size of endangered host populations. Potential coevolutionary misconceptions are that cowbirds are typically 'host tolerant'; cowbirds evict host nestmates; and the mafia effect is widespread. It is important to clarify these issues because such misconceptions could hinder our understanding of parasite-host interactions, and thus obscure the direction of basic research and of management efforts taken to limit cowbird impacts on endangered species. We discuss these issues and suggest future research directions to enhance our understanding of this fascinating species.
文摘Under the highly competitive market economy management system, economic management of Chinese enterprises tends to be diversity. With the continuous development of market economy, enterprises need choose the appropriate management methods according to the actual situation, which is to help enterprises to survive in the highly competitive environment. However, due to a variety of external factors, economic management situation is not optimistic. And it increases their sense of crisis. This article will make a systematic analysis of management strategies as the point of the enterprise management mode and innovation strategy under market economy.
