The fourth wave science and technology revolution is quickly ushering in a worldwide military revolution.The major powers such as the United States,Russia and China are all striving to catch up with the wave by accele...The fourth wave science and technology revolution is quickly ushering in a worldwide military revolution.The major powers such as the United States,Russia and China are all striving to catch up with the wave by accelerating their own research on new military technology and the deployment of new military equipment.This presents significant changes to the international security system:the existing disarmament and arms control system is on the brink of collapse,strategic competition among the big powers has intensified,and the risk of global turbulence is on the rise.The future of international security and its mechanism depends both on the method and direction of the technology revolution,and on the ability of the big powers to put aside their differences and avoid conflict in the major arenas of competition.In this process,China should seek to play a bigger and more constructive role.This would not only be conducive to world peace and development,but is also the only way for China to secure a seat in the future international system.展开更多
Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when...Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when the host“wins”the coevolutionary arms race.By recreating bygone species interactions,using artificial parasitism experiments,lingering defensive behaviors that evolved in the context of parasitism can be understood and may even be used to identify the unknown agent of parasitism past.Here we present the first study of this type by evaluating lingering“frontline”nest defenses that have evolved to prevent egg laying in a former brood parasite host.The Australian reed warbler Acrocephalus australis is currently not parasitized but is known to exhibit fine-tuned egg discrimination—a defensive behavior indicative of a past brood parasite–host arms race and common in closely related parasitized species.Here,using 3D-printed models of adult brood parasites,we examined whether the Australian reed warbler also exhibits frontline defenses to adult brood parasites,and whether we could use these defenses to identify the warbler’s“ghost of parasitism past.”Our findings provide evidence that the Australian reed warbler readily engages in frontline defenses that are considered adaptive specifically in the context of brood parasitism.However,individuals were unable to discriminate between adults of different brood parasite species at their nest.Overall,our results demonstrate that despite a relaxation in selection,defenses against brood parasitism can be maintained across multiple stages of the host’s nesting cycle,and further suggest that,in accordance with previous findings,that learning may be important for fine-tuning frontline defense.展开更多
In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races t...In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races termed gentes. Females of each gens specialize in parasitizing a particular host species. More than 20 such gentes are recognized in Europe. Each female Cuckoo lays eggs of constant appearance. Most gentes can be separated based on their distinct egg types, which in many cases mimic those of their hosts. Different gentes may occur in sympatry or may be separated geographically. Some gentes may occur in restricted parts of the host’s distribution area. These patterns raise some fundamental questions like: Why are some passerine species preferred as hosts while others are not? Why does a host population consist of individuals either accepting or rejecting Cuckoo eggs? Why is there marked variation in egg rejection behavior between various host populations? How distinct and host-specialized are Cuckoo gentes? These questions are discussed in relation to existing knowledge and future perspectives.展开更多
文摘The fourth wave science and technology revolution is quickly ushering in a worldwide military revolution.The major powers such as the United States,Russia and China are all striving to catch up with the wave by accelerating their own research on new military technology and the deployment of new military equipment.This presents significant changes to the international security system:the existing disarmament and arms control system is on the brink of collapse,strategic competition among the big powers has intensified,and the risk of global turbulence is on the rise.The future of international security and its mechanism depends both on the method and direction of the technology revolution,and on the ability of the big powers to put aside their differences and avoid conflict in the major arenas of competition.In this process,China should seek to play a bigger and more constructive role.This would not only be conducive to world peace and development,but is also the only way for China to secure a seat in the future international system.
文摘Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when the host“wins”the coevolutionary arms race.By recreating bygone species interactions,using artificial parasitism experiments,lingering defensive behaviors that evolved in the context of parasitism can be understood and may even be used to identify the unknown agent of parasitism past.Here we present the first study of this type by evaluating lingering“frontline”nest defenses that have evolved to prevent egg laying in a former brood parasite host.The Australian reed warbler Acrocephalus australis is currently not parasitized but is known to exhibit fine-tuned egg discrimination—a defensive behavior indicative of a past brood parasite–host arms race and common in closely related parasitized species.Here,using 3D-printed models of adult brood parasites,we examined whether the Australian reed warbler also exhibits frontline defenses to adult brood parasites,and whether we could use these defenses to identify the warbler’s“ghost of parasitism past.”Our findings provide evidence that the Australian reed warbler readily engages in frontline defenses that are considered adaptive specifically in the context of brood parasitism.However,individuals were unable to discriminate between adults of different brood parasite species at their nest.Overall,our results demonstrate that despite a relaxation in selection,defenses against brood parasitism can be maintained across multiple stages of the host’s nesting cycle,and further suggest that,in accordance with previous findings,that learning may be important for fine-tuning frontline defense.
文摘In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races termed gentes. Females of each gens specialize in parasitizing a particular host species. More than 20 such gentes are recognized in Europe. Each female Cuckoo lays eggs of constant appearance. Most gentes can be separated based on their distinct egg types, which in many cases mimic those of their hosts. Different gentes may occur in sympatry or may be separated geographically. Some gentes may occur in restricted parts of the host’s distribution area. These patterns raise some fundamental questions like: Why are some passerine species preferred as hosts while others are not? Why does a host population consist of individuals either accepting or rejecting Cuckoo eggs? Why is there marked variation in egg rejection behavior between various host populations? How distinct and host-specialized are Cuckoo gentes? These questions are discussed in relation to existing knowledge and future perspectives.
