Wild yaks(Bos mutus)ranged across the Tibetan Plateau in large herds before being forced to remote areas of the plateau.Consequently,little has been published about their behavioral ecology.We present the first extens...Wild yaks(Bos mutus)ranged across the Tibetan Plateau in large herds before being forced to remote areas of the plateau.Consequently,little has been published about their behavioral ecology.We present the first extensive study on wild yak behavior during the rut.We gathered data on activity budgets,aggressive/sexual behaviors,and the behavior of bulls inside and outside mixed groups during 11 days in 2010 and 9 days in 2011.Yaks ate less and were more social during the rut than during summer.Males ate less than females and socialized more during the rut.We observed yaks for 234.25 h and recorded 2,078 aggressive/sexual behaviors.Yak bulls inspected and tended cows showing off their profiles during lateral displays,the most common type of indirect aggression.Yak bulls inside mixed sex groups rested less and socialized more than bulls outside.Females initiated intense intra-sexual competition and led at least 25 bulls on chases.Females then incited fight frenzies of numerous bulls from inside and outside the groups before copulations,and fights could be intense.We discuss female choice selecting for large size and fighting ability in males,the similarity of yak and bison(genus Bison)behavior,and conservation implications.展开更多
As weapon system effectiveness is affected by many factors,its evaluation is essentially a multi-criterion decision making problem for its complexity.The evaluation model of the effectiveness is established on the bas...As weapon system effectiveness is affected by many factors,its evaluation is essentially a multi-criterion decision making problem for its complexity.The evaluation model of the effectiveness is established on the basis of metrics architecture of the effectiveness.The Bayesian network,which is used to evaluate the effectiveness,is established based on the metrics architecture and the evaluation models.For getting the weights of the metrics by Bayesian network,subjective initial values of the weights are given,gradient ascent algorithm is adopted,and the reasonable values of the weights are achieved.And then the effectiveness of every weapon system project is gained.The weapon system,whose effectiveness is relative maximum,is the optimization system.The research result shows that this method can solve the problem of AHP method which evaluation results are not compatible to the practice results and overcome the shortcoming of neural network in multilayer and multi-criterion decision.The method offers a new approach for evaluating the effectiveness.展开更多
During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive suc...During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing fishes in the Poecilia mexicana-species complex inhabit not only regular freshwater environments, but also independently colonized sulfidic （H2S-containing） habitats in three river drainages. In the current study, we found fighting intensities in staged contests to be considerably lower in some but not all sulfidic surface ecotypes and the sulfidic cave ecotype compared with populations from non-sulfidic surface sites. This is perhaps due to selection imposed by H2S, which hampers oxygen uptake and transport, as well as cellular respiration. Furthermore, migrants from sulfidic habitats may lose fights even if they do not show overall reduced aggressiveness, as phys- iological performance is likely to be challenged in the non-sulfidic environment to which they are not adapted. To test this hypothesis, we simulated migration of H2S-adapted males into H2S-free waters, as well as H2S-adapted cave-dwelling males into sulfidic surface waters. We found that intruders established dominance less often than resident males, independent of whether or not they showed reduced aggressiveness overall. Our study shows that divergent evolution of male aggressive behavior may also contribute to the maintenance of genetic differentiation in this system and we call for more careful evaluation of male fighting abilities in studies on ecological speciation.展开更多
文摘Wild yaks(Bos mutus)ranged across the Tibetan Plateau in large herds before being forced to remote areas of the plateau.Consequently,little has been published about their behavioral ecology.We present the first extensive study on wild yak behavior during the rut.We gathered data on activity budgets,aggressive/sexual behaviors,and the behavior of bulls inside and outside mixed groups during 11 days in 2010 and 9 days in 2011.Yaks ate less and were more social during the rut than during summer.Males ate less than females and socialized more during the rut.We observed yaks for 234.25 h and recorded 2,078 aggressive/sexual behaviors.Yak bulls inspected and tended cows showing off their profiles during lateral displays,the most common type of indirect aggression.Yak bulls inside mixed sex groups rested less and socialized more than bulls outside.Females initiated intense intra-sexual competition and led at least 25 bulls on chases.Females then incited fight frenzies of numerous bulls from inside and outside the groups before copulations,and fights could be intense.We discuss female choice selecting for large size and fighting ability in males,the similarity of yak and bison(genus Bison)behavior,and conservation implications.
文摘As weapon system effectiveness is affected by many factors,its evaluation is essentially a multi-criterion decision making problem for its complexity.The evaluation model of the effectiveness is established on the basis of metrics architecture of the effectiveness.The Bayesian network,which is used to evaluate the effectiveness,is established based on the metrics architecture and the evaluation models.For getting the weights of the metrics by Bayesian network,subjective initial values of the weights are given,gradient ascent algorithm is adopted,and the reasonable values of the weights are achieved.And then the effectiveness of every weapon system project is gained.The weapon system,whose effectiveness is relative maximum,is the optimization system.The research result shows that this method can solve the problem of AHP method which evaluation results are not compatible to the practice results and overcome the shortcoming of neural network in multilayer and multi-criterion decision.The method offers a new approach for evaluating the effectiveness.
文摘During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing fishes in the Poecilia mexicana-species complex inhabit not only regular freshwater environments, but also independently colonized sulfidic （H2S-containing） habitats in three river drainages. In the current study, we found fighting intensities in staged contests to be considerably lower in some but not all sulfidic surface ecotypes and the sulfidic cave ecotype compared with populations from non-sulfidic surface sites. This is perhaps due to selection imposed by H2S, which hampers oxygen uptake and transport, as well as cellular respiration. Furthermore, migrants from sulfidic habitats may lose fights even if they do not show overall reduced aggressiveness, as phys- iological performance is likely to be challenged in the non-sulfidic environment to which they are not adapted. To test this hypothesis, we simulated migration of H2S-adapted males into H2S-free waters, as well as H2S-adapted cave-dwelling males into sulfidic surface waters. We found that intruders established dominance less often than resident males, independent of whether or not they showed reduced aggressiveness overall. Our study shows that divergent evolution of male aggressive behavior may also contribute to the maintenance of genetic differentiation in this system and we call for more careful evaluation of male fighting abilities in studies on ecological speciation.
