The minor skeletal variations are very common on the supraorbital margin, and theirnomenclature still remains a problem. In this study, we adopted the term of supraorbltal and m.dialfrontal incisura or foramen as well...The minor skeletal variations are very common on the supraorbital margin, and theirnomenclature still remains a problem. In this study, we adopted the term of supraorbltal and m.dialfrontal incisura or foramen as well as major incisura. We observed 190 cases (118 males. 72females) or unearted modern Chinese adult crania in Xi'an region, and obtained 6 types. Their incisurae were round more than foramina, and the difference of side and sex was analysed. The frequencies or the supraorbital and medial frontal incisura or foramen, and the Percentage of the ratiobetween the number of foramina and incisurae were compared respectively with those of population inother regions. For the first time, the percentage which was also termed supraorbltal and medialfrontal foramen-incisura index was put forwaed. It is or a better statistical value for race and population studies.展开更多
Aggressive behavior when competing for resources is expected to increase as the ratio of competitors-to-resource ratio （CRR） units increases. Females are expected to be more aggressive than males when competing for ...Aggressive behavior when competing for resources is expected to increase as the ratio of competitors-to-resource ratio （CRR） units increases. Females are expected to be more aggressive than males when competing for food when body size is more strongly related to reproductive suc- cess in females than in males, whereas aggression is predicted to decrease under high ambient predation risk by natural selection. Under the risk allocation model, however, individuals under high ambient predation risk are expected to be more aggressive, and forage more in the absence of imminent risk than their low risk counterparts. An interaction between adult sex ratio （i.e., adult males/females）, ambient predation risk （high vs. low）, and sex on intrasexual competition for mates in Trinidadian guppies Poecilia reticulata has been shown. The interaction suggested an increase in aggression rates as CRR increased, except for males from the high predation population. To compare the patterns of competition for food versus mates, we replicated this study by using food patches. We allowed 4 male or 4 female guppies from high and low predation populations to com- pete for 5, 3, or 1 food patches. The foraging rate was higher in a high rather than low ambient pre- dation risk population. Surprisingly, CRR, sex, and population of origin had no effect on aggression rates. Despite other environmental differences between the 2 populations, the effect of ambient predation risk may be a likely explanation for differences in foraging rates. These results highlight the importance for individuals to secure food despite the cost of competition and predation.展开更多
文摘The minor skeletal variations are very common on the supraorbital margin, and theirnomenclature still remains a problem. In this study, we adopted the term of supraorbltal and m.dialfrontal incisura or foramen as well as major incisura. We observed 190 cases (118 males. 72females) or unearted modern Chinese adult crania in Xi'an region, and obtained 6 types. Their incisurae were round more than foramina, and the difference of side and sex was analysed. The frequencies or the supraorbital and medial frontal incisura or foramen, and the Percentage of the ratiobetween the number of foramina and incisurae were compared respectively with those of population inother regions. For the first time, the percentage which was also termed supraorbltal and medialfrontal foramen-incisura index was put forwaed. It is or a better statistical value for race and population studies.
文摘Aggressive behavior when competing for resources is expected to increase as the ratio of competitors-to-resource ratio （CRR） units increases. Females are expected to be more aggressive than males when competing for food when body size is more strongly related to reproductive suc- cess in females than in males, whereas aggression is predicted to decrease under high ambient predation risk by natural selection. Under the risk allocation model, however, individuals under high ambient predation risk are expected to be more aggressive, and forage more in the absence of imminent risk than their low risk counterparts. An interaction between adult sex ratio （i.e., adult males/females）, ambient predation risk （high vs. low）, and sex on intrasexual competition for mates in Trinidadian guppies Poecilia reticulata has been shown. The interaction suggested an increase in aggression rates as CRR increased, except for males from the high predation population. To compare the patterns of competition for food versus mates, we replicated this study by using food patches. We allowed 4 male or 4 female guppies from high and low predation populations to com- pete for 5, 3, or 1 food patches. The foraging rate was higher in a high rather than low ambient pre- dation risk population. Surprisingly, CRR, sex, and population of origin had no effect on aggression rates. Despite other environmental differences between the 2 populations, the effect of ambient predation risk may be a likely explanation for differences in foraging rates. These results highlight the importance for individuals to secure food despite the cost of competition and predation.
