Predation risks have been hypothesized to influence spawning behaviors of coral reef fishes that broadcast gametes pelagically. The duration of spawning ascents of 13 species were measured from video footage at a sing...Predation risks have been hypothesized to influence spawning behaviors of coral reef fishes that broadcast gametes pelagically. The duration of spawning ascents of 13 species were measured from video footage at a single spawning site for mul- tiple coral reef fishes to investigate ff this behavior was influenced by varying risks of predation. Fishes that spawned in pairs had as- cents of longer duration than group-spawning species. Duration of spawning ascents did not vary between fishes spawning at daytime and dusk, nor between group-spawning species with specific anti-predatory morphological adaptations. These results indicate that risk of predation may not significantly influence the duration of spawning ascents of pair spawning reef fishes at our study site, while group-spawning behaviors are influenced by predation. Avoidance of egg predation by benthic organisms and female mate choice are more likely to influence the pelagic spawning behaviors of all fishes observed [Current Zoology 58 （1）： 95-102, 2012].展开更多
Starting from the postulate that formation of heterosexual unions is necessarily affected by a numerical imbalance between the sexes in the marriage market,this paper uses data from a survey conducted in 2014-2015 in ...Starting from the postulate that formation of heterosexual unions is necessarily affected by a numerical imbalance between the sexes in the marriage market,this paper uses data from a survey conducted in 2014-2015 in three rural counties of Shaanxi,China,to analyse the mechanisms to cope with this rather particular socio-demographic situation and with the poverty that is endemic in the survey area,in order to achieve marriage by any means.This empirical study based on individual quantitative data analyses the consequences of the male marriage-squeeze from the point of view of married men.The difficulty of getting married is identified and taken into account to analyse three specific adaptation mechanisms:demographic adaptations,changes in social norms regarding mate selection criteria,and economic adaptations.Findings demonstrate that marriage timing and age gap between spouses are levers that enable men to enlarge their pool of potential mates.But monetization of marriage is one of the most immediate consequences of the competition between the men seeking to marry.In sum,the men who reported difficulties getting married did so later than the other men,have greater age-gap with their spouse,and are in a disadvantaged position when negotiating the terms of their marriage.We conclude that the male marriage-squeeze has to be understood not only in relation to how marriage is constructed as a family and social institution,but also as a catalyst for other inequalities,especially in terms of social and economic capital.展开更多
文摘Predation risks have been hypothesized to influence spawning behaviors of coral reef fishes that broadcast gametes pelagically. The duration of spawning ascents of 13 species were measured from video footage at a single spawning site for mul- tiple coral reef fishes to investigate ff this behavior was influenced by varying risks of predation. Fishes that spawned in pairs had as- cents of longer duration than group-spawning species. Duration of spawning ascents did not vary between fishes spawning at daytime and dusk, nor between group-spawning species with specific anti-predatory morphological adaptations. These results indicate that risk of predation may not significantly influence the duration of spawning ascents of pair spawning reef fishes at our study site, while group-spawning behaviors are influenced by predation. Avoidance of egg predation by benthic organisms and female mate choice are more likely to influence the pelagic spawning behaviors of all fishes observed [Current Zoology 58 （1）： 95-102, 2012].
文摘Starting from the postulate that formation of heterosexual unions is necessarily affected by a numerical imbalance between the sexes in the marriage market,this paper uses data from a survey conducted in 2014-2015 in three rural counties of Shaanxi,China,to analyse the mechanisms to cope with this rather particular socio-demographic situation and with the poverty that is endemic in the survey area,in order to achieve marriage by any means.This empirical study based on individual quantitative data analyses the consequences of the male marriage-squeeze from the point of view of married men.The difficulty of getting married is identified and taken into account to analyse three specific adaptation mechanisms:demographic adaptations,changes in social norms regarding mate selection criteria,and economic adaptations.Findings demonstrate that marriage timing and age gap between spouses are levers that enable men to enlarge their pool of potential mates.But monetization of marriage is one of the most immediate consequences of the competition between the men seeking to marry.In sum,the men who reported difficulties getting married did so later than the other men,have greater age-gap with their spouse,and are in a disadvantaged position when negotiating the terms of their marriage.We conclude that the male marriage-squeeze has to be understood not only in relation to how marriage is constructed as a family and social institution,but also as a catalyst for other inequalities,especially in terms of social and economic capital.
