Some rodents gather and store seeds.How many seeds they gather and how they treat those seeds is largely determined by seed traits such as mass,nutrient content,hardness of the seed coat,presence of secondary compound...Some rodents gather and store seeds.How many seeds they gather and how they treat those seeds is largely determined by seed traits such as mass,nutrient content,hardness of the seed coat,presence of secondary compounds,and germination schedule.Through their consumption and dispersal of seeds,rodents act as agents of natural selection on seed traits,and those traits influence how rodents forage.Many seeds that are scatter-hoarded by rodents are pilfered,or stolen,by other rodents,and seed traits also likely influence pilfering rates and seed fates of pilfered seeds.To clarify coevolutionary relationships between rodents and the plants that they disperse,one needs to understand the role of seed traits in rodent foraging decisions.We compared how the seeds of 4 species of plants that are dispersed by scatter-hoarding animals and that differ in value(singleleaf piñon pine,Pinus monophylla;desert peach,Prunus andersonii;antelope bitterbrush,Purshia tridentata;Utah juniper,Juniperus osteosperma)were pilfered and recached by rodents.One hundred artificial caches of the 4 seed species(25 per species)were prepared,and removal by rodents was monitored.Rodents pilfered high-value seeds more rapidly than the other seeds.Desert peach seeds,which contain toxic secondary compounds,were more frequently recached.Relatively low value seeds like Utah juniper and antelope bitterbrush were pil-fered more slowly and were sometimes left at cache sites,and seeds of the latter species were transported shorter distances to new cache sites.The background density of seeds also appeared to influence the relative value of seeds.展开更多
Many studies focus on rodent community pattern and changing at present in the world, but most of them are conducted in small plots. Few studies investigated the rodent community classification and diversity in semi-de...Many studies focus on rodent community pattern and changing at present in the world, but most of them are conducted in small plots. Few studies investigated the rodent community classification and diversity in semi-desert and desert areas at regional scale, although some researchers started to study the change of animal community patterns on a large scale. We investigated rodent communities in desert, non-irrigated farming land and desert steppe of Inner Mongolia, covering an area of 380,000 km2 from May to August in 1988-1993 and in 1998-2003, respectively, in order to reveal the changing characteristics of zonal rodent communities. The community classification and diversity of rodents were analyzed in research areas. The results suggested that the communities could be classified in 9 zonal types. Spermophilus dauricus, Cricetulus longicaudatus and Eutamias sibiricus were dominant species in Community I;Phodopus roborovskii, Cricetulus barabansis and Cricetulus longicaudatus were dominant in Community II;Meriones unguiculatus, Phodopus roborovskii and Cricetulus longicaudatus were dominant in Community III;Allactaga sibirica, Allactaga bullata and Spermophilus dauricus were dominant in Community IV;Allactaga bullata, Dipus sagitta and Meriones unguiculatus were dominant in Community V;Meriones meridianus, Spermophilus dauricus and Allactaga bullata were dominant in Community VI;Allactaga sibirica, Allactaga bullata and Dipus sagitta were dominant in Community VII;Phodopus roborovskii, Dipus sagitta and Allactaga sibirica were dominant in Community VIII;Meriones meridianus, Dipus sagitta and Allactaga sibirica were dominant in Community IX. The community diversity and evenness analysis showed that the edge effect of community, the effect of disturbance and habitat fragmentation and scale effect were significantly correlated with community diversity in the semi-desert and desert regions. The ordinal results of 9 zonal rodent communities were in accordance with the results analyzed with similar community indices, showing the habitat change in the characteristics of the above-mentioned groups.展开更多
文摘Some rodents gather and store seeds.How many seeds they gather and how they treat those seeds is largely determined by seed traits such as mass,nutrient content,hardness of the seed coat,presence of secondary compounds,and germination schedule.Through their consumption and dispersal of seeds,rodents act as agents of natural selection on seed traits,and those traits influence how rodents forage.Many seeds that are scatter-hoarded by rodents are pilfered,or stolen,by other rodents,and seed traits also likely influence pilfering rates and seed fates of pilfered seeds.To clarify coevolutionary relationships between rodents and the plants that they disperse,one needs to understand the role of seed traits in rodent foraging decisions.We compared how the seeds of 4 species of plants that are dispersed by scatter-hoarding animals and that differ in value(singleleaf piñon pine,Pinus monophylla;desert peach,Prunus andersonii;antelope bitterbrush,Purshia tridentata;Utah juniper,Juniperus osteosperma)were pilfered and recached by rodents.One hundred artificial caches of the 4 seed species(25 per species)were prepared,and removal by rodents was monitored.Rodents pilfered high-value seeds more rapidly than the other seeds.Desert peach seeds,which contain toxic secondary compounds,were more frequently recached.Relatively low value seeds like Utah juniper and antelope bitterbrush were pil-fered more slowly and were sometimes left at cache sites,and seeds of the latter species were transported shorter distances to new cache sites.The background density of seeds also appeared to influence the relative value of seeds.
文摘Many studies focus on rodent community pattern and changing at present in the world, but most of them are conducted in small plots. Few studies investigated the rodent community classification and diversity in semi-desert and desert areas at regional scale, although some researchers started to study the change of animal community patterns on a large scale. We investigated rodent communities in desert, non-irrigated farming land and desert steppe of Inner Mongolia, covering an area of 380,000 km2 from May to August in 1988-1993 and in 1998-2003, respectively, in order to reveal the changing characteristics of zonal rodent communities. The community classification and diversity of rodents were analyzed in research areas. The results suggested that the communities could be classified in 9 zonal types. Spermophilus dauricus, Cricetulus longicaudatus and Eutamias sibiricus were dominant species in Community I;Phodopus roborovskii, Cricetulus barabansis and Cricetulus longicaudatus were dominant in Community II;Meriones unguiculatus, Phodopus roborovskii and Cricetulus longicaudatus were dominant in Community III;Allactaga sibirica, Allactaga bullata and Spermophilus dauricus were dominant in Community IV;Allactaga bullata, Dipus sagitta and Meriones unguiculatus were dominant in Community V;Meriones meridianus, Spermophilus dauricus and Allactaga bullata were dominant in Community VI;Allactaga sibirica, Allactaga bullata and Dipus sagitta were dominant in Community VII;Phodopus roborovskii, Dipus sagitta and Allactaga sibirica were dominant in Community VIII;Meriones meridianus, Dipus sagitta and Allactaga sibirica were dominant in Community IX. The community diversity and evenness analysis showed that the edge effect of community, the effect of disturbance and habitat fragmentation and scale effect were significantly correlated with community diversity in the semi-desert and desert regions. The ordinal results of 9 zonal rodent communities were in accordance with the results analyzed with similar community indices, showing the habitat change in the characteristics of the above-mentioned groups.
