In a greenhouse experiment plasticity of clonal growth and clonal morphology of the stoloniferous rosette herb Halerpestes nahenica Ovcz. in response to differing levels of light intensity and nutrient availability wa...In a greenhouse experiment plasticity of clonal growth and clonal morphology of the stoloniferous rosette herb Halerpestes nahenica Ovcz. in response to differing levels of light intensity and nutrient availability was studied. Total plant dry weight, leaf area of primary ramets, total number of ramets and of stolons, and total stolon length were significantly reduced, while specific internode length and specific petiole length significantly increased under deep shading (6.25% of high light intensity, 5.3% of full daylight) or under low nutrient availability. Under low nutrient availability, mean stolon internode length of H. ruthenica was significantly larger while branching intensity and number of ramets smaller than those under high nutrient availability. These responses are consistent with the foraging model of clonal plants, indicating that H. nahenica is able to forage nutrients through the plastic responses of clonal growth and clonal. morphology when it grows in heterogeneous environments. However, under deep shading, both mean stolon internode length and mean petiole length were significantly reduced, which disagrees with the findings of many other stoloniferous herbs in response to low or medium levels of shading (ca. 13%-75% of high light intensity, >10% of full daylight), suggesting that under deep shading stoloniferous herbs may not forage light through the plastic responses of spacer length. Many traits such as total plant dry weight, total number and length of stolons, total length of secondary and tertiary stolons. total number of ramets, leaf area of primary ramets and branching intensity were markedly influenced by the interaction effect of light intensity and nutrient availability. Under high light intensity nutrient availability affected these traits more pronouncedly, however under low light intensity nutrient availability either did not affect or affected less markedly on these traits, indicating that fight intensity had significant effect on nutrient foraging in H. nahenica. Under deep shading or low nutrient availability, H. ruthenica may increase its mean stolon internode length by means of thinning stolon internodes (i.e., an increase in specific internode length), which provides it with more chance to escape from resource-poor sites.展开更多
The skull and mandible of a Late Miocene fossil pig,Chleuastochoerus,are compared morphologically with those of extant pigs and peccaries,and subjected to a functional analysis.The presence of a rostral bone in the sk...The skull and mandible of a Late Miocene fossil pig,Chleuastochoerus,are compared morphologically with those of extant pigs and peccaries,and subjected to a functional analysis.The presence of a rostral bone in the skull and relatively strong rostral muscles indicates that Chleuastochoerus possessed considerable digging ability,though the relatively narrow occipital surface and the shortness of the skull would have restricted the range of motion through which the skull could be swung.The distinctive pre-zygomatic plate and over-canine arch-niche may have played a role in protecting the skull and canines during digging.The massive masticatory muscles,reconstructed based on well-developed parietal and zygomatic crests,would have enabled the mouth to close quickly and contributed to moving the mandible both longitudinally and laterally.The configuration of the cranio-mandibular joint and its relatively high position show clearly that Chleuastochoerus was capable of both crushing and grinding movements during mastication.The comparatively simple structure of the crown surfaces of the cheek teeth suggests that the food of Chleuastochoerus may have been softer than that of extant suids.The diet of Chleuastochoerus is postulated to fall between those of true forest pigs and open habitat pigs,and the habitat of Chleuastochoerus to be relatively humid forest edge or nearby areas of open steppe.展开更多
文摘In a greenhouse experiment plasticity of clonal growth and clonal morphology of the stoloniferous rosette herb Halerpestes nahenica Ovcz. in response to differing levels of light intensity and nutrient availability was studied. Total plant dry weight, leaf area of primary ramets, total number of ramets and of stolons, and total stolon length were significantly reduced, while specific internode length and specific petiole length significantly increased under deep shading (6.25% of high light intensity, 5.3% of full daylight) or under low nutrient availability. Under low nutrient availability, mean stolon internode length of H. ruthenica was significantly larger while branching intensity and number of ramets smaller than those under high nutrient availability. These responses are consistent with the foraging model of clonal plants, indicating that H. nahenica is able to forage nutrients through the plastic responses of clonal growth and clonal. morphology when it grows in heterogeneous environments. However, under deep shading, both mean stolon internode length and mean petiole length were significantly reduced, which disagrees with the findings of many other stoloniferous herbs in response to low or medium levels of shading (ca. 13%-75% of high light intensity, >10% of full daylight), suggesting that under deep shading stoloniferous herbs may not forage light through the plastic responses of spacer length. Many traits such as total plant dry weight, total number and length of stolons, total length of secondary and tertiary stolons. total number of ramets, leaf area of primary ramets and branching intensity were markedly influenced by the interaction effect of light intensity and nutrient availability. Under high light intensity nutrient availability affected these traits more pronouncedly, however under low light intensity nutrient availability either did not affect or affected less markedly on these traits, indicating that fight intensity had significant effect on nutrient foraging in H. nahenica. Under deep shading or low nutrient availability, H. ruthenica may increase its mean stolon internode length by means of thinning stolon internodes (i.e., an increase in specific internode length), which provides it with more chance to escape from resource-poor sites.
基金supported by National Natural Science Foundation of China (Grant Nos. 41202002, 40730210)Chinese Academy of Sciences (Grant No. XDB03020104)+1 种基金Ministry of Science and Technology of China (Grant No. 2012CB821906)Key Deployment Project of Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences
文摘The skull and mandible of a Late Miocene fossil pig,Chleuastochoerus,are compared morphologically with those of extant pigs and peccaries,and subjected to a functional analysis.The presence of a rostral bone in the skull and relatively strong rostral muscles indicates that Chleuastochoerus possessed considerable digging ability,though the relatively narrow occipital surface and the shortness of the skull would have restricted the range of motion through which the skull could be swung.The distinctive pre-zygomatic plate and over-canine arch-niche may have played a role in protecting the skull and canines during digging.The massive masticatory muscles,reconstructed based on well-developed parietal and zygomatic crests,would have enabled the mouth to close quickly and contributed to moving the mandible both longitudinally and laterally.The configuration of the cranio-mandibular joint and its relatively high position show clearly that Chleuastochoerus was capable of both crushing and grinding movements during mastication.The comparatively simple structure of the crown surfaces of the cheek teeth suggests that the food of Chleuastochoerus may have been softer than that of extant suids.The diet of Chleuastochoerus is postulated to fall between those of true forest pigs and open habitat pigs,and the habitat of Chleuastochoerus to be relatively humid forest edge or nearby areas of open steppe.
