We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards,the Husab sand lizard Pedioplanis husabensis and Bradfield’s Namib day gecko living sympatrically in t...We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards,the Husab sand lizard Pedioplanis husabensis and Bradfield’s Namib day gecko living sympatrically in the Namib Desert.We measured theδ13C andδ15N ratios in lizard blood tissues with different turnover times(whole blood,red blood cells and plasma)to investigate lizard diet in different seasons.We also measured theδ13C andδ15N ratios in available arthropod prey and plant tissues on the site,to identify the avenues of nutrient movement between lizards and their prey.Through the use of stable isotope mixing models,we found that the two lizard species relied on a largely non-overlapping but seasonally variable array of arthropods:P.husabensis primarily fed on termites,beetles and wasps,while R.bradfieldi fed mainly on ants,wasps and hemipterans.Nutrients originating from C3 plants were proportionally higher for R.bradfieldi than for P.husabensis during autumn and late autumn/early winter,although not summer.Contrary to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C3 and C4/crassulacean acid metabolism(CAM)plant landscapes,we found that our lizard species primarily acquired nutrients that originated from C4/CAM plants.This work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.展开更多
The diet of the harvester termite Hodotermes mossambicus was investigated at two sites with distinct dietary components： C4 grasses （δ13 C isotope values, -13.8%0 to -14.0%0） and C3 plants （δ13C isotope values, ...The diet of the harvester termite Hodotermes mossambicus was investigated at two sites with distinct dietary components： C4 grasses （δ13 C isotope values, -13.8%0 to -14.0%0） and C3 plants （δ13C isotope values, -25.6%0 to -27.1%0）. By comparing observations of food items carried into the colony by the termites and carbon isotope ratios of whole termites （that determined assimilated carbon）, the relative proportion of the C3 and C4 plant food components of the termite diet was estimated. There was agreement between the observational data and stable carbon isotopic data, with grass representing approximately 93% of the diet ofH. mossambicus at two study sites （urban and rural） on the South African highveld. However, when correcting for mass of food items, that is, C3 and C4, carried by termites, the proportion of grass （C4） in the diet may be underestimated.展开更多
文摘We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards,the Husab sand lizard Pedioplanis husabensis and Bradfield’s Namib day gecko living sympatrically in the Namib Desert.We measured theδ13C andδ15N ratios in lizard blood tissues with different turnover times(whole blood,red blood cells and plasma)to investigate lizard diet in different seasons.We also measured theδ13C andδ15N ratios in available arthropod prey and plant tissues on the site,to identify the avenues of nutrient movement between lizards and their prey.Through the use of stable isotope mixing models,we found that the two lizard species relied on a largely non-overlapping but seasonally variable array of arthropods:P.husabensis primarily fed on termites,beetles and wasps,while R.bradfieldi fed mainly on ants,wasps and hemipterans.Nutrients originating from C3 plants were proportionally higher for R.bradfieldi than for P.husabensis during autumn and late autumn/early winter,although not summer.Contrary to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C3 and C4/crassulacean acid metabolism(CAM)plant landscapes,we found that our lizard species primarily acquired nutrients that originated from C4/CAM plants.This work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.
文摘The diet of the harvester termite Hodotermes mossambicus was investigated at two sites with distinct dietary components： C4 grasses （δ13 C isotope values, -13.8%0 to -14.0%0） and C3 plants （δ13C isotope values, -25.6%0 to -27.1%0）. By comparing observations of food items carried into the colony by the termites and carbon isotope ratios of whole termites （that determined assimilated carbon）, the relative proportion of the C3 and C4 plant food components of the termite diet was estimated. There was agreement between the observational data and stable carbon isotopic data, with grass representing approximately 93% of the diet ofH. mossambicus at two study sites （urban and rural） on the South African highveld. However, when correcting for mass of food items, that is, C3 and C4, carried by termites, the proportion of grass （C4） in the diet may be underestimated.
