PCR‐based techniques to determine diet of the Australian sea lion (Neophoca cinerea): a comparison with morphological analysis          下载免费PDF全文

Kristian J. Peters  Kathy Ophelkeller    Herdina  Nathan J. Bott  Simon D. Goldsworthy 《Marine Ecology》2015,36(4):1428-1439

Comprehensive dietary information for the endangered Australian sea lion (Neophoca cinerea) is currently limited by the deficiency and poor quality of identifiable prey remains recovered from regurgitate and faeces and the difficulty of observing feeding in the wild. In this study, we investigated DNA‐based prey detection methods using conventional (end‐point) and quantitative real‐time PCR (qPCR) on faeces collected from two captive Australian sea lions fed experimental diets of whole teleost fish, squid and shark tissue. PCR prey detection methods using the mitochondrial cytochrome oxidase subunit I (COI) and 16S genes combined with clone sequencing were compared with prey identified using traditional hard part analysis. The molecular results indicated that prey DNA was degraded. However, prey amplification was successful by targeting short (71 bp) DNA fragments. Both conventional PCR and qPCR techniques significantly increased prey detection compared with analysis of hard parts. For both sea lions, the hard part analysis was constrained by sporadic and extremely low recovery of fish otoliths (<2%), and cephalopod beaks were not recovered from the 116 squid fed. Comparisons between PCR techniques indicated comparable prey detection frequencies for all species tested; however, the sensitivity and greater resolution of qPCR improved prey detection by ~25% in one sea lion fed the experimental squid and perch. The detection of squid DNA ≤ 6 day post‐ingestion by qPCR further exhibits the ability and potential of this method to detect low concentrations of infrequent or pulse prey. This study highlights the use of DNA‐based analysis to detect prey taxa in the absence of identifiable hard prey remains.  相似文献   

Affluence drives the global displacement of land use   总被引：2，自引：0，他引：2  

Jan Weinzettel  Edgar G. Hertwich  Glen P. Peters  Kjartan Steen-Olsen  Alessandro Galli 《Global Environmental Change》2013,23(2):433-438

Increasing affluence is often postulated as a main driver for the human footprint on biologically productive areas, identified among the main causes of biodiversity loss, but causal relationships are obscured by international trade. Here, we trace the use of land and ocean area through international supply chains to final consumption, modeling agricultural, food, and forestry products on a high level of resolution while also including the land requirements of manufactured goods and services. In 2004, high-income countries required more biologically productive land per capita than low-income countries, but this connection could only be identified when land used to produce internationally traded products was taken into account, because higher-income countries tend to displace a larger fraction of land use. The equivalent land and ocean area footprint of nations increased by a third for each doubling of income, with all variables analyzed on a per capita basis. This increase came largely from imports, which increased proportionally to income. Export depended mostly on the capacity of countries to produce useful biomass, the biocapacity. Our analysis clearly shows that countries with a high biocapacity per capita tend to spare more land for nature. Biocapacity per capita can be increased through more intensive production or by reducing population density. The net displacement of land use from high-income to low-income countries amounted to 6% of the global land demand, even though high-income countries had more land available per capita than low-income countries. In particular, Europe and Japan placed high pressure on ecosystems in lower-income countries.  相似文献   

Drivers of change in Brazil’s carbon dioxide emissions     

Manfred Lenzen  Roberto Schaeffer  Jonas Karstensen  Glen P. Peters 《Climatic change》2013,121(4):815-824

Brazil’s economic development has been underpinned by a diverse and – in a global comparison – unusual set of energy carriers, notably hydroelectricity and ethanol from sugar cane. Its energy mix makes Brazil one of the least energy-related carbon-intensive economies worldwide. Given that the country is fast becoming one of the world’s economic powerhouses, decision-makers need to understand the drivers underlying past and current carbon dioxide emissions trends. We therefore investigate a) which key long-term drivers have led to Brazil’s unique emissions profile, and b) the implications of these drivers for Brazil’s national policies. We show that Brazil’s emissions are growing mainly due to increasing individual standards of living, exports and population size, and that this growth is so far unchallenged by technological and structural improvements toward lower emissions intensities and more efficient production structures. As these trends are likely to continue amidst growing international pressure on key economies to reduce their carbon emissions, a decoupling of drivers from emissions is needed to simultaneously meet development and environmental goals.  相似文献   

Population Structure of Adult Blue Crabs, <Emphasis Type="Italic">Callinectes sapidus</Emphasis>, in Relation to Physical Characteristics in Barnegat Bay,New Jersey     

Paul R. Jivoff  Jennifer M. Smith  Valerie L. Sodi  Stacy M. VanMorter  Kathryn M. Faugno  Amy L. Werda  Margaret J. Shaw 《Estuaries and Coasts》2017,40(1):235-250

Blue crabs (Callinectes sapidus) are an important species in coastal or lagoonal estuaries where adult population characteristics may differ as compared to drowned-river estuaries. Barnegat Bay, in southern New Jersey, is composed of two large embayments: one without and one with a salinity gradient. We tested the influence of physical characteristics on the abundance, sex ratio, and size of adult blue crabs and examined variation in measures of reproductive potential (e.g., sperm stores) in both sexes in Barnegat Bay from June to September, 2008–2009. Population structure was distinct between the embayments due to sex-specific responses to salinity: male abundance was negatively correlated with salinity whereas adult females were more abundant in high salinity because of proximity to Barnegat Inlet. This produced high sex ratios in low salinity areas and low sex ratios in high salinity areas. Summer was a growing season for adult males while in late summer-early fall, juvenile males recruited to the adult size class. The spawning season lasted from May to August and ovigerous females were concentrated near the inlets. Information on female sperm stores and ovarian development identified two cohorts of adult females: females that will spawn in the current summer and females that will not spawn until the following summer. Thus, not all adult females near the spawning grounds were members of the current spawning stock. This suggests that annual estimates of spawning stock size which overlook the proximity of females to spawning are overestimating the current spawning stock in Barnegat Bay and other estuaries.  相似文献   

Supermagnetic enhancement,superparamagnetism, and archaeological soils     

Clare Peters  Roy Thompson 《Geoarchaeology》1999,14(5):401-413

A range of mineral magnetic measurements have been carried out on archaeological sediments from Orkney and Cyprus. In a soil profile from Orkney, a magnetic enhancement factor of over 200 is observed in susceptibility data between the bedrock and a Norse sediment. The magnetic enhancement is associated with an increase in superparamagnetic grains probably caused by burning. Until now it has proved difficult to confirm the presence of superparamagnetic grains in natural samples using room temperature magnetic measurements. However, clear differences are to be found between the hysteresis loops of various magnetic domain states, including superparamagnetism. An algorithm has been developed to unmix hysteresis loops in terms of constituent domain states of ferrimagnetic iron oxides. Unmixing 128 hysteresis loops of archaeological sediments has shown that the dominant domain state in all sediments is superparamagnetic. Remarkably uniform superparamagnetic grain sizes of between 80 and 95 Å were found for all 128 sediments. © 1999 John Wiley & Sons, Inc.  相似文献