Drivers of intrapopulation variation in resource use in a generalist predator, the macaroni penguin

Intrapopulation variation in resource use occurs in many populations of generalist predators with important community and evolutionary implications. One of the hypothesised mechanisms for such widespread variation is ecological opportunity, i.e. resource availability determined by intrinsic constraints and extrinsic conditions. In this study, we combined tracking data and stable isotope analysis to examine how breeding constraints and prey conditions influenced intrapopulation variation in resource use in a generalist predator, the macaroni penguin Eudyptes chrysolophus. Isotopic variation was also examined as a function of breeding success, individual traits and individual specialisation. Variation in isotope ratios was greatest across multiple tissue types when birds were able to undertake mid-range foraging trips (i.e. during incubation and pre-moult). This variation was highly consistent between years that spanned a 3-fold difference in local prey Euphausia superba density, and was also highly consistent at the individual level between 2 years that had similar prey densities. Furthermore, by comparing our results with previous work on the same population, it appeared that a decrease in local prey availability can also increase intrapopulation variation in resource use during periods with more restricted foraging ranges (i.e. during brood-guard and crèche). This study highlights the importance of considering ecological interactions that operate on multiple spatio-temporal scales when examining the drivers of resource use in populations of generalist predator

Extended Superscaling of Electron Scattering from Nuclei

An extended study of scaling of the first and second kinds for inclusive electron scattering from nuclei is presented. Emphasis is placed on the transverse response in the kinematic region lying above the quasielastic peak. In particular, for the region in which electroproduction of resonances is expected to be important, approximate scaling of the second kind is observed and the modest breaking of it is shown probably to be due to the role played by an inelastic version of the usual scaling variable.Comment: LaTeX, 36 pages including 5 color postscript figures and 4 postscript figure

Superscaling of Inclusive Electron Scattering from Nuclei

We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low energy loss side of the quasielastic peak exhibit the superscaling property, i.e., the scaling functions f(\psi') are not only independent of momentum transfer (the usual type of scaling: scaling of the first kind), but coincide for A \geq 4 when plotted versus a dimensionless scaling variable \psi' (scaling of the second kind). We use this behavior to study as yet poorly understood properties of the inclusive response at large electron energy loss.Comment: 33 pages, 12 color EPS figures, LaTeX2e using BoxedEPSF macros; email to [email protected]

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Stable isotope analysis of human and faunal remains from the Anglo-Saxon cemetery at Berinsfield, Oxfordshire: Dietary and social implications

Stable carbon and nitrogen isotope values were obtained from human and faunal bones from the Early Anglo-Saxon cemetery site at Wally Corner, Berinsfield, Oxfordshire, U.K. These values were used to characterize the diet of the burial community as a whole and to analyse dietary patterns within sub-groups determined by sex, age, grave goods, and possible household arrangement. While dietary variability is observed in all sub-groups tested, we identify an apparent distinction between the average diets of individuals classified as “wealthy” and “intermediately wealthy” and those classified as “poor”. A similar dietary difference indicates a status-based age differential between males under and over 30 years old, also reflected in the archaeological record. A notable absence of dietary differentiation was noted between males and females at Berinsfield, indicating that sex-based societal classification did not significantly influence an individual's access to the various food sources available to the Berinsfield community. Conclusions drawn from these isotopic data are of use in adding to the picture of daily life and social structure in early Anglo-Saxon Britain

Ancient mitochondrial DNA from hair

NoThe DNA content of hair [1.] and [2.] is typically low compared to other tissues, as hair cells undergo dehydration and catabolic breakdown of nucleic acids and organelles during keratinisation [3]. As a consequence, ancient hair specimens have not been widely used as a source of ancient DNA. However, mitochondrial DNA (mtDNA) has been extracted from degraded and old hair samples, including burnt specimens [4], 100-year-old Native American samples [5], and wool from a 9,400 year old Bighorn sheep [6]. We have investigated the potential of hair as an aDNA source by analyzing DNA survival in 12 samples which range from 60 to >64,800 years of age and their susceptibility to contamination with modern DNA. mtDNA was successfully amplified, cloned, and sequenced from 10 of the 12 hair samples following decontamination procedures (Table 1). DNA was quantified using Quantitative Real-Time PCR in a subset of the samples (Table 1). The survival of high copy numbers of 16S DNA from the 3,000 year-old Pazyryk horse hairs is consistent with the observation that DNA survives longer at sub-zero temperatures [7]. Of greater surprise was the persistence of high numbers of 16S and Control Region DNA molecules in hairs sampled from a bison mummy 14C dated to >64,800 years. This result was independently replicated and extends the time frame from which authentic DNA has been retrieved from hair by at least seven-fold, placing it on a par with the oldest authentic DNA retrieved from bones and teeth [8]. No nuclear DNA could be amplified from the bison hair, consistent with observations of modern hair samples [1.] and 9. M.R. Wilson, D. Polanskey, J. Butler, J.A. DiZinno, J. Replogle and B. Budowle, Extraction, PCR amplification and sequencing of mitochondrial DNA from human hair shafts, Biotechniques 18 (1995), pp. 662¿669.[9.]. It is probably significant that the bison hairs are exceedingly well preserved ¿ the atomic carbon to nitrogen ratio (3.47) is similar to modern mammal hair [10.] and [11.] and histological analysis of the specimen demonstrates the only structural modifications to be slight cuticular loss and adherent deposits (Supplemental data)