Low genetic diversity after a bottleneck in a population of a critically endangered migratory marine turtle species

Hawksbill turtles (Eretmochelys imbricata), which are distributed throughout the world's oceans, have undergone drastic declines across their range, largely due to anthropogenic factors. Assessing sizes, genetic variability and structure of their populations at global and regional levels is critical to the development of conservation management strategies. Here, nuclear and mitochondrial markers were used to analyse patterns of parentage and population structure in hawksbill turtles in United Arab Emirates (UAE) waters, utilizing samples from two life stages (hatchlings and juveniles), and to compare the UAE population with neighboring populations. Weak genetic differentiation was detected between juveniles and hatchlings and between the nesting sites of Dubai and Sir Bu Nair. Parentage analysis suggested that only 53 females and 74–80 males contributed to the hatchlings from 67 nests across three nesting sites in UAE (Dubai, Sir Bu Nair, Abu Dhabi). No females were identified as nesting in more than one location. In Dubai and Abu Dhabi, single paternity was the norm (75%), whereas on Sir Bu Nair, multiple paternity was detected in the majority of nests (67%). Polygyny was also frequently detected on Sir Bu Nair (15% of the overall number of males), but not in the other nesting sites. Comparison of the UAE population with published data from other populations suggests that population structure exists both within the Gulf and between the Gulf and Indian Ocean populations, and that the UAE population has lower genetic variability than the Seychelles population. Finally, the data suggest that the UAE population, and the Gulf population overall, experienced a bottleneck/founder event. The observed overall low genetic variability, evidence of population structure in the Gulf, and strong differentiation between the Gulf and the Indian Ocean populations, raises concerns about the sustainability of this species in this near-enclosed basin. These results highlight the need for regional collaboration in the development of management measures for the long-term conservation of this Critically Endangered specie

Plans for a 10-m Submillimeter-wave Telescope at the South Pole

A 10 meter diameter submillimeter-wave telescope has been proposed for the NSF Amundsen-Scott South Pole Station. Current evidence indicates that the South Pole is the best submillimeter-wave telescope site among all existing or proposed ground-based observatories. Proposed scientific programs place stringent requirements on the optical quality of the telescope design. In particular, reduction of the thermal background and offsets requires an off-axis, unblocked aperture, and the large field of view needed for survey observations requires shaped optics. This mix of design elements is well-suited for large scale (square degree) mapping of line and continuum radiation from submillimeter-wave sources at moderate spatial resolutions (4 to 60 arcsecond beam size) and high sensitivity (milliJansky flux density levels). the telescope will make arcminute angular scale, high frequency Cosmic Microwave Background measurements from the best possible ground-based site, using an aperture which is larger than is currently possible on orbital or airborne platforms. Effective use of this telescope will require development of large (1000 element) arrays of submillimeter detectors which are background-limited when illuminated by antenna temperatures near 50 K.Comment: 12 pages, 3 figure

Habitat Patch Occupancy Dynamics of Glaucous-winged Gulls (larus glaucescens) ii: A Continuous-time Model

The diurnal distribution and abundance dynamics of loafing Glaucous-winged Gulls (Larus glaucescens) were examined at Protection Island National Wildlife Refuge, Strait of Juan de Fuca, Washington. Asynchronous movement of gulls among three habitat patches dedicated to loafing was modeled as a function of environmental variables using differential equations. Multiple time scale analysis led to the derivation of algebraic models for habitat patch occupancy dynamics. The models were parameterized with hourly census data collected from each habitat patch, and the resulting model predictions were compared with observed census data. A four-compartment model explained 41% of the variability in the data. Models that predict the dynamics of organism distribution and abundance enhance understanding of the temporal and spatial organization of ecological systems, as well as the decision-making process in natural resource management. © 2005 Rocky Mountain Mathematics Consortium

The Magnitude-Size Relation of Galaxies out to z ~ 1

As part of the Deep Extragalactic Evolutionary Probe (DEEP) survey, a sample of 190 field galaxies (I_{814} <= 23.5) in the ``Groth Survey Strip'' has been used to analyze the magnitude-size relation over the range 0.1 < z < 1.1. The survey is statistically complete to this magnitude limit. All galaxies have photometric structural parameters, including bulge fractions (B/T), from Hubble Space Telescope images, and spectroscopic redshifts from the Keck Telescope. The analysis includes a determination of the survey selection function in the magnitude-size plane as a function of redshift, which mainly drops faint galaxies at large distances. Our results suggest that selection effects play a very important role. A first analysis treats disk-dominated galaxies with B/T < 0.5. If selection effects are ignored, the mean disk surface brightness (averaged over all galaxies) increases by ~1.3 mag from z = 0.1 to 0.9. However, most of this change is plausibly due to comparing low luminosity galaxies in nearby redshift bins to high luminosity galaxies in distant bins. If this effect is allowed for, no discernible evolution remains in the disk surface brightness of bright (M_B < -19) disk-dominated galaxies. A second analysis treats all galaxies by substituting half-light radius for disk scale length, with similar conclusions. Indeed, at all redshifts, the bulk of galaxies is consistent with the magnitude-size envelope of local galaxies, i.e., with little or no evolution in surface brightness. In the two highest redshift bins (z > 0.7), a handful of luminous, high surface brightness galaxies appears that occupies a region of the magnitude-size plane rarely populated by local galaxies. Their wide range of colors and bulge fractions points to a variety of possible origins.Comment: 19 pages, 12 figures. Accepted for publication in the Astrophysical Journa

Landscape-scale variation in an anthropogenic factor shapes immune gene variation within a wild population

Understanding the spatial scale at which selection acts upon adaptive genetic variation in natural populations is fundamental to our understanding of evolutionary ecology, and has important ramifications for conservation. The environmental factors to which individuals of a population are exposed can vary at fine spatial scales, potentially generating localized patterns of adaptation. Here, we compared patterns of neutral and major histocompatibility complex (MHC) variation within an island population of Berthelot's pipit (Anthus berthelotii) to assess whether landscape-level differences in pathogen-mediated selection generate fine-scale spatial structuring in these immune genes. Specifically, we tested for spatial associations between the distribution of avian malaria, and the factors previously shown to influence that distribution, and MHC variation within resident individuals. Although we found no overall genetic structure across the population for either neutral or MHC loci, we did find localized associations between environmental factors and MHC variation. One MHC class I allele (ANBE48) was directly associated with malaria infection risk, while the presence of the ANBE48 and ANBE38 alleles within individuals correlated (positively and negatively, respectively) with distance to the nearest poultry farm, an anthropogenic factor previously shown to be an important determinant of disease distribution in the study population. Our findings highlight the importance of considering small spatial scales when studying the patterns and processes involved in evolution at adaptive loci

Molecular techniques reveal cryptic life history and demographic processes of a critically endangered marine turtle

The concept of ‘effective population size’ (Ne), which quantifies how quickly a population will lose genetic variability, is one of the most important contributions of theoretical evolutionary biology to practical conservation management. Ne is often much lower than actual population size: how much so depends on key life history and demographic parameters, such as mating systems and population connectivity, that often remain unknown for species of conservation concern. Molecular techniques allow the indirect study of these parameters, as well as the estimation of current and historical Ne. Here, we use genotyping to assess the genetic health of an important population of the critically endangered hawksbill turtle (Eretmochelys imbricata), a slow-to-mature, difficult-to-observe species with a long history of severe overhunting. Our results were surprisingly positive: we found that the study population, located in the Republic of Seychelles, Indian Ocean, has a relatively large Ne, estimated to exceed 1000, and showed no evidence of a recent reduction in Ne (i.e. no genetic bottleneck). Furthermore, molecular inferences suggest the species' mating system is conducive to maintaining a large Ne, with a relatively large and widely distributed male population promoting considerable gene flow amongst nesting sites across the Seychelles area. This may also be reinforced by the movement of females between nesting sites. Our study underlines how molecular techniques can help to inform conservation biology. In this case our results suggest that this important hawksbill population is starting from a relatively strong position as it faces new challenges, such as global climate change

Categorial Compositionality: A Category Theory Explanation for the Systematicity of Human Cognition

Classical and Connectionist theories of cognitive architecture seek to explain systematicity (i.e., the property of human cognition whereby cognitive capacity comes in groups of related behaviours) as a consequence of syntactically and functionally compositional representations, respectively. However, both theories depend on ad hoc assumptions to exclude specific instances of these forms of compositionality (e.g. grammars, networks) that do not account for systematicity. By analogy with the Ptolemaic (i.e. geocentric) theory of planetary motion, although either theory can be made to be consistent with the data, both nonetheless fail to fully explain it. Category theory, a branch of mathematics, provides an alternative explanation based on the formal concept of adjunction, which relates a pair of structure-preserving maps, called functors. A functor generalizes the notion of a map between representational states to include a map between state transformations (or processes). In a formal sense, systematicity is a necessary consequence of a higher-order theory of cognitive architecture, in contrast to the first-order theories derived from Classicism or Connectionism. Category theory offers a re-conceptualization for cognitive science, analogous to the one that Copernicus provided for astronomy, where representational states are no longer the center of the cognitive universe—replaced by the relationships between the maps that transform them

The X-ray spectra and spectral variability of intermediate type Seyfert galaxies: ASCA observations of NGC 4388 and ESO 103-G35

The X-ray spectra of two intermediate type Seyfert galaxies are investigated using ASCA observations separated by more than a year. Both NGC 4388 and ESO 103-G35 exhibit strong, narrow Fe K alpha line emission and absorption by cold neutral gas with a column density ~ 10^23 cm^-2, characteristic of the X-ray spectra of type 2 Seyfert galaxies. The power law continuum flux has changed by a factor of 2 over a time-scale of ~ 2 years for both objects, declining in the case of NGC 4388 and rising in ESO 103-G35. No variation was observed in the equivalent width of the Fe K alpha line in the spectra of NGC 4388, implying that the line flux declined with the continuum. We find that the strength of the line cannot be accounted for by fluorescence in line-of-sight material with the measured column density unless a `leaky-absorber' model of the type favored for IRAS 04575-7537 is employed. The equivalent width of the Fe K alpha emission line is seen to decrease between the observations of ESO 103-G35 while the continuum flux increased. The 1996 observation of ESO 103-G35 can also be fitted with an absorption edge at 7.4 $\pm$ 0.2 keV due to partially ionized iron, and when an ionized absorber model is fitted to the data it is found that the equivalent column of neutral hydrogen rises to 3.5 x 10^23 cm^-2. The Fe K alpha line flux can be accounted by fluorescence in this material alone and this model is also a good representation of the 1988 and 1991 Ginga observations. There is then no requirement for a reflection component in the ASCA spectra of ESO 103-G35 or NGC 4388.Comment: 45 pages, 5 tables, 11 figures. Accepted for publication in the Astrophysical Journa

The DEEP Groth Strip Survey IX: Evolution of the Fundamental Plane of Field Galaxies

Fundamental Plane studies provide an excellent means of understanding the evolutionary history of early-type galaxies. Using the Low Resolution Imaging Spectrograph on the Keck telescope, we obtained internal stellar kinematic information for 36 field galaxies in the Groth Strip--21 early-type and 15 disk galaxies. Their redshifts range from 0.3--1.0, with a median redshift 0.8. The slope of the relation shows no difference compared with the local slope. However, there is significant evolution in the zero-point offset; an offset due to evolution in magnitude requires a 2.4 magnitude luminosity brightening at z=1. We see little differences of the offset with bulge fraction, which is a good surrogate for galaxy type. Correcting for the luminosity evolution reduces the orthogonal scatter in the Fundamental Plane to 8%, consistent with the local scatter. This scatter is measured for our sample, and does not include results from other studies which may have different selection effects. The difference in the degree of evolution between our field sample and published cluster galaxies suggests a more recent formation epoch--around z=1.5 for field galaxies compared to z>2.0 for cluster galaxies. The magnitude difference implies that the field early-type galaxies are about 2 Gyr younger than the cluster ellipticals using standard single-burst models. However, the same models imply a significant change in the rest-frame U-B color from then to present, which is not seen in our sample. Continuous low-level star formation, however, would serve to explain the constant colors over this large magnitude change. A consistent model has 7% of the stellar mass created after the initial burst, using an exponentially decaying star formation rate with an e-folding time of 5 Gyr.Comment: 25 pages, accepted for publication in the Astrophysical Journal, high resolution version at http://hoku.as.utexas.edu/~gebhardt/FPpaper.p