<div>Inferring genetic population structure in endangered, highly migratory species such as sea turtles is a necessary but difficult task in order to design conservation and management plans. Genetically discrete populations are not obvious in highly migratory species, yet require unique conservation planning due to unique spatial and behavioral life-history characteristics. Population structure may be inferred using slowly evolving mitochondrial DNA (mtDNA), but some populations may have diverged recently and are difficult to detect using mtDNA. In these cases, rapidly evolving nuclear microsatellites may better elucidate population structuring. Bayesian inference and ordination may be useful for assigning individuals to inferred populations when populations are unknown. It is important to carefully examine population inference results to detect hierarchical population structuring, and to use multiple, mathematically diverse methods when inferring and describing population structure from genetic data. Here I use Bayesian inference, ordination, and multiple genetic analyses to investigate population structure in Olive ridley sea turtles (ORs; Lepidochelys olivacea) nesting in northwestern Costa Rica (NWCR) and across the entire Eastern Tropical Pacific (ETP). Mitochondrial DNA did not show structure within NWCR, and existing data from prior studies are not appropriately published to compare NWCR to Mexican ORs. In NWCR, Bayesian inference suggested one population, but ordination suggested four moderately structured populations with high internal relatedness, and moderate to high levels of connectivity. In the ETP, Bayesian inference suggested a Mexican and Central American population, but hierarchical analysis revealed a third subpopulation within Mexico. Ordination revealed nine cryptic clusters across the ETP that primarily corresponded to Mexican and Central American populations but contained individuals from both populations, some from other, distant nesting sites. The subpopulation within Mexico was well-defined after ordination, and all clusters displayed high 10 internal relatedness and moderate genetic differentiation. Bottlenecks were detected in both putative populations, at seven Mexican and two Central American nesting beaches, and in six out of nine inferred clusters, including three out of four Mexican clusters. Bottleneck events may have played some role in cluster differentiation. Migration was significant from Mexico to Central America at multiple levels, but did not necessarily agree with potential migrants elucidated by ordination. Migration was generally lower between ordination-inferred clusters than between nesting sites or Bayesian-inferred clusters. Phylogenetic trees generally supported structuring by ordination, rather than by Bayesian inference. Structuring in ordination not tied to bottleneck events could be due to mating behaviors or patterns of nesting beach colonization dictated by environmental features. In this study, ordination provided a more practical and nuanced framework for defining MUs and DIPs in ETP ORs than did STRUCTURE. This may be due to hierarchical structuring within ETP ORs that may be present in other sea turtle populations and species. In the case of ETP ORs, hierarchical structure may be an artefact of recent population bottlenecks and subsequent recolonization of nesting beaches, or due to mating at foraging grounds or along migratory routes. Bayesian inference may not be the best method for population inference in highly migratory species such as sea turtles, which have a high potential for broad scale genetic connectivity, and therefore may display hierarchical population structuring not easily related to nesting sites. Future studies, and perhaps published studies, should incorporate Bayesian inference and ordination, as well as other measures of population divergence and descriptive statistics, when searching for population structure in highly migratory species such as sea turtles.</div>

<p> </p><p> </p><p> </p><p>The extinction risk of threatened species has traditionally been assessed by the use of tools of Population Viability Analysis (PVA). Species interactions, however, have seldom been accounted for in PVA:s. The omission of species interactions in risk assessments may further lead to serious mistakes when setting target sizes of populations. Even a slight abundance decrease of a target species may result in changes of the community structure; in the worst case leading to a highly impoverished community. Of critical importance to conservation is therefore the question of how many individuals of a certain population that is needed in order to avoid this kind of consequences. In the current study, a stochastic multispecies model is used to estimate minimum ecological viable populations (MEVP); earlier defined as “the minimum size of a population that can survive before itself or some other species in the community becomes extinct”. The MEVP:s are compared to population sizes given by a single species model where interactions with other species are treated as a constant source incorporated in the species specific growth rate. MEVP:s are found to be larger than the population sizes given by the single species model. The results are trophic level dependent and multispecies approaches are suggested to be of major importance when setting target levels for species at the basal level. Species at higher trophic levels, however, are altogether more prone to extinction than species at the basal level, irrespective of food web size and food web complexity.</p><p> </p>

The extinction risk of threatened species has traditionally been assessed by the use of tools of Population Viability Analysis (PVA). Species interactions, however, have seldom been accounted for in PVA:s. The omission of species interactions in risk assessments may further lead to serious mistakes when setting target sizes of populations. Even a slight abundance decrease of a target species may result in changes of the community structure; in the worst case leading to a highly impoverished community. Of critical importance to conservation is therefore the question of how many individuals of a certain population that is needed in order to avoid this kind of consequences. In the current study, a stochastic multispecies model is used to estimate minimum ecological viable populations (MEVP); earlier defined as “the minimum size of a population that can survive before itself or some other species in the community becomes extinct”. The MEVP:s are compared to population sizes given by a single species model where interactions with other species are treated as a constant source incorporated in the species specific growth rate. MEVP:s are found to be larger than the population sizes given by the single species model. The results are trophic level dependent and multispecies approaches are suggested to be of major importance when setting target levels for species at the basal level. Species at higher trophic levels, however, are altogether more prone to extinction than species at the basal level, irrespective of food web size and food web complexity.

Thesis (M.N.)--Memorial University of Newfoundland, School of Nursing, 2001. / Typescript. Bibliography: leaves 91-97.

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Background: Physical functioning and mobility of older populations are of increasing interest when populations are aging. Lower body functioning such as walking is a fundamental part of many actions in daily life. Limitations in mobility threaten independent living as well as quality of life in old age. In this study we examine differences in physical aging and convert those differences into the everyday measure of single years of age. Methods: We use the English Longitudinal Study of Ageing, which was collected biennially between 2002 and 2012. Data on physical performance, health as well as information on economics and demographics of participants were collected. Lower body performance was assessed with two timed walks at normal pace each of 8 ft (2.4 m) of survey participants aged at least 60 years. We employed growth curve models to study differences in physical aging and followed the characteristic-based age approach to illustrate those differences in single years of age. Results: First, we examined walking speed of about 11,700 English individuals, and identified differences in aging trajectories by sex and other characteristics (e.g. education, occupation, regional wealth). Interestingly, higher educated and non-manual workers outperformed their counterparts for both men and women. Moreover, we transformed the differences between subpopulations into single years of age to demonstrate the magnitude of those gaps, which appear particularly high at early older ages. Conclusions: This paper expands research on aging and physical performance. In conclusion, higher education provides an advantage in walking of up to 15 years for men and 10 years for women. Thus, enhancements in higher education have the potential to ensure better mobility and independent living in old age for a longer period. (author's Abstract)

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This paper examines the effect of high-speed broadband expansion on the rural population and number of rural workplaces in Sweden in the years 2009 and 2014. Previous studies conducted on the subject have found positive correlations between broadband expansion and economic growth. However, most previous studies have been focused on urban areas and the transition from no broadband to basic broadband. This study focuses on the shift from basic broadband to high-speed access in rural areas in all 290 municipalities of Sweden. This paper uses cross-sectional data to perform OLS regressions to test the effect that an expansion of high-speed broadband has on rural population and rural workplaces. An accessibility measure is constructed to control for different access that each municipality has to the rest of the population as well as to control for spatial dependencies. The results of this paper show that there is a significant correlation between high-speed broadband expansion and the number of rural workplaces.

There is evidence that infaunal bivalves in New Zealand are not as abundant as they once were with overfishing and habitat modification contributing to the decline in density and health of cockles. The population biology and abundance of the bivalve Austrovenus stutchburyi (tuangi) in eight beds in four estuaries was assessed both seasonally (13 seasons) and annually (7 years) as little is known about the cockle beds in the Canterbury region of New Zealand. As with populations of similar species worldwide, there were site specific differences in population structure (density and size ranges) with the highest densities at Takamatua (>1500/m²), and the lowest at Port Levy (<350/m²). Gonad indices varied between male and female cockles. Male reproductive cycles were similar at all sites with male cockles being reproductively active year round, while females were more active in spring and summer. Temporal and spatial site specific differences occurred in cockle condition with high salinity sites having higher condition indices (CI) than low salinity sites. There were spatial and temporal variations in salinity (3-35ppt), sediment structure (fine sand through to predominantly silt), water temperature (6-20°C), nutrient supply (total volatile solids (TVS) 0.002- 0.15mg/L) and contaminant levels. Metal pollution indices (MPI) ranged between 3 and 11. Three cockle transplant trials were undertaken both within and between estuarine systems. Caged cockles survived well, and cage design needed to allow vertical movement of the bivalves within the substrate to reduce mortality. At the end of the 12 month trial, approximately 45% of the cockles remained in the plots. The condition of transplanted cockles was similar to naturally occurring cockles. Recommendations are made to optimise the success of cockle transplants. Large scale, un-caged placement of 25-30mm length cockles in the mid-low tide region of areas with stable, but not necessarily uncontaminated substrate, moderate salinity and temperature and with a reliable nutrient supply is recommended. The results from the thesis research can be applied to other infaunal bivalves in New Zealand allowing more successful restoration processes leading to increased species diversity and ecosystem functioning.

This dissertation is a compilation of four separate studies under the umbrella of the Chemical Abundance of Stars in the Halo (CASH) Project. The overall goal of the CASH project is to gain a better understanding of the events and processes that occurred during the early universe that shaped the composition of the stars that we observe today. In order to do so, we have conducted a comprehensive study of the abundances of the oldest observable stars. These stars have preserved the chemical signature of the material from which they formed in their atmospheres. The old, metal-poor stars that make up the stellar halo thus provide a means to study the history of the universe. We will discuss the motivation for the project in Chapter 1, introducing the field of metal-poor halo stars and providing background about the processes that have contributed to the chemical make up of the stars. The first generation of stars that created much of the material from which these stars formed are discussed, along with the low-mass evolved stars that synthesized additional elements in their interiors that are also observed in metal-poor stars today. Utilizing so-called ``snapshot'' spectra obtained with the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory, we provide abundances for 262 stars over the sample. In Chapter 2, we present Robospect, a new code to automatically measure and deblend line equivalent widths for both absorption and emission spectra. We used this code to calculate equivalent width measurements, which provide the foundation of the analysis, from our spectra. We test the accuracy of these measurements against simulated spectra as well as manual equivalent width measurements of five stellar spectra over a range of signal-to-noise values and a set of long slit emission spectra. We find that Robospect accurately matches both the synthetic and manual measurements, with scatter consistent with the expectations based on the data quality and the results of Cayrel (1988). In Chapter 3, we present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the CASH project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R ~15,000) and corresponding high-resolution (R~35,000) Magellan MIKE spectra. The stars span a metallicity range from [Fe/H] from -2.9 to -3.9, including four new stars with [Fe/H]<-3.7. These pilot sample stars are the most metal-poor ([Fe/H]≲-3.0) of the brightest stars included in CASH and are used to calibrate a newly-developed, automated stellar parameter and abundance determination pipeline. This code is used for the entire CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum. We find four stars to be carbon-enhanced metal-poor (CEMP) stars, confirming the trend of increasing [C/Fe] abundance ratios with decreasing metallicity. Two of these objects can be classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]<-3. We also find four neutron-capture enhanced stars in the sample, one of which has [Eu/Fe] of 0.8 with clear r-process signatures. In Chapter 4, we present stellar parameters and abundances for the full CASH sample of 263 metal-poor halo star candidates derived from snapshot spectra obtained with the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We determine abundance statistics and trends for 16 elements over the full sample. We identify astrophysically-interesting stars that merit further investigation, including carbon-enhanced metal-poor stars, neutron-capture element enhanced stars, and extremely metal-poor stars. We note one Li giant with a unique abundance pattern. In Chapter~5 we present a detailed abundance analysis of 23 elements for a newly discovered carbon-enhanced metal-poor (CEMP) star, HE 0414-0343, from the CASH sample. Its spectroscopic stellar parameters are T_eff=4863 ,K, log g=1.25, ξ=20 km/s, and [Fe/H]=-2.24. Radial velocity measurements covering seven years indicate HE 0414-0343 to be a binary. HE 0414-0343 has [C/Fe]=1.44 and is strongly enhanced in neutron-capture elements but its abundances cannot be reproduced by a solar-type s-process pattern alone. It could be classified as ``CEMP-r/s'' star but we find that no r-process component is required as explanation of this and other similar stars classified as ``CEMP-s'' and ``CEMP-r/s'' stars. Rather, based on comparisons with AGB star nucleosynthesis models, we suggest a new physically-motivated classification scheme, especially for the still poorly-understood ``CEMP-r/s'' stars. Importantly, it reflects the continuous transition between these so-far distinctly treated subgroups: CEMP-sA, CEMP-sB, and CEMP-sC. The [Y/Ba] ratio parameterizes the classification and can thus be used to classify any future such stars. Possible causes for the transition include the number of thermal pulses the AGB companion underwent and the effect of different AGB star masses on their nucleosynthetic yields. We then speculate that higher AGB masses may explain ``CEMP-r/s'' or now CEMP-sB and CEMP-sC stars, whereas less massive AGB stars would account for ``CEMP-s'' or CEMP-sA stars. Based on a limited set of AGB models, we suggest the abundance signature of HE~0414$-$0343 to have come from a >1.3 M_⊙ mass AGB star and a late-time mass transfer, thereby making it a CEMP-sC star. Finally, in Chapter 6, we summarize our results and provide future directions for the project. / text