Freshwater burrowing mussels (unionids) play a vital role in freshwater ecosystems through nutrient cycling and promoting biodiversity. They have unique life histories directly related to aquatic vertebrates during an obligate parasitic larval stage, known as glochidia. Human interference has largely impacted mussel populations causing them to become the most endangered group of animals in North America. Genetic data has revealed taxonomic issues related to valve morphology, such as valve plasticity and cryptic speciation, that has caused identification issues in the field. Using both genetic and morphometric methods, I determined the phylogenetic placement of an isolated population of mussels within the tribe Lampsilini. I also investigated whether this population was a morph of a previously known Lampsilin species or if they were worthy of being treated as an evolutionarily significant unit (ESU) or an undescribed species. In addition, I expanded the known phylogeny of Lampsilin by including three species (Lampsilis fasciola, Lampsilis hydiana, Ligumia subrostrata) not included in previous phylogenies. Genetic analysis involved sequencing cytochrome c oxidase subunit 1 (COI) and 16s ribosomal RNA (rrnL) genes and producing maximum likelihood trees with bootstrap values for each gene individually and combined. Genetic results showed that an population from an isolated pond (named Junk Pond in this study) were closely related to members of the genus Ligumia (pondmussels), with Ligumia subrostrata being their closest relative. Morphologically, these Junk Pond mussels were noticeably different from other Ligumia species, so genetic and morphometric data was used to try and characterize this population of mussels from Junk Pond. The genetic distance between these two groups, measured using K2P distance method, were like the distances of other known sister species within Lampsilini. Morphometric analysis involved landmark and semi-landmark analyses to quantify the differences of the internal and external shapes of the shell, respectively, and determine differences that could be species defining characteristics. Landmark analysis results showed that Ligumia subrostrata and the Junk Pond mussels had similar internal valve structures though semi-landmark results showed differences among all groups including L. subrostrata and the Junk Pond mussels. I determined that this isolated population, due to its geographic isolation, genetic differences, variant shell morphology, and limited population size, should be treated as an ESU. The expanded Lampsilin tree showed a few differences involving Ligumia nasuta that did not support a previously published tree. Many other relationships within this phylogeny agreed with previously published works. The isolated population of the Junk Pond mussels are worthy of future research using more genetic data, such as COI, and morphometric work involving other Lampsilin members in order to conclude whether this group are worthy of being recognized as an undescribed species.

Study of the genetic relationships and evolutionary histories of pupfish populations (Cyprinodontidae: Cyprinodon spp.) from the remnant aquatic habitats of Death Valley was approached by exploring the genetic structure and divergence within and among populations using mitochondrial and nuclear DNA markers. The findings of these studies illustrate the influences of population size and isolation time in the divergence of small, fragmented populations largely via genetic drift. The information revealed in this study has implications for assessing priorities in the conservation of the unique evolutionary heritage among populations of the Death Valley pupfishes. A new retrotransposable element family was identified and characterized. This family of genetic elements was uncovered during a search of the pupfish genome for transposable elements to be used as molecular markers for population analyses. The description of this element family, named "Swimmer 1" (SW1), provides new insights into the evolution of long interspersed nuclear elements (LINEs) in vertebrates. Therefore, a full characterization of the SW1 element family was undertaken in the Japanese medaka (Oryzias latipes) as well as in the pupfish genome. The Japanese medaka is a model organism widely used for genetic and developmental biology studies. / Ph. D.

Crosscutting concepts such as scale, proportion, and quantity are recognised by U.S. science standards as a potential vehicle for students to integrate their scientific and mathematical knowledge; yet, U.S. students and adults trail their international peers in scale and measurement estimation. Culturally based knowledge of scale such as measurement units may be built on evolutionarily-based systems of number such as the approximate number system (ANS), which processes approximate representations of numerical magnitude. ANS is related to mathematical achievement in pre-school and early elementary students, but there is little research on ANS among older students or in science-related areas such as scale. Here, we investigate the relationship between ANS precision in public school U.S. seventh graders and their accuracy estimating the length of standard units of measurement in SI and U.S. customary units. We also explored the relationship between ANS and science and mathematics achievement. Accuracy estimating the metre was positively and significantly related to ANS precision. Mathematics achievement, science achievement, and accuracy estimating other units were not significantly related to ANS. We thus suggest that ANS precision may be related to mathematics understanding beyond arithmetic, beyond the early school years, and to the crosscutting concepts of scale, proportion, and quantity.

The genus Chrysopsis (Asteraceae) contains eleven species native to Florida, including the newly described species, Chrysopsis delaneyi. Populations of this endemic plant species inhabit the Lake Wales Ridge (LWR) and the Atlantic Ridge (AR) of the Florida peninsula. Differences in morphology have been demonstrated within C. delaneyi, based on their locations. My objective was to determine the relationships between the LWR and the AR populations by analysis of chloroplast sequence and nuclear sequence variation. Approximately 160 samples of C. delaneyi and its sister species C. scabrella have been collected from fifteen sites throughout Florida. Six single base differences were detected, one insertion, and one variable short duplication. A total of four haplotypes (i.e.: groups that have different combinations of polymorphisms) have been found. For the most part, one haplotype is found in LWR populations and is indistinguishable from that found in C. scabrella. Another haplotype is found primarily in AR populations and is more similar to haplotypes found in the more distantly related C. highlandsensis and C. floridana. One haplotype is found within populations of C. scabrella. The last haplotype in one AR population contains two polymorphic loci, one site is representative of the AR populations, and the other site is that of the LWR populations. Only one mixed population has been found, at the northern end of the AR range. These results are not consistent with taxonomic relationships inferred from morphological characteristics; hence the results suggest that chloroplast DNA (cpDNA) relationships may be the consequence of one or more instances of chloroplast capture.

No description available.

本文主要探討存戶決策對銀行投資組合決策之影響，及其可能引發之系統性風險的程度。以代表性銀行開始分析，假設銀行投資於安全性資產與風險性資產，而存戶依其決策可能會產生兩個均衡同時存在之情形。本文利用演化的力量，發展出以風險性資產報酬率作為均衡選擇之標準：當風險性資產報酬率低於某一水準時，擠兌的均衡會單獨發生。並比較銀行考慮擠兌發生可能性時，其投資組合承擔風險之程度，及可能引發的銀行倒閉機率大小。推廣至二家模型，發現愈多家銀行在作投資決策考慮存戶擠兌之可能性，愈會增加經濟體系中之系統性風險，顯示銀行與存戶之衝突與金融體系之脆弱性。最後討論資本適足性管制與央行最後貸款人角色能否有效降低銀行倒閉機率。

La conservation au niveau population est extrêmement nécessaire pour limiter la perte de biodiversité au sein d'une espèce ou d'un complexe d'espèces. Ainsi, l'évaluation de la variabilité inter-populationnelle dans le complexe est reconnue comme première étape importante pour bien définir les plans de conservation des espèces menacées. Arenaria grandiflora form un complexe d'espèces herbacées pérennes à courte durée de vie (4 ans en moyenne) menacé dans certains sites de ses zones de distribution en Europe. A ce jour, sa taxonomie n'est pas bien résolue, ce qui entraîne des problèmes potentiels pour mettre en oeuvre une conservation efficace de ce taxon. Une variation inter-populationnelle du complexe d'espèces A. grandiflora est présentée dans cette étude aux niveaux génétiques, cytogénétiques et morphométriques. Quatre méthodes ont été utilisées : des marqueurs microsatellites nucléaires, une approche cytogénétique, la cytométrie en flux, et enfin la morphométrie sur les feuilles. De plus, les études phénotypiques de variation de taux de germination entre stocks de graines ont été développées. Une différenciation significative entre les profils de variations moléculaires, cytogénétiques et phénotypiques a été détectée dans le complexe d'espèces. Deux cytotypes (diploïdes 2n=2x=22 et tétraploïdes 2n = 4x = 44) ont été mis en évidence en utilisant à la fois des méthodes classiques et des méthodes plus récentes (marqueurs microsatellites, nombres chromosomiques et cytométrie de flux). Le complexe d'espèces d'A; grandiflora présente une forte variation de la valeur de l'ADN 2C, la taille du génome varie de 2.11 ± 0.74 pg à 2.70 ± 0.11 pg pour les populations diploïdes et de 4.30 ± 1.51 pg à 5.27 ± 0.14 pg pour les populations de tétraploïdes. En outre, les grains de tétraploïdes germent significativement mieux que les graines des diploïdes. Les feuilles diffèrent considérablement entre les diploïdes (aciculaires et linéaires) et les tétraploïdes (lancéolées). Cette étude peut être considérée comme préliminaire pour une révision taxonomique de ce complexe d'espèces. D'autre part, grâce à l'ensemble des résultats obtenus, il est également possible de revisiter le concept d'unités évolutives significatives (ESUs) dans le complexe d'espèces A. grandiflora et donc de définir les groupes de populations devant faire l'objet de mesures distinctes. Ainsi, il est possible d'évaluer la pertinence de plans déjà entrepris et de proposer de nouveaux plans de restauration efficaces pour l'avenir de ce complexe d'espèces. / Population-level conservation is being extremely required to restrain the biodiversity loss within a species. So, the assessment of the variability within the species complex is being renowned as an important first step to well implement the future conservation settings for threatened species. The species complex of Arenaria grandiflora is a short-lived perennial herbaceous and a threatened taxon in certain of sites of its distribution areas in Europe, with unresolved gentics and taxonomy, which lead to potential problems in the conservation and utilization of the resource. A differenciation among populations of the species complex of A. grandiflora is presented in this study based on the genetic, cytogenetic and phenotypic patterns. Intraspecific ploidy level varaition is an important aspect of numerous species, so, the present study explores this phenomenon within the A. grandiflora species complex in some type of populations (27 natural populations). To infer the intraspecific genetic and cytogenetic patterns of variability among the studied natural populations of the investigated species complex (A. grandiflora), three methods were used : nuclear microsatellite markers, cytogenetic and flow cytometry approaches. Moreover, the phenotypic patterns of variation among both the stock of seeds and the herbarium materials of A. grandiflora were defined. These patterns were detected using three methods of seed germination (in vitro culture, filter papers and potting soil) and morphometric approaches. A significant differentiation among populations' patterns of molecular, cytogenetic and phenotypic variation was detected within the A. grandiflora species complex. Presence of two closely related cytotypes (diploids 2n=2x=22 and tetraploids 2n=4x=44) was detected using both classical and more recent methods (chromosome number count and flow cytometry respectively). The species complex of A. grandiflora exhibits high variation in 2C-DNA value, the genome size ranges from 2.11 ± 0.74 pg to 2.70 ± 0.11 pg for the diploid populations and from 4.30 ± 1.51 pg to 5.27 ± 0.14 pg for the tetraploid populations. Moreover, the seeds of tetraploids germinate well and in high proportion than the seeds of the diploid ones. In addition, both acicular and linear leaves from the diploid populations differ significantly within the diploids and with the lanceolate leaves of the tetraploid ones. New protocol of seed germination for the tetraploids by in vitro culture after scarifying was described for th first time. The affected factors on seed germination percentages were determinated by an explanatory model of six predictors (altitude, longitude, latitude, ploidy levls, both period and condition of seed storage). Consequently, all these findings are fundamental for the determination of the evolutionarily significant units (ESUs) within A. grandiflora species complex and thus the definition of efficient restoration plans in the future. This study would consider as the preliminary signal for necessary revision for the intraspecific taxonomic keys problematic for this species complex.

No description available.

Scale, proportion, and quantity constitute a “crosscutting concept” in science education – a concept that pervades science and can help students connect their knowledge across topics and disciplines. An understanding of wide ranges of size is a prerequisite for the learning of scale. Students must have a good understanding of size and scale if they are to leverage them to connect their science understanding. In this study, we examine two qualitatively different types of knowledge that may underlie the understanding of size and scale: the evolutionarily-based approximate number sense, and the culturally-based understanding of measurement units. We explore how closely these two types of knowledge are related to size and scale knowledge useful for secondary science classrooms. This study has implications for instruction: evolutionarily-based abilities are biologically primary, are acquired universally, and are motivating, whereas culturally-based abilities are biologically secondary, and depend on instruction, practice, and external motivation. Different educational approaches might be better suited to biologically primary and secondary abilities. The results of an empirical study with 36 seventh grade students are reported.

No description available.