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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Assessing Morphometric and Otolith Measurements of Red Snapper, Lutjanus campechanus, to Characterize a Recreational Headboat Fishing in the Gulf of Mexico's Exclusive Economic Zone

Carrillo, Nicole Amber 02 October 2013 (has links)
As a highly targeted species, red snapper have been overfished since the 1970’s. Inadequate monitoring and reporting of discard rates impedes regulatory measures which are in place to allow red snapper populations to reach a healthy, sustainable level. This study documented the relationship between morphometric measurements and otolith analysis of red snapper caught from a recreational headboat fishing exclusively in the GOM’s EEZ of the upper Texas coast. The collected data of this research show that of the 594 red snapper caught within the sample group, 76% of the fish were discarded; analysis of the lengths of these discarded fish show that 15.5% were of regulation size (16 inches) or larger, clear evidence that high-grading is occurring. The effort for the total amount of red snapper caught by each individual angler within the sample group was measured to determine on average, approximately two red snapper were caught per person, per hour. The size distribution ranged from 16 to 32 inches with a mean total length of 21.32 inches for retained fish while discarded fish ranged from 5.5 to 22.5 inches with a mean of 14.23. Weight distribution ranged from 1.5 to 18.5 pounds with a mean of 5.81 pounds for retained fish and 0.20 to 6 pounds with a mean of 1.57 pounds for discarded fish. Age distribution ranged from 3 to 14 years of age; red snapper can live over 50 years, however relatively none (2.42%) older than 10 years were present in the sample, demonstrating a highly truncated population. Because fecundancy increases with age in females, longevity extends reproduction potential for red snapper. Management of reef fishes, and red snapper in particular, are difficult due to variances in growth rates and habitat use, complex population structure, and increasing reproduction levels with maturity. Recommendations for management include implementing an educational outreach program, reducing effort and discard rates, lowing rates of exploitation, and creating a marine reserve. Future research should address the entire Texas coast population of for-hire vessels (charter and headboats) to obtain data on discard rates and age distribution of red snapper.
62

Morphometric And Genetic Differentiation Between Anatolia And Cyprus Bombus (bombus) Terrestris (l. 1758) Populations

Beton, Damla 01 October 2004 (has links) (PDF)
MORPHOMETRIC AND GENETIC DIFFERENTIATION BETWEEN ANATOLIA AND CYPRUS BOMBUS (BOMBUS) TERRESTRIS (L. 1758) POPULATIONS BETON, Damla M. Sc., Department of Biology Supervisor: Prof. Dr. Aykut Kence September 2004, 86 pages Four microsatellite loci were used to investigate differentiation in Bombus terrestris, a bumblebee of interest for its high value crops pollination. Two bumblebee populations, one from Ankara (the capital of Turkey) and one from North Cyprus were analyzed. In these populations, the total number of alleles detected per polymorphic locus ranged from 7 to 12. FST genetic distance between Ankara and North Cyprus B. terrestris populations based on four microsatellite loci was calculated as 0,09351. This applies that there is significant (P&lt / 0,001) differentiation between Anatolian and Cypriot populations. Moreover, statistically significant differences between two populations were found in wing characters studied. According to the potential for local adaptation and individual fitness of bumblebees, microsatellite data calls for protection of Bombus terrestris populations against importation of bumblebees of foreign origin which are used as crop pollinator.
63

A morphometric approach to facial growth prediction

Botchevar, Ella 25 October 2017 (has links)
BACKGROUND: Orthodontists rely heavily on cephalometric analysis to assess growth potential and direction. Geometric morphometrics examines shape and can help the clinician reach more accurate diagnoses and predict future growth. PURPOSE: The aims of this study are: 1) Determine principle components describing craniofacial shape changes; 2) Assess shape changes in growing subjects; 3) Develop a model for craniofacial growth prediction using geometric morphometrics. RESEARCH DESIGN: The Cranial base, maxilla and mandible were digitized on 330 lateral cephalograms from ages 6-16 (n=33). Generalized Procrustes analysis was performed on the longitudinal data sample. Principle Component, Discriminant Function and Two-Block Partial Least Squares analysis were assessed against changes in individual structures to determine if changes in the maxillary, mandibular or cranial base are related to changes in shape of the overall craniofacial form. RESULTS: PCA shows that the first six principle components account for 67.7 – 77.0% of the observed shape variance in each region and 56.0% of the whole form. Multivariate regression analysis predicts the shape of the entire craniofacial complex at 16 years old based on the shape observed at 6 years old with 94% certainty. An intraclass correlation coefficient of 0.98 confirms reliability. CONCLUSION: Morphometric analyses indicate that changes in maxillofacial morphology during skeletal maturation are linear. The shape of the craniofacial complex does not change significantly and growth pattern is maintained. Our model can predict the craniofacial shape at 16 years of age based on the shape observed at 6 years of age.
64

Three-dimensional analysis of mandibular landmarks, planes and shape, and the symphyseal changes associated with growth and orthodontic treatment

Deller, Cecilia Mercedes 25 October 2017 (has links)
OBJECTIVE: To test reliability of 3D mandibular landmarks, planes of reference and surfaces and assess their correlation to conventional 2D cephalometric measurements. To analyze changes in three-dimensional shape of the symphysis due to growth and orthodontic treatment. METHODS: This was a retrospective analysis of CBCTs of healthy orthodontic patients. 32 subjects were included, 16 males and 16 females. Mean ages of 10.6 ± 1.5 years and 15.0 ± 0.9 years before and after treatment, respectively. The mean follow up time was 4.3 years. Subjects free of any craniofacial anomalies, and no observable pathology on panoramic radiograph were. 15 subjects had CVM 1 and 17 subjects had CVM 2 before orthodontic treatment. All subjects had CVM 5 after orthodontic treatment. For the first phase, 3D mandibular landmark identifications were digitized. Planes and landmarks were constructed and compared with conventional 2D mandibular measurements. For the second phase, mandibles were isolated by removing surrounding structures. Pearson correlation and paired t-test were performed to test for correlation and differences between 2D and 3D measurements, respectively. Statistical analysis was performed using SAS 9.4. Software. MorphoJ software (Version 2.0, www.flywings.org.uk) was used for symphysis shape analysis; and Discriminant Function Analysis (DFA) between pre-treatment and post-treatment was used for statistical analysis of the symphysis. RESULTS: We found statistical significant positive correlation between 2D and 3D pre-treatment ramus height (P-value =0.01), post-treatment ramus height (P-value < 0.0001), pre-treatment corpus length (P-value 0.0003), post-treatment corpus length (P-value 0.04), pre-treatment gonial angle (P-value <0.0001), and post-treatment gonial angle (P-value=0.05). Also, statistically significant differences in 2D ramus height (P=0.001), 3D ramus height (P-value=0.002), 2D corpus length (P-value <0.01), and 3D corpus length (P-value <0.01). For symphysis shape comparing between pre-treatment and post-treatment, we found that there is no statistically significant difference between them (P-value= 0.99). CONCLUSION: These results demonstrated statistically significant positive correlation between certain 2D and 3D measurements, pre-treatment and post-treatment differences in 2D and 3D measurements showed consistent results. Symphysis shapes do break out as distinctly separate groups, but the differences between the means is small.
65

Review of South African genera of the family hexabothriidae price, 1942, parasites of chondrichthyan fishes

Vaughan, David Brendan January 2009 (has links)
Magister Scientiae (Biodiversity and Conservation Biology) / The oligonchoinean monogenean family Hexabothriidae Price, 1942 currently consists of approximately 60 valid species, representing 15 genera. Hexabothriids are gill parasites of chondrichthyan fishes (sharks, rays and chimaeras). Some hexabothriid species have been reported as problematic in public aquaria, directly responsible for host pathology and subsequent host mortalities. However, without information on specific hexabothriid species and their host associations, accurate captive management of hexabothriids in public aquaria is hindered. Hexabothriid taxonomy is in a state of confusion. The historic taxonomic restoration of the priority of Hexabothrium sees the beginning of the taxonomic uncertainty of the hexabothriids, and is continued into the present literature particularly among lower-level taxa in Hexabothriidae. In addition, there is currently no consensus for a single accepted morphometric protocol for the discrimination of hexabothriid taxa, which leads to unnecessary ambiguity of character variable nomenclature, measurement and interpretation. A call for stability in the nomenclature and morphometric discrimination of species is therefore proposed. A novel morphometric protocol is tested for the sclerotised haptoral armature, supported by the proteolytic digestion of structures for optimal representation. Character variables, subjected to univariate and multivariate analyses were systematically accepted or rejected based on their potential to discriminating species of Callorhynchocotyle Suriano and Incorvaia, 1986. The hexabothriid genera Callorhynchocotyle and Branchotenthes, represented by South African taxa, are reviewed, using these variables. Four Callorhynchocotyle species and 2 Branchotenthes species are redescribed with the inclusion of some new voucher specimens.
66

A morphological analysis of weevils from sub-Antarctic Prince Edward Islands: an assessment of ecological influences

Janse van Rensburg, Lindie 24 August 2006 (has links)
The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-free Prince Edward Islands represent ideal ecosystems for addressing questions relating to the partitioning of potential influences of anthropogenic changes, such as climate change and alien species on ecosystem functioning. Consequently, weevil species were used in the present investigation to address questions of morphological change over time with reference to climate change and mouse predation. As a prelude to the assessment of morphological changes over time, the six currently recognised weevil species, namely, Bothrometopus randi, B. parvulus, B. elongatus, Ectemnorhinus similis, E. marioni and Palirhoeus eatoni from both Marion and Prince Edward Islands were confirmed by morphometric analyses. However, the taxonomic status of Ectemnorhinus weevil species on both islands is much more complex than previously considered. A multi-faceted approach based on both morphometric and molecular (COI gene) data suggest the presence of a single species, comprising diverse, genetically discrete populations on Marion Island and two genetically distinct species on Prince Edward Island. The assessment of morphological changes over time included the four remaining weevil species (B. elongatus, B. randi, B. parvulus and P. eatoni) occurring on both Marion and Prince Edward Islands, collected non-consecutively over five decades. These analyses suggest morphometric size differences between samples from both Marion and Prince Edward Islands collected in the mid-1960s and 1970s and those collected recently. Similarly, samples from both islands collected in the early- to mid-1980s also showed morphometric shape differences with those collected recently for both Prince Edward and Marion Islands, respectively. Generalized Linear Models (GLZ) suggested year of sampling to contribute more, to both, morphometric size and shape in all species sampled on both islands, while temperature contributed more to shape for species collected on Marion Island. Given the consistent pattern of morphological change over time for both the mouse-infested Marion Island and the mousefree Prince Edward Island, it is possible that climate change rather than mouse predation may primarily influence weevil morphological changes on the two islands. Subsequent analyses extended the question of weevil morphological changes over time with reference to climate change and mouse-predation, and included sub-fossil weevil elytra and head capsule remains collected on Marion Island mire habitats. As a prelude to these analyses, an attempt was made to first identify the sub-fossil samples (using head capsules) with reference to recent samples of the currently recognised weevil species on both islands. While species-level identifications were not possible, morphometric analyses suggest that the sub-fossil remains belong to the Ectemnorhinus group of weevils. Sub-fossil weevil remains recovered in mire sediments from 2 m and 2.5 m depths, considered to represent different dimensions in space and time, were dated at 789 BC and 2331 BC, respectively. Subsequent analyses showed no significant morphometric changes in sub-fossil material between the various depths, predating the effects of climate change on both islands and the introduction of the house mouse (Mus musculus) on Marion Island in the early 1800s. However, a comparison between the sub-fossil remains and recently collected material considered to represent a period characterised by climate change and mouse-predation showed significant morphometric differences over time. However, the questions investigated in this study need to be investigated further because the potential ecological influences driving ecosystem functioning on the islands may be much more complex than currently understood. / Thesis (PhD (Entomology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted
67

Fossil Moles from the Gray Fossil Site, TN: Implications for Diversification and Evolution of North American Talpidae

Oberg, Danielle 01 May 2018 (has links)
The Gray Fossil Site (GFS) is one of the richest Cenozoic terrestrial localities in the eastern United States. This study describes the first talpid specimens recovered from the GFS. Using measurements and comparisons of dental and humerus morphology, I identify 4 talpids (Parascalops nov. sp., Quyania cf. Q. europaea, Mioscalops (= Scalopoides) sp., and an unidentified stem desman) occurring at the GFS. Humeral morphology has been used to diagnose talpid species and study relationships. A geometric morphometric analysis showed that humerus shape is highly reflective of locomotor ecology in extant talpids and allows ecological inferences for fossil talpids. Hierarchical cluster analysis using morphometric data allowed examination of similarity among taxa and helped to secondarily verify taxonomic designations for the GFS taxa. The resulting phenogram showed strong similarity to the most up-to-date molecular cladogram and actually matched phylogenetic relationships substantially better than any morphological cladistic analyses to date.
68

Two-dimensional landmark analysis of Spinocyrtid brachiopods of Euramerica during the Givetian

Layng, Alexander Patrick 01 August 2017 (has links)
Recent inquiry into the nomenclature of several species within Spinocyrtia has led to questions concerning name applicability and validity, particularly whether Delthyris granulosa and Spinocyrtia (Spirifer) granulosa are synonymous. This study utilized two-dimensional outline landmark analysis, a form of geometric morphometric analysis, to evaluate interspecific variation among these species. I took over a thousand photographs of over a hundred specimens of brachiopods belonging to the family Spinocyrtiidae. Ninety-six specimens originated from the Givetian outcrop belt of New York state, three were from northwestern Ohio, there was single Canadian specimen, and there was a single German specimen. The results from these analyses indicate that the mophospaces of Spinocyrtia (Spirifer) congesta, S. (Spirifer) granulosa, and S?. (Spirifer) marcyi are statistically (p < 0.05) distinct from one another.
69

Functional morphology and evolution of the adapiform dentition, with particular emphasis on the Asian Sivaladapidae

White, Jessica Lynn 01 January 2006 (has links)
This study utilizes two-dimensional geometric morphometric techniques to address molar shape variation in extinct and extant prosimians using the relative orientation of selected homologous molar landmarks (paraconid, protoconid, metaconid, entoconid, hypoconid, hypoconulid, metaconulid, and the intersection of the cristid obliqua with the protolophid). Molar shape was studied using Thin-Plate Splines analysis to explore variation using shape variables simultaneously, rather than by comparing inter-landmark distances, as in traditional studies. The sampled extant taxa included members from the Malagasy lemur families Lepilemuridae, Lemuridae, and Indriidae, as well as Asian Lorisidae. Extant taxa were categorized using taxonomic, as well as dietary, categories to determine if intra-sample variation was correlated with either category. Results suggest that frugivores (and gramnivores) generally exhibit a relatively wide anterior talonid basin and little trigonid torsion (observed as the angle of the protolophid relative to the long axis of the molar). Folivores, on the other hand, generally exhibit a constricted anterior talonid and higher degrees of trigonid torsion. Lorisid omnivores were found to exhibit constricted anterior talonids, but little trigonid torsion. The Thin-Plate Splines technique was also applied to a sample of three extinct adapiform families: Notharctidae, Adapidae, and Sivaladapidae. These comparisons were aimed at further exploration into dietary adaptation and diversity in extinct prosimians, and to specifically address the paleobiology of the Asian sivaladapids. Like their extant counterparts, adapiforms generally varied also in the relative orientation of the trigonid basin and in the dimensions of the talonid basin. In addition, the relative location of the paraconid also varied significantly within several adapiform families. Results of this study specifically highlight shape variation within several prosimian lineages, suggesting that a broader perspective of morphological diversity can be appreciated through analyzing adaptation within a particular family. For the sivaladapid genera, Sivaladapis and Hoanghonius, in particular, as well as North American Notharctidae, a molar shape similar to Nycticebus (an Asian loris) was noted. For Adapidae, a similarity with extant indriids was revealed. In summary, it is suggested here that multiple lines of morphological evidence should be employed to gain the broadest perspective of extinct primate adaptation.
70

Inferring lifestyle and locomotor habits of extinct sloths through scapula morphology and implications for convergent evolution in extant sloths

Grass, Andy Darrell 01 July 2014 (has links)
Despite the restricted morphology and distribution of sloths today, fossils sloths show a wide variety of forms and behaviors and used to range from South America to Alaska. These extinct forms have in the past simply been lumped together as "ground sloths", separated from modern "tree sloths". However there are intermediate forms that have been posited to be semi-arboreal. In other groups such as primates the shape of the shoulder blade has been shown to vary significantly between groups with different arboreal behaviors. This study used geometric morphometrics to examine the scapulae of modern and extinct sloths to show that these three locomotor groups can in fact be distinguished by their shoulder blade shape. Juveniles of giant ground sloths also have significantly different shoulder blade shapes than the much larger adults, however they do not overlap with the smaller intermediate sloths, so may have been just as terrestrial as their parents despite their much smaller size. Finally, ontogenetic trajectories of several sloth genera do not show evidence of having different slopes. They start and end in different areas of morhospace but are all on parallel paths. This argues against the hypothesis of convergence in modern tree sloths, which despite both having an unusual suspensory lifestyle are not closely related. Rather they are both retaining an ancestral growth trajectory that all sloths have possessed.

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