Thesis (Ph.D.)--Boston University / The electron microscope was used to study comparatively the interrenal tissue of species selected from three vertebrate classes which were chosen as representatives of a particular segment of the evolutionary tree. Certain similarities exist in the interrenals of the species chosen, inasmuch as a similar cordal arrangement of cortical cells, as well as an intermingling of chromaffin and interrenal tissue have been described. In addition, the interrenal cells have been shown to be under the influence of the pituitary gland in all vertebrates. The bases for comparison of the species selected are evolutionary ties, the fact that the interrenal cells produce certain hormones common to all classes, and the fact that the enzymes necessary for hormone production reside in or on the mitochondria. Nine species of animals were used: three amphibians, four reptiles, and two birds, each representing a different order. Several fixatives were tried, but the one most frequently used was a phosphate buffered 1% osmium solution (Millonig, 1962) with modifications to suit the pH and osmolarity of the animal involved. Tissues were fixed for 1/2 to 1 1/2 hours at 4°C. Dehydration was effected in graded acetenes and the material was embedded in either Vestopal W, Araldite 502 or Maraglas 655. Vestopal W gave the most contrast and stability, but was the most difficult to section. Sectioning was accomplished with a Leitz, Hnxley, or PorterBlum microtome with a glass knife. Sections of gold or silver color were chosen for electron microscopy, which were 900 - 1500 A thick (Peachey, 1958). Sections were also cut 1u thick and stained with 1% aqueous methylene blue for light microscopy. The thin sections were picked up on slotted, uncoated grids and routinely stained with phosphotungstic acid. Some were also stained with lead hydroxide or uranyl acetate. The grids were then viewed and photographed with an RCA-EMU-2B or with a Siemens Elmiskop I electron microscope [TRUNCATED]

Tesis para optar al Grado de Magíster en Ciencias Animales y Veterinarias mención Medicina Preventiva Animal. / Las especies invasoras son actualmente la segunda mayor amenaza para la biodiversidad siendo un componente generalizado y significativo del cambio ambiental global causado por los seres humanos. Si bien durante las últimas décadas se describe una declinación de las poblaciones de reptiles y anfibios a nivel mundial, son cada vez más los registros de especies de estos grupos que se desplazan a nuevos hábitats muchas veces generando efectos negativos sobre estos ambientes. Tarentola mauritanica o salamanqueja común, es una especie de reptil que ha sido reportada como introducida en diferentes países incluyendo Chile, donde al parecer de manera accidental se transportaron individuos junto con materiales importados para el Metro de Santiago. Con el fin de confirmar molecularmente la presencia de esta especie, determinar su origen y describir su fauna parasitaria, en el presente estudio se capturó a individuos de la población encontrada en la ex Ciudad de Niño en la comuna de San Miguel, Región Metropolitana. Mediante la secuenciación de un segmento de 12S y 16S ARNr fue posible confirmar que Tarentola mauritanica mauritanica es la especie introducida en nuestro país. Asimismo, utilizando secuencias obtenidas de congéneres desde diferentes zonas de su distribución natural, se realizaron análisis filogenéticos para determinar la procedencia de este reptil. Dada la baja diversidad genética mitocondrial descrita para esta especie en el clado europeo, no fue posible obtener esta información. Finalmente, se observó que los individuos capturados presentaron menor diversidad y densidad parasitaria que lo descrito para la especie en su distribución natural, lo cual concuerda con lo reportado para diferentes especies introducidas a nivel mundial / Nowadays invasive alien species are considered the second major threat to biodiversity and a significant component of the global environmental change induced by human population. Even though it has been described a declination of reptile and amphibian populations worldwide there is an increasing amount of reports from these animals moving to new habitats causing negative effects over the colonized environments. Tarentola mauritanica (Moorish Gecko) is a reptile that has been reported as introduced in different countries around the world. Apparently, they arrived to Chile traveling together with imported materials for the Subway (Metro de Santiago). The aim of the present study was to confirm using molecular methods the presence of T. mauritanica in Chile, to determinate its origin and to describe its parasites. The samples were taken from the gecko population located in ex Ciudad de Niño (Comuna de San Miguel, Región Metropolitana, Chile). Sequencing fragments from 12S and 16S rRNA it was confirmed that Tarentola mauritanica mauritanica is the alien introduced species in our country. Likewise, phylogenetic analysis were conducted comparing the obtained sequences with others from individuals within their natural distribution to determine the origin of this population. Nevertheless, it was not possible given the low mitochondrial genetic diversity of the European clade of this specie. Regarding the parasitic burden, the sampled specimens showed a lower diversity and density of parasites when compared with individuals from population within their natural distribution. This finding was expected according to what has been reported to different introduced alien species around the world

Made available in DSpace on 2014-06-11T19:30:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-07Bitstream added on 2014-06-13T20:40:03Z : No. of bitstreams: 1 gavira_rsb_me_rcla.pdf: 847914 bytes, checksum: 30801f5783f8efbfaed2c1c9ebf88cd8 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O grupo das serpentes é formado por animais estritamente carnívoros que ingerem suas presas inteiras, sem mastigação. Algumas espécies podem tolerar períodos prolongados de jejum intercalados com ingestão ocasional de presas muito grandes em relação à sua massa corpórea. Tais serpentes apresentam, dentre todos os vertebrados, algumas das mais dramáticas especializações morfológicas, comportamentais e fisiológicas associadas à alimentação. Uma das consequências da ingestão de grandes massas de alimento é o excepcional aumento da taxa metabólica pós-prandial, referido como Ação Dinâmica Específica (ADE). A magnitude dessa resposta metabólica pós-prandial depende essencialmente do tamanho e da natureza do alimento, associado a fatores como o tamanho corpóreo e a temperatura do ambiente. No entanto, raros são os trabalhos que caracterizaram a ADE de espécies de serpentes neotropicais e examinaram os fatores que potencialmente poderiam afetar esta resposta. Deste modo, ao longo dos dois capítulos que compõem a presente dissertação, investiguei alguns dos determinantes proximais do aumento metabólico pós-prandial da urutu-cruzeiro, Bothrops alternatus (Serpentes, Viperidae). O capítulo I foi dedicado à investigação dos efeitos da temperatura e do termoperíodo sobre a ADE de Bothrops alternatus (Serpentes, Viperidae). O capítulo II foi dedicado ao estudo dos efeitos do tamanho da presa sobre a ADE de Bothrops alternatus (Serpentes, Viperidae). Nossos resultados mostraram que o aumento da temperatura corpórea é acompanhado por uma aceleração do processo digestivo às custas de um maior incremento metabólico. A variação destes parâmetros ocorre de maneira inteiramente proporcional de forma que a energética da ADE não foi afetada pela variação da temperatura... / Not available

The purpose of this study was to record the relationships between the reptiles and amphibians of Wise County and the ecological subdivisions of the area. Wise County was chosen because of the heterogenity of the area and because of its proximity to other counties which have been previously and similarly studied.

A dissertation submitted to the faculty of science, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of science, Johannesburg, 2018 / Defining the spatial distributions of species with regards to habitat selection and landscape structure is an important part of biogeography, ecology and conservation research. I investigated reptile occurrence and community structure in two patches of dry forest in north western Madagascar using detection/non-detection data collected on repeated transect surveys for four years. A Bayesian hierarchical occupancy model and multispectral satellite imagery were used to assess the effects of vegetation structure, proximity to human development and edge proximity on the site presence of 37 squamate species in the context of taxonomic family and Threat Status. Mean species richness was highest at sites within a forest patch (23 (4, 30)). Sites with dense green vegetation promoted the highest levels of reptile occupancy among the Chamaeleonidae and Gekkoniidae families (with regression coefficient estimates up to 0.75 (0.12, 1.53)) and all species were more likely to occur at sites closer to the forest patch periphery. The Boidae had the widest 95% CRI for the regression coefficient estimates representing the effects of habitat variables on occupancy, indicating that they are highly variable in their habitat use. The regression coefficient estimates of mean reptile occupancy had 95% credible intervals (CRIs) including zero due to high variability between species. The proximity to roads did not have a statistically significant effect on any of the species, and Uroplatus guentheri was the only species which showed a significant preference for being further from a settlement (0.81 (0.05, 1.77)). The findings demonstrated the importance of using caution when assessing Threat Status at a regional level and suggest that the Red List’s measure of Population Trend may be significantly influenced by imperfect detection / MT 2019

Presence-absence data for amphibians, chelonians, saurians, ophidians, and the terrestrial and aquatic ecological guilds of reptilians were analyzed using multivariate analyses. Geographically consistant distributional patterns were found for all faunal groupings. The correspondence between analyses of the different taxa and guilds was not perfect, but similarities were found. All analyses agreed on the presence of a distinctive region in east Texas. Most analyses also agreed on the presence of distinctive regions in south Texas, the Trans-Pecos, the Edwards Plateau, and north-west Texas. There is strong correspondence between interpretations of the analyses based on the amphibian, saurian, ophidian, and terrestrial reptilian distributions, and the biotic provinces produced by earlier, subjective analyses. The Edwards Plateau and a region on the western periphery of east Texas were found to be transitional between other, more faunally distinctive areas for most fauna! groups. Detailed examination of these regions suggested they are best described as clinal in nature. The environmental variables which were most effective in explaining patterns in the distribution of the various taxa and guilds were related to precipitation. However, variations in temperature and physiography were also important predictors of distribution for several of the groups. The distributions of soil and vegetation associations were also found to be related to amphibian and reptilian distribution.

The evolution of snakes (Squamata: Serpentes) represents a major transition in squamate reptiles and involves extensive modifications in the body plan. Functional morphology and phylogeny are integrated to discuss adaptive morphological traits in the origin of snakes and in the evolution of the venom-injecting apparatus among lizards, which is convergent with that in snakes. The focus of these analyses is to determine how to best optimize morphological traits on the phylogeny and to use character distribution in terminal taxa to estimate ecological adaptation in ancestral nodes. To study the locomotion transition from lizards to snakes, 45 virtual models of the squamate bony labyrinth in the inner ear were reconstructed. The results show morphological diversifications of the vestibular region among burrowers, generalists and marine swimmers. The vestibule is enlarged in fossorial species, and reduced in marine snakes and the marine lizard Platecarpus coryphaeus. To quantify the morphological differences and provide tractable methods to reconstruct locomotion in ancestral snakes, I performed three-dimensional geometric morphometric analysis of the 45 samples, using six landmarks and 22 semilandmarks. ANOVA tests on the Procrustes coordinates supported differences among fossorial, generalist, and aquatic locomotion categories. Phylogenetic signal was insignificant in the Procrustes coordinates. Using a phylogeny with the 44 extant samples as terminal taxa, I reconstructed shape coordinates of all internal nodes. Reconstructed shape of the vestibular region of key ancestral nodes in snakes preferred a terrestrial origin for crown-group snakes. Morphological proxies used in this study can be applied to stem snakes to estimate locomotion. Methodologically, this study provides a novel approach to resolve the question whether snakes become limbless on land or in the oceans. Evolution of the venom-injection apparatus in lizards is discussed, based on new material of Estesia mongoliensis. A total-evidence phylogenetic analysis of anguimorph lizards is performed with 86 anguimorph taxa coded to 435 morphological characters and four genes. The matrix includes eight new morphological characters. The total-evidence phylogeny suggests that Estesia Mongoliensis is a basal monstersaur whose crown groups are Heloderma, the only living venomous lizards. Presence of tooth flanges with venom grooves is recognized as a new monstersaurian synapomorphy in this study. Estesia mongoliensis has venom grooves comparable to extant Heloderma, but has a deeper root-to-tip groove in the caudal tooth carina, revealing morphological variations of lizard venom delivery apparatus that are not recorded in extant species.

Thesis (Ph. D.)--University of Oregon, 2001. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 121-147). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Hong Kong, 2008.

No description available.