Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves - ).

Theses (M.S.)--Marshall University, 2005. / Title from document title page. Includes abstract. Document formatted into pages: contains viii, 94 p. Bibliography: p. 92-94.

Thesis (Ph. D.)--University of Chicago, 1908. / "Reprinted from the Journal of geology, vol. XVII, no. 1, Jan.-Feb., 1909." Includes bibliographical references.

Thesis (M.S. in zoology)--Washington State University, May 2007. / Includes bibliographical references (p. 17-23).

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]

No description available.

Ribonucleic acid (RNA) from calf spleen tissue was isolated and purified by a modified Kirby phenol procedure. The absorption maximum of the isolate occurred at 260 mµ indicating the presence of nucleic acids and the absorption minima recorded at 230 mµ and 280 mµ indicated the absence of peptides and proteins. Colorimetric analyses indicated the presence of RNA and the absence of peptide, protein, DNA and carbohydrate contamination. Chromatographic analysis indicated the absence of carbohydrate contamination only after the purification with 2-methoxyethanol. The spleen RNA prepared by the phenol method was undegraded and demonstrated three distinct molecular species when analysed with the ultracentrifuge; a 27S fraction, an 18S fraction and an 8S fraction. Competent early gastrula ectoderm and embryos of Xenopus laevis exposed to undegraded spleen RNA demonstrated no tissue-specific induction. However, in both the in vitro and in vivo experimental series an enhancement of development was observed. A possible explanation of this phenomena was discussed. / Science, Faculty of / Zoology, Department of / Graduate

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.

Thesis submitted to th~ Faculty of Scien9,~1 University of the Witwate:esrandJ JOham1esburg I' - 0 in fuJ,filmep:c of the reqtt!,'lernents for the degree .of DoCtor of .Philo~ ~phy JOHANNESBURG C/ o (~J July 1994 / species of anurens , By utilizing acoustio playbaok " "." :1.. (1 ',' .., experiments the exact' rlature it! call timing' in, five species was determined.' ~t)'U): specie~, each exl1ibi ted one "of three" distinot:: types Qf chozus organizatioh, while in one sp~ci.es it. was not possible to demonstrQ.te any chorus organization. The distinct: t.ype Qf ("chorus organizatidh that a species • c;. -" < . " ,', '. ~hib:l t;s . was shown to be a function of '"call duration and 0 behavioural refractory period. Go' . c' .~ The Significance of oall intensity in male~male '.\. interactions and female mate choice was determined in fU:t;"ther acoust,i21 ~layback experiments. ':Males"exhibited a. g.t,-,d",ed·type of'" r.esponSe, with the perc~ntage of ,.'aggresSive ;:, . caitn~,\~pc:r:easi'1l9with increasing intensity?f the playback. 11 Althou~tf females wer~ unable to compute absoltl,te intensity / ' they We,'~.1{:;l pr~fer~ntiall.Y attracted to thE! louder of two calls in simple" two-choice sitl,:lations, but their q,isc;riJninatory ability was impaired" in more complex situations ..Males of H. marmoratus. were ;found to call at ;f:~~~ c; coflsi:stentl.y different tepetit~on rates and :females l) preferE:mtiall,y selected :faster r~tes in simple two.;ochoice I;> experiments aSq~ell as in +,.1;ief;i.eld .. This study prqvides va~uable~' insigllt into t'~ " ' dynainios of several species, E.f;!.ab.l4J)'ij<' '8 understanding of the 'function· and signif Lcance ubiquitou~ phenomenon of chorus organi.zation.

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