• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 195
  • 115
  • 26
  • 11
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • Tagged with
  • 458
  • 79
  • 78
  • 63
  • 60
  • 48
  • 33
  • 33
  • 29
  • 28
  • 27
  • 26
  • 23
  • 22
  • 22
  • 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.
81

A study of Cosmocercoides dukae (Holl, 1928) Wilkie, 1930 (Nematoda: Cosmocercidae) from amphibians in Ohio /

McGraw, James Carmichael January 1968 (has links)
No description available.
82

Influence of injury, nerves and wound epidermis on cell cycle events in amphibian limb regeneration /

Loyd, Robert Merrill January 1978 (has links)
No description available.
83

Terrestrial amphibian distribution, habitat associations and downed wood temperature profiles in managed headwater forests with riparian buffers in the Oregon Coast Range /

Kluber, Matthew R. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 107-117). Also available on the World Wide Web.
84

Multivariate Analyses of Amphibian and Reptilian Distribution in Texas

Ward, Rocky 08 1900 (has links)
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.
85

Factors Influencing Oviposition Among Pond-Breeding Amphibians: Exotic Vegetation, Oviposition Braces, and Cover

Callison, Catherine Mary 01 July 2001 (has links)
I examined oviposition in four pond-breeding amphibians (northwestern salamander [Ambystoma gracile], long-toed salamander [Ambystoma macrodactylum], Pacific treefrog [Hyla regilla], northern red-legged frog [Rana aurora aurora]), at Burlington Bottoms, a lowland riverine site in northwestern Oregon, to determine whether differential use of native versus exotic plant substrates occurs. I found differential use in all four species, but use was inconsistent with the hypothesis that selection for native plants (or selection against exotic plants) was occurring. If selection was occurring, the pattern implied that reed canarygrass (Phalaris arundinacea), a widespread exotic in this lowland system, was sometimes favored. However, inconsistent use of reed canarygrass led me to examine the alternative that substrate strength (measured as density, diameter, and mass), rather than plant status, might be the basis of selection. Species used for oviposition differed in strength, but eggs were not consistently laid on braces based on my strength measures. Failure to find support for this hypothesis led to examination of a third hypothesis for two species (red-legged frog and northwestern salamander), that cover characteristics of the oviposition brace or nearby vegetation might influence egg mass location. Analysis of structural complexity of species used as a brace (as percent cover within 15 em of the egg mass) did reveal a pattern consistent with complexity, but that was species-specific. Red-legged frogs selected braces with significantly more nearspace cover; northwestern salamanders selected braces with sparser cover. Comparison of marginal shrub and tree cover to the number of red-legged frog egg masses revealed that ponds with < 50% shrub/tree cover had few (< 5) masses. Ponds with ≥ 50% shrub/tree cover had many (≥ 10) masses. More complex vegetation may provide greater protection for egg masses or ovipositing red-legged frogs but further investigation is clearly warranted. Elucidating northwestern salamander cover requirements will require examining more occupied ponds. In particular, more refined examination, using experimental manipulation, is needed to verify the cover relationships revealed in this study. Meanwhile, managers should treat cover as important in red-legged frog oviposition life history, paying special attention to minimizing loss of marginal shrub and tree cover.
86

Population trends, conservation and the trade in amphibians in Asia

White, Steve January 2005 (has links)
published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
87

The ecology of chytridiomycosis, an emerging infectious disease of Australian rainforest frogs /

Woodhams, Douglas Craig. January 2003 (has links)
Thesis (Ph.D.) - James Cook University, 2003. / Typescript (photocopy). Appendices: leaves 216-231, [3] Bibliography: leaves 197-215.
88

Habitat classification and characteristics of small mammal and amphibian communities in beaver-pond habitats of the Oregon Coast Range /

Suzuki, Nobuya. January 1992 (has links)
Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 72-80). Also available on the World Wide Web.
89

Caracterização citogenetica de especies e populações de Pseudopaludicola (Leiuperidae, Anura) / Cytogenetic caracterization of species and populations of Pseudopaludicola (Leiuperidae, Anura)

Favero, Eduardo Rondelli 12 August 2018 (has links)
Orientadores: Shirlei Maria Recco-Pimentel, Ana Cristina Prado Veiga-Menoncello / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-12T04:20:05Z (GMT). No. of bitstreams: 1 Favero_EduardoRondelli_M.pdf: 1364067 bytes, checksum: 03d34437fbe08a46a8cdd3631aaedcc9 (MD5) Previous issue date: 2008 / Resumo: O gênero Pseudopaludicola, pertencente à família Leiuperidae, compreende atualmente 12 espécies de rãs de pequeno tamanho, distribuídas pela América do Sul, sendo a ocorrência de oito delas foi relatada para o Brasil. Devido à grande semelhança morfológica entre espécies, algumas ocorrendo em simpatria, confusões taxonômicas são freqüentes. Alguns estudos morfológicos acerca deste gênero foram realizados, mas as relações de parentesco inter- e intragenéricas de Pseudopaludicola permanecem pouco esclarecidas. As poucas informações citogenéticas para o gênero Pseudopaludicola restringiam-se apenas à determinação do número de cromossomos e análise do cariótipo por métodos de coloração convencional. Para Pseudopaludicola falcipes, em especial, foi descrita uma variação intra-específica do número de cromossomos, de 2n=16 à 2n=20. O presente estudo visa contribuir com dados citogenéticos para a caracterização de espécies de Pseudopaludicola e para o entendimento dos processos envolvidos na evolução cariotípica do gênero. Foram analisados os cariótipos de exemplares de Pseudopaludicola falcipes, P. ameghini (sensu Cope, 1887) e P. mystacalis de suas respectivas localidades-tipo (região de Porto Alegre, RS e Chapada dos Guimarães, MT), de P. mystacalis e de P. ternetzi, de Uberlândia (MG), de Pseudopaludicola aff. falcipes I, II, III e IV, da região noroeste do estado de São Paulo (municípios de Santa Fé do Sul, Vitória Brasil, Palestina e Icém), de Pseudopaludicola aff. mystacalis I, II, III e IV, dos municípios de Icém (SP), Barreirinhas (MA) e Urbano Santos (MA) e Pseudopaludicola sp. 1, 2 e 3, sendo as duas primeiras provenientes de Poconé (MT) e a terceira de Santa Terezinha (MT). As metáfases foram obtidas de suspensões de células de epitélio intestinal e testículo, e coradas com Giemsa ou submetidas às técnicas impregnação por prata (Ag-NOR) para detecção de NOR e de bandamento C, para a localização de heterocromatina. Os dados obtidos revelaram uma variação interespecífica quanto ao número de cromossomos. Dentre os espécimes provenientes de Poconé, MT, havia dois cariótipos distintos, com 2n=22 e com 2n=16 cromossomos (Pseudopaludicola sp. 1 e 2) e os de Icém, SP, com indivíduos 2n=20 e 2n=16 cromossomos (Pseudopaludicola aff. mystacalis, respectivamente I e II). Pseudopaludicola falcipes e Pseudopaludicola sp.1, de Poconé, apresentaram 2n=22 e a NOR localizada na região pericentromérica do braço longo do par 8. Estas espécies diferiram, na morfologia da NOR, sendo heteromórfica em P. falcipes e homomórfica em Pseudopaludicola sp. 1, e na localização de algumas bandas heterocromáticas. Pseudopaludicola ameghini (sensu Cope, 1887), P. ternetzi e Pseudopaludicola aff. mystacalis I de Icém apresentaram 2n=20 cromossomos e a NOR localizada na região telomérica do braço longo do par 9. O cariótipo de P. ternetzi diferiu do de P. ameghini tanto pela classificação morfológica distinta do par 7 quanto pelo padrão de distribuição de heterocromatina. Pseudopaludicola mystacalis, bem como todos os espécimes de Pseudopaludicola aff. falcipes I, II, III e IV, Pseudopaludicola aff. mystacalis II, III e IV e Pseudopaludicola sp. 2 e 3 apresentaram 2n=16 cromossomos metacêntricos e submetacêntricos, com a NOR localizada na região pericentromérica do braço curto do par 4. Vários espécimes apresentaram um heteromorfismo de tamanho em relação aos homólogos do par 4 (morfo 4 e morfo 4'), alterando a classificação desse cromossomo para metacêntrico em algumas populações. Em P. mystacalis, P. aff. falcipes I, II, III e IV, P. aff. mystacalis II, III e IV e Pseudopaludicola sp 2 e 3 foram detectados blocos de heterocromatina fortemente marcados nas regiões pericentroméricas no braço curto do par 1 e longo do par 2. Os resultados obtidos mostram que P. ameghini (sensu Cope, 1887) com 2n=20 e P. mystacalis com 2n=16, são unidades taxonômicas distintas e que os espécimes tidos como Pseudopaludicola aff. falcipes) e como Pseudopaludicola sp. mostraram-se citogeneticamente relacionados à P. mystacalis e não à P. falcipes que possui 2n=22 cromossomos. Desta forma, os nossos dados sugerem a retirada de P. ameghini da sinonímia de P. mystacalis e reforçam a necessidade de uma revisão taxonômica no gênero. / Abstract: The genus Pseudopaludicola (family Leiuperidae) comprises 12 species of small sized frogs, which are widely distributed in South America. In Brazil, eight species are described within this genus, and several of them are sympatric. The relevant morphological similarities among the Pseudopaludicola species have contributed to the still poor understanding of many aspects of their taxonomy, including inter- and intrageneric relationships. Cytogenetic data on Pseudopaludicola have been restricted to karyotype analyses using conventional Giemsa staining. Variation in intraspecific chromosomal number was described in P. falcipes, ranging from 2n=16 to 2n=20. In the present work, Brazilian Pseudopaludicola species were submitted to cytogenetic analysis aiming at their further characterization and attempting to better understanding the karyotypical evolution of this genus. The analyzed species were Pseudopaludicola falcipes (Porto Alegre, RS), P. ameghini (sensu Cope, 1887) and P. mystacalis (Chapada dos Guimarães, MT), P. mystacalis and P. ternetzi (Uberlândia, MG), P. aff. falcipes I, II, III and IV (respectively from Santa Fé do Sul, Vitória Brasil, Palestina and Icém, SP), P. aff. mystacalis I, II, III and IV (Icém, SP, Barreirinhas, MA, and Urbano Santos, MA), and Pseudopaludicola sp. 1 and sp. 2 (Poconé, MT) and sp. 3 (Santa Terezinha, MT). Metaphases were obtained from suspensions of intestinal epithelium and testicular cells, and stained with Giemsa or submitted to silver staining technique in order to detect the nucleolus organizing regions (Ag-NOR), and C-banding, for heterochromatin localization. The results revealed interspecific chromosomal number variation. In the Pseudopaludicola sp. 1 and 2 specimens (Poconé MT), two distinct karyotypes were identified, respectively with 2n=22 and 2n=16 chromosomes. Within the Pseudopaludicola aff. mystacalis from Icém, SP, the analyzed specimens had 2n=20 and 2n=16 chromosomes, being nominated I and II, respectively. These data clearly indicated two criptic species of Pseudopaludicola within each of those two localities. The P. falcipes and Pseudopaludicola sp.1 (Poconé, MT) had 2n=22 and the NOR was located at the pericentromeric region in the long arm of the pair 8. The species differed in the NOR morphology, which was heteromorphic in P. falcipes and homomorphic in Pseudopaludicola sp.1, as well as in the localization of some C-bands. Pseudopaludicola ameghini (sensu Cope, 1887), P. ternetzi and Pseudopaludicola aff. mystacalis I (Icém, SP) had 2n=20 chromosomes and the NOR was located on the telomeric region in the long arm of the pair 9. The karyotypes of P. ternetzi and P. ameghini differed in the pair 7 morphology and in the heterochromatin distribution pattern. All analyzed specimens of P. mystacalis, P. aff. falcipes I, II, III and IV, P. aff. mystacalis II, III and IV, and Pseudopaludicola sp. 2 and 3, showed 2n=16 chromosomes, which were all metacentric and submetacentric, with the NOR located in the pericentromeric region of the short arm of the pair 4. In several of those specimens, the size heteromorphism of the pair 4 altered, from submetacentric to metacentric, the classification of one of the homologous of that pair. Strong pericentromeric C-bands were detected on the short arm of the pair 1 and on the long arm of the pair 2 in P. mystacalis, P. aff. falcipes I, II, III and IV, P. aff. mystacalis II, III and IV, and Pseudopaludicola sp. 2 and 3. As based on the cytogenetic data, P. ameghini (sensu Cope, 1887), with 2n = 20, and P. mystacalis, with 2n = 16, are distinct taxonomic units, and the specimens formerly identified as P. aff. falcipes and as Pseudopaludicola sp. were indeed cytogenetically closely related to P. mystacalis and not to P. falcipes, which has 2n = 22 chromosomes. Hence, our data suggest that P. ameghini is not a P. mystacalis synonymy and emphasize the importance of a taxonomic review of the genus Pseudopaludicola. / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural
90

The herpetofauna of Egypt : species, communities and assemblages

Ahmed, Sherif M. Baha El Din January 2001 (has links)
No description available.

Page generated in 0.0705 seconds