• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 172
  • 22
  • 16
  • 8
  • 8
  • 8
  • 8
  • 8
  • 8
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 291
  • 36
  • 29
  • 21
  • 18
  • 16
  • 16
  • 16
  • 15
  • 14
  • 14
  • 14
  • 13
  • 12
  • 12
  • 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.
51

The vocal behaviour of the Spring Peeper, Hyla crucifer/

Rosen, Michael. January 1974 (has links)
No description available.
52

Morphology and systematics of the Solomon Island Ranid frogs

Norris, Rachel Mary. January 2002 (has links) (PDF)
"December 2002" Bibliography: leaves 230-241. Ch. 1. Introduction -- Ch. 2. Historical account -- Ch. 3. Morphometrics -- Ch. 4. Osteology of Solomon Islands ranids -- Ch. 4. Karyology of the Solomon Islands ranids -- Ch. 6. Phylogenetic analysis -- App. 1: Material examined -- App. 2: Discriminant function analysis -- App. 3: Character descriptions. "This study validates the Solomon Islands taxa (using morphometrics) and explores the biology of the Solomon Islands ranids, with detailed osteological descriptions, external morphology and karyology. Using characters from these data sets a cladistic analysis using parsimony reconstructed a phylogeny of thes frogs...Phylogenetic analysis using maximum parsimony found three equally parsimonious trees. Subsequent character reanalysis (successive weighting) produced one parsimonious tree. The phylogenies indicate multiple invasion events into the Solomon Islands by these ranid frogs and despite the high level of endemism, monophyly is not supported."
53

Phylogeography, population history and conservation genetics of the endangered green and golden bell frog (Litoria aurea)

Burns, Emma Louise, School of Biological, Earth & Environmental Sciences, UNSW January 2004 (has links)
The green and golden bell frog (Litoria aurea) is an Australian hylid, which was once common with a relatively continuous distribution. Historically, this distribution extended from northern New South Wales (NSW), as far as Ballina, to East Gippsland in Victoria; with inland populations as far west as Bathurst and Tumut. Today the species is reported to have disappeared from 80% of its former range and remaining populations are mostly fragmented and typically restricted to the coastline, extending from Yuraygir National Park (northern NSW) to East Gippsland. In this thesis, I report a comprehensive study designed to identify the phylogeographic and conservation genetic parameters of L. aurea. In doing so, I also investigate evolutionary relationships within the ???bell frog??? species group. In this study, microsatellite and mitochondrial DNA (mtDNA) markers are employed. The development of species-specific microsatellite markers and the collection of samples was a substantial component of the study. These markers and samples should prove useful for future studies of L. aurea and perhaps more generally the ???bell frogs???. Initially, a large-scale assessment of genetic structure and diversity in L. aurea using microsatellite markers was undertaken. Twenty-one locations were sampled from throughout the species range covering 1000 kilometres of the east coast of Australia. Levels of allelic diversity and heterozygosity were high (uncorrected mean alleles/locus and HE: 4.8-8.8 and 0.43-0.8 respectively) compared to other amphibian species and significant differences among sampled sites were recorded. Despite recent population declines, no sites displayed a genetic signature indicative of a population bottleneck. Significant genetic structuring (overall FST = 0.172) was detected throughout the species range, but was relatively low compared to previous amphibian studies that used microsatellites. In addition, some areas sampled within continuous habitat showed evidence of weak genetic structuring (data subset FST = 0.034). Next, relationships among extant bell frogs (Litoria aurea species-group) were investigated, using mitochondrial ND4 nucleotide sequence data. Analyses supported a clade comprised of the temperate members of the species-group, L. aurea, L. cyclorhyncha, L. moorei, and L. raniformis but failed to support the inclusion of the tropical bell frog L. dahlii in this group. Relationships among the four members of the bell frog clade correlated with geographical distribution: the south-western Australian bell frogs (L. cyclorhyncha, L. moorei) and the south-eastern Australian bell frogs (L. aurea, L. raniformis) were reciprocally monophyletic. Results also indicated that divergence of these two lineages occurred during the late Miocene, which was consistent with results of previous studies and with more general assertions that much of the major differentiation and radiation of the Australian biota predated the Quaternary. Following this, intraspecific phylogeography of L. aurea using two mitochondrial genes COI and ND4 was investigated. I examined extant populations from throughout the species??? range, sequencing 263 individuals from twenty-six locations. Recent evolutionary history, as well as the current population structure of L. aurea, was inferred from the resulting pattern of genetic variation amongst haplotypes, in conjunction with demographic and population analyses. Results indicated that there were no phylogeographic divisions within L. aurea, despite a general consensus that amphibians are highly structured. However, I did still detect significant structure amongst extant populations (FST = 0.385). Overall, patterns of haplotype relatedness, high haplotypic diversity (mean h = 0.547) relative to low nucleotide diversity (mean Pi= 0.003), and mismatch distribution analysis supported a Pleistocene expansion hypothesis with continued restricted dispersal and gene flow. Taken together, the results of this thesis indicate that L. aurea is a species with relatively weak population and phylogeographic structure compared to other amphibians. The data provide no support for the existence of distinct evolutionary lineages within L. aurea, implying that there are no historically isolated populations that should be viewed as separate evolutionarily significant units. Nevertheless, remaining populations are still significantly structured but not all populations are genetically distinct. Low phylogeographic structure, coupled with evidence for recent gene flow among many sites would permit ???well managed??? intervention to mediate gene flow amongst currently isolated populations, and I provide some guidelines for the implementation of such conservation strategies. However, there is no evidence to suggest that supplementation through artificial immigration is at this time necessary given current levels of genetic variation within populations. In the short-term, conservation management in L. aurea should focus on the protection of local populations and habitat to promote population connectivity to ensure processes that maintain adaptive diversity and evolutionary potential are conserved. Preservation of the species??? natural range and the maintenance of dense networks of suitable habitat, in conjunction with maximising local carrying capacity and reproductive output, as well as minimising known threats, are key to securing the long-term persistence of the green and golden bell frog.
54

Morphology and systematics of the Solomon Island Ranid frogs / Rachel M. Norris.

Norris, Rachel Mary January 2002 (has links)
"December 2002" / Bibliography: leaves 230-241. / viii. 356, [25] leaves : ill. (some col.), map (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / "This study validates the Solomon Islands taxa (using morphometrics) and explores the biology of the Solomon Islands ranids, with detailed osteological descriptions, external morphology and karyology. Using characters from these data sets a cladistic analysis using parsimony reconstructed a phylogeny of thes frogs...Phylogenetic analysis using maximum parsimony found three equally parsimonious trees. Subsequent character reanalysis (successive weighting) produced one parsimonious tree. The phylogenies indicate multiple invasion events into the Solomon Islands by these ranid frogs and despite the high level of endemism, monophyly is not supported." / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2003
55

The germ cell history of Rana cantabrigensis Baird ...

January 1932 (has links)
Thesis (Ph. D.)--University of Michigan, 1930. / Thesis note on label mounted on p. [497] of pt. 1. "Sonderabdruck aus Zeitschrift für zellforschung und mikroskopische anatomie ... 16. band, 3. und 4. ... heft." "Literature cited" at end of each part.
56

Behavioral neuroendocrinology of the green treefrog (Hyla cinerea) /

Burmeister, Sabrina Suzanne, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 87-99). Available also in a digital version from Dissertation Abstracts.
57

Ontogeny and evolutionary morphology of the skeleton in frogs

Yeh, Jennifer Jean 13 April 2011 (has links)
Not available / text
58

SOME ASPECTS OF PTERIDINE BIOSYNTHESIS IN AMPHIBIANS

Stackhouse, Hamilton Lee, 1933- January 1964 (has links)
No description available.
59

ULTRASTRUCTURE AND CYTOCHEMICAL PROPERTIES OF IRIDOPHORES IN AMPHIBIANS

Taylor, John Dirk, 1939- January 1967 (has links)
No description available.
60

Pigmentation changes of Rana pipiens and Xenopus laevis during larval development and at metamorphosis

Collins, Sheila Joan, 1935- January 1961 (has links)
No description available.

Page generated in 0.0223 seconds