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Brigham Young University

1. Benavides, Edgar. Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal.

Degree: PhD, 2006, Brigham Young University

In this collection of papers I have summarized my investigations into the field of evolutionary genetics and more specifically into patterns of biodiversity and evolutionary processes. The lizards (and frogs) studied here share common features in that they are largely present in unique environments, which are also regions that are biologically understudied. Most of these taxa show high degrees of endemism, interesting natural history characteristics, and each group manifests distinctive adaptations of general evolutionary interest. My work in the genus Telmatobius has been a progressive approach that began in my MS program, and it first focused on alpha taxonomy, morphological variation, and species boundaries. This work led to new studies initiated and completed at BYU involving further taxonomic revision (Formas et al., 2003; Chapter 1), and then revisiting and re-evaluating species boundaries established earlier (with allozyme markers) and this time with population level molecular (mitochondrial DNA) markers (Chapter 2). Our results indicate that the striking differences in size, coloration and general appearance in the various Lake Titicaca morphotypes are not genetically based. Further, there is evidence that these morphotypes have evolved very rapidly after demographic bottlenecks eroded present genetic variability. Telmatobius frogs of Lake Titicaca are listed by the International (IUCN) as critically endangered. We support this classification and further suggest studies to explore open questions like the possibility of adaptation along ecological resource gradients. Lizards of the genus Microlophus are interesting but for different reasons, and studies of this group constitutes the bulk of my dissertation work. The genus includes both Galapagos insular species, and continental taxa distributed in a linear gradient along > 4000 km of the western coast of South America. In studying Microlophus I first tackled the unresolved phylogenetic relationships within the genus (Chapter 3) and then pay attention to phylogeographic aspects of the most speciose lizard radiation in the Galapagos Archipelago (Chapter 4). Chapter 3 is a single manuscript provisionally accepted in the journal Systematic Biology. This paper introduces the lizard genus Microlophus (“lava lizards”) as a study system, and includes a large nuclear data set accompanied by an equally large mitochondrial data set (7877 characters in total). This paper explicitly differentiates among sequence alignments of gene regions that vary in tempo and class of mutational events. We show that this recognition is important and we suggest ways to appropriately deal with the alignment of multi-locus non-coding DNA data sets. A secondary finding in this study is that mtDNA and nDNA topologies are discordant with each other but that both are strongly supported, and that the nuclear topology is concordant with species distribution patterns along coastal South America. We hypothesize that in this particular region of the tree, the nuclear genome recovers a topology…

Subjects/Keywords: nuclear introns; alignment; length mutations; Microlophus; secondary contact; mitochondrial-nuclear conflict; phylogenetics; Galapagos; mtDNA; phylogeography; nested clade analysis; colonization routes; volcanism; lava lizards; Biology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Benavides, E. (2006). Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal. (Doctoral Dissertation). Brigham Young University. Retrieved from https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=2299&context=etd

Chicago Manual of Style (16th Edition):

Benavides, Edgar. “Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal.” 2006. Doctoral Dissertation, Brigham Young University. Accessed January 22, 2021. https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=2299&context=etd.

MLA Handbook (7th Edition):

Benavides, Edgar. “Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal.” 2006. Web. 22 Jan 2021.

Vancouver:

Benavides E. Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal. [Internet] [Doctoral dissertation]. Brigham Young University; 2006. [cited 2021 Jan 22]. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=2299&context=etd.

Council of Science Editors:

Benavides E. Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal. [Doctoral Dissertation]. Brigham Young University; 2006. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=2299&context=etd


University of Gothenburg / Göteborgs Universitet

2. Elmgren, Anders 1961-. Molecular genetics of the human Lewis and plasma fucosyltransferases.

Degree: 1998, University of Gothenburg / Göteborgs Universitet

The human Lewis histo-blood group system is composed of several structurally well-characterized carbohydrate antigens. These are involved in different biological processes, e.g., embryogenesis, tissue differentiation, inflammation, dissemination of cancer cells and bacterial adhesion. Their biosynthesis is dependent on different fucosyltransferases which are expressed at different levels in different cell populations. The FUT3 gene encoded Lewis a-(1,3/1,4)-fucosyltransferase (EC 2.4.1.65) is expressed in epithelial cells. It is responsible for the synthesis of the Lea and Leb antigens. The inheritance of the functional Le-allele is necessary for the appearance of the Lea or Leb antigens on erythrocytes, while the deficient le-allele is found in a homozygous state in individuals with the Le(a-b-) phenotype. The FUT6 gene encoded a-(1,3)-fucosyltransferase, found in the liver, is responsible for the synthesis of the sialyl-Lex epitope on the acute-phase protein a1-acid glycoprotein. The secreted form of this enzyme is identified as the plasma a-(1,3)-fucosyltransferase (EC 2.4.1.152). The aims of this study were to i) identify molecular explanations in the FUT3 gene for the human erythrocyte Le(a-b-) phenotype, ii) identify molecular explanations in the FUT6 gene for deficient plasma a-(1,3)-fucosyltransferase activities and iii) establish screening procedures for natural mutations in the FUT3 and FUT6 genes. The coding regions of the FUT3 and FUT6 genes were amplified by PCR. DNA was prepared from Swedish blood donors and from members of Indonesian plasma a-(1,3)-fucosyltransferase deficient pedigrees. Amplified DNA fragments were cloned and sequenced. By this approach we discovered the two FUT3 point mutations, T202C and C314T, located on the same allele. These mutations were found on both alleles only in Le(a-b-) individuals. By using chimeric DNA constructs and subsequent expression in COS-7 cells, followed by immunofluorescent and enzymatic studies, we showed that T202C was the essential inactivating mutation. We also established PCR-based screening techniques for all known FUT3 mutations. A non-inactivating FUT6 nucleotide change, C738T, was identified. This mutation interfered with a published PCR-RFLP method for the detection of the known inactivating G739A mutation. We developed an extended genotyping strategy for the appropriate screening for these and other nucleotide substitutions in the FUT6 gene. Two FUT6 missense mutations, C730G and C907G, which we also identified, were found to be responsible for reduced a-(1,3)-fucosyltransferase activities using the COS-7 cell expression assay. These results enable allelic characterization of the human FUT3 and FUT6 genes, which can be used as new diagnostic tools in studies on Lewis histo-blood group antigen expression in health and disease.

Subjects/Keywords: Lewis histo-blood group system; a-(1; 3)-fucosyltransferase genes; a-(1; 3)-fucosyltransferases; erythrocytes; plasma; allele; point mutations; polymerase chain reaction; restriction fragment length polymorphism; sequencing; cloning; expression; COS-7

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Elmgren, A. 1. (1998). Molecular genetics of the human Lewis and plasma fucosyltransferases. (Thesis). University of Gothenburg / Göteborgs Universitet. Retrieved from http://hdl.handle.net/2077/10793

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Elmgren, Anders 1961-. “Molecular genetics of the human Lewis and plasma fucosyltransferases.” 1998. Thesis, University of Gothenburg / Göteborgs Universitet. Accessed January 22, 2021. http://hdl.handle.net/2077/10793.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Elmgren, Anders 1961-. “Molecular genetics of the human Lewis and plasma fucosyltransferases.” 1998. Web. 22 Jan 2021.

Vancouver:

Elmgren A1. Molecular genetics of the human Lewis and plasma fucosyltransferases. [Internet] [Thesis]. University of Gothenburg / Göteborgs Universitet; 1998. [cited 2021 Jan 22]. Available from: http://hdl.handle.net/2077/10793.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Elmgren A1. Molecular genetics of the human Lewis and plasma fucosyltransferases. [Thesis]. University of Gothenburg / Göteborgs Universitet; 1998. Available from: http://hdl.handle.net/2077/10793

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.