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You searched for subject:(Microlophus). Showing records 1 – 2 of 2 total matches.

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Texas A&M University

1. Garza, Mark Isaac. Predator induced defenses in prey with diverse predators.

Degree: MS, Wildlife and Fisheries Sciences, 2006, Texas A&M University

Phenotypic plasticity is an environmentally based change in phenotype and can be adaptive. Often, the change in an organism's phenotype is induced by the presence of a predator and serves as a defense against that predator. Defensive phenotypes are induced in freshwater physid snails in response to both crayfish and molluscivorous fish. Alternative morphologies are produced depending on which of these two predators snails are raised with, thus protecting them from each of these predators' unique mode of predation. Snails and other mollusks have been shown to produce thicker, differently shaped shells when found with predators relative to those found without predators. This production of thicker, differently shaped shells offers better protection against predators because of increased predator resistance. The first study in this thesis explores costs and limits to plasticity using the snailfish- crayfish system. I exposed juvenile physid snails (using a family structure) to either early or late shifts in predation regimes to assess whether developmental flexibility is equally possible early and late in development. Physid snails were observed to produce alternative defensive morphologies when raised in the presence of each of the two predators. All families responded similarly to the environment in which they were raised. Morphology was found to be heritable, but plasticity itself was not heritable. Morphology was found to become less flexible as snails progressed along their respective developmental pathways. In the second study, I raised physid snails with and without shell-crushing sunfish and examined the differences in shell thickness, shell mass, shell size and shell microstructural properties between the two treatment groups. Shells of snails raised with predators were found to be larger, thicker and more massive than those raised without predators, but differences in microstructure were found to be insignificant. I conclude that the observed shell thickening is accomplished by the snails' depositing more of the same material into their shells and not by producing a more complex shell composition. Advisors/Committee Members: DeWitt, Thomas J. (advisor), Coganto, Anthony I. (committee member), Fitzgerald, Lee (committee member).

Subjects/Keywords: inducible defenses; shell morphology; Physa; Lepomis microlophus; morphometrics

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

APA (6th Edition):

Garza, M. I. (2006). Predator induced defenses in prey with diverse predators. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/3309

Chicago Manual of Style (16th Edition):

Garza, Mark Isaac. “Predator induced defenses in prey with diverse predators.” 2006. Masters Thesis, Texas A&M University. Accessed February 28, 2021. http://hdl.handle.net/1969.1/3309.

MLA Handbook (7th Edition):

Garza, Mark Isaac. “Predator induced defenses in prey with diverse predators.” 2006. Web. 28 Feb 2021.

Vancouver:

Garza MI. Predator induced defenses in prey with diverse predators. [Internet] [Masters thesis]. Texas A&M University; 2006. [cited 2021 Feb 28]. Available from: http://hdl.handle.net/1969.1/3309.

Council of Science Editors:

Garza MI. Predator induced defenses in prey with diverse predators. [Masters Thesis]. Texas A&M University; 2006. Available from: http://hdl.handle.net/1969.1/3309


Brigham Young University

2. 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 February 28, 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. 28 Feb 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 Feb 28]. 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

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