Thesis (Ph. D.)--University of Chicago, Committee on the Developmental Biology. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, 2001. / Includes bibliographical references. Also available on the Internet.

Made available in DSpace on 2014-06-12T18:07:00Z (GMT). No. of bitstreams: 2 arquivo6328_1.pdf: 594892 bytes, checksum: ad966bc75b78fa320dbe40edeebed97e (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / Algumas espécies de gafanhotos são pragas milenares de áreas cultivadas em diversas regiões do mundo, provocando grandes prejuízos econômicos e ecológicos em períodos de explosão populacional. No Brasil, as espécies mais ameaçadoras, que causam danos significativos às lavouras e pastagens, são Rhammatocerus schistocercoides, Stiphra robusta e Schistocerca pallens, nenhuma das quais foi geneticamente bem caracterizada, apesar da grande importância prática. Neste trabalho foi iniciada a caracterização genética de S. pallens, através da localização por hibridização in situ dos genes Lys, Hsp70 e Hsp83 em cromossomos meióticos. Aproximadamente 700 núcleos foram analisados para os três genes e o percentual médio de marcação foi de 68,49%. Após análise de 108 núcleos marcados, com uma freqüência de 94,44% o gene Lys foi mapeado no cromossomo G1. O gene Hsp70 foi mapeado no cromossomo G2, onde foram observadas 89,94% das marcações do total de 199 núcleos marcados. Para o loco Hsp83 foram contados 163 núcleos marcados, dos quais 97,54% das marcações foram localizadas em um cromossomo médio identificado como M7. Para todos os genes hibridizados outras marcações foram observadas, mas todas em freqüências inferiores a 30%. Estes são os primeiros genes mapeados em S. pallens, sendo também os primeiros genes de cópia única mapeados na família Acrididae. Além de servir como novos marcadores para individualização cromossômica, os dados da localização destes genes poderão ser úteis como marcas físicas para um eventual programa de seqüenciamento genômico da espécie

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 413-447).

Phenotypic plasticity is the ability of the genotype to express alternative phenotypes in response to different environmental conditions and this is considered to be an adaptation in which a species can survive and persist in a rapidly changing environment. Some grasshoppers and locusts are capable of expressing an extreme form of density-dependent phenotypic plasticity, known as locust phase polyphenism. At low population density, the individuals typically have a cryptic coloration as nymphs, are less active, and only seek out conspecifics for reproductive purposes. At high density, however, they develop a drastically different phenotype in which they have a conspicuous coloration, are much more active, and tend to stay together in large groups. The American Birdwing grasshopper, Schistocerca americana, is a non-swarming species related to the desert locust, S. gregaria, which shows density-dependent phenotypic plasticity in behavior, color, and morphology. In this thesis, I have identified the duration of crowding necessary for a 6th instar S. americana reared in the isolated condition to express the typical crowded behavior. The behavior changed after just one hour of crowding and the effect of crowding diminished after 48 hours to near-complete isolated behavior. In reverse, the crowded condition was isolated, but behavior did not significantly change over time. Gene expression of the following three genes suspected of having a role in behavior change were investigated based on studies of S. gregaria: protein kinase A (PKA), L-Tryptophan-5-monooxygenase (T-5), and Aromatic L-amino acid decarboxylase (Decarb). T-5 was up-regulated in the long-term isolated condition compared to the long-term crowded condition. T-5 and Decarb were up-regulated in isolated individuals that were crowded for 10 hours compared to the long-term isolated condition. This study represents a novel contribution in the study of phenotypic plasticity as it establishes the time course of behavioral and molecular plasticity in a non-swarming grasshopper for the first time.

Statement Qf the problem. The green valley grasshopper, Schistoceroa venusta Scudder, is one of the most common grasshoppers to be found in the San Joaquin Valley and environs. Despite the fact that the insect is commonplace, very little work has been done on its biology. It was the purpose of this study, therefore, to learn by field and laboratory observations of the life cycle and habits of Schistoceroa venusta.

No description available.

<p>Social learning, defined as learning from other individuals, has been well studied in vertebrates and social insect species. In order to promote further understanding of the evolution of social learning, I tested a non-social insect for social learning and socially influenced behaviour. The desert locust (Schistocerca gregaria) is a gregarious insect which has the opportunity for social learning and can benefit from such ability. Locusts showed rapid individual learning, preferring a diet they have experienced over another of equal nutritional quality. Adult locusts also showed socially influenced behaviour, preferring to eat and lay eggs in the vicinity of other locusts over doing so alone. Fifth instar locusts did not show the same socially influenced behaviours. Neither adult nor nymphs showed social learning after interacting with previously fed models or after observing models feed through a screen. These results provide evidence for socially influenced behaviour in locusts and for a difference in social behaviour between nymphs and adults. Further research utilizing locusts as a model system may help us gain a better understanding of the evolution of social learning.</p> / Master of Science (MS)

No description available.