Desiccation survival traits in natural populations of two sibling species of the genus Drosophila.
Item
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Title
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Desiccation survival traits in natural populations of two sibling species of the genus Drosophila.
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Identifier
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AAI9521288
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identifier
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9521288
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Creator
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Laverde, Michael Joseph.
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Contributor
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Co-Advisers: Louis Levine | Robert F. Rockwell
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Date
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1995
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Entomology | Biology, Biostatistics | Biology, Genetics
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Abstract
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Desiccation is a primary problem for all land insects. This thesis project investigated the question: What is the relationship between the traits of desiccation resistance, vagility, and body size?;Many traits may contribute to survival in a desiccating environment. This study focused on desiccation resistance (survival), vagility (movement away from a central area), and body size. A comparative examination of these traits over time for the sibling species Drosophila melanogaster and D. simulans was performed. These have been tested for desiccation resistance at four time periods (4, 8, 12, and 24 hours), for adult vagility in the Sakai double-ringed system at two time periods (4 and 24 hours), and for body size estimated from the length of the III longitudinal vein in the right wing. These measurements have been taken over a two year period (two seasons) on four collections. Annual, seasonal, species, and sex differences and changes, as well as expressed genotypic variances and patterns of correlation were investigated.;Generally D. melanogaster is more resistant to desiccation and larger than D. simulans, possibly representing different evolutionary histories for the species. Females were found generally more resistant to desiccation than their male counterparts in both species, and have a larger body size. The larger females may have more fat and internal water storage allowing them to resist desiccation better than the males in order to ensure successful depositing of their eggs. No annual, seasonal, or temporal changes were detected. Very little, if any, expressed genetic variance was found for any of the traits between the two species and between the sexes. The genetic architecture of these populations may have been modified by natural selection such that the genetic variance is not expressed as phenotypic differences, or have been reduced. Desiccation resistance was found to be linked with a greater vagility and a smaller body size. A lower vagility for less desiccation resistant flies may act to keep them in a suitable microhabitat. Desiccation resistance, vagility, and body size may be just three of many traits that contribute to a complex phenotype allowing greater survival with respect to desiccation stress.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
