1984 — 2009 |
Coyne, Jerry Allen |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Genetic Basis of Species Differences in Drosophila
DESCRIPTION: The PI plans to continue his very successful research program on the genetic basis of speciation. This Drosophila based research has primarily focused on differences between very closely related species that may have been important in the isolation of species. In particular, much of the proposed work is motivated by a growing body of evidence that pre- zygotic isolation may be the most common and first arising form of isolation for speciation events. The study of phenotypes associated with recent speciation events can be complex. One class of phenotypes are species differences that may have arisen as a component of the evolution of reproductive isolation. Often these differences are sex-limited so that there are at least four classes of organisms to examine in this context (males and females in each of two species). A second class of phenotype are features of pairs of organisms (e.g. anything associated with pre- zygotic limits to hybrid sex, such as mate choice) and there are two reciprocal pairs that can be considered for each pair of sibling species. Also these phenotypes must usually be measured in comparison to their intra-specific form. A third class includes at least two interesting phenotypes that are only manifest in species hybrids, sterility and inviability. These can be studied in both reciprocal crosses, potentially, depending on hybrid inviability and the genetic tools available to avoid it. The proposed research will focus on phenotypes in each of these three categories, subjecting each to a gene mapping protocol.
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1 |
1985 — 1986 |
Coyne, Jerry Allen |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Quantitative and Ecological Genetics of Drosophila @ University of Maryland College Pk Campus
The purpose of this proposal is to elucidate the amount of morphological variation within and among natural populations of Drosophila melanogaster which is actually due to genetic variation, to understand the selective significance of spatial and temporal variation of morphology of this species in nature, and to relate this variation to mi-gration behavior. The first objective will be accomplished by measuring the heritabilities of two traits within a population in nature, and to relate these to heritabilities determined in the traditional way in the laboratory. In addition, heritabilities of traits among populations will be determined by capturing flies along geographical and altitudinal gradients, measuring two characters on flies from nature, and relating these to the measurements on their laboratory-reared progeny. These studies will enable us to determine how much morphological variation seen in nature is due to genetic variation, how much to environmental influences, and the way in which genes and environment interact in nature. In addition, morphological patterns in traits which seem due to selective differences among populations will be studied in the laboratory to determine the nature of selection acting on the characters. Possible selective differences among natural populations will also be examined by studying geographic variation of important life history characters in D. melanogaster and their relation to temperature. Finally, the significance of geographic variation in both d. melanogaster and D. pseudoobscura will be studied indirectly by determining the ability of individuals to migrate and exchange genes over substantial distances in nature. The amount of such migration will indicate whether differences among populations in other traits such as allozymes may be ascribed to natural selection, or may be due to random genetic drift. The work has implications for human evolution and animal breeding since it forms a model system for questions about the inference of genotype from phenotype in nature, and about norms of reaction of genotypes. Such matters arise frequently in animal breeding studies and discussions of differences between human subgroups. In addition, the interaction of migration, drift, and selection studied here is of relevance to human subgroups. In addition, the interaction of migration, drift, and selection studied here is of relevance to human populations, which have become genetically differentiated for unknown reasons in the face of unknown amounts of migration.
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0.922 |
1986 |
Coyne, Jerry Allen |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Quantiative and Ecological Genetics of Drosophilia |
0.958 |
1991 — 1992 |
Coyne, Jerry Allen |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Genetic Basis of Species Differences in Drosphila
The long-term goal of this project is to understand the process of speciation through genetic analysis of its products: closely-related species. Our method uses classical genetic techniques to reveal the numbers, locations, and effects of genes causing sexual isolation and morphological differences between Drosophila species, and genes causing sterility and inviability of their hybrids. A collection of such analyses, conducted in three different Drosophila groups, will reveal patterns that address the following questions: 1. Are reproductive isolation and morphological differences between species due to only a few genes of large effect, or do they have a more polygenic basis? 2. Where are the genes causing reproductive isolation? Are they located in similar regions among different species pairs of a group, implying genetic "hotspots" of speciation? When they cause sexual isolation (mating discrimination), which aspects of courtship are affected? 3. Are the genes causing sexual isolation concentrated on the sex chromosomes, like those causing postzygotic isolation? 4. Is the genetic basis of sexual isolation similar in males and in females? 5. Are there consistent patterns to the genetics of reproductive isolation that hold across different groups? 6. What is the genetic basis of maternal effects that cause sterility of hybrids? 7. Can genetic drift contribute to speciation in small colonizing populations? Our data will not only help resolve current controversies about the genetics of speciation, but also motivate new theories. The results may be relevant to understanding the origin of species in other animals, including humans.
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0.958 |
1996 — 2000 |
Coyne, Jerry Charlesworth, Brian (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Population Genetics of Transposable Elements
9527717 CHARLESWORTH Transposable elements (TEs) are DNA sequences that are present in multiple copies in the genomes of most organisms, including humans. They can make new copies of themselves, which can insert into new places in the genome. Sometimes these insertions cause mutations of nearby genes, and a number of mutations involved in human genetic diseases have originated this way. It seems clear that TEs behave, at least in part, as parasites on the genomes of their hosts, using them as a vehicle for their own transmission. The forces responsible for controlling the abundances of TEs in the genomes of their hosts are a matter for continuing research. Understanding these forces is important for our knowledge of the factors that shape the organization of the genome, and for the origin of mutations. The fruitfly Drosophila is a useful model organism for research into these questions. The properties of TEs are similar in Drosophila and other organisms such as humans; in Drosophila the short generation time and ease of study allow genetic questions to be addressed much more efficiently than in larger organisms. The proposed research continues an investigation of the population-level properties of Drosophila TEs. A major objective is to obtain more precise estimates of the rates at which Drosophila TEs move around the genome; this information is vital for interpreting previous studies of the distribution of TEs between individuals. A second objective is to examine TEs that are inserted at a particular site in the genome in all studied individuals. These cases are exceptional, as the adverse effects of TE insertions usually mean that TE insertions are found only at low frequencies at a given location.
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1 |
1998 — 1999 |
Coyne, Jerry |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Dissertation Research: Conspecific Sperm Precedence in Drosophila
Coyne 9801476
In many organisms occurring in nature, males and females often demonstrate fitness-related differences in mating. A female may benefit by allowing only certain of the sperm she receives to fertilize her eggs, while a male benefits by encouraging the female to use as many of his sperm as possible, at the expense of other males. When these interests conflict, an evolutionary struggle between males and females results. This struggle can create perpetual change in internal reproductive anatomy and physiology, such that males and females that encounter one another often evolve reproductive systems that are finely tuned to one another, but are different from the reproductive systems of other closely related animals. Such differences in internal reproductive systems may then prevent subsequent interbreeding between groups, contributing to the differences that lead to the origin of new species.
The investigators have discovered evidence of this process within the widely studied genus of fruit flies, Drosophila. When sperm from two closely related species of Drosophila compete for the eggs of a single female, those sperm from a male of the same species as the female invariably out-compete the sperm from the more distantly related male. The proposed research will investigate 1) how widespread evidence of the described process is in the Drosophila genus, 2) how rapidly the described differences in internal reproductive systems can evolve, 3) the mechanism by which sperm gain a competitive advantage over sperm of other species, and 4) the mechanisms of competition among sperm from males of the same species. This project will further our understanding of the importance of internal reproductive phenomena in the origin of differences among species.
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