Genetic Structure and Change in Natural Populations of Drosophila robusta: Systematic Inversion and Inversion Association Frequency Shifts in the Great Smoky Mountains
Etges WJ. 1984. Genetic Structure and Change in Natural Populations of Drosophila robusta: Systematic Inversion and Inversion Association Frequency Shifts in the Great Smoky Mountains. Evolution. 38(3):675-688
Chromosome shifts (inversions) in the fruit flies studied were apparently linked to elevation. Populations of Drosophila robusta inhabiting the Great Smoky Mountains exhibit clines in inversion and inversion association frequencies over an altitudinal transect spanning 3,800' in elevation. Collections made in the summer of 1981 showed systematic directional shifts in inversion and inversion association frequencies in all populations, when compared to the earlier collections in 1947 (Stalker and Carson, 1948) and in 1958-1959 (Levitan, 1978). toward higher elevation genotypes in the intervening 34 years. A cline in X chromosome inversion association XL-2. XR-2 shifted from a statistically significant positive relationship with altitude to a statistically significant negative relationship over that time period. Linkage disequilibria between inversions on opposite arms of the X chromosome is strong and shows patterns characteristic of the Southern Appalachians. In all populations studied, there is an excess of "repulsion" combinations 1S and S2 with a corresponding deficiency of combinations SS and 12. Linkage disequilibrium of inversions on opposite arms of the second chromosome or between arms on different chromosomes was not detected. A genetic ordination of the transect populations showed for both the 1947 and 1981 data sets that the middle elevation populations contained modal frequencies of all genetic elements surveyed. The populations at lower and higher elevations were more genetically distinct from each other and the middle elevation populations, and were more extreme in combined inversion and inversion association frequencies than the middle elevation populations.
- Type
- Journal Article
- Authors
- Etges, William
- Units
- GRSM
- Keywords
- Animal Studies, Chromosomes, Drosophila (genus-insects), Great Smoky Mountains National Park NC TN, GRSM-00232, Insects (Insecta)