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THE RELATION OF GENETIC STRUCTURE TO ENVIRONMENTAL STRUCTURE: GAMMARUS MINUS IN A KARST AREA

1979; Oxford University Press; Volume: 33; Issue: 1Part1 Linguagem: Inglês

10.1111/j.1558-5646.1979.tb04674.x

1558-5646

James L. Gooch, Steven W. Hetrick,

Species Distribution and Climate Change

A species possesses an internal genetic mensionality decreases in stepping-stone structure that is compounded on the ge-models of isotropic gene flow (Kimura and netic architecture of constituent local pop-Weiss, 1964; Kimura and Maruyama, ulations.Each local population may be 1971).(3) G. minus in the Mid-Appalasubtly unique in its coadapted gene enchians is largely confined t6 springs, semble, including the fine tuning of its spring runoff, and stream caves situated genic regulatory system.More obviously in carbonate strike valleys.Each local and more approachably, populations may population is partially isolated from others be differentiated in allele frequencies at in the local drainage system, and more single structural loci.profoundly isolated from populations in This study describes the regional genet-other streams and in other regions of carie patterns of allozyme loci in the amphi-bonate outcrop.Holsinger (1969) discusses pod crustacean Gammarus minus Say in the Appalachian zoogeography of the a karst area of southeastern West Virgin-Gammaridae in greater detail.ia.It is a part of an investigation of thisIn Virginia and West Virginia this species throughout the mid-Appalachian species is widely distributed in the Ridge portion of its range, whose initial purpose and Valley physiographic province and is to map the genetic relationships among flanking areas, where its populations are populations onto the highly structured en-mainly located in the headward reaches of vironment of this region.feeders of trunk streams that trend north-Gammarus minus is highly differentiated east-southwest along linear strike valleys in allele frequencies at several loci over floored by Paleozoic limestones and doloshort distances.There are at least three pos-mites.Some of these valleys are marked sible reasons for this fact.(1) As in other by karst development.A particularly expericardians, females of G. minus brood tensive karst topography is displayed on their young in a ventral marsupium, and the Greenbrier Limestone of Mississippian there is no specific migratory stage in the age in Pocahontas, Greenbrier, and Monlife history.(2) This species is principally roe Counties of southeastern West Virginfound in freshwater lotic streams.Individ-ia.This is a highly structured environual streams are essentially one-dimen-ment in which G. minus is found in three sional habitats from the viewpoint of gene ecophenotypic forms.The primary aim of flow, and drainage networks have a di-this study has been to map allozyme allele mensionality between one and two (anal-frequencies and levels of heterozygosity ogous to roads in Cavalli-Sforza and Bod-onto the structured topography to determer, 1971).There is a greater decrease of mine their concordance.The second goal genetic correlation with distance as di-has been to determine if the ecophenotypic