Author Description

Evolutionary Biology, ofwhichthisisthetwenty-thirdvolume, continues toofferitsreadersawiderangeoforiginalarticles, reviews, andcom mentariesonevolution, inthebroadestsenseofthatterm. Thetopicsof thereviewsrangefromanthropology, molecularevolution, andpaleo biologytoprinciplesofsystematics. Inrecentvolumes, abroadspectrumofarticleshaveappearedon suchsubjectsasbiochemicalsystematics, comparativemorphologyand embryology, evolutionaryecology, biogeography, andpaleobiology. We havealsoattemptedtoprovideaforumforconflictingideas. Articlessuch asthese, oftentoolongforstandardjournals, arethematerialfor Evo lutionary Biology. Theeditorscontinuetosolicitmanuscriptsonaninternationalscale inanefforttoseethateveryoneofthemanyfacetsofbiologicalevolution iscovered. Manuscriptsshouldbesenttoeitherofthefollowing: Max K. Hecht, DepartmentofBiology, QueensCollegeoftheCityUniversity ofNewYork, Flushing, NewYork11367, orBruceWallace, Department ofBiology, VirginiaPolytechnicInstituteandStateUniversity, Blacks burg, Virginia24061. TheeditorswishtocongratulateDr. GhilleanT. Pranceonhisnew appointmentatKewBotanicalGardensandthankhimforhiscollabo rativeeffortsineditingthepastninevolumes. TheEditors vII Contents 1. MaintenanceofaHereditaryVirus: TheSigmaVirusin PopulationsofItsHost, Drosophila melanogaster 1 Annie Fleuriet Introduction 1 FrenchPopulationsof Drosophila melanogaster........... 2 PolymorphismofPopulations 2 CharacteristicsofWildStrainsoftheSigmaVirus 3 EffectsoftheInfectionuponCarriers................. 7 ExperimentalPopulations.......................... 9 MaintenanceoftheVirusinFrenchNaturalPopulations... 12 GeographicalVariationofthe Drosophila-SigmaSystem 14 PolymorphismofPopulations 14 ViralCharacteristics.............................. 17 TentativeInterpretationoftheGeographicalPatternObserved 18 OtherSystemsofVerticallyTransmittedViruses 22 ExistenceofDifferentSensitivitiestotheVirus 22 Chara