Article

Genetica

, Volume 108, Issue 1, pp 91-100

First online:

Geographical Clines for Quantitative Traits in Natural Populations of a Tropical Drosophilid: Zaprionus Indianus

  • Dev KaranAffiliated withDepartment of Biosciences, Maharshi Dayanand UniversityLaboratoire Populations, Génétique et Evolution, Centre National de la Recherche Scientifique
  • , Seema DubeyAffiliated withDepartment of Biosciences, Maharshi Dayanand University
  • , Brigitte MoreteauAffiliated withLaboratoire Populations, Génétique et Evolution, Centre National de la Recherche Scientifique
  • , Ravi ParkashAffiliated withDepartment of Biosciences, Maharshi Dayanand University
  • , Jean R. DavidAffiliated withLaboratoire Populations, Génétique et Evolution, Centre National de la Recherche Scientifique

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Abstract

We analyzed natural populations of Zaprionus indianusin 10 Indian localities along a south-north transect (latitude: 10–31°3 N). Size traits (body weight, wing length and thorax length) as well as a reproductive trait (ovariole number) followed a pattern of clinal variation, that is, trait value increased with latitude. Wing/thorax ratio, which is inversely related to wing loading, also had a positive, but non-significant correlation with latitude. By contrast, bristle numbers (sternopleural and abdominal) exhibited a non-significant but negative correlation with latitude. Sex dimorphism, estimated as the female/male ratio, was very low in Z. indianus, contrasting with results already published in other species. Genetic variations among populations were also analyzed according to other geographic parameters (altitude and longitude) and to climatic conditions from each locality. A significant effect of altitude was found for size traits. For abdominal bristles, a multiple regression technique evidenced a significant effect of both latitude and altitude, but in opposite directions. Genetic variations were also correlated to climate, and mainly with average year temperature. Taking seasonal variations into account failed however to improve the predictability of morphometrical variations. The geographic differentiation of Z.indianusfor quantitative traits suggests adaptive response to local conditions, especially to temperature, but also reveals a complex situation according to traits investigated and to environmental parameters, which does not match results on other drosophilid species.

altitude clines latitude phenotypic variability temperature Zaprionus indianus