biogeographical survey identifies consistent alternative physiological optima and a minor role for environmental drivers in maintaining a polymorphism生物地理学调查确定一致的替代生理最适条件和环境驱动的次要角色维护一个多态性.pdfVIP

Biogeographical Survey Identifies Consistent Alternative Physiological Optima and a Minor Role for Environmental Drivers in Maintaining a Polymorphism 1 1 2 Arne Iserbyt *, Hans Van Gossum , Robby Stoks 1 Evolutionary Ecology Group, Antwerp University, Antwerp, Belgium, 2 Laboratory of Aquatic Ecology and Evolutionary Biology, University of Leuven, Leuven, Belgium Abstract The contribution of adaptive mechanisms in maintaining genetic polymorphisms is still debated in many systems. To understand the contribution of selective factors in maintaining polymorphism, we investigated large-scale (.1000 km) geographic variation in morph frequencies and fitness-related physiological traits in the damselfly Nehalennia irene. As fitness-related physiological traits, we investigated investment in immune function (phenoloxidase activity), energy storage and fecundity (abdomen protein and lipid content), and flight muscles (thorax protein content). In the first part of the study, our aim was to identify selective agents maintaining the large-scale spatial variation in morph frequencies. Morph frequencies varied considerably among populations, but, in contrast to expectation, in a geographically unstructured way. Furthermore, frequencies co-varied only weakly with the numerous investigated ecological parameters. This suggests that spatial frequency patterns are driven by stochastic processes, or alternatively, are consequence of highly variable and currently unidentified ecological conditions. In line with this, the investigated ecological parameters did not affect the fitness-related physiological traits differently in both morphs. In the second part of the study, we aimed at identifying trade- offs between fitness-re