Data from: Persistence of the ecological niche in pond damselflies underlies a stable adaptive zone despite varying selection

Following the development of regression-based methods to estimate natural
and sexual selection, evolutionary biologists have quantified the
strength, mode, and direction of selection in natural populations.
Although this approach has been successful, its limitations include the
lack of replication across species, which compromises the generality of
the inferences beyond microevolutionary time scales. Here, we carried out
a comparative study of selection on wing shape and body size across
multiple populations of two closely related pond damselflies: Enallagma
cyathigerum and Ischnura elegans (Odonata: Coenagrionidae). We found weak
stabilizing selection on wing shape in both sexes, and no evidence that
selection on this trait differed between the species. In contrast, the
selection of body size was curvilinear in males and directional in
females, with differences in form (males) and intensity (females) between
the species. By analyzing selection in each local pond, we found that
selection on male body size was shaped by various population
characteristics that reflect local mating systems. Furthermore, the
relationship between mating system characteristics and directional
selection was remarkably consistent across these species. Finally, we
present a graphical model that links contemporary selection with
macroevolution. Based on this model, we conclude that the persistence of
ecological modes of life in pond damselflies explains why varying
selection in nature may still result in a stable adaptive zone lasting
millions of years.