Data from: Seasonal polyphenism in wing coloration affects species recognition in rubyspot damselflies (Hetaerina spp.)

Understanding how phenotypic plasticity evolves and in turn affects the
course of evolution is a major challenge in modern biology. By definition,
biological species are reproductively isolated, but many animals fail to
distinguish between conspecifics and closely related heterospecifics. In
some cases, phenotypic plasticity may interfere with species recognition.
Here, we document a seasonal polyphenism in the degree of dark wing
pigmentation in smoky rubyspot damselflies (Hetaerina titia) – a shift so
pronounced that it led early researchers to classify different forms of H.
titia as separate species. We further show how the seasonal colour shift
impacts species recognition with the sympatric congener Hetaerina occisa.
Interspecific aggression (territorial fights) and reproductive
interference (mating attempts) are much more frequent early in the year,
when H. titia more closely resembles H. occisa, compared to later in the
year when the dark phase of H. titia predominates. Using wing colour
manipulations of tethered damselflies, we show that the seasonal changes
in interspecific interactions are caused not only by the seasonal colour
shift but also by shifts in discriminatory behaviour in both species. We
also experimentally tested and rejected the hypothesis that learning
underlies the behavioural shifts in H. occisa. An alternative hypothesis,
which remains to be tested, is that the seasonal polyphenism in H. titia
wing coloration has resulted in the evolution of a corresponding seasonal
polyphenism in species recognition in H. occisa. This study illustrates
one of the many possible ways that plasticity in species recognition cues
may influence the evolution of interspecific interactions.