Fig. 4

The annual migratory circuit of the green darner dragonfly (Anax junius) in eastern North America. Green darners have three generations per year: a spring migratory generation which travels from the southern coastal states as far north as southern Canada (dark blue and black arrows); an autumn migratory generation which returns to the southern coastal states (light blue and grey arrows); and a non-migratory generation which develops during the winter in the south (grey shaded area). The level of connectivity in this species is not clear. a One plausible scenario is that migratory connectivity is high, with populations west of the Appalachian Mountains (blue arrows) remaining largely separate from populations to the east (black and grey arrows). b An alternative scenario is that there is frequent mixing across the entire range, leading to a single panmictic population in eastern North America with low connectivity. Green darners are also found to the west of the Rocky Mountains, and it is not clear if this population is connected to that in the east. Further genetic and tracking studies are required to resolve these issues