Fig. 2

Variation of the spatial (continuous line) and temporal (hatched line) migratory connectivity (Mantel Rm statistic) en route between tagging sites along a latitudinal gradient of cells of 1 × 1 degree (values close to 0 = weak migratory connectivity, values close to 1 = strong migratory connectivity). Populations converged near the Florida peninsula but maintained a finer scale spatial structure (continuous line). We calculated the median latitude of the 16 intervals of 5°N tested. Observations between 37 and 33 °N did not include enough receiving stations for a robust statistical interpretation. Populations maintained a temporal segregation (hatched line) in the early stages of migration, but no differences associated to the origin was found south of 38°N, despite a slight increase, but weak connectivity, in the last detections south of 30°N. Vertical bars represent 95% confidence limits based on 100 bootstrap samples. The read horizontal line represents the y-intercept = 0