Figure 5

Candidate composite barriers. A: The top 1,380 candidate barriers that are topographically similar to the individual barriers that comprise the reference barrier for the Arctic Ocean, which has promoted ring diversification in the bird species complex Larus, and to the individual barriers that comprise the reference barrier for Central Asia, which has promoted which has promoted ring diversification in the bird species Phylloscopus trochiloides. B: Candidate composite barriers evaluated for groups of individual barriers showing the same number of sub-units (that is, cohesive barriers), the same inflection, and that are similar in total size and inter-barrier proximity. Seven of the 14 candidate composite barriers are shown to illustrate exemplary barriers and simplify map interpretation; the other candidates are provided in our model database (see Methods).