After publication, we discovered that the degrees of freedom in Table 2 are listed incorrectly. The correct values should be 34 for "within populations" (as opposed to 24), and 39 for "total" (as opposed to 29). All other values in this table are correct, and this transcription error does not change our inferences.
Correction to Table 2
14 March 2014
After publication, we discovered that the degrees of freedom in Table 2 are listed incorrectly. The correct values should be 34 for "within populations" (as opposed to 24), and 39 for "total" (as opposed to 29). All other values in this table are correct, and this transcription error does not change our inferences.Competing interests
None