Genetic Structure in the Cactus Wren in Coastal Southern California

The purpose of this addendum is to update results and conclusions reported in Barr et al. 2013 based on the addition of new genetic samples to the original dataset. The additional samples include five samples from Palos Verdes in 2013 that were collected incidental to other projects there, and three samples from a new site, West Coyote Hills, that we were approved for access in 2013. Three other additional samples came from those collected in 2012 but not analyzed in Barr et al. 2013, including one that originally failed to genotype but was amplified with additional attempts and two that were removed from the previous analyses using a very conservative interpretation of sibship results. Original analyses did not include these samples though the probabilities of these sibship relationships were low (<0.95; Hauser et al. 2011), thereby preventing spurious population structure from being detected because of potential biases from closely-related individuals in the dataset. With further analyses and a thorough understanding of overall population structure in Cactus Wrens, these lower probability sibships were determined to have no effect on population structure patterns and were hence returned to the dataset.