Payne N, JA Erwin, J Morrison, J Dwyer and M Culver. 2023. Genomic Insights into Isolation of the Threatened Florida Crested Caracara (Caracara plancus). J Heredity, 14:esad057. doi: 10.1093/jhered/esad057.
Abstract
We conducted a population genomic study of the crested caracara (Caracara plancus) using samples (n = 290) collected from individuals in Florida, Texas, and Arizona, USA. Crested caracaras are non-migratory raptors ranging from the southern tip of South America up to the southern United States, including a federally protected relict population in Florida long thought to have been isolated since the last ice age. Our objectives were to evaluate genetic diversity and population structure of Florida’s apparently isolated population and to evaluate taxonomic relationships of caracaras at the northern edge of their range. Using DNA purified from blood samples, we conducted double-digest restriction site associated DNA sequencing and sequenced the mitochondrial ND2 gene. Analyses of population structure using over 9000 SNPs suggest two major clusters are best supported, one cluster including only Florida individuals and the other cluster including Arizona and Texas individuals. Both SNPs and mitochondrial haplotypes reveal the Florida population to be highly differentiated genetically from Arizona and Texas populations, whereas Arizona and Texas populations are moderately differentiated from each other. The Florida population’s mitochondrial haplotypes form a separate monophyletic group, while Arizona and Texas populations share mitochondrial haplotypes. Results of this study provide substantial genetic evidence that Florida’s crested caracaras have experienced long-term isolation from caracaras in Arizona and Texas, representing a distinct evolutionary lineage possibly warranting distinction as an Evolutionarily Significant Unit (ESU) or subspecies. Inclusion of these results will aid development of conservation strategies focused on long-term survival of Florida’s distinct, panmictic population.