Genomic Differentiation Among the Most Important Global Populations of Striated Caracara (Phalcoboenus australis)

BALZA ULISES; LOIS NICOLÁS; KATIE HARRINGTON; PÜTZ, KLEMENS; RAYA REY, ANDREA; CEBALLOS SANTIAGO

Fort Lauderdale

Conferencia; Annual Meeting of the Raptor Research Foundation; 2022

Raptor Research Foundation

Island raptors are more threatened than continental species. The four extant species of Andean caracaras(genus Phalcoboenus ) diverged from their sister species, the widespread Chimango Caracara (Milvagochimango ) about 2 Ma, but their detailed phylogenetics remains unclear. The southernmost Phalcoboenus , theStriated Caracara P. australis , diverged roughly 600 ka and presents a disjunct distribution restricted to islandsin southern South America and the Malvinas/Falkland Islands (MI/FI). The global population is estimated at1,000-2,500 mature individuals, with roughly 65% restricted to Isla de los Estados (IDLE, Fuegian archipelago)and the MI/FI. Whether the species had a continental or insular origin is still unknown. Using 72 samples fromboth IDLE and MI/FI, we used Next Generation sequencing techniques to analyze the phylogenetic structure,genetic variation, and degree of differentiation of the species’ putative main populations. Phylogeneticanalyses suggest reciprocal monophyly between the two populations and a degree of differentiation of similarmagnitude with respect to the external group (Chimango Caracara). The clustering analyses and the Fst valueswere consistent in indicating a differentiation of a greater degree between IDLE and MI/FI, and of a lesserdegree within three islands sampled in MI/FI. Overall, our results suggest that the two archipelagos representindependent lineages and that the differentiation is not recent. Our results further advocate for at least twoglacial refuges generating separate lineages in the early speciation of P. australis . The Striated Caracara mayoccur in a series of naturally fragmented populations, many of which could harbor unique variants on arelatively small spatial scale with little to no genetic connectivity. From a conservation perspective, our resultssuggest that the two primary populations (IDLE and MI/FI) should be considered as distinct management unitsand that the global population estimates should be reassessed accordingly.