Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

• Published in: PloS one Vol. 15; no. 11; p. e0240698
• Main Authors: Blanco, Juan Carlos, Ballesteros, Fernando, Palomero, Guillermo, López-Bao, José Vicente
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 02.11.2020; Public Library of Science (PLoS)
• Subjects: Animal behavior; Animal populations; Animals; Bears; Biology and Life Sciences; Demographics; Demography; Earth Sciences; Ecology and Environmental Sciences; Female; Females; Formal Comment; Gene Flow; Genetics, Population; Habitats; Human Activities; Humans; Male; Migration; Mortality; Mountains; Poaching; Population Dynamics; Restoration; Social Sciences; Spain; Subpopulations; Ursidae - physiology; Ursus arctos; Spain; Cantabrian Mountains
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0240698

In a genetic study on brown bears (Ursus arctos) in the Cantabrian Mountains, Gregório et al. (2020) interpreted the asymmetrical gene flow they found from the eastern subpopulation towards the western one as an exodus of bears forced to flee from the eastern nucleus "with higher human disturbance and poaching", concluding that connectivity may be operating as a means for eastern Cantabrian bears to find more suitable territories. In this reply, we maintain that the explanations of Gregorio et al. contradict the source-sink theory and we also present demographic data not considered by these authors showing that the eastern subpopulation is not declining, but persistently increasing. After reviewing the demographic and genetic studies published during the last 20 years, we conclude that the connectivity between the two subpopulations is operating as a route which allows the regular movement of males and the restoration of the gene flow across the whole Cantabrian population.