title: Surprising migration and population size dynamics in ancient Iberian brown bears (Ursus arctos).
abstract: The endangered brown bear populations (Ursus arctos) in Iberia have been suggested to be the last fragments of the brown bear population that served as recolonization stock for large parts of Europe during the Pleistocene. Conservation efforts are intense, and results are closely monitored. However, the efforts are based on the assumption that the Iberian bears are a unique unit that has evolved locally for an extended period. We have sequenced mitochondrial DNA (mtDNA) from ancient Iberian bear remains and analyzed them as a serial dataset, monitoring changes in diversity and occurrence of European haplogroups over time. Using these data, we show that the Iberian bear population has experienced a dynamic, recent evolutionary history. Not only has the population undergone mitochondrial gene flow from other European brown bears, but the effective population size also has fluctuated substantially. We conclude that the Iberian bear population has been a fluid evolutionary unit, developed by gene flow from other populations and population bottlenecks, far from being in genetic equilibrium or isolated from other brown bear populations. Thus, the current situation is highly unusual and the population may in fact be isolated for the first time in its history.
authors.affiliation: Centro Mixto, Universidad Complutense de Madrid-Instituto de Salud Carlos III de Evolución y Comportamiento Humanos, c/Sinesio Delgado 4 Pabellon 14, 28029 Madrid, Spain. cvaldiosera@isciii.es
authors.forename: Cristina E
authors.initials: CE
authors.lastname: Valdiosera
authors.forename: José Luis
authors.initials: JL
authors.lastname: García-Garitagoitia
authors.forename: Nuria
authors.initials: N
authors.lastname: Garcia
authors.forename: Ignacio
authors.initials: I
authors.lastname: Doadrio
authors.forename: Mark G
authors.initials: MG
authors.lastname: Thomas
authors.forename: Catherine
authors.initials: C
authors.lastname: Hänni
authors.forename: Juan-Luis
authors.initials: JL
authors.lastname: Arsuaga
authors.forename: Ian
authors.initials: I
authors.lastname: Barnes
authors.forename: Michael
authors.initials: M
authors.lastname: Hofreiter
authors.forename: Ludovic
authors.initials: L
authors.lastname: Orlando
authors.forename: Anders
authors.initials: A
authors.lastname: Götherström
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D003116:Color; D008969:Molecular Sequence Data; D010802:Phylogeny; D011156:Population Density; D013030:Spain; D001503:Ursidae / Q000502:physiology*