title: Sea-level driven glacial-age refugia and post-glacial mixing on subtropical coasts, a palaeohabitat and genetic study.
abstract: Using a novel combination of palaeohabitat modelling and genetic mixture analyses, we identify and assess a sea-level-driven recolonization process following the Last Glacial Maximum (LGM). Our palaeohabitat modelling reveals dramatic changes in estuarine habitat distribution along the coast of California (USA) and Baja California (Mexico). At the LGM (approx. 20 kya), when sea level was approximately 130 m lower, the palaeo-shoreline was too steep for tidal estuarine habitat formation, eliminating this habitat type from regions where it is currently most abundant, and limiting such estuaries to a northern and a southern refugium separated by 1000 km. We assess the recolonization of estuaries formed during post-LGM sea-level rise through examination of refugium-associated alleles and approximate Bayesian computation in three species of estuarine fishes. Results reveal sourcing of modern populations from both refugia, which admix in the newly formed habitat between the refuges. We infer a dramatic peak in habitat area between 15 and 10 kya with subsequent decline. Overall, this approach revealed a previously undocumented dynamic and integrated relationship between sea-level change, coastal processes and population genetics. These results extend glacial refugial dynamics to unglaciated subtropical coasts and have significant implications for biotic response to predicted sea-level rise.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA gadolby@ucla.edu.
authors.forename: Greer A
authors.identifier: 0000-0002-5923-0690
authors.initials: GA
authors.lastname: Dolby
authors.affiliation: Scripps Institution of Oceanography-Marine Biology Research Division, UC San Diego, La Jolla, CA 92093-0218, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Hechinger
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Ellingson
authors.affiliation: Centro de Investigación en Alimentación y Desarrollo, A.C.-Unidad Guaymas, Carretera al Varadero Nacional km. 6.6, Colonia Las Playitas, Guaymas, Sonora 85480, México.
authors.forename: Lloyd T
authors.initials: LT
authors.lastname: Findley
authors.affiliation: Facultad de Ciencias, Universidad Autónoma de Baja California. Carretera Transpeninsular Ensenada - Tijuana No. 3917, Colonia Playitas, C.P. 22860, Ensenada, Baja California, México.
authors.forename: Julio
authors.initials: J
authors.lastname: Lorda
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA djacobs@ucla.edu.
authors.forename: David K
authors.initials: DK
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002140:California; D017753:Ecosystem; D063366:Estuaries; D005399:Fishes / Q000145:classification*; D014644:Genetic Variation; D005828:Genetics, Population; D008800:Mexico; D008954:Models, Biological; D000068236:Refugium
keywords: Baja California; Last Glacial Maximum; approximate Bayesian computation; estuaries; recolonization