title: Evolutionary and demographic history of the Californian scrub white oak species complex: an integrative approach.
abstract: Understanding the factors promoting species formation is a major task in evolutionary research. Here, we employ an integrative approach to study the evolutionary history of the Californian scrub white oak species complex (genus Quercus). To infer the relative importance of geographical isolation and ecological divergence in driving the speciation process, we (i) analysed inter- and intraspecific patterns of genetic differentiation and employed an approximate Bayesian computation (ABC) framework to evaluate different plausible scenarios of species divergence. In a second step, we (ii) linked the inferred divergence pathways with current and past species distribution models (SDMs) and (iii) tested for niche differentiation and phylogenetic niche conservatism across taxa. ABC analyses showed that the most plausible scenario is the one considering the divergence of two main lineages followed by a more recent pulse of speciation. Genotypic data in conjunction with SDMs and niche differentiation analyses support that different factors (geography vs. environment) and modes of speciation (parapatry, allopatry and maybe sympatry) have played a role in the divergence process within this complex. We found no significant relationship between genetic differentiation and niche overlap, which probably reflects niche lability and/or that multiple factors, have contributed to speciation. Our study shows that different mechanisms can drive divergence even among closely related taxa representing early stages of species formation and exemplifies the importance of adopting integrative approaches to get a better understanding of the speciation process.
authors.affiliation: Department of Integrative Ecology, Estación Biológica de Doñana, EBD-CSIC, Avda. Américo Vespucio s/n, E-41092, Seville, Spain.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Ortego
authors.affiliation: Department of Integrative Ecology, Estación Biológica de Doñana, EBD-CSIC, Avda. Américo Vespucio s/n, E-41092, Seville, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Noguerales
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Box 957239, Los Angeles, CA, 90095, USA.
authors.forename: Paul F
authors.identifier: http://orcid.org/0000-0002-4464-8453
authors.initials: PF
authors.lastname: Gugger
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Box 957239, Los Angeles, CA, 90095, USA.|Institute of the Environment and Sustainability, University of California, Box 951496, Los Angeles, CA, 90095-1496, USA.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Sork
mesh_terms: D001499:Bayes Theorem; D002140:California; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D049810:Genetic Speciation; D005828:Genetics, Population; D005838:Genotype; D018895:Microsatellite Repeats; D008957:Models, Genetic; D010802:Phylogeny; D029963:Quercus / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: Bayesian inference; Quercus; genetic structure; hybridization; niche divergence; palaeo-distribution modelling; species distribution modelling