title: Phylogeny and biogeography of the American live oaks (Quercus subsection Virentes): a genomic and population genetics approach.
abstract: The nature and timing of evolution of niche differentiation among closely related species remains an important question in ecology and evolution. The American live oak clade, Virentes, which spans the unglaciated temperate and tropical regions of North America and Mesoamerica, provides an instructive system in which to examine speciation and niche evolution. We generated a fossil-calibrated phylogeny of Virentes using RADseq data to estimate divergence times and used nuclear microsatellites, chloroplast sequences and an intron region of nitrate reductase (NIA-i3) to examine genetic diversity within species, rates of gene flow among species and ancestral population size of disjunct sister species. Transitions in functional and morphological traits associated with ecological and climatic niche axes were examined across the phylogeny. We found the Virentes to be monophyletic with three subclades, including a southwest clade, a southeastern US clade and a Central American/Cuban clade. Despite high leaf morphological variation within species and transpecific chloroplast haplotypes, RADseq and nuclear SSR data showed genetic coherence of species. We estimated a crown date for Virentes of 11 Ma and implicated the formation of the Sea of Cortés in a speciation event ~5 Ma. Tree height at maturity, associated with fire tolerance, differs among the sympatric species, while freezing tolerance appears to have diverged repeatedly across the tropical-temperate divide. Sympatric species thus show evidence of ecological niche differentiation but share climatic niches, while allopatric and parapatric species conserve ecological niches, but diverge in climatic niches. The mode of speciation and/or degree of co-occurrence may thus influence which niche axis plants diverge along.
authors.affiliation: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA.
authors.forename: Jeannine
authors.initials: J
authors.lastname: Cavender-Bares
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, 58190 Michoacán, México.
authors.forename: Antonio
authors.initials: A
authors.lastname: González-Rodríguez
authors.affiliation: Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8106, USA.
authors.forename: Deren A R
authors.initials: DA
authors.lastname: Eaton
authors.affiliation: The Morton Arboretum, Lisle, IL 60532, USA.|The Field Museum, Chicago, IL 60605, USA.
authors.forename: Andrew A L
authors.initials: AA
authors.lastname: Hipp
authors.affiliation: Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Beulke
authors.affiliation: Department of Biology, Duke University, Raleigh, NC 27708, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Manos
mesh_terms: D002489:Central America; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D051456:Gene Flow; D049810:Genetic Speciation; D014644:Genetic Variation; D005828:Genetics, Population; D007438:Introns; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009656:North America; D010802:Phylogeny; D058974:Phylogeography; D011156:Population Density; D029963:Quercus / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: RADseq; Sea of Cortés; Virentes; conservation; ecological and climatic niches; fossil calibration; genomic data; introgression; phylogeography