title: Hybrid apomicts trapped in the ecological niches of their sexual ancestors.
abstract: Asexual reproduction is expected to reduce the adaptive potential to novel or changing environmental conditions, restricting or altering the ecological niche of asexual lineages. Asexual lineages of plants and animals are typically polyploid, an attribute that may influence their genetic variation, plasticity, adaptive potential, and niche breadth. The genus Boechera (Brassicaceae) represents an ideal model to test the relative ecological and biogeographic impacts of reproductive mode and ploidy because it is composed of diploid sexual and both diploid and polyploid asexual (i.e., apomictic) lineages. Here, we demonstrate a strong association between a transcriptionally conserved allele and apomictic seed formation. We then use this allele as a proxy apomixis marker in 1,649 accessions to demonstrate that apomixis is likely to be a common feature across the Boechera phylogeny. Phylogeographic analyses of these data demonstrate (i) species-specific niche differentiation in sexuals, (ii) extensive niche conservation between differing reproductive modes of the same species, (iii) ploidy-specific niche differentiation within and among species, and (iv) occasional niche drift between apomicts and their sexual ancestors. We conclude that ploidy is a substantially stronger and more common driver of niche divergence within and across Boechera species although variation in both traits may not necessarily lead to niche evolution on the species scale.
authors.affiliation: Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany; mau@ipk-gatersleben.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Mau
authors.affiliation: Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712;
authors.forename: John T
authors.initials: JT
authors.lastname: Lovell
authors.affiliation: Department of Bioanalytics, Coburg University of Applied Sciences and Arts, 96450 Coburg, Germany;
authors.forename: José M
authors.initials: JM
authors.lastname: Corral
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany;
authors.forename: Christiane
authors.initials: C
authors.lastname: Kiefer
authors.affiliation: Department of Biodiversity and Plant Systematics, Centre for Organismal Studies Heidelberg, 69120 Heidelberg, Germany; and.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Koch
authors.affiliation: Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany; Department of Crop Production, College of Agriculture, Kwara State University, PMB 1530 Ilorin, Kwara State, Nigeria.
authors.forename: Olawale M
authors.initials: OM
authors.lastname: Aliyu
authors.affiliation: Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany;
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Sharbel
mesh_terms: D000483:Alleles; D005075:Biological Evolution; D019607:Brassicaceae / Q000502:physiology*; D019070:Cell Lineage; D017753:Ecosystem; D005819:Genetic Markers / Q000235:genetics; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes; D009656:North America; D010312:Parthenogenesis; D010802:Phylogeny; D058974:Phylogeography; D011003:Ploidies; D012639:Seeds / Q000378:metabolism
chemical_list: D005819:Genetic Markers
keywords: APOLLO; Boechera; UPGRADE2; geographic parthenogenesis; niche conservation