Abstract Detail

Bryology and Lichenology

Piatkowski, Bryan [1], Weston, Dave [1], Aguero, Blanka [2], Duffy, Aaron [2], Imwattana, Karn [2], Healey, Adam [3], Schmutz, Jeremy [3], Shaw, Jonathan [2].

Local adaptation fuels genomic divergence between incipient species in the Sphagnum magellanicum complex.

New plant species can evolve through the reinforcement of reproductive isolation via local adaptation along habitat gradients. Peat mosses (Sphagnaceae) are an emerging model system for the study of evolutionary genomics and have well-documented niche differentiation among species. Previous molecular studies have demonstrated that one globally distributed species, Sphagnum magellanicum, is a complex of several lineages that are phylogenetically and ecologically distinct. Here, we describe the architecture of genomic differentiation between populations in the S. magellanicum complex collected from along a latitudinal gradient in eastern North America and demonstrate the role of natural selection in driving their speciation. Phylogenomic analysis resolves a northern clade (S. diabolicum sp. nov.) sister to a clade containing largely southern populations (S. magni sp. nov.). Coalescent simulations favor a model of secondary contact in which this divergence is no older than 200,000 generations with more recent gene flow occurring where the species ranges overlap. We find using sliding-window analyses that genetic differentiation is concentrated within “islands” of the genome spanning up to 300 kilobases that are characterized by elevated genetic divergence (FST and dXY), suppressed recombination, and reduced nucleotide diversity. Genes within these regions have increased rates of non-synonymous substitution and are enriched for biological processes related to abiotic stress response, anatomical development, photoperiodism, and hormone-mediated signaling. We suggest that the heterogeneity of differentiation across the genome is a result of linked selection and reflects local adaptation to contrasting climatic regimes. This research provides insight into the process of speciation in a group of ecologically important plants and strengthens our predictive understanding of how plant populations will respond as Earth’s climate rapidly changes.

1 - Oak Ridge National Laboratory, Biosciences Division, 1 Bethel Valley Rd, Oak Ridge, TN, 37830, USA
2 - Duke University, Department of Biology, Box 90338, Durham, NC, 27708, USA
3 - HudsonAlpha Institute for Biotechnology, Genome Sequencing Center, 601 Genome Way, Huntsville, AL, 35806, USA

comparative genomics
peat moss
Climate Gradients .

Presentation Type: Oral Paper
Number: BL1004
Abstract ID:257
Candidate for Awards:None

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