Abstract Detail

Molecular Ecology

Puppo, Pamela [1], Di Santo, Lionel [2], Hamilton, Jill [3].

The role of polyploidy in evolutionary niche divergence across the range of Geum triflorum Pursh.

Given the pace of global environmental change, the ability of plants to rapidly adapt to changing conditions is crucial for long-term species persistence. However, adaptation to changing conditions requires substantial genetic variation through which natural selection may act. Whole genome duplications (WGD) may provide an important source of genetic variation necessary for adaptation to heterogeneous environments. Duplicate gene copies may evolve independently in response to a combination of relaxed selection for one redundant gene copy and purifying selection on the other, leading to differential expression across duplicate gene copies. Thus genomic restructuring and rebalancing of gene expression across duplicated genes following genome duplication may provide the necessary functional genetic variance needed to persist under rapidly changing conditions. Allopolyploids, derived from a hybridization event between diploid lineages, provide ideal systems to evaluate the influence of selection on the evolutionary trajectory of duplicate genes across differentiated sub-genomes. In this study we use the allohexapoloid, Geum triflorum Pursh. to ask whether habitat of origin can predict sub-genome expression variation across a species' range. An herbaceous perennial, G. triflorum is common to the midwestern prairies, with peripheral and disjunct populations associated with critically imperiled alvar habitats, characterized by a thin layer of soil over limestone. Alvar habitats experience extreme temporal fluctuation in water availability relative to prairie habitats, which maintain water levels due to increased soil depth. Thus, we hypothesize that environmental heterogeneity across these distinct environments will contribute to the evolution of functional variation in across sub-genomes. We sequenced the leaf transcriptome of G. triflorum seedlings grown together in a common environment sourced from three distinct environments: prairie, peripheral alvar, and disjunct alvar. In addition, we used RNA-seq to sequence the leaf transcriptome of two of the diploid progenitors, Waldsteinia geoides and Coluria geoides. Preliminary transcriptome assemblies indicate that reads of G. triflorum successfully map onto associated diploid progenitors, indicating that duplicate genes associated with ancestral sub-genomes is possible. Furthermore, our preliminary data indicate that there is differential expression of duplicate genes associated with either sub-genome across environments. A number of transcripts associated with each ancestral sub-genome appear to show environment-specific gene expression. This may suggest that the evolution of duplicate genes has provided an important mechanism necessary for expansion and persistence of G. triflorum across extreme environments.

1 - North Dakota State University, Department of Biological Sciences, 1340 Bolley Drive, Fargo, ND, 58108, USA
2 - North Dakota State University, 1340 Bolley Drive, Fargo, ND, 58108, Estados Unidos
3 - North Dakota State University, Biological Sciences, PO Box 6050, Dept. 2715, Fargo, ND, 58102, United States

whole genome duplication
midwestern prairies

Presentation Type: Oral Paper
Number: 0002
Abstract ID:359
Candidate for Awards:None

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