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Ning, Weixuan [1], Meudt, Heidi [2], Nicolas, Antoine [3], Plunkett, Gregory [4], Tate, Jennifer [1].

Phylogenomic analysis of New Zealand polyploid Azorella (Apiaceae).

All angiosperms have at least one whole genome duplication or polyploidization event in their evolutionary history. Thus, polyploidization has been one of the main evolutionary forces to promote their genetic, genomic, and functional variation. Post-polyploidization genomic modification plays important roles in driving morphological diversification as well as new habitat colonization. In order to understand how polyploidy has led to species radiation and diversification, a diverse polyploid lineage provides an excellent system to resolve the origins and biogeographic history of closely related polyploids. Investigating the traits associated with genomic doubling can offer insights into the post-polyploidization genomic changes and species diversification. Azorella sections Schizeilema and Stilbocarpa are a well-defined perennial subalpine lineage comprising 17 species that are morphologically diverse and have varying ploidal levels of 4x, 6x or 10x. Specifically, A. polaris (6x), A. robusta and A. lyallii in Azorella section Stilbocarpa are subantarctic island megaherbs. By contrast, the 14 species in Azorella section Schizeilema (4x, 6x and 10x) are smaller rhizomatous rosette herbs, but vary in leaf size and shape. These 14 species are endemic to New Zealand, except A. fragosea, which is endemic to Australia. Initial phylogenomic analysis of target-enrichment sequencing data from 29 individuals using the universal Angiosperm 353 kit suggests species in Azorella section Schizeilema are more closely related to the Chilean relative A. ranunculus in section Ranunculus than to species in section Stilbocarpa. In addition, across all 29 sequenced individuals, an assessment of the mean heterozygosity across sites and allele divergence shows that the mean heterozygosity is 82% (median 88%) and mean allele divergence is 2.1% (median 2%), which indicates high proportions of hybrid origins among sequenced samples, as would be expected for allopolyploid species. To complete the sampling for this project, 53 additional individuals of 19 populations from field or herbarium collections will be sequenced. Furthermore, traits such as genome size, stomatal guard cell length, and stomatal density will be measured using multiple individuals from at least two different populations to test whether they are correlated with post-polyploidization genomic variation. Finally, to explore the relationship of polyploidy in niche space, publicly available environmental raster layers for soil, climate and elevation will be used to build the ecological niche space model for each New Zealand Azorella species. Overall, this project aims to interpret the reticulate origins of New Zealand polyploid Azorella species, to understand their diversification in morphological traits and niche space after polyploidization.

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1 - Massey University, School Of Fundamental Sciences, Private Bag 11222, Palmerston North, 4442, New Zealand
2 - Museum Of New Zealand Te Papa Tongarewa, Botany, PO Box 467, Cable St, Wellington, 6140, New Zealand
3 - Manhattan College, Biology, Leo Building - Room 317D, 4513 Manhattan College Parkway, Riverdale, NY, 10471, United States
4 - New York Botanical Garden, Cullman Program For Molecular Systematics, 2900 Southern Blvd., Bronx, NY, 10458, United States

genomic size variation

Presentation Type: Oral Paper
Session: PHYLOI, Phyogenomics I
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 11:15 AM(EDT)
Number: PHYLOI006
Abstract ID:218
Candidate for Awards:None

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