Covering the bases: population genomic structure ofLemna minorand the cryptic speciesL. japonicain Switzerland

Abstract

Duckweeds, including the common duckweed Lemna minor, are increasingly used to test eco-evolutionary theories. Yet, despite its popularity and near-global distribution, the understanding of its genetic variation is still limited. It is essential that this is resolved, because of the impact genetic diversity has on experimental responses and scientific understanding. Through whole-genome sequencing, we assessed the genetic diversity and population genomic structure of 23 natural Lemna spp. populations from their natural range in Switzerland. We used two distinct analytical approaches, a reference-free kmer approach and the classical reference-based one. Two genetic clusters were identified across the species distribution, corresponding to species -level divisions. The first cluster contained the targeted L. minor individuals and the second contained individuals from a cryptic species: Lemna japonica. Within the L. minor cluster, we identified a well-defined population structure with little intra-population genetic diversity but high inter-population diversity. In L. japonica, the population structure was significantly weaker and genetic variation between a subset of populations was as low as within populations. This study revealed that Lemna japonica is more widespread than previously thought. Our findings empower more robust genotype-to-phenotype analyses in duckweed ecology and evolution, realizing the full potential of L. minor in eco-evolutionary research.

Leaf spectroscopy reveals drought response variation inFagus sylvaticasaplings from across the species’ range

“…Trimmed sequencing reads were analysed using the kmerGWAS pipeline (v0.2) (Voichek & Weigel, 2020) according to the manual found on github (https://github.com/voichek/kmersGWAS). The k-mer database was built using KMC (v3) (Kokot et al, 2017) with the default k-mer size and settings (-k 31 -mac 5 -p 0.2), equivalent to the approach in (Schmid et al, 2024). The k-mer table containing the presence/absence pattern of each 31 bp k-mer in the population was then used to derive the kinship matrix.…”