POPULATION GENETIC STRUCTURE OF TWO CRYPTIC DUCKWEED SPECIES (Lemna minor & L. turionifera) IN ALBERTA USING A GENOTYPING-BY-SEQUENCING APPROACH

Abstract

Identifying the population genetic structure is important for the development of species-specific management plans. Investigating the population genetics of cryptic species is even more critical. Here we focus on two cryptic duckweed species, Lemna minor L. and L. turionifera Landolt, which have overlapping ranges in our study region of Alberta, Canada, and elsewhere, and are easily mistaken for one another. We used genotyping-by-sequencing to determine the population genetic structure of both duckweed species. A total of 192 samples were sequenced and after filtering, >16,000 SNP were used to examine patterns of genetic diversity between and within L. minor and L. turionifera. The two species showed clear differentiation. When examining L. turionifera singly, we found no evidence of genetically distinct populations among 67 samples from 43 sites. In contrast, when examining L. minor singly, we discovered at least three genetically distinct populations among the 30 samples from eight sites, even though these were from a small geographic area. We also examined the relationship between surface water quality variables and the distribution of the two Lemna species. The sites containing L. turionifera had a wider range of water chemistry variables suggesting they are more tolerant of different environmental conditions. In contrast, each of the three genetically distinct L. minor groups had different water chemistry profiles. Large differences between L. minor and L. turionifera in their regional distributions and degrees of genetic differentiation highlight the importance of documentation and careful monitoring of Lemna species within Alberta, and in other regions where they co-occur.

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

“…These findings are in line with previous research based on lower resolution genetic markers (Cole & Voskuil, 1996;Hart et al, 2019;Bog et al, 2022). However, more genetic variation was found here relative to the comparable geographical range reported in Senevirathna et al, (2023). These results indicate that when including populations from multiple sites in an experimental setting, chances are high that these combined populations contain multiple clonal genotypes.…”

“…Discrepancies in previous findings may be due to the fact that many genetic studies have examined a limited portion of the species’ range, and importantly, used low-resolution genetic markers, which are not intercomparable, such as allozyme loci (Vasseur et al ., 1993; Cole & Voskuil, 1996), ISSR markers (El-Kholy et al ., 2015), Amplified Fragment Length Polymorphisms (Bog et al ., 2022) or microsatellite loci (Hart et al ., 2019; Kerstetter et al ., 2023; Usui & Angert, 2024). Only recently genomic tools have been applied to this model system, a genotyping-by-sequencing study identified three genetically distinct populations of L. minor within a circa 160 km-transect in Canada (Senevirathna et al ., 2023).…”

Temperature-dependence and genetic variation in resource acquisition strategies in a model freshwater plant

“…High genetic similarity may be present in the Lemna species complex in this region due to the facultatively clonal nature of duckweeds and extremely low mutation rates (Sandler et al, 2020). However, Senevirathna et al (2023) It is possible, however, that we did not observe this trade-off because the Lemna species complex as a whole is not constrained by the gleaner-opportunist trade-off. For example, some work has shown that cryptophytes (a phylum of phytoplankton) are not constrained by this trade-off for photosynthetic light acquisition (Swanson et al, 2023).…”

“…Plants are facultatively asexual, with reproduction occurring mostly through rapid clonal budding of daughter fronds (Docauer, 1983). Duckweeds in the Lemna species complex can tolerate a wide range of water chemistries and nutrient levels, with a doubling time of 2 to 5 days in optimal conditions (Docauer, 1983;Senevirathna et al, 2023;Ziegler et al, 2015). We sampled 20 unique accessions of the Lemna species complex from across 20 sites around Vancouver, British Columbia, Canada, and the Pacific Northwest region including Washington, USA (Table S1).…”

Covering the bases: Population genomic structure of Lemna minor and the cryptic species L. japonica in Switzerland

“…Discrepancies in previous findings may be due to the fact that many genetic studies have examined a limited portion of the species' range, and importantly, used low‐resolution genetic markers, which are not intercomparable, such as allozyme loci (Cole & Voskuil, 1996; Vasseur et al., 1993), ISSR markers (El‐Kholy et al., 2015), Amplified Fragment Length Polymorphisms (Bog et al., 2022), or microsatellite loci (Hart et al., 2019; Kerstetter et al., 2023; Usui & Angert, 2024). Only recently genomic tools have been applied to this model system, a genotyping‐by‐sequencing study identified three genetically distinct populations of L. minor within a 160 km transect in Canada (Senevirathna et al., 2023).…”