Hide and seek: molecular barcoding clarifies the distribution of two cryptic duckweed species across Alberta

Abstract

Regional and global biodiversity may be underestimated due to the presence of cryptic species: species that are morphologically similar, but genetically distinct. Here we focus on two cryptic duckweed species, Lemna minor and L. turionifera, which have overlapping geographic ranges and are easily mistaken for one another. We developed species-specific primers based on DNA barcoding sequences to facilitate the rapid identification of these two monomorphic duckweeds, allowing us to investigate their presence and distribution in Alberta, Canada. While current reports indicate the presence of L. turionifera (and the morphologically distinct L. trisulca) in Alberta, our data indicate that L. minor is also present, predominantly in the southern part of the province. Thus, this paper (1) contributes to the accuracy and completeness of a regional flora, and (2) provides useful and flexible tools for the rapid molecular identification of cryptic Lemna species, species of wide interest in such diverse fields as biotechnology, toxicology, bioremediation, and ecology. 

Species interactions in three Lemnaceae species growing along a gradient of zinc pollution

“…minor and L . turionifera can be equally challenging (Senevirathna et al, 2021). Therefore, we separated the species using a floating ring (Figure ).…”

“…To the best of our knowledge, this is the first study investigating L. turionifera growth rates in the presence or absence of a competitor. Recently, it has been found that some populations previously thought to be L. minor were in fact L. turionifera (Senevirathna et al, 2021). It is thus possible that L. turionifera has a wider geographic distribution than previously thought and is, therefore, a good candidate for phytoremediation in many regions of the world.…”

“…They float on the water surface and are very similar in terms of their morphology. In particular, non-gibbous L. gibba and L. minor fronds cannot be distinguished by eye (De Lange & Pieterse, 1973) but the differentiation between L. minor and L. turionifera can be equally challenging (Senevirathna et al, 2021). Therefore, we separated the species using a floating ring (Figure S4).…”

Species interactions in three Lemnaceae species growing along a gradient of zinc pollution

“…In particular, non-gibbous L. gibba and L. minor fronds cannot be distinguished by eye but the differentiation betweenL. minor and L. turionifera can be equally challenging (Senevirathna et al, 2021). Therefore, we separated the species using a floating ring (Figure S4).…”

High tolerance to zinc but limited evidence for local adaptation in the aquatic plant species Lemna gibba/minor

“…However, L. gibba is rarely observed in Switzerland (IUCN status: critically endangered; (InfoFlora 2022), and thus finding new L. gibba populations is unexpected. It is, however, possible that there is a cryptic presence of L. gibba in Switzerland, which could be revealed using molecular barcoding (Senevirathna et al 2021). Future studies using wild populations of L. minor or other morphologically similar duckweed species such as Lemna japonica, Lemna turionifera and Lemna minuta should be aware that cryptic species may be potentially present.…”