Pathways of introduction of the invasive aquatic plant Cabomba caroliniana

Abstract

The pathway and frequency of species' introductions can affect the extent, impact, and management of biological invasions. Here, we examine the pathway of introduction of the aquatic plant Cabomba caroliniana (fanwort) into Canada and the northern United States using plastid DNA sequence (intergenic spacers atpF-atpH, trnH-psbA, and trnL-trnF) and DNA content analyses. We test the hypothesis that the spread of fanwort is a result of commercial trade by comparing a Canadian population (Kasshabog Lake, ON) to native populations from southern U.S., introduced populations in northern U.S., and plants from commercial retailers. Thirteen plastid haplotypes were identified throughout North America, including one dominant haplotype, which was present in all C. caroliniana populations. Several rare haplotypes were used to infer shared colonization history. In particular, the Canadian population shared two rare alleles with a population from Massachusetts, suggesting range expansion of C. caroliniana from the northern U.S. However, the possibility of a commercial introduction cannot be excluded, as common alleles were shared between the Canadian population and both commercial and southern U.S. sources. Variation in C. caroliniana genome size was bimodal and populations were classified into “high” and “low” categories. The Canadian population had DNA contents similar to several northern U.S. populations (low DNA content). This may provide additional support for range expansion from these introduced populations rather than from commercial sources or populations in the southern U.S., which had high DNA content.

Bioinformatic Workflows for Generating Complete Plastid Genome Sequences—An Example from Cabomba (Cabombaceae) in the Context of the Phylogenomic Analysis of the Water-Lily Clade

“…One way to explain this observation is the presence of a greater genetic diversity within C. caroliniana than currently known. This hypothesis is supported by the results of McCracken et al [ 41 ] as well as the findings of this investigation. We found that the plastid genomes of our two samples of C. caroliniana differ from each other by a total of 12 nucleotide changes across the aligned coding regions as well as several DNA insertions/deletions ( Table 5 ).…”

“…The species C. caroliniana is also peculiar in exhibiting an unusual chloroplast dimorphism [ 70 ] and a nuclear genome size considerably larger than those of other taxa in the plant order Nymphaeales [ 71 ]. Based on the complete plastid genome sequences presented here, future research may evaluate if the regions identified by McCracken et al [ 41 ] as most variable across the plastid genome are indeed the preferred genetic markers for delimiting populations in C. caroliniana .…”

“…The genus Cabomba comprises five species of perennial aquatic plants that naturally occur in tropical and subtropical freshwater in the Americas, particularly in the southern United States, Mexico, Central and South America [ 39 , 40 ]. One of the species of Cabomba , C. caroliniana , has spread to aquatic ecosystems across the globe [ 41 ] and is considered a highly invasive species in many regions of the world [ 42 , 43 ]. Moreover, Cabomba is one of two genera of the plant family Cabombaceae, which belongs to one of the earliest diverging lineages of the flowering plants [ 6 ].…”

A boat hitchhiker’s guide to survival: Cabomba caroliniana desiccation resistance and survival ability

“…Cabomba, or water fanwort, is a submersed aquatic macrophyte native to freshwaters of South and North America (Ørgaard, 1991). Introduced worldwide as a popular aquarium species, it became a serious aquatic invasive species in many countries including Australia, USA (outside its native range), Canada, the Netherlands and China (Ørgaard, 1991;Les & Mehrhoff, 1999;Wilson et al, 2007;van Valkenburg et al, 2011;McCracken et al, 2013).…”

Insights into the dynamics of genome size and chromosome evolution in the early diverging angiosperm lineage Nymphaeales (water lilies)

“…Five species are currently recognised in Cabomba, some of which have received considerable attention given their impact as serious invasive weeds outside their native habitat (Ghahramanzadeh et al 2013;McCracken et al 2013). The genus is also receiving interest as a potential model for studying the early evolution of angiosperms (Vialette-Guiraud et al 2011).…”