Crins, Bill

In 2008, the first North American water soldier (Stratiotes aloides) population was discovered in the Trent River, Ontario. Water soldier is an invasive aquatic plant with sharp, serrated leaves that has the potential to spread rapidly through dispersed vegetative fragments. Although it is too late to prevent water soldier establishment in the Trent River, its local distribution remains limited. In this study, environmental DNA (eDNA) was explored as a potential tool for early detection of water soldier. Species-specific markers were designed from chloroplast DNA regions matK and rbcL, and a qPCR assay with rbcL primers yielded the most sensitive detection of water soldier eDNA. Positive detections were obtained from six of 40 sampling locations, of which five were collected in Seymour Lake, an area with large patches of water soldier. As water soldier plants were known to be present at these sites, high eDNA concentrations were expected. The sixth positive detection from Trent Lock 5 (50 km downstream of Lake Seymour) was unexpected as it was obtained at a site with no water soldier sightings. This is one of the first studies to demonstrate the effectiveness of eDNA detection from aquatic plants.

Author Keywords: aquatic plant, eDNA, environmental DNA, invasive species, Stratiotes aloides, water soldier

According to the Invasional Meltdown Hypothesis (IMH), invasive species may interact in their introduced range and facilitate future invasions. This study investigated the possibility that Alliaria petiolata, an invasive allelopathic herbaceous plant in Ontario, is facilitating invasions by additional alien species. Two allelopathic focal species were chosen for this study: the native Solidago canadensis and the invasive A. petiolata. Field surveys in southern Ontario that quantified plant biodiversity in plots that included one or both focal species revealed no support for the IMH, although fewer species co-existed with A. petiolata than with S. canadensis. A year-long recruitment experiment in Peterborough, Ontario, also produced results inconsistent with the IMH, although did provide some evidence that A. petiolata limited recruitment of other species. These results collectively show negative impacts on regional biodiversity by A. petiolata, even in the absence of an invasional meltdown.

Author Keywords: allelopathy, Alliaria petiolata, co-occurrence surveys, invasional meltdown hypothesis, invasive species, Solidago canadensis

Magnolia acuminata (Cucumber tree) is the only native Magnolia in Canada, where it is both federally and provincially listed as endangered.Magnolia acuminata in Canada can be found inhabiting pockets of Carolinian forest within Norfolk and Niagara regions of southwestern Ontario. Using a combination of nuclear and chloroplast markers, this study assessed the genetic diversity and differentiation of M. acuminata in Canada, compared to samples from the core distribution of this species across the United States. Analyses revealed evidence of barriers to dispersal and gene flow among Ontario populations, although genetic diversity remains high and is in fact comparable to levels of diversity estimated across the much broader range of M. acuminata in the USA. When examining temporal differences in genetic diversity, our study found that seedlings were far fewer than mature trees in Ontario, and in one site in particular, diversity was lower in seedlings than that of the adult trees. This study raises concern regarding the future viability of M. acuminata in Ontario, and conservation managers should factor in the need to maintain genetic diversity in young trees for the long-term sustainability of M. acuminata in Ontario.

Author Keywords: conservation genetics, cpDNA, forest fragmentation, Magnolia acuminata, microsatellites, population genetic structure