3/23/2023 0 Comments Genodive sequnce datasemen cells are flagellated and fragile, but form resistant resting cysts following sexual reproduction (Figueroa & Rengefors, 2006). These blooms reduce the recreational value of lakes as the cells expel mucilage threads upon physical contact (Cronberg et al., 1988), which causes the water to become slimy and may result in skin irritation (Sörensen, 1954). This species can dominate the phytoplankton community almost completely, up to 98% of the biomass, and last at high density for several months (Lebret et al., 2012). One of these is the raphidophyte Gonyostomum semen, which forms nuisance algal blooms in freshwater environments across the world (Karosiene et al., 2014 Rengefors et al., 2012). Typically, microalgal species are noted only once they form nuisance blooms, when cell densities in monitoring samples are high enough to be detected and identified.ĭespite the methodological impediments and often lacking historical data, there are a few documented invasive microalgal species (Padisák et al., 2016). Thus, it has been difficult to obtain conclusive evidence showing that the microalga in question was not present in a specific habitat previously, or when it started becoming more abundant. Nevertheless, studies on microalgal invasions and expansions are still relatively few, and are hampered by methodological issues associated with the detection and identification of ephemeral and nonpathogenic microorganisms (Litchman, 2010). In freshwater systems, increased nutrient levels together with climatic changes are suggested to have increased cyanobacterial HABs (Michalak et al., 2013 Paerl & Otten, 2013). In the ocean, these HABs are mainly attributed to range expansion due to increased seawater temperatures and eutrophication (Gobler et al., 2017), as well as human-mediated dispersal through ballast water and aquaculture (Bolch & de Salas, 2007 Lilly et al., 2002). In recent decades there has been an increase in the report of harmful algal blooms (HABs) in freshwater and marine environments around the world (Anderson et al., 2002 Paerl & Otten, 2013). While most focus has been on multicellular animals and plants, especially in terms of conservation issues, microbial organisms undergo equivalent changes. The ever-increasing anthropogenic impact on the natural environment, including climate change, has increased scientific interest in these processes. Habitat range expansion and species invasions are important processes in determining species biogeographies and biodiversity patterns. This genetic signature suggests that the observed gene flow may be due to dispersal by autumn migratory birds, which act as dispersal vectors of resistant resting propagules that form at the end of the G. While we had expected a pattern of recent expansion northwards, the data demonstrated gene flow from the northeast/east towards the southwest/west. Despite significant genetic differentiation among lakes, we found only limited isolation-by-distance. Our data revealed a distinct population genetic structure, demonstrating a divide of western and eastern populations that probably represent different lineages. semen, which has a huge genome (32 Gbp), we faced particular challenges, but were nevertheless able to recover over 1000 single nucleotide polymorphisms at high coverage. semen using RAD (restriction-site-associated DNA) tag sequencing. The aim of the present study was to determine the genetic structure and dispersal pathways of G. The question of whether the species has expanded its habitat range or if it was already present in the lakes but was too rare to be detected remains unanswered. One such species is the nuisance microalga Gonyostomum semen (Raphidophyceae), which has increased in occurrence in northern Europe in recent decades. However, this research is challenging due to the ephemeral nature, small size and mostly low concentrations of microalgae in the environment. This is also true for harmful algal blooms, which have been reported to have increased in frequency. Species invasion and range expansion are currently under scrutiny due to increasing anthropogenic impact on the natural environment.
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