Mabel Fuentes MSc Candidate, Colautti Lab Genetic exploration of two invasive species to study rapid evolution and invasion genetics Classical genetics entails the study of spontaneous or introduced genomic mutations, analyzing the corresponding phenotypes, and then identifying the affected genes. Today's research is based on reverse genetics, which starts with the gene sequence and then explores its functions by analyzing the phenotype of an induced mutation. But how do we move from that specific phenotype to analyze fitness in a population?
Ecological genetics approach goes the other direction, observing the impact of a phenomenon in an ecosystem and analyzing community interactions, population dynamics, fitness, and observing a particular phenotype that may be of interest. There are not many studies that analyze the genes associated with a phenotype in the context of a natural community. In other words, how do we go from studying ecosystem diversity to genetic diversity? Invasive species provide the opportunity to study the expression of genes in populations subject to a changing environment. Since invasive species are known to adapt quickly and spread rapidly thus posing a threat to native ecosystems, more information on the genetic mechanisms of invasion can give us clues to how natural species can adapt to rapid changes, including under future climate change scenarios. My research provides evidence for the functional annotation of the draft genomes of Alliaria petiolata (garlic mustard) and Lythrum salicaria (purple loosestrife). These two plant species of Eurasian origin have successfully invaded and spread across North America. Each species has characteristics that make them valuable as a model for invasion. Alliaria petiolata belongs to the family Brassicaceae and dominates forest understories in absence of disturbance and produces glucosinolates and flavonoids as defensive chemicals that affect the growth of competitors. In contrast, L. salicaria belongs to the family Lythraceae, invades wetlands and has rapidly evolved differences in flowering time to adapt to differences in season length. Both species are highly prolific with the difference that L. salicaria is an obligate outcrossed, so populations maintain a higher level of genetic variation in comparison with A. petiolata which is known to have a comparatively higher rate of self fertilization. Using the draft genomes of both species as a reference, my research has focused on the assembly and analysis of the transcriptome (RNA) of samples from different conditions. For A. petiolata, RNA was extracted from leaf and root samples from individual plants subjected to mechanical injury and exposed to jasmonic acid to mimic herbivory. From these data candidate genes could be identified as potentially having a role in defense metabolic pathways. For L. salicaria, RNA was extracted from floral tissue of early and late flowering plants to predict candidate genes associated with flowering time. Using this new information, the draft genome annotations assemblies can be further improved, which will enable future molecular and functional genomic studies to investigate the genetic mechanisms of invasion and rapid adaptation in novel environments. Comments are closed.
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