http://cfs.nrcan.gc.ca/authors/read/22917?format=title Publications by R. Ahumada en-ca 2012-10-29 06:24:39 MST 2012-10-29 06:24:39 MST webmaster@nofc.cfs.nrcan.gc.ca http://cfs.nrcan.gc.ca/publications?id=34166 Understanding the evolutionary histories of invasive species is critical to adopt appropriate management strategies, but this process can be exceedingly complex to unravel. As illustrated in this study of the worldwide invasion of the woodwasp Sirex noctilio, population genetic analyses using coalescent-based scenario testing together with Bayesian clustering and historical records provide opportunities to address this problem. The pest spread from its native Eurasian range to the Southern Hemisphere in the 1900s and recently to Northern America, where it poses economic and potentially ecological threats to planted and native Pinus spp. To investigate the origins and pathways of invasion, samples from five continents were analysed using microsatellite and sequence data. The results of clustering analysis and scenario testing suggest that the invasion history is much more complex than previously believed, with most of the populations being admixtures resulting from independent introductions from Europe and subsequent spread among the invaded areas. Clustering analyses revealed two major source gene pools, one of which the scenario testing suggests is an as yet unsampled source. Results also shed light on the microevolutionary processes occurring during introductions, and showed that only few specimens gave rise to some of the populations. Analyses of microsatellites using clustering and scenario testing considered against historical data drastically altered our understanding of the invasion history of S. noctilio and will have important implications for the strategies employed to fight its spread. This study illustrates the value of combining clustering and ABC methods in a comprehensive framework to dissect the complex patterns of spread of global invaders. Mon, 29 Oct 2012 http://cfs.nrcan.gc.ca/publications?id=34166 http://cfs.nrcan.gc.ca/publications?id=32925 The woodwasp Sirex noctilio, together with its mutualistic fungal symbiont Amylostereum areolatum, is the most damaging invasive pest of Pinus spp. in the Southern Hemisphere.The nematode Deladenus sir icidicola parasitizes Sirex noctilio larvae and is the most effective biological control agent against this woodwasp. Nothing is known regarding the genetic diversity of D. siricidicola, even though such knowl edge would be invaluable in improving sustainable biological control programs. Theaimof this study was to develop microsatellite markers to study the genetic diversity of D. siricidicola populations. Microsatel lite enrichment was performed using Fast Isolation by AFLP of Sequences Containing repeats (FIASCO) and fragments were then sequenced using 454 GS-FLX pyrosequencing. From the 1.2 megabases of sequence data, 166 microsatellite containing contigs were identified. Twenty-six primer pairs were designed using the web-based program Primer3 and screened for polymorphism in populations of the nematode from different sources in the Southern Hemisphere. Seventeen primers amplified microsatellite-containing loci of interest. No length polymorphism was present in any of the microsatellite repeats in these populations. Regions flanking the microsatellites also showed no polymorphism,except for one transition observed in an Argentinean strain for locus Ds316. Twelve of the loci showed polymorphism between the Southern Hemisphere and Canadian sources of D. siricidicola. The lack of diversity in Southern Hemisphere populations of D. siricidicola couldaffectthe abilityof this nematode to adapt to different environments and host types where it is used in biological control programs, and should thus be considered as a factor in future control strategies and research projects. Mon, 28 Nov 2011 http://cfs.nrcan.gc.ca/publications?id=32925