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Crawford, Lindsay A.; Koscinski, Daria; Keyghobadi, Nusha 2012-09-18 Despite much discussion of the importance of quantifying and reporting genotyping error in molecular studies, it is still not standard practice in the literature. This is particularly a concern for amplified fragment length polymorphism (AFLP) studies, where differences in laboratory, peak-calling and locus-selection protocols can generate data sets varying widely in genotyping error rate, the number of loci used and potentially estimates of genetic diversity or differentiation. In our experience, papers rarely provide adequate information on AFLP reproducibility, making meaningful comparisons among studies difficult. To quantify the extent of this problem, we reviewed the current molecular ecology literature (470 recent AFLP articles) to determine the proportion of studies that report an error rate and follow established guidelines for assessing error. Fifty-four per cent of recent articles do not report any assessment of data set reproducibility. Of those studies that do claim to have assessed reproducibility, the majority (~90%) either do not report a specific error rate or do not provide sufficient details to allow the reader to judge whether error was assessed correctly. Even of the papers that do report an error rate and provide details, many (≥23%) do not follow recommended standards for quantifying error. These issues also exist for other marker types such as microsatellites, and next-generation sequencing techniques, particularly those which use restriction enzymes for fragment generation. Therefore, we urge all researchers conducting genotyping studies to estimate and more transparently report genotyping error using existing guidelines and encourage journals to enforce stricter standards for the publication of genotyping studies.
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Maxwell, Sheri A.; Thistlewood, Howard M. A.; Keyghobadi, Nusha 2013-11-01 1. Population connectivity and movement are key ecological parameters influencing the impact of pests, and are important considerations in control strategies. For many insects, these parameters are difficult to assess directly, although they may be assessed indirectly using population genetic data. 2. We used microsatellite markers to examine population genetic structure of the western cherry fruit fly, the main pest of cherry crops in western North America, in British Columbia, Canada, and make inferences about connectivity and potential for movement among populations. 3. Comparing populations from four geographical regions (separated by up to approximately 400 km), we found significant genetic differentiation both among and within regions. Using populations as the units of analysis, we observed significant isolation by distance (IBD) at larger spatial scales but not below approximately 20 km. By contrast, using individual flies as the units of analysis, we found significant IBD at scales as small as < 100 m. We saw no evidence of genetic differentiation among populations sampled from different species/varieties of plants. 4. Our results suggest that the movement of individual flies is limited, although high levels of gene flow are maintained at scales of up to 20 km, possibly through combined effects of stepping-stone gene flow and large population sizes.
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Talbot, Benoit; Vonhof, Maarten J.; Broders, Hugh G.; Fenton, Brock; Keyghobadi, Nusha 2018-03-07 Parasite-host relationships create strong selection pressures that can lead to adaptation and increasing specialization of parasites to their hosts. Even in relatively loose host-parasite relationships, such as between generalist ectoparasites and their hosts, we may observe some degree of specialization of parasite populations to one of the multiple potential hosts. Salivary proteins are used by blood-feeding ectoparasites to prevent hemostasis in the host and maximize energy intake. We investigated the influence of association with specific host species on allele frequencies of salivary protein genes in Cimex adjunctus, a generalist blood-feeding ectoparasite of bats in North America. We analysed two salivary protein genes: an apyrase, which hydrolyses ATP at the feeding site and thus inhibits platelet aggregation, and a nitrophorin, which brings nitrous oxide to the feeding site, inhibiting platelet aggregation and vasoconstriction. We observed more variation at both salivary protein genes among parasite populations associated with different host species than among populations from different spatial locations associated with the same host species. The variation in salivary protein genes among populations on different host species was also greater than expected under a neutral scenario of genetic drift and gene flow. Finally, host species was an important predictor of allelic divergence in genotypes of individual C. adjunctus at both salivary protein genes. Our results suggest differing selection pressures on these two salivary protein genes in C. adjunctus depending on the host species.

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