Quantitative Trait Loci Associated with Photoperiodic Response and Stage of Diapause in the Pitcher-Plant Mosquito, Wyeomyia smithii

Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, Oregon 97403-5289, USA.
Genetics (Impact Factor: 5.96). 06/2007; 176(1):391-402. DOI: 10.1534/genetics.106.068726
Source: PubMed


A wide variety of temperate animals rely on length of day (photoperiodism) to anticipate and prepare for changing seasons by regulating the timing of development, reproduction, dormancy, and migration. Although the molecular basis of circadian rhythms regulating daily activities is well defined, the molecular basis for the photoperiodic regulation of seasonal activities is largely unknown. We use geographic variation in the photoperiodic control of diapause in the pitcher-plant mosquito Wyeomyia smithii to create the first QTL map of photoperiodism in any animal. For critical photoperiod (CPP), we detect QTL that are unique, a QTL that is sex linked, QTL that overlap with QTL for stage of diapause (SOD), and a QTL that interacts epistatically with the circadian rhythm gene, timeless. Results presented here confirm earlier studies concluding that CPP is under directional selection over the climatic gradient of North America and that the evolution of CPP is genetically correlated with SOD. Despite epistasis between timeless and a QTL for CPP, timeless is not located within any detectable QTL, indicating that it plays an ancillary role in the evolution of photoperiodism in W. smithii. Finally, we highlight one region of the genome that includes loci contributing to CPP, SOD, and hormonal regulation of development.

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Available from: Derrick K Mathias, Jul 29, 2014
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    • "polygenic, epistasis) or genomic architecture (e.g. chromosomal rearrangements), have confounded the identification of genes underlying variation in diapause timing (Tauber et al., 1977; Feder et al., 2002; Bradshaw et al., 2005; Mathias et al., 2007; Emerson et al., 2010; Wadsworth et al., 2015). Despite these difficulties, genes involved in the transitions of diapause phases have been identified. "
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    • "Behavioural and physiological, especially endocrinological , changes associated with diapause development have been intensively studied in several species during the last 100 years (eg Tauber et al., 1986; de Kort, 1990; Denlinger, 2002). However, the genetic and molecular mechanisms underpinning diapause development are less well known (eg Mathias et al., 2007; MacRae, 2010; Ragland et al., 2011; Schmidt, 2011; Fabian et al., 2012). For instance, the underlying molecular machinery that senses photoperiodic changes and integrates and conveys this information to downstream endocrinological elements remains poorly understood (Sim & Denlinger, 2008). "
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    • "However, most Drosophila studies focus on the ability to enter diapause as a binary response and do not address whether the identified loci are responsible for change in diapause timing and synchronization with seasonal environments. In contrast, the evolution of diapause timing has been emphasised in moths, butterflies , and pitcher plant mosquitoes, leading to clearly identified quantitative trait loci (QTL) (Dopman et al., 2005; Mathias et al., 2007; Kunte et al., 2011). Yet, the identity of the causal loci in these genomic regions and how allelic variation leads to altered physiological pathways and shifts in seasonal timing in nature all remain as outstanding questions. "
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