Background. One of the major systems we work on is Drosophila melanogaster which has served for decades as an important model for understanding local adaptation. Fly populations arrayed along latitudinal and altitudinal clines exhibit patterns of genetically based phenotypic differentiation in morphological and life-history traits consistent with local adaptation to temperate environments (Paaby et al.2014, Bergland et al. 2016, Machado et al. 2016). Genetically based phenotypic differentiation in fitness related traits also occurs among seasons. For instance, flies sampled in spring - the recent descendants of individuals that survived winter - tend to be more hardy whereas those sampled during fall - the descendants of those individuals that prospered during summer - tend to invest more resources into reproduction. Quantitative genetic variation in these stress tolerance and life-history traits is thus shaped over seasonal time scales (10-15 generations) and we can identify polymorphisms that vary through time and space (Bergland et al. 2014) and underlie local adaptation.
Current project - photoperiodism & thermoperiodism. Flies that survive winter often do so by entering a physiologically protective state called ‘diapause.’ As in other species, diapause in flies is cued by the perception of short days and cold temperatures (photo- and thermoperiodism, respectively). We are currently investigating the genetic and neurological basis of photoperiodism and thermoperiodism in D. melanogaster. This work is in collaboration with Paul Schmidt at UPenn.
Current project - identification of functional polymorphisms genome-wide. Our previous work has identified hundreds of polymorphisms that vary in frequency through time and space (Bergland et al. 2014, Bergland et al. 2016). We do not know the function of many of these polymorphisms. To ameliorate this, we are conducting cis-eQTL experiments in an experimental orchard we are building at Morven.
Current project - population genomics of Drosophila. The Bergland participates in several consortia, DrosRTEC and DrosEU, whose aim is to sample and resequence fly populations on multiple continents and over decadal time scales. Such efforts will provide valuable information to the broader community about the dynamic process of adaptation in the wild. These efforts are led by members of the Bergland lab, as well as many labs throughout the world. Our consortia are open to anyone and we are actively sampling flies and continuing our organization efforts. Please be in touch if you are interested in participating.