Heritable variation in courtship patterns in Drosophila melanogaster.
Bottom Line: We found heritable variation along the expected trajectory for courtship behaviors, including the tendency to initiate courtship and rate of progression through courtship, suggesting a genetic basis to male modulation of courtship behavior based on feedback from unrelated, outbred, and genetically identical females.We assessed the genetic basis of variation of the transition with the greatest heritability--from copulation to no engagement with the female--and identified variants in Serrate and Furin 1 as well as many other polymorphisms on the chromosome 3R associated with this transition.Our findings suggest that courtship is a highly dynamic behavior with both social and genetic inputs, and that males may play an important role in courtship initiation and duration.
Affiliation: Department of Biological Sciences, W. M. Keck Center for Behavioral Biology and Program in Genetics, North Carolina State University, Raleigh, North Carolina 27695-7614.Show MeSH
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Mentions: A subset of males never initiated any interaction with females during the courtship assays, failing to score greater than “2” (movement) on the MMP scale at any point of observation over the duration of the assay. To explore this further, we analyzed the incidence of noninitiating males by line (Figure 2A). We fit distributions to the data and found that a Normal 2 mixture model fits better than an exponential model (Akaike information criterion = −950.75 and −666.56, respectively). The presence of two normal curves suggests that there are two distinct groups that differ in initiation. That is, in most lines, all males initiated courtship with females, but in a few lines roughly 15% of males never initiated. We then compared the overall MMP score for these lines including or excluding the noninitiating males (Figure 2B). Somewhat surprisingly, we found that noninitiating males are found exclusively in lines with a moderate- to high-MMP score (140−210), but are almost entirely absent in lines with low MMP scores (under 140). To test whether these lines are generally impaired for locomotion, we correlated the proportion of males not initiating per line with previously assayed startle response data (Jordan et al. 2007). We found no relationship between the two (Figure S1). Thus, it is not the case that low MMP lines often do not initiate courtship, nor is it the case that noninitiating males are physically less able to court. Instead, males from moderate MMP lines may possess a threshold to initiate courtship, and once that threshold is passed, they are typically successful at copulating, whereas males from low MMP lines always initiate courtship behavior but often are not successful at copulating within the timeframe of this assay.
Affiliation: Department of Biological Sciences, W. M. Keck Center for Behavioral Biology and Program in Genetics, North Carolina State University, Raleigh, North Carolina 27695-7614.