Adaptation to a novel predator inDrosophila melanogaster: How well are we able to predict evolutionary responses?

Abstract

Evolutionary theory is sufficiently well developed to allow for short-term prediction of 2 evolutionary trajectories. In addition to the presence of heritable variation, prediction requires knowledge of the form of natural selection on relevant traits. While many studies 4 estimate the form of natural selection, few examine the degree to which traits evolve in the predicted direction. In this study we examine the form of natural selection imposed 6 by mantid predation on wing size and shape in the fruitfly, Drosophila melanogaster.We then evolve populations of D. melanogaster under predation pressure, and examine 8 the extent to which wing size and shape have responded in the predicted direction. We demonstrate that wing form partially evolves along the predicted vector from selection, 10 more so than for control lineages. Furthermore, we re-examined phenotypic selection after ∼30 generations of experimental evolution. We observed that the magnitude of selection 12 on wing size and shape was diminished in populations evolving with mantid predators, while the direction of the selection vector differed from that of the ancestral population 14 for shape. We discuss these findings in the context of the predictability of evolutionary responses, and the need for fully multivariate approaches. 16 20 52 lar morphologies in response to predation for several fish species (O'Steen et al., 2002; Langerhans et al., 2004; Dayton et al., 2005; Langerhans and Makowicz, 2009) suggests 54 a strong and consistent regime of selection. Similar results have also been observed for shell morphology among populations of snails in apparent response to predation (Auld 56 and Relyea, 2011; DeWitt et al., 2000 DeWitt et al., , 1999. When selection is relaxed by the removal of predators, even for just a few generations, trait means have been shown to change 58 dramatically (Reznick et al., 1990(Reznick et al., , 1997 Reznick and Ghalambor, 2005), consistent with predation maintaining trait values in the face of potentially antagonistic selective effects. 60The prevalence of diverse, and often costly, traits that mediate interactions with predators suggests that predation profoundly influences fitness. 62In this study we investigate how multivariate wing form of Drosophila melanogaster evolves along the trajectory predicted by initial estimates of phenotypic selection in re-64 sponse to predation by mantid nymphs (Tenodera aridifolia sinensis). This novel experimental system has a rather rare (but see Svensson and Friberg, 2007; Kuchta and 66 Svensson, 2014) and useful attribute in which the wings are not consumed when the fly is captured by its mantid predator ( figure 1A). This allows us to collect the wings from 68 both surviving and consumed flies to estimate the form and magnitude of natural selection 5 on both size and shape. Multivariate shape provides a robust framework for evaluating 70 evolutionary predictions. While size only varies along one axis, a high dimensional representation of shape is less likely to change in the pre...

Does increased heat resistance result in higher susceptibility to predation? A test using Drosophila melanogaster selection and hardening

“…Adaptive responses to predation risk may be modified by other stressors, as environmental stress can increase the costs (Hanazato, ; Huber et al ., ; Teplitsky et al ., ) or decrease investment in defences (Barry, ; Relyea, ; Teplitsky et al ., ). A few studies have tested for heritability in predator avoidance traits and usually found substantial genetic variation (Grant & Mettler, ; Stirling et al ., ; Relyea, ; Brokordt et al ., ; DeNieu et al ., ; but see Blumstein et al ., ). Whether predator avoidance is genetically correlated with other types of stress resistance is largely unknown (but see Jansen et al ., ).…”