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Synopsis Flight muscle histolysis is a widespread strategy used by insects to break down functional flight muscle and modulate the energetic costs associated with flight muscle use and maintenance. The variable field cricket, Gryllus lineaticeps, undergoes histolysis during their transition between dispersal flight and reproduction. Despite the importance of histolysis on insect reproduction and fitness, the molecular mechanisms driving this flight muscle breakdown are not well understood. Here, we show that beclin-mediated autophagy, a conserved lysosomal-dependent degradation process, drives breakdown of dorsal longitudinal flight muscle in female flight-capable G. lineaticeps. We found that female G. lineaticeps activate autophagy in their dorsal longitudinal flight muscle (DLM), but to a greater extent than the neighboring dorsoventral flight muscle (DVM) during histolysis. RNA interference knockdown of beclin, a gene that encodes a critical autophagy initiation protein, delayed DLM histolysis, but did not affect DVM histolysis. This suggests that crickets selectively activate autophagy to break down the DLMs, while maintaining DVM function for other fitness-relevant activities such as walking. Overall, we confirmed that autophagy is a critical pathway used to remodel flight muscle cells during flight muscle histolysis, providing novel insights into the mechanisms underlying a major life history transition between dispersal and reproduction. 

Synopsis The evolution of flight in an early winged insect ancestral lineage is recognized as a key adaptation explaining the unparalleled success and diversification of insects. Subsequent transitions and modifications to flight machinery, including secondary reductions and losses, also play a central role in shaping the impacts of insects on broadscale geographic and ecological processes and patterns in the present and future. Given the importance of insect flight, there has been a centuries-long history of research and debate on the evolutionary origins and biological mechanisms of flight. Here, we revisit this history from an interdisciplinary perspective, discussing recent discoveries regarding the developmental origins, physiology, biomechanics, and neurobiology and sensory control of flight in a diverse set of insect models. We also identify major outstanding questions yet to be addressed and provide recommendations for overcoming current methodological challenges faced when studying insect flight, which will allow the field to continue to move forward in new and exciting directions. By integrating mechanistic work into ecological and evolutionary contexts, we hope that this synthesis promotes and stimulates new interdisciplinary research efforts necessary to close the many existing gaps about the causes and consequences of insect flight evolution. 

Abstract Tropicalization is a term used to describe the transformation of temperate ecosystems by poleward‐moving tropical organisms in response to warming temperatures. In North America, decreases in the frequency and intensity of extreme winter cold events are expected to allow the poleward range expansion of many cold‐sensitive tropical organisms, sometimes at the expense of temperate organisms. Although ecologists have long noted the critical ecological role of winter cold temperature extremes in tropical–temperate transition zones, the ecological effects of extreme cold events have been understudied, and the influence of warming winter temperatures has too often been left out of climate change vulnerability assessments. Here, we examine the influence of extreme cold events on the northward range limits of a diverse group of tropical organisms, including terrestrial plants, coastal wetland plants, coastal fishes, sea turtles, terrestrial reptiles, amphibians, manatees, and insects. For these organisms, extreme cold events can lead to major physiological damage or landscape‐scale mass mortality. Conversely, the absence of extreme cold events can foster population growth, range expansion, and ecological regime shifts. We discuss the effects of warming winters on species and ecosystems in tropical–temperate transition zones. In the 21st century, climate change‐induced decreases in the frequency and intensity of extreme cold events are expected to facilitate the poleward range expansion of many tropical species. Our review highlights critical knowledge gaps for advancing understanding of the ecological implications of the tropicalization of temperate ecosystems in North America.