Muscle potentials in insect flight muscles decrease in amplitude and increase in duration with decreasing temperature. Amplitudes fall to zero at distinct temperatures, which are characteristic for different species. Chill-coma temperature is thus denned here as the critical temperature below which flight muscles cannot be activated. Chill-coma temperatures were 2°C in the species of butterflies measured and −2 to 0°C in the moths. In the species of Hymenoptera, Coleoptera and Diptera measured, chill-coma temperatures ranged from 3 to 14°C. The rate of decline of muscle potential amplitudes with decreasing temperature was different for different species. Rates were smaller over most of the temperature range for species that warm up from low environmental temperatures to reach thoracic temperatures necessary for flight. Amplitudes decreased faster at higher thoracic temperatures in species that start shivering only at higher ambient temperatures. Temperature has a similar effect on durations of muscle potentials in different species. Between 25 and 15°C, durations increased by 100% in all species. The results suggest that cold-adaptation is not strongly related to chill-coma temperature but is strongly related to the rate of decline of muscle potential amplitudes.
In the field: an interview with Martha Muñoz
Martha Muñoz is an Assistant Professor at Yale University, investigating the evolutionary biology of anole lizards and lungless salamanders. In our new Conversation, she talks about her fieldwork in Indonesia, Costa Rica, the Dominican Republic and the Appalachian Mountains, including a death-defying dash to the top of a mountain through an approaching hurricane.
Call for new preLighters
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preLights is the preprint highlighting community supported by The Company of Biologists. At the heart of preLights are our preLighters: early-career researchers who select and write about interesting new preprints for the research community. We are currently looking for new preLighters to join our team. Find out more and apply here.
Graham Scott in conversation with Big Biology
Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. In this JEB-sponsored episode, they discuss the concept of symmorphosis and the evolution of the oxygen cascade.
Trap-jaw ants coordinate tendon and exoskeleton for perfect mandible arc
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Trap-jaw ants run the risk of tearing themselves apart when they fire off their mandibles, but Greg Sutton & co have discovered that the ants simultaneously push and pull the mandibles using energy stored in a head tendon and their exoskeleton to drive the jaws in a perfect arc.
Hearing without a tympanic ear
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In their Review, Grace Capshaw, Jakob Christensen-Dalsgaard and Catherine Carr explore the mechanisms of hearing in extant atympanate vertebrates and the implications for the early evolution of tympanate hearing.
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