Environmental and genetic control of cold tolerance in the Glanville fritillary butterfly

Abstract

Thermal tolerance has a major effect on individual fitness and species distributions and can be determined by genetic variation and phenotypic plasticity. We investigate the effects of developmental and adult thermal conditions on cold tolerance, measured as chill coma recovery (CCR) time, during the early and late adult stage in the Glanville fritillary butterfly. We also investigate the genetic basis of cold tolerance by associating CCR variation with polymorphisms in candidate genes that have a known role in insect physiology. Our results demonstrate that a cooler developmental temperature leads to reduced cold tolerance in the early adult stage, whereas cooler conditions during the adult stage lead to increased cold tolerance. This suggests that adult acclimation, but not developmental plasticity, of adult cold tolerance is adaptive. This could be explained by the ecological conditions the Glanville fritillary experiences in the field, where temperature during early summer, but not spring, is predictive of thermal conditions during the butterfly's flight season. In addition, an amino acid polymorphism (Ala‐Glu) in the gene flightin, which has a known function in insect flight and locomotion, was associated with CCR. These amino acids have distinct biochemical properties and may thus affect protein function and/or structure. To our knowledge, our study is the first to link genetic variation in flightin to cold tolerance, or thermal adaptation in general.

Beyond thermal melanism: association of wing melanization with fitness and flight behaviour in a butterfly

“…However, as the cold-exposed individuals were unintentionally released into the enclosure at an older age and on warmer days, these results should be interpreted with caution. Interestingly, a previous study on the same system showed that cooler developmental conditions led to reduced cold tolerance in adults ( de Jong & Saastamoinen, 2018 ). However, we cannot say whether the potentially altered thermoregulation behaviour found here stems from a physical constraint (i.e.…”

Improved chromosome-level genome assembly of the Glanville fritillary butterfly (Melitaea cinxia) integrating Pacific Biosciences long reads and a high-density linkage map

“…Experimental manipulations under more controlled conditions are also possible owing to the small size, high fecundity, and relatively short generation time of the species. Consequently, our understanding of the species includes knowledge of life history variation across development stages [ 4 , 5 ], dispersal dynamics [ 6 , 7 ], species interactions with host plants and parasitoids [ 8–12 ], and stress tolerance [ 13 , 14 ]. During the past decade, the system has also been used to study genetic and evolutionary processes, such as identifying candidate genes underlying variation and evolution of dispersal in fragmented habitats [ 15 ] and host plant preference [ 16 ], and assessing allelic variation and its dynamics in space and time [ 17–19 ].…”

Effects of adult temperature on gene expression in a butterfly: identifying pathways associated with thermal acclimation

“…To gain a more complete understanding of the prospects and limitations of beneficial acclimation in buffering effects of temperature variation, a better understanding of the underlying mechanisms is important. At the mechanistic level, phenotypic plasticity in thermal tolerance may be caused by environmental effects on gene and protein expression or biosynthetic pathways [21, 22], but currently our understanding of the underlying mechanisms is very limited [15, 23–27]. Recent developments in sequencing techniques though have opened up new opportunities to address this issue, enabling unbiased approaches by targeting entire genomes and transcriptomes [15, 28].…”