Tropical high-altitude insects show limited capacity to handle high temperatures

Abstract

Growing summer season, increased anthropogenic activities poses a continual challenge to resident species. Ectotherms like insects are especially vulnerable to rapid climatic changes. High-altitude tropical insect populations have been rarely examined for their responses to high-temperature. We exposed a tropical highland out-bred population of Drosophila melanogaster from the Himalayas to growing summer conditions in outdoor mesocosm units. Population response to thermal changes was tracked over ninety days at phenotypic and genotypic level. Whole genomic resequencing data suggested a clear seasonal allelic shift. Interestingly, the general heat responsive genes were missing in the summer due to monsoon allele shift; an atypical response noted for high-altitude populations. Instead, candidates involved in kinases and phosphorylation emerged as key players. Heat-knockdown time decreased over time indicating a limited ability to handle increasing temperature. Merging data from both allelic shifts and heat-knockdown time indicated a limited capacity for high-altitude insects in handling climate warming.

Host–Parasitoid Phenology, Distribution, and Biological Control under Climate Change

“…Tropical ectotherms will be most adversely affected by climate change since their physiological optimum temperature is much closer to those at higher altitudes [77][78][79]. This implies that the sooner a certain degree of temperature is reached in this area, the higher the risk of extinction, since species will have less time to disperse naturally to track their physiological optimum climate.…”

Clinal variation as a tool to understand climate change

“…Little is known about the genetic bases for clines in Africa and Asia. It would be insightful to investigate the genetic and genomic basis of clinal variation observed in Africa and Asia ( Rajpurohit et al, 2022 ) and compare these with temperate counterparts. Perhaps the complex network of biotic interactions available in tropical and sub-tropical Asia and Africa could mean populations have options for relocation, alternate host/food sources and thus lowered vulnerability to extinction.…”