Evolution of a fatty acyl-CoA elongase underlies desert adaptation in .

Traits that allow species to survive in extreme environments such as hot-arid deserts have independently evolved in multiple taxa. However, the genetic and evolutionary mechanisms underlying these traits have thus far not been elucidated. Here, we show that , a desert-adapted fruit fly species, has evolved high desiccation resistance by producing long-chain methyl-branched cuticular hydrocarbons (mbCHCs) that contribute to a cuticular lipid layer reducing water loss.

Desiccation resistance differences in species can be largely explained by variations in cuticular hydrocarbons.

Maintaining water balance is a universal challenge for organisms living in terrestrial environments, especially for insects, which have essential roles in our ecosystem. Although the high surface area to volume ratio in insects makes them vulnerable to water loss, insects have evolved different levels of desiccation resistance to adapt to diverse environments. To withstand desiccation, insects use a lipid layer called cuticular hydrocarbons (CHCs) to reduce water evaporation from the body surface.

Repression precedes independent evolutionary gains of a highly specific gene expression pattern.

Highly specific expression patterns can be caused by the overlapping activities of activator and repressor sequences in enhancers. However, few studies illuminate how these sequences evolve in the origin of new enhancers. Here, we show that expression of the bond gene in the semicircular wall epithelium (swe) of the Drosophila melanogaster male ejaculatory bulb (EB) is controlled by an enhancer consisting of an activator region that requires Abdominal-B driving expression in the entire EB and a repressor region that restricts this expression to the EB swe.

Sociosexual environments can drive the evolution of plasticity in mating behavior.

How do male mating behaviors evolve in response to a competitive social environment? Using an experimental evolution approach, Dore et al. demonstrated that sociosexual environments can lead to the evolution of novel plastic male mating behaviors in Drosophila melanogaster, with both mating latency and mating duration extended in male-biased populations after exposure to male rivals.

Antagonistic pleiotropy can promote adaptation to patchy environments.

How do gene variants with opposing effects on fitness in juvenile and adult insects perform in different ecological settings? Marden et al. used alleles of two antagonistic genes involved in metabolism and oxygen sensing in the Glanville fritillary butterfly as a model to demonstrate how these genes can antagonistically affect larval development and the adaptation of adults to different landscapes. This paper provides a case study for understanding how antagonistic pleiotropy can contribute to species adaption in patchy environments.

The evolution of insect metallothioneins.

Metallothioneins (MTs) are a family of cysteine-rich metal-binding proteins that are important in the chelating and detoxification of toxic heavy metals. Until now, the short length and the low sequence complexity of MTs have hindered the inference of robust phylogenies, hampering the study of their evolution. To address this longstanding question, we applied an iterative BLAST search pipeline that allowed us to build a unique dataset of more than 300 MT sequences in insects.

Superficially Similar Adaptation Within One Species Exhibits Similar Morphological Specialization but Different Physiological Regulations and Origins.

Animals have developed numerous strategies to contend with environmental pressures. We observed that the same adaptation strategy may be used repeatedly by one species in response to a certain environmental challenge. The ladybird displays thermal phenotypic plasticity at different developmental stages.