Diurnal and developmental differences in gene expression between adult dispersing and flightless morphs of the wing polymorphic cricket, Gryllus firmus: Implications for life-history evolution. (May 2018)

• Record Type: Journal Article
• Authors: Zera, Anthony J.; Vellichirammal, Neetha Nanoth; Brisson, Jennifer A.
• Is Part Of: Journal of insect physiology. Volume 107(2018)
• Page Start: 233
• Page End: 243
• Publication Date: 2018-05
• Subjects: Wing polymorphism -- Morph-specific gene expression -- Circadian rhythm -- Life history -- Insulin-like peptide -- Juvenile hormone; Insects -- Physiology -- Periodicals; Insectes -- Physiologie -- Périodiques; Insects -- Physiology; Periodicals; 571.157
• DOI: 10.1016/j.jinsphys.2018.04.003
• Languages: English
• ISSNs: 0022-1910

Abstract

Graphical abstract: Highlights: G. firmus morphs differ chronically in hormonal and metabolic gene expression. LW(f) females exhibit greater diel change in gene expression than SW females. Diel gene expression co-varies with a morph-specific JH titer circadian rhythm. In G. firmus, JH may regulate genes involved in morph-specific cyclic diel activity. ILP and ECD may regulate chronic morph differences in reproduction and metabolism. Abstract: The functional basis of life history adaptation is a key topic of research in life history evolution. Studies of wing-polymorphism in the cricket Gryllus firmus have played a prominent role in this field. However, prior in-depth investigations of morph specialization have primarily focused on a single hormone, juvenile hormone, and a single aspect of intermediary metabolism, the fatty-acid biosynthetic component of lipid metabolism. Moreover, the role of diurnal variation in life history adaptation in G. firmus has been understudied, as is the case for organisms in general. Here, we identify genes whose expression differs consistently between the morphs independent of time-of-day during early adulthood, as well as genes that exhibit a strong pattern of morph-specific diurnal expression. We find strong, consistent, morph-specific differences in the expression of genes involved in endocrine regulation, carbohydrate and lipid metabolism, and immunity – in particular, in the expression of an insulin-like-peptide precursor gene and genes involved in triglyceride production. We also find that the flight-capable morph exhibited a substantially greater number of genes exhibiting diurnal change in gene expression compared with the flightless morph, correlated with the greater circadian change in the hemolymph juvenile titer in the dispersing morph. In fact, diurnal differences in expression within the dispersing morph at different times of the day were significantly greater in magnitude than differences between dispersing and flightless morphs at the same time-of-day. These results provide important baseline information regarding the potential role of variable gene expression on life history specialization in morphs of G. firmus, and the first information on genetically-variable, diurnal change in gene expression, associated with a key life history polymorphism. These results also suggest the existence of prominent morph-specific circadian differences in gene expression in G. firmus, possibly caused by the morph-specific circadian rhythm in the juvenile hormone titer.