Phenotypic plasticity in sex pheromone production in Bicyclus anynana butterflies.

Emilie Dion,Antónia Monteiro,Joanne Y Yew

doi:10.1038/srep39002

Abstract

Phenotypic plasticity refers to the environmental control of phenotypes. Cues experienced during development (developmental plasticity) or during adulthood (acclimatization) can both affect adult phenotypes. Phenotypic plasticity has been described in many traits but examples of developmental plasticity in physiological traits, in particular, remain scarce. We examined developmental plasticity and acclimatization in pheromone production in the butterfly Bicyclus anynana in response to rearing temperature. B. anynana lives in the African tropics where warm rearing temperatures of the wet season produce active males that court and females that choose, whereas cooler temperatures of the dry season lead to choosy less active males and courting females. We hypothesized that if male pheromone production is costly, it should be reduced in the dry season form. After describing the ultrastructure of pheromone producing cells, we showed that dry season males produced significantly less sex pheromones than wet season males, partly due to acclimatization and partly due to developmental plasticity. Variation in levels of one of the compounds is associated with differential regulation of a pheromone biosynthetic enzyme gene. This plasticity might be an adaptation to minimize pheromone production costs during the stressful dry season.

Highlights

Phenotypic plasticity is the ability of a genotype to produce different phenotypes in response to environmental cues such as diet, photoperiod, or temperature[1,2]
Developmental plasticity occurs in the form of a seasonal polyphenism for some butterfly species such as Bicyclus anynana, where two or more distinct phenotypes, without intermediates, are produced in response to environmental cues experienced during development
Temperatures experienced during larval and pupal stages lead to the development of two distinct adult phenotypes adapted to the two main seasons: the wet season (WS) form and the dry season (DS) form[14], which differ in morphology, behavior, and physiology

Summary

Introduction

Phenotypic plasticity is the ability of a genotype to produce different phenotypes in response to environmental cues such as diet, photoperiod, or temperature[1,2]. Developmental plasticity occurs in the form of a seasonal polyphenism for some butterfly species such as Bicyclus anynana, where two or more distinct phenotypes, without intermediates, are produced in response to environmental cues experienced during development. In WS males, in particular, these eyespot centers are larger and conspicuous, compared to the duller and smaller ones of the DS male[16] These ornaments vary in size and brightness, and are correlated with the sex role reversal[16,19]. In warm conditions, when food availability is higher, both seasonal forms use energetic reserves at a higher rate, and become more active They court more, leading to faster mating[20]. MSP2 titers and its relative ratio to other MSP components are indicators of male age and inbreeding status[28,29]

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