Female prereproductive coloration reduces mating harassment in damselflies

Abstract

Conspicuous female coloration can evolve through male mate choice or via female-female competition thereby increasing female mating success. However, when mating is not beneficial, such as in pre-reproductive females, selection should favor cryptic rather than conspicuous coloration to avoid male detection and the associated harassment. Nevertheless, conspicuous female coloration occurs in many prereproductive animals, and its evolution remains an enigma. Here, I studied conspicuous female coloration in Agriocnemis femina damselflies, in which the conspicuous red color of the immature females changes to a less conspicuous green approximately a week after their emergence. I measured body size, weight, and egg numbers of the female morphs and found that red females are smaller and lighter and do not carry developed eggs. Finally, I calculated the occurrence frequency and mating frequency of red and green females in several populations over a three-year period. The results demonstrate that red females mated less frequently than green females even when red females were the abundant morph in the populations. I concluded that conspicuous female coloration is likely to function as a warning signal of sexual unprofitability, thereby reducing sexual harassment for females and unprofitable mating for males.

Different stress from parasites and mate choice in two female morphs of the blue-tailed damselfly

“…In previous studies, female morphs of some species have been shown to differ in clutch size (Bots et al 2009(Bots et al , 2010bBouton et al 2011;Sánchez-Guillén et al 2017;Khan 2020) and egg size (Takahashi and Watanabe 2010b;Takahashi and Kawata 2013), but in other species there was no difference (Iserbyt et al 2013). In our study, we found a similar growth of larvae born from andromorph and gynomorph B-females.…”

Sexual and developmental variations of ecto-parasitism in damselflies

“…These species are widely distributed in South Asia, South East Asia, and Australia [50][51]. They are commonly found in grasslands associated with ponds, lakes, marshes and in paddy fields, and cohabit with Ceriagrion coromandelianum, A. kalinga A. lacteola, and Orhterum sabina [49]. The males of A. femina are differentiated from other sympatric species by the size and shape of anal appendages (Epiproct larger than cerci) [50;Fig 1c].…”

“…Agriocnemis femina is a common damselfly in the northeastern region of Bangladesh [53,54], while A. pygmaea is commonly found in central and southwestern region of Bangladesh [49,55].…”

“…We then measured body weight, total body length, abdomen area and thorax area of damselflies. First, we placed the damselflies on an absorbent paper for exactly two minutes to evaporate the ethanol [49] and then weighed the damselfly on a balance (Shimadzu ATY 224 electronic balance, Shimadzu Corporation, Japan). Next, we positioned the damselflies laterally along with a scale and took photographs.…”

“…We measured total body length, and abdomen length, width of the fifth abdominal segment, length and width of thorax of the damselflies from the digital photographs using the ImageJ software [64]. Later, we calculated abdomen area and thorax area using equation (area = 1/2 × width × π × length) [49].…”