Sexual selection is influenced by both developmental and adult environments

Abstract

Sexual selection is often assumed to be strong and consistent, yet increasing research shows it can fluctuate over space and time.Few experimental studies have examined changes in sexual selection in response to natural environmental variation. Here, we use a difference in resource quality to test for the influence of past environmental conditions and current environmental conditions on male and female mate choice and resulting selection gradients for leaf-footed cactus bugs, Narnia femorata. We raised juveniles on natural high-and low-quality diets, cactus pads with and without ripe cactus fruits. New adults were again assigned a cactus pad with or without fruit, paired with a potential mate, and observed for mating behaviors. We found developmental and adult encounter environments affected mating decisions and the resulting patterns of sexual selection for both males and females. Males were not choosy in the low-quality encounter environment, cactus without fruit, but they avoided mating with small females in the high-quality encounter environment. Females were choosy in both encounter environments, avoiding mating with small males. However, they were the choosiest when they were in the low-quality encounter environment. Female mate choice was also context dependent by male developmental environment. Females were more likely to mate with males that had developed on cactus with fruit when they were currently in the cactus with fruit environment. This pattern disappeared when females were in the cactus without fruit environment. Altogether, these results experimentally demonstrate context-dependent mate choice by both males and females. Furthermore, we demonstrate that simple, seasonal changes in resources can lead to fluctuations in sexual selection.

Seasonal Effects on the Population, Morphology and Reproductive Behavior of Narnia femorata (Hemiptera: Coreidae)

“…Females fly among cactus patches to mate, feed, and oviposit. Males will frequently mount and make genital contact with females [35]. Females that are ready to mate will open up their genital plates and allow male genitalia to penetrate [35].…”

“…Males will frequently mount and make genital contact with females [35]. Females that are ready to mate will open up their genital plates and allow male genitalia to penetrate [35]. Successful males will turn 180 degrees and may remain attached for up to several hours [35].…”

“…Females that are ready to mate will open up their genital plates and allow male genitalia to penetrate [35]. Successful males will turn 180 degrees and may remain attached for up to several hours [35]. Females control whether or not a genital contact results in a mating.…”

“…Females control whether or not a genital contact results in a mating. They can refuse to mate in a variety of ways, including simply keeping their genital plates closed, striking males with their legs, running away from males, and pushing their abdominal tip down against the cactus surface [35]. They can also dislodge males once they have started to mate [29].…”

“…lata flowers in the late spring and fruit ripens throughout the summer and into the fall. Fruit availability begins to decline after its peak in June [35]. One reason for the decline is that N. femorata is not the only cactus fruit consumer.…”