An Integrative View of Postcopulatory Sexual Selection in a Soldier Fly: Interplay Between Cryptic Mate Choice and Sperm Competition

Abstract

Cryptic female choice (CFC) can occur in the same species in conjunction with other postcopulatory processes, such as sperm competition (SC) and cryptic male choice (CMC). However, each of these processes has been mostly studied in isolation. Little is known about how they interact with each other and how this interplay affects the role they play in sexual selection. This chapter addresses the interplay between CFC, CMC, and SC in the soldier fly, Merosargus cingulatus (Diptera: Stratiomyidae). Soldier flies mate at oviposition sites; both sexes mate multiply and males perform copulatory courtship. Here, we describe the different postcopulatory processes that occur in this species: Females use control of oviposition timing as a CFC mechanism. Males show cryptic preferences for larger females and respond to SC cues by increasing copulation duration. Male reproductive success is, therefore, a result of a number of factors: oviposition behavior, copulatory courtship, copulation duration, female size, and male density at the oviposition site. The interaction between CFC and other postcopulatory processes sheds light on its potential impact on sexual selection and evolution.

Male coloration affects female gestation period and timing of fertilization in the guppy (Poecilia reticulata)

“…Control of the timing of fertilization (or oviposition after copulation) by females has been reported in several arthropods [ 40 – 43 ]. In these species, the lengthened period of female sexual receptivity due to delayed fertilization increases the opportunity for re-mating; as a result, females are able to bias fertilization towards preferred males [ 41 ]. By mating with colorful males with large orange areas, female guppies can gain indirect benefits that they produce offspring with high anti-predator ability [ 38 ] and algal-foraging ability [ 44 ], and sons with more attractive ornaments inherited from the sire [ 45 , 46 ].…”

No neonates without adults

“…Likewise, females may require stimulation from males, [43] and potentially assess mates based on the pattern or duration of their wing buzzing (i.e., courtship songs), a trait which may have originally evolved, or become co-opted as an antipredator defense, [44] and one which is present throughout the Diptera. [43,45,46] Mating cage experiments further suggest mate choice in H. illucens is both age-and size-structured, [13] and potentially cryptic, which may be similar to that of other stratiomyids, such as Hermetia comstocki Williston [17,47] and Merosargus cingulatus Schiner, [48] though little else is known.…”

“…[ 43,45,46 ] Mating cage experiments further suggest mate choice in H . illucens is both age‐ and size‐ structured, [ 13 ] and potentially cryptic, which may be similar to that of other stratiomyids, such as Hermetia comstocki Williston [ 17,47 ] and Merosargus cingulatus Schiner, [ 48 ] though little else is known.…”