Variation in the benefits of multiple mating on female fertility in wild stalk‐eyed flies

Abstract

Polyandry, female mating with multiple males, is widespread across many taxa and almost ubiquitous in insects. This conflicts with the traditional idea that females are constrained by their comparatively large investment in each offspring, and so should only need to mate once or a few times. Females may need to mate multiply to gain sufficient sperm supplies to maintain their fertility, especially in species in which male promiscuity results in division of their ejaculate among many females. Here, we take a novel approach, utilizing wild‐caught individuals to explore how natural variation among females and males influences fertility gains for females. We studied this in the Malaysian stalk‐eyed fly species Teleopsis dalmanni. After an additional mating, females benefit from greatly increased fertility (proportion fertile eggs). Gains from multiple mating are not uniform across females; they are greatest when females have high fecundity or low fertility. Fertility gains also vary spatially, as we find an additional strong effect of the stream from which females were collected. Responses were unaffected by male mating history (males kept with females or in male‐only groups). Recent male mating may be of lesser importance because males in many species, including T. dalmanni, partition their ejaculate to maintain their fertility over many matings. This study highlights the importance of complementing laboratory studies with data on wild‐caught populations, where there is considerable heterogeneity between individuals. Future research should focus on environmental, demographic and genetic factors that are likely to significantly influence variation in individual female fecundity and fertility.

Limits to environmental masking of genetic quality in sexual signals

“…After eclosion, flies of each cross were collected and frozen at −20°C. All males were measured for eyespan (the distance between the outermost tips of the eyes, Chapman et al, 2017;David et al, 1998) and thorax (the distance between the centre of the most posterior point of the head to the joint between the meta-thoracic legs and the thorax, Meade et al, 2017;Rogers, Denniff, Chapman, Fowler, & Pomiankowski, 2008) to a tolerance of 0.01 mm, using a video camera mounted on a monocular microscope and imagej image capture software v.1.46 (Schneider, Rasband, & Eliceiri, 2012). The repeatability of these morphological trait measurements is very high at >99% (David et al, 1998).…”

An empirical test of the bet‐hedging polyandry hypothesis: Female red flour beetles avoid extinction via multiple mating

“…Moreover, multiple mating is usually costly and risky for females (e.g., time and energy consumption and increased predation and infection; Arnqvist & Rowe, 2005; Harano et al., 2006). Nevertheless, female multiple mating is ubiquitous in many animals (and plants); thus, the evolutionary significance of polyandry has received considerable attention from many evolutionary biologists (e.g., Jennions & Petrie, 2000; Meade et al., 2017; Nason & Kelly, 2020; Pizzari & Wedell, 2013; Simmons, 2005; Yasui, 1998; Zeh & Zeh, 2003).…”

“…In the absence of direct benefits, if females obtain some genetic (indirect) benefits for the offspring (e.g., good genes or genetic diversity) from males, then polyandrous females would be favored (Jennions & Petrie, 2000; Yasui, 1998). These hypotheses have been investigated by numerous empirical and theoretical studies (e.g., Jennions & Petrie, 2000; Meade et al., 2017; Nason & Kelly, 2020; Pizzari & Wedell, 2013; Simmons, 2005; Zeh & Zeh, 2003). Today, the increasing studies have reported the benefits of female multiple mating with different males (e.g., García‐González et al., 2015; Lewis et al., 2020; Power & Holman, 2014; Snook, 2014).…”

Bodyweight-Related Polyandry in the Tobacco Cutworm Moth Spodoptera litura (Lepidoptera: Noctuidae)

“…Studies have suggested that polyandry allows females to gain direct benefits by replenishing sperm and nutrition from the ejaculate (Meade et al 2017), and indirect benefits in terms of offspring genetic diversity and ‘good genes’ (Taylor et al 2014, Rafter et al 2018). However, there are many costs of mating in general, particularly in multiple matings, such as energy costs and disease transmission (Okada et al 2017).…”