Remote copulation: male adaptation to female cannibalism

Abstract

Sexual cannibalism by females and associated male behaviours may be driven by sexual conflict. One such male behaviour is the eunuch phenomenon in spiders, caused by total genital emasculation, which is a seemingly maladaptive behaviour. Here, we provide the first empirical testing of an adaptive hypothesis to explain this behaviour, the remote copulation, in a highly sexually cannibalistic orb-web spider Nephilengys malabarensis . We demonstrate that sperm transfer continues from the severed male organ into female genitals after the male has been detached from copula. Remote copulation increases the total amount of sperm transferred, and thus probably enhances paternity. We conclude that the mechanism may have evolved in response to sexual cannibalism and female-controlled short copulation duration.

Challenging the Aggressive Spillover Hypothesis: Is Pre‐Copulatory Sexual Cannibalism a Part of a Behavioural Syndrome?

“…,b), remote copulation (Li et al. ) or may vary in their risk to fall victim to the female even in the absence of specific counter‐strategies (Arnqvist & Henriksson ; Roggenbuck et al. ).…”

“…In those cases where males' fitness benefits of sexual cannibalism exceed the benefits of future matings, for example, in spiders with strict male monogamy, males may be selected for sacrificing their body during or after copulation (Andrade , ; Schneider & Elgar ; but see Li et al. ). In a polygamous species, however, it may be in the male's interest to avoid female attacks (Barry et al.…”

A glimpse into the sexual biology of the “zygiellid” spider genus Leviellus

“…This resembles the eunuch behavior of Herennia Thorell 1877 (Kuntner 2005;Kuntner et al 2009b), but not that of other nephilids where males leave a palp in the female genital tract (Kuntner et al 2009c;Kralj-Fišer et al 2011;Li et al 2012), nor that of Tidarren Chamberlin & Ivie 1934 where the single-palped male spontaneously dies while copulating and thus functions as a whole-body mating plug (Knoflach & van Harten 2001). Although the eunuch's behavior in Leviellus is clearly not obligate, it may nevertheless be suggestive of some level of post-mating sterility in males.…”

The evolution of genital complexity and mating rates in sexually size dimorphic spiders

“…Because sexual cannibalism strongly depends on the mating status of the female, we translated the experimental data on post-copulatory sexual cannibalism by virgin females [13, 39, 48, 49, 51, 56, 60–62, 64, 72, 75–77] to average percentage scores per species (Additional file 1: Table S1).…”