A mate to die for? A model of conditional monogyny in cannibalistic spiders

Abstract

Monogynous males in various species actively limit themselves to mating with a single female in their lifetime. Whereas previous models have considered monogyny as an obligate mating strategy, here we explore the potential of monogyny to evolve as a context-specific (conditional) behavior. Using a state-dependent dynamic game model based on the biology of the cannibalistic spider Argiope bruennichi, we confirm that conditional monogyny can evolve under broad conditions, including an even sex ratio. We predict that males should make a terminal investment when mating with large, virgin females, especially if population density is low and the encounter occurs late in the season. We encourage empirical tests for the existence of conditional monogyny in all species where monogyny occurs in the absence of strict morphological constraints that would make it obligatory.

Differential investment and size-related mating strategies facilitate extreme size variation in contesting male spiders

“…These elements are part of an evolutionary scenario resulting in very low male mating rates (Fromhage, Elgar, & Schneider, 2005;Fromhage, Jacobs, & Schneider, 2007) and males may benefit from conditional strategies involving variable mating investment, depending on the value of a female (Fromhage & Schneider, 2012). Using a theoretical approach, Rittschof, Hilber, Tudor, and St Mary (2012) have evaluated potential mating strategies in Nephila clavipes, a species similar in reproductive biology to our study species.…”

Cryptic Female Choice Within the Genus Argiope: A Comparative Approach

“…The plug consists of a genital fragment, and breakage of this fragment renders the pedipalp dysfunctional (Uhl et al 2007; see below for more details). Hence, males have the option to use both pedipalps with the same female in a monogynous mating system or use each one with another female in a bigynous mating system (Fromhage and Schneider 2012). As the female has paired genital openings each leading to a separate spermatheca (Vöcking et al 2013;Herberstein et al 2011a), a male can only plug both by mating twice with the same female (monogyny) and thus monopolize the female.…”

“…They achieved this in two ways: either through a single long copulation or by a brief first copulation followed by a second long copulation with the same female. A model revealed that such a conditional mating strategy can evolve under conditions that apply to A. bruennichi (Fromhage and Schneider 2012). The most important variables are (i) a high variation in female quality, and (ii) seasonal as well as (iii) spatial differences in selection regimes.…”

Sexual Cannibalism as a Manifestation of Sexual Conflict

“…However, they copulate only very briefly with less preferred females and thereby double their chances of surviving their first copulation. Singly mated males can then walk off to search for another female that ideally will be of higher quality (bigynous mating strategy) (Welke and Schneider 2010;Fromhage and Schneider 2012;. In general, mate choice should evolve if mating costs are very high for males, because quality differences between females, if present, matter a lot for the lifetime reproductive success of a male that has a maximum mating rate of two (modeled by Fromhage and Schneider 2012).…”

“…Singly mated males can then walk off to search for another female that ideally will be of higher quality (bigynous mating strategy) (Welke and Schneider 2010;Fromhage and Schneider 2012;. In general, mate choice should evolve if mating costs are very high for males, because quality differences between females, if present, matter a lot for the lifetime reproductive success of a male that has a maximum mating rate of two (modeled by Fromhage and Schneider 2012). However, even in systems with low male mating rates and a theoretical expectation of male mate choice, cognitive demands and constraints may have to be taken into account as well.…”