Adaptation versus pleiotropy: why do males harm their mates?

Sexual selection and genital evolution

“…Alternatively or additionally, females might increase investment in current reproduction, thereby maximizing the reproductive success of their most recent mate, if they perceive genital damage as a threat to their future survival [36 -38]. As yet, there is relatively little experimental support for either of these hypotheses [37,38]. The question of whether male genitalia are specifically adapted to cause damage to the female reproductive tract, or that damage occurs as a pleiotropic effect (of male adaptations for sperm competition for example) therefore remain matters of debate [26,37,38].…”

The Cost of Mating: Influences of Life History Traits and Mating Strategies on Lifespan in Two Closely RelatedYponomeutaSpecies

“…Apparently, any advantageous effects of mating on female lifespan were outweighed by disadvantageous ones. This net negative effect on female lifespan might be a side effect (i.e., pleiotropic) of male traits that are beneficial in sperm competition; alternatively, males might deliberately harm females in order to stimulate a higher oviposition rate or to prevent females from remating (as is formulated in the adaptive harm hypothesis: [6,44]). There are few studies on Lepidoptera in which lifespan of mated females is compared with virgin female lifespan; in many studies only lifespan of single-mated females has been compared with that of multiple-mated ones.…”

“…Knowledge of the species-specific advantages and disadvantages of monandry (females mate only once) and polyandry (females mate more than once) is important for understanding the adaptive significance of mating systems. Negative effects of multiple mating include an increase of energy and time spent on mating, as well as the concomitant increased vulnerability to predation, sexual diseases, parasites, and pathogens [6]. Furthermore, an excess of sperm can have a negative effect on both egg production rate (and thus female fecundity) and fertility ( [7], and references therein).…”

“…Furthermore, an excess of sperm can have a negative effect on both egg production rate (and thus female fecundity) and fertility ( [7], and references therein). In addition, in polyandrous species, mating may reduce female lifespan as a consequence of male manipulation [6][7][8][9]. Manipulation comprises both the transfer of toxic compounds, such as those found in Drosophila fruit flies [10], the bruchid Acanthoscelides obtectus [11], or the nematode Caenorhabditis elegans [12], and physical damage, such as that brought about by bed bugs [13], the bruchid Callosobruchus maculatus [14], or the dung fly Sepsis cynipsea [15].…”

Introduction. Sexual conflict: a new paradigm?

“…(a) The costs of conflict Following the work of several authors ( Johnstone & Keller 2000;Hosken et al 2003;Morrow et al 2003;Lessells 2005), it is clear that the harm inflicted on females by their mates can come about in several ways. It may be divided up into: (i) the fitness disadvantage due to an individual being shifted away from its optimum value for a trait over which conflict occurs (the 'shared trait' (Rowe & Day 2005) or 'conflict trait' (Lessells 2006), an example might be the energetic costs to females of mating more frequently than is optimal; and (ii) harm which reduces fitness through direct effects on traits that are not subject to sexually antagonistic selection, for instance female lifespan may be reduced by seminal fluid chemicals, but lifespan is not actually a trait over which there is any conflict of interest.…”