How Well Do Mating Frequency and Duration Predict Paternity Success in the Polygynandrous Water Strider Aquarius Remigis?

Abstract

The relationship between mating success and paternity success is a key component of sexual selection but has seldom been estimated for species in which both sexes mate with many partners (polygynandry). We used a modification of Parker's sterile male technique to measure this relationship for the water strider Aquarius remigis in 47 laboratory populations simulating natural conditions of polygynandry. We also tested the hypothesis that prolonged copulation, a characteristic of this species, enhances paternity success. Mating behavior and paternity success were assayed for four days while males and females freely interacted. Paternity success was also assayed for an additional 7 days when females were isolated from males. Mating success significantly predicted paternity success and accounted for < or = 36% of the variance. Copulation duration was negatively related to both mating success and paternity success and did not explain any of the residual variance in paternity success. Thus, we found no evidence that prolonged copulation functions as a paternity assurance strategy in this species. Comparisons of sterile and fertile males suggested that paternity success is directly influenced by the quantity of sperm transferred. Our results support previous studies that have used mating success to estimate sexual selection, but also highlight the potential importance of sperm competition and other postinsemination processes.

Size-assortative mating and sexual size dimorphism are predictable from simple mechanics of mate-grasping behavior

“…Because in typical water striders male fitness, unlike female fitness, is positively correlated with the mating frequency [22,27], the field data can be used to reasonably estimate selection coefficients from the information of male's, but not the female's, mating status at the time of sampling. We have estimated selection coefficients on male TTL and, separately, on male FTG in the natural population of 141 males and 101 females sampled.…”

“…For consistency we also calculated analogical selection gradients for the females (Table A2). However, because female fitness in water striders is typically not strongly related to the mating frequency [22,27], and because our study design focuses on estimating male mating success and selection on males, we further focused on males only.…”

“…Water strider males grasp tightly the female's thorax with their forelegs in order to overcome the female's resistance. Males are very persistent in opposing female attempts of throwing them off because frequency of mating is positively associated with male fitness [27]. After the end of sperm transfer the male typically remains on the female in a "guarding" position.…”

Plasticity of Mating Duration in Response to Slightly Biased Operational Sex Ratios in the Water Strider (Aquarius remigis): The Effect of Cohabitation Under Standard Laboratory Conditions

“…The common water strider (Aquarius remigis) provides a model system for the study of mate competition and plasticity as it displays a spectrum of reproductive behaviors (Rubenstein, 1989;Jabłonski and Kaczanowski, 1994;Rowe et al, 1994;Jablonski and Vepsäläinen, 1995;Vepsäläinen and Savolainen, 1995;Vermette and Fairbairn, 2002;Arnqvist and Rowe, 2005). Males are known to mate with females from as short as 15 min to over 10 h (Sih et al, 2002), and freely migrate across social environments that vary considerably in population density and sex ratio (Krupa and Sih, 1993).…”

Genital morphology and taxonomy of the water strider Aquarius remigis (Say) (Insecta, Hemiptera-Heteroptera: Gerridae)

“…), the monophyly of the A. remigis group is supported strongly on the basis of the antennal and male genital characters listed above, as well as a few more homoplastic characters (Damgaard & Cognato, 2005). The morphology of the male genitalia follows the general gerromorphan plan (Andersen, 1975, 1982), and the uniquely extended dorsal vesical plate in A. remigis has probably evolved in order to increase the ability of males to achieve intromission in spite of active female resistance, and to maintain intromission during the prolonged copulation that is characteristic of this species (Fairbairn, 1988a, 1990; Weigensberg & Fairbairn, 1994; Campbell & Fairbairn, 2001; Vermette & Fairbairn, 2002; Fairbairn et al ., 2003; Bertin & Fairbairn, 2005). Based on the resemblance of male genitalia throughout the A. remigis group (Michel, 1961; Gallant & Fairbairn, 1996; this study), it is reasonable to assume that all members share this mating strategy.…”