Paternity analyses in wild‐caught and laboratory‐reared Caribbean cricket females reveal the influence of mating environment on post‐copulatory sexual selection

Abstract

Polyandry is ubiquitous in insects and provides the conditions necessary for male- and female-driven forms of post-copulatory sexual selection to arise. Populations of Amphiacusta sanctaecrucis exhibit significant divergence in portions of the male genitalia that are inserted directly into the female reproductive tract, suggesting that males may exercise some post-copulatory control over fertilization success. We examine the potential for male-male and male-female post-copulatory interactions to influence paternity in wild-caught females of A. sanctaecrucis and contrast our findings with those obtained from females reared in a high-density laboratory environment. We find that female A. sanctaecrucis exercise control by mating multiple times (females mount males), but that male-male post-copulatory interactions may influence paternity success. Moreover, post-copulatory interactions that affect reproductive success of males are not independent of mating environment: clutches of wild-caught females exhibit higher sire diversity and lower paternity skew than clutches of laboratory-reared females. There was no strong evidence for last male precedence in either case. Most attempts at disentangling the contributions of male-male and male-female interactions towards post-copulatory sexual selection have been undertaken in a laboratory setting and may not capture the full context in which they take place--such as the relationship between premating and post-mating interactions. Our results reinforce the importance of designing studies that can capture the multifaceted nature of sexual selection for elucidating the role of post-copulatory sexual selection in driving the evolution of male and female reproductive traits, especially when different components (e.g. precopulatory and post-copulatory interactions) do not exert independent effects on reproductive outcomes.

Paternity analysis of wild‐caught females shows that sperm package size and placement influence fertilization success in the bushcricket Pholidoptera griseoaptera

“…; Bretman & Tregenza ; Simmons et al . ; Simmons & Beveridge ; Oneal & Knowles ; Turnell & Shaw ,b), none of these have used the relative position of sperm within the female's reproductive tract to predict the pattern of sperm use. Even if laboratory‐based studies and other taxa are included, the number of previous studies that have been able to relate directly the relative position of sperm within the female's reproductive tract to sperm use by the female is very limited (Droge‐Young et al .…”

“…As expected, a higher number of competing males also reduced the chances of siring offspring for each male. While previous studies of orthopteran insects have used microsatellite analysis to estimate the degree of polyandry and paternity skew in field-mated females (Hockham et al 2004;Bretman & Tregenza 2005;Simmons et al 2007;Simmons & Beveridge 2010;Oneal & Knowles 2015;Turnell & Shaw 2015a,b), none of these have used the relative position of sperm within the female's reproductive tract to predict the pattern of sperm use. Even if laboratory-based studies and other taxa are included, the number of previous studies that have been able to relate directly the relative position of sperm within the female's reproductive tract to sperm use by the female is very limited (Droge-Young et al 2016).…”

“…; Simmons et al . ; Simmons & Beveridge ; Turnell & Shaw ,b; Oneal & Knowles ). Some studies of vertebrates, such as those of feral Soay sheep, Ovis aries (Preston et al .…”

“…Laboratory studies of factors associated with sperm precedence are unlikely to reflect conditions experienced in the field, such as the females' natural number of mates and natural remating intervals (Zeh & Zeh 1994;Simmons 2001;Lewis et al 2005;Oneal & Knowles 2015). Zeh & Zeh (1994), for example, found that, in a species of pseudoscorpion (Cordylochernes scorpioides), last-male sperm precedence broke down when females were mated with more than two males.…”

“…The degree of polyandry and paternity skew (i.e. inequality among paternity shares) has been quantified in females that have mated with multiple males under natural field conditions using hypervariable molecular markers (Taylor et al 2014) in a variety of taxa including, for example, arthropods such as crickets and bushcrickets (Orthoptera: Ensifera; Bretman & Tregenza 2005;Hockham et al 2004;Simmons et al 2007;Simmons & Beveridge 2010;Turnell & Shaw 2015a,b;Oneal & Knowles 2015). Some studies of vertebrates, such as those of feral Soay sheep, Ovis aries (Preston et al 2003), have additionally used direct observations of mating in the field to examine factors that affect patterns of sperm use in field-mated females.…”