Sexual selection by cryptic female choice and the evolution of primate sexuality

2003 ◽  
Vol 11 (S1) ◽  
pp. 195-199 ◽  
Author(s):  
Alan Dixson
Author(s):  
Patricia L.R. Brennan ◽  
Dara N. Orbach

The field of post-copulatory sexual selection investigates how female and male adaptations have evolved to influence the fertilization of eggs while optimizing fitness during and after copulation, when females mate with multiple males. When females are polyandrous (one female mates with multiple males), they may optimize their mating rate and control the outcome of mating interactions to acquire direct and indirect benefits. Polyandry may also favor the evolution of male traits that offer an advantage in post-copulatory male-male sperm competition. Sperm competition occurs when the sperm, seminal fluid, and/or genitalia of one male directly impacts the outcome of fertilization success of a rival male. When a female mates with multiple males, she may use information from a number of traits to choose who will sire her offspring. This cryptic female choice (CFC) to bias paternity can be based on behavioral, physiological, and morphological criteria (e.g., copulatory courtship, volume and/or composition of seminal fluid, shape of grasping appendages). Because male fitness interests are rarely perfectly aligned with female fitness interests, sexual conflict over mating and fertilization commonly occur during copulatory and post-copulatory interactions. Post-copulatory interactions inherently involve close associations between female and male reproductive characteristics, which in many species potentially include sperm storage and sperm movement inside the female reproductive tract, and highlight the intricate coevolution between the sexes. This coevolution is also common in genital morphology. The great diversity of genitalia among species is attributed to sexual selection. The evolution of genital attributes that allow females to maintain reproductive autonomy over paternity via cryptic female choice or that prevent male manipulation and sexual control via sexually antagonistic coevolution have been well documented. Additionally, cases where genitalia evolve through intrasexual competition are well known. Another important area of study in post-copulatory sexual selection is the examination of trade-offs between investments in pre-copulatory and post-copulatory traits, since organisms have limited energetic resources to allocate to reproduction, and securing both mating and fertilization is essential for reproductive success.


Author(s):  
Leigh W. Simmons

Darwin viewed sexual selection as a process that ended with mate acquisition, assuming that females are fundamentally monogamous, mating with just one male. ‘Sexual selection after mating’, however, shows this assumption to be false. Sexual selection continues long after the physical act of mating is over, as sperm compete inside a female’s reproductive tract and females bias the paternity of their young by selectively using sperm from particular males. Multiple mating by females has turned out to be ubiquitous across animal taxa. The far-reaching evolutionary consequences of sperm competition and cryptic female choice for the evolution of reproductive traits are examined, from the gametes themselves to the adult organisms producing them.


1997 ◽  
Vol 75 (6) ◽  
pp. 905-918 ◽  
Author(s):  
Bernhard A. Huber ◽  
William G. Eberhard

The pholcid spider Physocyclus globosus (Taczanowski, 1873) was observed and videotaped courting and copulating, and genital mechanics and movements were analyzed by serial sectioning of freeze-fixed pairs. Just prior to copulation, the chelicerae of the male engage an apophysis on the female's epigynum. During copulation the male vibrates his abdomen rhythmically and makes repeated, relatively stereotyped twisting and flexing movements with his pedipalps, which are inserted simultaneously but asymmetrically in the female. The palps squeeze the female in the area of her epigyneal plate. Copulation with non-virgin females results in the extrusion of a mass of sperm from the female's genitalia during copulation or up to several minutes after it ends; no such masses result from copulations with virgin females. Sperm extrusion was not associated consistently with precedence of sperm from either the first or the second male. It is argued that the palpal movements, and perhaps most rhythmic genitalic movements, in spiders may best be interpreted as a result of sexual selection by means of cryptic female choice, and probably function to provide females with additional information about the male. Pholcids in general, and some genera in particular (including Physocyclus), may be unusual in that the vigour of males may play a significant role during copulatory courtship, as their palps have massive muscles that are only used during copulation.


Evolution ◽  
2019 ◽  
Vol 73 (12) ◽  
pp. 2415-2435 ◽  
Author(s):  
William G. Eberhard ◽  
Gerlind U.C. Lehmann

2019 ◽  
Author(s):  
Stefan Lüpold ◽  
Jonathan Bradley Reil ◽  
Mollie K. Manier ◽  
Valérian Zeender ◽  
John M. Belote ◽  
...  

AbstractHow males and females contribute to joint reproductive success has been a long-standing question in sexual selection. Under postcopulatory sexual selection (PSS), paternity success is predicted to derive from complex interactions among females engaging in cryptic female choice and males engaging in sperm competition. Such interactions have been identified as potential sources of genetic variation in sexually selected traits but are also expected to inhibit trait diversification. To date, studies of interactions between females and competing males have focused almost exclusively on genotypes and not phenotypic variation in sexually selected traits. Here, we characterize within- and between-sex interactions inDrosophila melanogasterusing isogenic lines with heritable variation in both male and female traits known to influence competitive fertilization. We found surprisingly few genotypic interaction effects on various stages of PSS such as female remating interval, copulation duration, sperm transfer, or sperm storage. Only the timing of female sperm ejection depended on female × male genotypic interactions. By contrast, several reproductive events, including sperm transfer, female sperm ejection and sperm storage, were explained by two- and three-way interactions among sex-specific phenotypes. We also documented complex interactions between the lengths of competing males’ sperm and the female seminal receptacle, which are known to have experienced rapid female-male co-diversification. Our results highlight the non-independence of sperm competition and cryptic female choice and demonstrate that complex interactions between the sexes do not limit the ability of multivariate systems to respond to directional sexual selection.Significance statementFor species with internal fertilization and female promiscuity, postcopulatory sexual selection (PSS) is believed to depend, in part, on complex interactions between rival males and between the sexes. Although little investigated, clarifying such interactions is critical as they may limit the efficacy of PSS in the diversification of reproductive traits (e.g., ejaculate biochemistry and sperm, genitalia and female reproductive tract morphology). Here, we resolve how sex-specific traits and their interactions contribute to key reproductive events and outcomes related to competitive fertilization success, including traits known to have experienced rapid diversification. Our results provide novel insights into the operation and complexity of PSS and demonstrate that the processes of sperm competition and cryptic female choice are not independent selective forces.


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