Sperm Competition in Mammals

Gomendio, Montserrat; Harcourt, Alexander H.; Roldán, Eduardo R. S.

doi:10.1016/b978-012100543-6/50041-6

Cited by 227 publications

(212 citation statements)

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“…Sperm length is positively correlated with the probability of encountering sperm competition in some groups of animals, but not in others (62,67,68). Sperm length does not appear to be correlated with the thickness of the zona pellucida in mammals (69). The sperm of internally fertilizing species of fish and echinoids, which would seem to need less swimming ability, are nevertheless longer than those of external fertilizers in the same groups.…”

Section: Evolutionary Consequences Of Postcopulatory Selection Genitamentioning

confidence: 87%

“…The rapid diversification of fertilization molecules in mammals (83) is not likely to be explained by selection for species isolation, because the complex male-female interactions before copulation, and internal female barriers such as reduced sperm transport, probably make interactions between heterospecific eggs and sperm very rare (69). Both sperm proteins and egg coat zona pellucida glycoproteins show rapid divergence because of selection (91), and the ZP2 and ZP3 egg glycoproteins are among the 10% most different proteins between rodents and humans (83).…”

Section: Evolutionary Consequences Of Postcopulatory Selection Genitamentioning

confidence: 99%

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Postcopulatory sexual selection: Darwin's omission and its consequences

Eberhard

2009

Proc. Natl. Acad. Sci. U.S.A.

173

155

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In one of his few major oversights, Darwin failed to appreciate that male-male competition and sexual selection can continue even after copulation has begun. The postcopulatory equivalents of both direct male-male battles (sperm competition) and female choice (cryptic female choice) occur within the female's body. Recognition of this hidden, but intense, sexual competition provides new insights into a variety of fields. These include the hyperdiverse and paradoxically elaborate morphology of both sperm and male genitalia, the equally puzzling and elaborate morphology of nongenitalic male structures that are specialized to grasp and stimulate females, powerful manipulative effects of substances in male semen on female reproductive physiology, paradoxical male courtship behavior that occurs after copulation has already begun, variability in parental investments, and the puzzlingly complex and diverse interactions between sperm and female products that surround animal eggs and between male gametophytes and female tissues in flowering plants. Many bizarre traits are involved, including male genitalia that are designed to explode or fall apart during copulation leaving behind parts within the female, male genitalia that ''sing'' during copulation, potent seminal products that invade the female's body cavity and her nervous system to influence her behavior, and a virtual Kama Sutra of courtship behavior performed after rather than before genital coupling, including male-female dialogues during copulation.cryptic female choice ͉ sexually antagonistic coevolution P icture a pile of freshly-cut weeds at the sunny edge of a tropical forest. Metallic green flies dart and circle over it, chasing one another in short dashes. Your eye is caught when a chase ends as one fly grasps another in midair and the pair immediately lands on the pile of weeds. Their genitalia are already coupled, and the male immediately turns to face away from the female. After a few seconds, paradoxically (because he is already securely attached), he begins to court, rhythmically waving his colorful hind legs and tapping the female's abdomen. The courtship continues for a few minutes as the pair remains coupled, and then the flies separate. The female walks down into the pile where she lays eggs (her larvae will feed on the rotting vegetation), while the male rejoins the frenetic chases above the pile.Why would a male fly wait to court a female until after he has already achieved his evolutionary objective of copulating with her? The answer (recently worked out by a Brazilian graduate student, F. Barbosa, personal communication) had to wait for Ͼ100 years after Darwin's great book on sexual selection (1) that explained so many other aspects of male-female sexual interactions.

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Section: Evolutionary Consequences Of Postcopulatory Selection Genitamentioning

confidence: 87%

Section: Evolutionary Consequences Of Postcopulatory Selection Genitamentioning

confidence: 99%

Postcopulatory sexual selection: Darwin's omission and its consequences

Eberhard

2009

Proc. Natl. Acad. Sci. U.S.A.

173

155

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“…quantity of sperm depends on gonad size; bigger testes produce more spermatozoa that are of better quality (GOMENDIO et al 1998;MONTOTO et al 2011).…”

Section: Sexual Maturation In Common Vole Malesmentioning

confidence: 99%

Sexual Maturation in Common Vole (<I>Microtus arvalis</I>) Males Raised under Laboratory Conditions

Miska

Kruczek

Kapusta

2014

folia biol (krakow)

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MISKA A., KRUCZEK M., KAPUSTA J. 2014. Sexual maturation in Common vole (Microtus arvalis) males raised under laboratory conditions. Folia Biologica (Kraków) 62: 135-142.The common vole is one of the most numerous rodents in Europe and Asia but its reproductive biology is not fully described. It is thought that females reach reproductive abilities at a very young age, however, there is no data concerning male sexual maturation. The aim of the present study was to determine the rate of sexual maturation of males of the common vole. Research was carried out on 4, 6, 8 and 10 week-old animals. Body, testes and accessory sex glands weights were compared to evaluate morphological development. Epididymal sperm quality was assessed by a motility test, sperm tail membrane integrity, viability, maturity and sperm head morphology. Moreover, the number of sperm cells in 1 mm ! of semen was evaluated. The largest body weights were observed in 8 and 10 week-old males, which also possessed the highest relative weights of gonads and accessory sex glands. These groups of males produce about 2 times more gametes than 6 week-old individuals. The highest seamen quality was noted in 8 and 10 week-old males. Based on the obtained results, it is concluded that among the investigated age groups the most appropriate male age for fertile copulation is between 8 and 10 weeks.

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“…However, it is timely to reassess epididymal functions as the use of procedures based on IVF will increase the proportion of infertile men in a population (and so increase the cost of public health) and there is an increasing number of reports of birth defects in babies conceived through assisted reproduction (Nair 2008). Further, as sperm competition is a significant factor in achieving paternity in many other species (Smith 1984b;Birkhead 1995;Gomendio et al 1998) and there is increasing evidence that evolution is male-driven (Crow 1997;Ellegren and Fridolfsson 1997;Hurst and Ellegren 1998;Li et al 2002), it is timely to reassess how epididymal function has evolved from monotremes to higher mammals.…”

Section: Sperm Maturation In the Epididymismentioning

confidence: 99%

Testicular descent, sperm maturation and capacitation. Lessons from our most distant relatives, the monotremes

Ecroyd

Nixon

Dacheux

et al. 2009

Reprod. Fertil. Dev.

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The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and ova from both groups share many of the proteins that are thought to be involved in gamete interaction, and although epididymal sperm maturation is significant it is probably less complex in monotremes than in other mammals. However, the monotreme epididymis is unique in forming spermatozoa into bundles of 100 with greatly enhanced motility compared with individual spermatozoa. Bundle formation involves a highly organised interaction with epididymal proteins, and the bundles persist during incubation in vitro, except in specialised medium, in which spermatozoa separate after 3 h incubation. It is suggested that this represents an early form of capacitation. Abstract. The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and ova from both groups share many of the proteins that are thought to be involved in gamete interaction, and although epididymal sperm maturation is significant it is probably less complex in monotremes than in other mammals. However, the monotreme epididymis is unique in forming spermatozoa into bundles of 100 with greatly enhanced motility compared with individual spermatozoa. Bundle formation involves a highly organised interaction with epididymal proteins, and the bundles persist during incubation in vitro, except in specialised medium, in which spermatozoa separate after 2-3 h incubation. It is suggested that this represents an early form of capacitation.

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Sperm Competition in Mammals

Cited by 227 publications

References 235 publications

Postcopulatory sexual selection: Darwin's omission and its consequences

Postcopulatory sexual selection: Darwin's omission and its consequences

Sexual Maturation in Common Vole (<I>Microtus arvalis</I>) Males Raised under Laboratory Conditions

Testicular descent, sperm maturation and capacitation. Lessons from our most distant relatives, the monotremes

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