Integrating Perspectives on Rodent Sperm Competition

Ramm, Steven A.; Stockley, Paula

doi:10.1016/bs.asb.2016.02.003

Cited by 9 publications

(14 citation statements)

References 295 publications

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“…For rodents, the role of post‐copulatory competition in the evolution of copulatory plugs is unclear (Ramm & Stockley, ), and a number of other nonmutually exclusive functions of copulatory plugs have been hypothesized, such as gradual sperm release, sperm transport and cervical stimulation (reviewed in Voss, ). Comparatively, rodent species with relatively larger testes, a proxy for sperm competition intensity, have relatively larger seminal vesicles – the organs responsible for producing plug proteins – and relatively larger copulatory plugs (Ramm et al ., ).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, even if copulatory plugs are relevant to postcopulatory competition, these evolutionary conflicts over plug efficacy between the sexes and between rivals are likely to lead to situations in which copulatory plugs are not fully effective in preventing female remating. For rodents, the role of post-copulatory competition in the evolution of copulatory plugs is unclear (Ramm & Stockley, 2016), and a number of other nonmutually exclusive functions of copulatory plugs have been hypothesized, such as gradual sperm release, sperm transport and cervical stimulation (reviewed in Voss, 1979). Comparatively, rodent species with relatively larger testes, a proxy for sperm competition intensity, have relatively larger seminal vesiclesthe organs responsible for producing plug proteinsand relatively larger copulatory plugs (Ramm et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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The copulatory plug delays ejaculation by rival males and affects sperm competition outcome in house mice

Sutter

Lindholm

2016

J of Evolutionary Biology

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Females of many species mate with multiple males (polyandry), resulting in male–male competition extending to post‐copulation (sperm competition). Males adapt to such post‐copulatory sexual selection by altering features of their ejaculate that increase its competitiveness and/or by decreasing the risk of sperm competition through female manipulation or interference with rival male behaviour. At ejaculation, males of many species deposit copulatory plugs, which are commonly interpreted as a male adaptation to post‐copulatory competition and are thought to reduce or delay female remating. Here, we used a vertebrate model species, the house mouse, to study the consequences of copulatory plugs for post‐copulatory competition. We experimentally manipulated plugs after a female's first mating and investigated the consequences for rival male behaviour and paternity outcome. We found that even intact copulatory plugs were ineffective at preventing female remating, but that plugs influenced the rival male copulatory behaviour. Rivals facing intact copulatory plugs performed more but shorter copulations and ejaculated later than when the plug had been fully or partially removed. This suggests that the copulatory plug represents a considerable physical barrier to rival males. The paternity share of first males increased with a longer delay between the first and second males' ejaculations, indicative of fitness consequences of copulatory plugs. However, when males provided little copulatory stimulation, the incidence of pregnancy failure increased, representing a potential benefit of intense and repeated copulation besides plug removal. We discuss the potential mechanisms of how plugs influence sperm competition outcome and consequences for male copulatory behaviour.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The copulatory plug delays ejaculation by rival males and affects sperm competition outcome in house mice

Sutter

Lindholm

2016

J of Evolutionary Biology

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“…Similarly, male bank voles develop larger seminal vesicles when exposed to social cues associated with high social competition during sexual development [ 16 ]. In each case, the reported effects are likely to be adaptive because increased sperm production rates and/or larger seminal vesicles promote male success under sperm competition, the risk of which is increased at high population density as females of these species mate with multiple males [ 35 ]. Increased investment in ejaculate production may also facilitate an increased rate of multiple mating by males, although previous studies suggest a stronger response to cues of competition than likely mating rate [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

“…By contrast to these previous studies, to our knowledge, the findings of the present study provide the first evidence of increased sperm production, with potentially adaptive benefits, linked to maternal social experience. Increased sperm production is likely to be beneficial to male fitness under high population density, both by facilitating multiple mating and by promoting fertilization success under an elevated risk of sperm competition [ 35 ].…”

Section: Discussionmentioning

confidence: 99%

Increased sperm production linked to competition in the maternal social environment

2020

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Maternal or early life effects may prepare offspring for similar social conditions to those experienced by their mothers. For males, the ability to achieve mating and fertilization success is a key social challenge. Competitive conditions may therefore favour increased body size or ejaculate production in male offspring. We tested this experimentally by comparing reproductive traits of adult male bank voles ( Myodes glareolus ), whose mothers had experienced contrasting encounter regimes with female conspecifics while breeding. We found that daily sperm production rates and epididymis mass were significantly higher when dams had experienced more frequent encounters with female conspecifics. This response to maternal and early life experience was specific to sperm production and storage, with no evidence for effects on male body mass or the size of testes and accessory reproductive glands. Our findings reveal a potentially adaptive effect of maternal and early life experience on the development of sperm production, which is worthy of wider investigation.

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“…Experimental and induced studies carried out on primates, carnivores and rodents to test the hypothesis that divergent baculum evolution is driven by postcopulatory sexual selection, produced different results according to taxonomic group (Ramm & Stockley, ; Simmons & Firman, ). For primates, a correlation between baculum size and periods of intromission was reported, where in species with a smaller baculum, copulation typically involves one or several short penetrations, and in species with a larger baculum, copulation involves prolonged penetration or continued copulation after ejaculation (Brindle & Opie, ; Dixson, ).…”

Section: Discussionmentioning

confidence: 99%

Histomorphology of the glans penis in Vespertilionidae and Phyllostomidae species (Chiroptera, Mammalia)

Jubilato

Comelis

Bueno

et al. 2019

Journal of Morphology

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The penises of bats are taxonomically distinctive in size and shape. In addition, they are variable in microscopic anatomy, indicating that histomorphological studies of copulatory organs of bats may help understanding their successful reproductive strategies. We studied adult males of 13 species of vespertilionid and phyllostomid bats.Both families exhibited the basic structure of the vascular penis of mammals: the hydrostatic elements of the corpora cavernosa and the corpus spongiosum surrounding the urethra, as well as accessory cavernous tissue. Variation in the position and amount of the tissues were observed in these families. Vespertilionid bats have a small glans penis with abundant accessory cavernous tissue on the prepuce and a highly variable baculum. The baculum varied in size and morphology, even among congeneric species, such as the three Lasiurus species and the two Myotis species.Phyllostomid species possess no bacula, but vascular structures are present to produce penile stiffening, particularly on the glans. Variation in the microscopic anatomy of the phyllostomid prepuce was observed, for example, Artibeus species had accessory cavernous tissue surrounded by a tunica albuginea, but Carollia perspicillata had two bundles of striated musculature and some adipose tissue; abundant pigments were present in the prepuce of most species. K E Y W O R D S baculum, bat, male reproductive tract

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Integrating Perspectives on Rodent Sperm Competition

Cited by 9 publications

References 295 publications

The copulatory plug delays ejaculation by rival males and affects sperm competition outcome in house mice

The copulatory plug delays ejaculation by rival males and affects sperm competition outcome in house mice

Increased sperm production linked to competition in the maternal social environment

Histomorphology of the glans penis in Vespertilionidae and Phyllostomidae species (Chiroptera, Mammalia)

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