Size and Function of Mammalian Testes in Relation to Body Size

Kenagy, G. J.; Trombulak, Stephen C.

doi:10.2307/1380997

Cited by 508 publications

(487 citation statements)

References 0 publications

Supporting

Mentioning

443

Contrasting

Unclassified

Order By: Relevance

“…Relative testes size is a useful indicator of probable female promiscuity in the absence of more direct evidence, because it is well established that species with multi-male or promiscuous mating systems typically have relatively large testes for their body size (RTS . 1), whereas those with monogamous or polygynous (single male) mating systems typically have relatively small testes (RTS , 1) (Kenagy & Trombulak 1986; see also Harcourt et al 1981;Møller 1989). With the possible exception of Meles meles (Evans et al 1989), data on relative testes size were broadly consistent with available genetic evidence.…”

Section: Methodssupporting

confidence: 52%

“…A promiscuous mating system is here broadly defined as one in which females typically mate with more than one male within a given oestrus period (Clutton-Brock 1989); (ii) genetic evidence for multiple paternity within litters conceived under natural or semi-natural conditions; and/or (iii) relatively large mean testes size. To determine whether testes were relatively large compared with an average male mammal of the same order and body size, I used the relative testes size (RTS) values calculated by Kenagy & Trombulak (1986), based on regression equations for mean species body and testes mass across a range of mammalian orders. Relative testes size is a useful indicator of probable female promiscuity in the absence of more direct evidence, because it is well established that species with multi-male or promiscuous mating systems typically have relatively large testes for their body size (RTS .…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Female multiple mating behaviour, early reproductive failure and litter size variation in mammals

Stockley

2003

Proc. R. Soc. Lond. B

105

View full text Add to dashboard Cite

Female promiscuity is widespread among mammals, although its function is poorly understood. Recently, much interest has been generated by the hypothesis that female promiscuity, combined with postcopulatory paternity-biasing mechanisms, may function to reduce the costs of reproductive failure resulting from genetic incompatibility. Here, a comparative approach is used to determine if average rates of reproductive failure differ for polytocous mammal species with contrasting levels of female multiple-mating behaviour. After control for phylogeny, promiscuous species were found to have significantly lower rates of early reproductive failure than monogamous and polygynous species, in which females are relatively monandrous. Monandrous females appear to compensate for higher early reproductive failure with increased ova production, and thus produce comparable average litter sizes to those of more promiscuous females. However, there is significantly more variation around the average litter sizes produced by relatively monandrous females. These findings are broadly consistent with predictions of the genetic incompatibility avoidance hypothesis, although it is emphasized that alternative explanations cannot be ruled out on the basis of the comparative evidence presented. Further studies are needed to explore ecological correlates of multiple-mating behaviour, to investigate potential post-copulatory paternity-biasing mechanisms, and to identify the causes of reproductive failure in natural mammal populations.

show abstract

Section: Methodssupporting

confidence: 52%

Section: Methodsmentioning

confidence: 99%

Female multiple mating behaviour, early reproductive failure and litter size variation in mammals

Stockley

2003

Proc. R. Soc. Lond. B

105

View full text Add to dashboard Cite

show abstract

“…Males of many bat species are, however, well equipped with relatively large testes, which has been interpreted as an adaptive response to postcopulatory sexual selection (Hosken 1997(Hosken , 1998Wilkinson & McCracken 2003). Testicular tissue can represent a substantive energetic investment (Kenagy & Trombulak 1986), and an extraordinary range of combined testes mass has been documented across bat species: from 0.12 to 8.4% of body mass, which exceeds that of any other mammalian order (Wilkinson & McCracken 2003). Primates by comparison, which have been widely used as evidence that sexual selection influences testes size, exhibit combined testis mass ranging only from 0.02 to 0.75% of body mass (Harvey & Harcourt 1984).…”

Section: Introductionmentioning

confidence: 99%

Mating system and brain size in bats

2005

View full text Add to dashboard Cite

The contribution of sexual selection to brain evolution has been little investigated. Through comparative analyses of bats, we show that multiple mating by males, in the absence of multiple mating by females, has no evolutionary impact on relative brain dimension. In contrast, bat species with promiscuous females have relatively smaller brains than do species with females exhibiting mate fidelity. This pattern may be a consequence of the demonstrated negative evolutionary relationship between investment in testes and investment in brains, both metabolically expensive tissues. These results have implications for understanding the correlated evolution of brains, behaviour and extravagant sexually selected traits.

show abstract

“…they are non-orthogonal), a sequential (type I) sum of squares was used, adding the two predictors to the models in the following order: body mass, testes mass. For the graphical representation of RTS (figure 1), and for the calculation of RTS values in table 1, and only in these cases, RTS was calculated using Kenagy and Trombulak's rodent-specific regression equation: RTS ¼ testes mass/0.031 Â body mass 0.77 [43].…”

Section: (G) Statistical Analysesmentioning

confidence: 99%

A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation

et al. 2016

View full text Add to dashboard Cite

Sperm competition, a prevalent evolutionary process in which the spermatozoa of two or more males compete for the fertilization of the same ovum, leads to morphological and physiological adaptations, including increases in energetic metabolism that may serve to propel sperm faster but that may have negative effects on DNA integrity. Sperm DNA damage is associated with reduced rates of fertilization, embryo and fetal loss, offspring mortality, and mutations leading to genetic disease. We tested whether high levels of sperm competition affect sperm DNA integrity. We evaluated sperm DNA integrity in 18 species of rodents that differ in their levels of sperm competition using the sperm chromatin structure assay. DNA integrity was assessed upon sperm collection, in response to incubation under capacitating or non-capacitating conditions, and after exposure to physical and chemical stressors. Sperm DNA was very resistant to physical and chemical stressors, whereas incubation in noncapacitating and capacitating conditions resulted in only a small increase in sperm DNA damage. Importantly, levels of sperm competition were positively associated with sperm DNA fragmentation across rodent species. This is the first evidence showing that high levels of sperm competition lead to an important cost in the form of increased sperm DNA damage.

show abstract

Size and Function of Mammalian Testes in Relation to Body Size

Cited by 508 publications

References 0 publications

Female multiple mating behaviour, early reproductive failure and litter size variation in mammals

Female multiple mating behaviour, early reproductive failure and litter size variation in mammals

Mating system and brain size in bats

A cost for high levels of sperm competition in rodents: increased sperm DNA fragmentation

Contact Info

Product

Resources

About