Sperm Competition: Mating System, Not Breeding Season, Affects Testes Size of Primates

1995 ◽  
Vol 9 (3) ◽  
pp. 468 ◽  
Author(s):  
A. H. Harcourt ◽  
A. Purvis ◽  
L. Liles
Keyword(s):  
Mating System ◽  
Sperm Competition ◽  
Breeding Season ◽  
Testes Size

Mating Tactics in the Tropical Millipede Alloporus Uncinatus (Diplopoda: Spirostreptidae)

Behaviour ◽  
1993 ◽  
Vol 124 (1-2) ◽  
pp. 45-56 ◽  
Author(s):  
Steven R. Telford ◽  
J. Mark Dangerfield
Keyword(s):  
Sex Ratio ◽  
Mating System ◽  
Sperm Competition ◽  
Breeding Season ◽  
Female Choice ◽  
Laboratory Experiments ◽  
Mating Behaviour ◽  
Operational Sex Ratio ◽  
Mating Tactics ◽  
Mate Acquisition

AbstractField and laboratory observations of mating behaviour in a population of the tropical millipede Alloporus uncinatus were carried out over one breeding season. Males obtained mates through random encounters and by forming triplet associations with copula pairs. The occurrence of triplet associations in the field was coincident with a highly male biased operational sex ratio. Mate acquisition by males was apparently stochastic and direct physical competition did not occur. In laboratory experiments mating was size-selective probably as a consequence of female choice. We consider the possibility that sperm competition has contributed to the evolution of the mating system in this species.

Erratum: Sperm Competition: Mating System, Not Breeding System, Affects Testes Size of Primates

1996 ◽  
Vol 10 (2) ◽  
pp. 306 ◽  
Author(s):  
A. H. Harcourt ◽  
A. Purvis ◽  
L. Liles
Keyword(s):  
Mating System ◽  
Sperm Competition ◽  
Breeding System ◽  
Testes Size

Relative testis size and mating systems in anurans: large testis in multiple-male mating in foam-nesting frogs

2011 ◽  
Vol 61 (2) ◽  
pp. 225-238 ◽  
Author(s):  
Wen Bo Liao ◽  
Zhi Ping Mi ◽  
Cai Quan Zhou ◽  
Ling Jin ◽  
Xian Han ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Published Data ◽  
Male Mating ◽  
Data Sets ◽  
Testis Size ◽  
Data Set ◽  
Monogamous Species ◽  
Large Testis ◽  
Testes Size ◽  
Testis Mass

AbstractComparative studies of the relative testes size in animals show that promiscuous species have relatively larger testes than monogamous species. Sperm competition favours the evolution of larger ejaculates in many animals – they give bigger testes. In the view, we presented data on relative testis mass for 17 Chinese species including 3 polyandrous species. We analyzed relative testis mass within the Chinese data set and combining those data with published data sets on Japanese and African frogs. We found that polyandrous foam nesting species have relatively large testes, suggesting that sperm competition was an important factor affecting the evolution of relative testes size. For 4 polyandrous species testes mass is positively correlated with intensity (males/mating) but not with risk (frequency of polyandrous matings) of sperm competition.

2. Mating systems, or who goes with whom, and for how long

2018 ◽  
pp. 16-33
Author(s):  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Mating System ◽  
Social Relationships ◽  
Breeding Season ◽  
Mating Systems ◽  
Practical Applications ◽  
Multiple Partners ◽  
Monogamous Species ◽  
Genetic Techniques ◽  
Males And Females

‘Mating systems, or who goes with whom, and for how long’ examines the variation in how males and females associate during the breeding season, ranging from brief couplings with multiple partners to lifelong monogamy. It also shows how the discovery that females mate with many partners, even in supposedly monogamous species such as songbirds, was made possible by modern genetic techniques. Variation in mating systems holds considerable implications for the operation of sexual selection. The way that animal mating systems have been explained historically is outlined before considering how a more contemporary understanding of genetic and social relationships has reshaped our thinking and how understanding a species’ mating system can have practical applications.

scholarly journals Male crickets adjust ejaculate quality with both risk and intensity of sperm competition

2007 ◽  
Vol 3 (5) ◽  
pp. 520-522 ◽  
Author(s):  
Leigh W Simmons ◽  
Amy Denholm ◽  
Chantelle Jackson ◽  
Esther Levy ◽  
Ewa Madon
Keyword(s):  
Sperm Competition ◽  
High Intensity ◽  
Teleogryllus Oceanicus ◽  
Competition Theory ◽  
Rival Male ◽  
Testes Size ◽  
Increasing Risk ◽  
Live Sperm

Sperm competition theory predicts that males should increase their expenditure on the ejaculate with increasing risk of sperm competition, but decrease their expenditure with increasing intensity. There is accumulating evidence for sperm competition theory, based on examinations of testes size and/or the numbers of sperm ejaculated. However, recent studies suggest that ejaculate quality can also be subject to selection by sperm competition. We used experimental manipulations of the risk and intensity of sperm competition in the cricket, Teleogryllus oceanicus . We found that males produced ejaculates with a greater percentage of live sperm when they had encountered a rival male prior to mating. However, when mating with a female that presented a high intensity of sperm competition, males did not respond to risk, but produced ejaculates with a reduced percentage of live sperm. Our data suggest that males exhibit a fine-tuned hierarchy of responses to these cues of sperm competition.

Copulation calls in wild Mueller’s gibbons (Hylobates muelleri)

2019 ◽  
Vol 20 (2) ◽  
pp. 362-374
Author(s):  
Yoichi Inoue ◽  
Waidi Sinun ◽  
Kazuo Okanoya
Keyword(s):  
Mating System ◽  
Social Organization ◽  
Sperm Competition ◽  
Mate Guarding ◽  
Conservation Area ◽  
Mating Activity ◽  
Selective Pressures ◽  
Female Promiscuity ◽  
Vocal Signals ◽  
The Relationship

Abstract Mating activity of a wild Mueller’s gibbon group (Hylobates muelleri) was observed in the Danum Valley Conservation Area, Sabah, Malaysia. The purpose of this study was to investigate the function of copulation calls in gibbons. The female emitted copulation calls at the time of intromission and pelvic thrusting. Copulation calls were composed of two notes and one of them was sung only while mating. Approximately half of copulation calls were sung near the range boundary. Mating with copulation calls sometimes occurred while singing. According to the model that female copulation calls have evolved under the selective pressures of risk of infanticide and sperm competition, copulation calls should be rare in species with little female promiscuity. As gibbons usually live in pair-living social organization and have a monogamous mating system, no vocal signals by female gibbons are considered to be needed. However, clear copulation calls were emitted by the female. It suggests that the relationship between paired gibbons is unstable. Copulation calls by the female Mueller’s gibbon may function to increase mate guarding and strengthen the pair bond.

scholarly journals Contrasting effects of large density changes on relative testes size in fluctuating populations of sympatric vole species

2014 ◽  
Vol 281 (1792) ◽  
pp. 20141291 ◽  
Author(s):  
Ines Klemme ◽  
Carl D. Soulsbury ◽  
Heikki Henttonen
Keyword(s):  
Sperm Competition ◽  
Species Interactions ◽  
Large Scale ◽  
Density Fluctuations ◽  
Ecological Processes ◽  
Evolutionary Response ◽  
Density Relationship ◽  
Testes Size ◽  
Male Reproductive Effort ◽  
Fluctuating Populations

Across species, there is usually a positive relationship between sperm competition level and male reproductive effort on ejaculates, typically measured using relative testes size (RTS). Within populations, demographic and ecological processes may drastically alter the level of sperm competition and thus, potentially affect the evolution of testes size. Here, we use longitudinal records (across 38 years) from wild sympatric Fennoscandian populations of five species of voles to investigate whether RTS responds to natural fluctuations in population density, i.e. variation in sperm competition risk. We show that for some species RTS increases with density. However, our results also show that this relationship can be reversed in populations with large-scale between-year differences in density. Multiple mechanisms are suggested to explain the negative RTS–density relationship, including testes size response to density-dependent species interactions, an evolutionary response to sperm competition levels that is lagged when density fluctuations are over a certain threshold, or differing investment in pre- and post-copulatory competition at different densities. The results emphasize that our understanding of sperm competition in fluctuating environments is still very limited.

scholarly journals Sperm competition and the evolution of testes size in birds

2005 ◽  
Vol 18 (3) ◽  
pp. 557-567 ◽  
Author(s):  
T. E. PITCHER ◽  
P. O. DUNN ◽  
L. A. WHITTINGHAM
Keyword(s):  
Sperm Competition ◽  
Testes Size

scholarly journals Testes size, testosterone production and reproductive behaviour in a natural mammalian mating system

2011 ◽  
Vol 81 (1) ◽  
pp. 296-305 ◽  
Author(s):  
Brian T. Preston ◽  
Ian R. Stevenson ◽  
Gerald A. Lincoln ◽  
Steven L. Monfort ◽  
Jill G. Pilkington ◽  
...  
Keyword(s):  
Mating System ◽  
Reproductive Behaviour ◽  
Testosterone Production ◽  
Testes Size
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