Extra-pair paternity, sperm competition and the evolution of testis size in birds

1995 ◽  
Vol 36 (5) ◽  
pp. 357-365 ◽  
Author(s):  
A. P. Moller ◽  
J. V. Briskie
Keyword(s):  
Sperm Competition ◽  
Testis Size ◽  
Extra Pair Paternity

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.

Cooperatively breeding cichlid fish adjust their testis size but not sperm traits in relation to sperm competition risk

2008 ◽  
Vol 62 (11) ◽  
pp. 1701-1710 ◽  
Author(s):  
Satoshi Awata ◽  
Tomohiro Takeyama ◽  
Yoshimi Makino ◽  
Yuko Kitamura ◽  
Masanori Kohda
Keyword(s):  
Sperm Competition ◽  
Cichlid Fish ◽  
Testis Size ◽  
Cooperatively Breeding ◽  
Sperm Competition Risk ◽  
Sperm Traits

scholarly journals Intromittent Organ Morphology and Testis Size in Relation to Mating System in Waterfowl

The Auk ◽  
2002 ◽  
Vol 119 (2) ◽  
pp. 403-413 ◽  
Author(s):  
Christopher R. Coker ◽  
Frank McKinney ◽  
Helen Hays ◽  
Susan V. Briggs ◽  
Kimberly M. Cheng
Keyword(s):  
Body Size ◽  
Sperm Competition ◽  
Unit Area ◽  
Morphological Characteristics ◽  
Adaptive Significance ◽  
Mating Strategies ◽  
Testis Size ◽  
Museum Specimens ◽  
Size Number ◽  
Actual Mechanism

Abstract The waterfowl family Anatidae is one of very few avian taxa that possesses an intromittent organ. This paper examines the adaptive significance of the intromittent organ in waterfowl by determining the relationships between intromittent organ morphology and the intensity of sperm competition (as reflected by frequency of forced extrapair copulations [FEPCs]). Intromittent organ morphological characteristics, including length and circumference (adjusted for body size), number of ridges and knobs (per unit area), ridge or knob height, ridge or knob span, and area covered by ridges and knobs, were measured from scaled drawings of museum specimens of 54 waterfowl species (33 genera), 27 of which were ranked by frequency of FEPC (1 = monogamous, 2 = rare FEPC, 3 = frequent FEPC, and 4 = polygynous or promiscuous). Testes sizes were also investigated in relation to FEPCs, where testes mass (adjusted for body size) from 44 species (24 genera) were obtained (29 species with mating strategies). The size of the testes, the length of the intromittent organ, the height of the intromittent organ ridges and knobs, and the area covered by ridges and knobs increased significantly with the frequency of FEPC, and those relationships exist after correcting for common ancestry constraints. These results are consistent with the hypothesis that waterfowl intromittent organs are involved in sperm competition. Further research into the actual mechanism by which the intromittent organ is involved would be worthwhile.

scholarly journals Collective sperm movements in Peromyscus mice are shaped by phylogenetic history and post-copulatory sexual selection

2020 ◽  
Author(s):  
Kristin A. Hook ◽  
W. David Weber ◽  
Heidi S. Fisher
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Reproductive Tract ◽  
Swimming Performance ◽  
Aggregate Size ◽  
Female Reproductive Tract ◽  
Testis Size ◽  
Limited Evidence ◽  
Closely Related Species ◽  
Sperm Migration

AbstractIn some species, sperm form motile, coordinated groups as they migrate through the female reproductive tract. Collective sperm migration is posited to have evolved to improve sperm swimming performance, and thus may be beneficial in a competitive context, but limited evidence supports this theory. Here we investigate sperm aggregation across closely-related species of Peromyscus mice that naturally vary by mating system. We find that phylogenetic history predicts the likelihood that sperm will aggregate but that variation in aggregate size negatively associates with relative testis size, suggesting that sperm competition has a stabilizing effect on this trait. Moreover, we show that sperm aggregation is not kinematically beneficial for all species, and we hypothesize that swimming performance is dependent on the orientation and composition of sperm groups. To test this, we compared sperm from the two sister-species that aggregate most frequently and find that sperm of the species that evolved under intense sperm competition forms aggregates with efficient geometry more frequently than sperm from its monogamous congener. Together, our results are consistent with the hypothesis that sperm aggregation evolved to improve motility in a competitive context; however, when monogamy evolved secondarily, relaxed sexual selection allowed for less efficient strategies to persist.

scholarly journals Virility does not Imply Immensity: Testis size, Accessory Gland Size and Ejaculate depletion pattern do not Evolve in Response to Experimental Manipulation of Sex Ratio in Drosophila melanogaster

2015 ◽  
Author(s):  
◽  
Zeeshan Ali Syed ◽  
N G Prasad
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Ratio ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Experimental Manipulation ◽  
Reproductive Organ ◽  
Accessory Gland ◽  
Testis Size ◽  
Gland Size ◽  
Competition Theory

Sperm competition theory predicts that increase in sperm competition should result in bigger male reproductive organ(s) or higher ejaculate investment. We test this idea using experimental evolution in Drosophila melanogaster. We maintained replicate populations of Drosophila under male (M) and female (F) biased sex ratio regimes for more than a hundred generations. Males in M regime have evolved higher sperm competitive ability than those in F. We measured the testes and the accessory gland size of virgin and singly mated males from the M and F populations. The M and F males do not differ in either testis or accessory gland size. Additionally, ejaculate investment is not different in the M and F males, as measured by reduction in testis and accessory gland sizes. Thus, contrary to theoretical prediction and evidence from other species, evolved differences in sperm competitive ability is not due to evolution of testis/accessory gland size or strategic ejaculate investment in these populations.

Sperm Competition in Fishes: The Evolution of Testis Size and Ejaculate Characteristics

1997 ◽  
Vol 149 (5) ◽  
pp. 933-954 ◽  
Author(s):  
P. Stockley ◽  
M. J. G. Gage ◽  
G. A. Parker ◽  
A. P. Møller
Keyword(s):  
Sperm Competition ◽  
Testis Size
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