Sperm competition risk affects ejaculate strategy in terms of sperm number but not sperm size in squid

2021 ◽  
Author(s):  
Yoko Iwata ◽  
Noriyosi Sato ◽  
Noritaka Hirohashi ◽  
Yoshiro Watanabe ◽  
Warwick H. H. Sauer ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Sperm Number ◽  
Sperm Competition Risk ◽  
Sperm Size

scholarly journals Sperm midpiece length predicts sperm swimming velocity in house mice

2010 ◽  
Vol 6 (4) ◽  
pp. 513-516 ◽  
Author(s):  
Renée C. Firman ◽  
Leigh W. Simmons
Keyword(s):  
Sperm Competition ◽  
Sperm Morphology ◽  
House Mice ◽  
Swimming Velocity ◽  
Sperm Velocity ◽  
Sperm Midpiece ◽  
Sperm Competition Risk ◽  
Sperm Size ◽  
The Relationship

Evolutionary biologists have argued that there should be a positive relationship between sperm size and sperm velocity, and that these traits influence a male's sperm competitiveness. However, comparative analyses investigating the evolutionary associations between sperm competition risk and sperm morphology have reported inconsistent patterns of association, and in vitro sperm competition experiments have further confused the issue; in some species, males with longer sperm achieve more competitive fertilization, while in other species males with shorter sperm have greater sperm competitiveness. Few investigations have attempted to address this problem. Here, we investigated the relationship between sperm morphology and sperm velocity in house mice ( Mus domesticus ). We conducted in vitro sperm velocity assays on males from established selection lines, and found that sperm midpiece size was the only phenotypic predictor of sperm swimming velocity.

scholarly journals Sperm competition in tropical versus temperate zone birds

2013 ◽  
Vol 280 (1752) ◽  
pp. 20122434 ◽  
Author(s):  
Tomáš Albrecht ◽  
Oddmund Kleven ◽  
Jakub Kreisinger ◽  
Terje Laskemoen ◽  
Taiwo C. Omotoriogun ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Life History Traits ◽  
Multivariate Model ◽  
Temperate Zone ◽  
Tropical Species ◽  
Migration Distance ◽  
Novel Approach ◽  
Sperm Competition Risk ◽  
Sperm Size ◽  
Reduced Risk

Sperm competition represents an important component of post-copulatory sexual selection. It has been argued that the level of sperm competition declines in birds towards the equator. However, to date, sperm competition estimates have been available mainly for avian species inhabiting the northern temperate zone. Here we apply a novel approach, using the coefficient of between-male variation (CV bm ) in sperm size as an index for sperm competition risk, in a comparative analysis of 31 Afrotropical and 99 northern temperate zone passerine species. We found no difference in sperm competition risk between the two groups, nor any relationship with migration distance. However, a multivariate model indicated that sperm competition risk was highest in species with a combination of low body mass and few eggs per clutch. The effect of clutch size was most pronounced in tropical species, which indicates that sperm competition risk in tropical and temperate species is differently associated with particular life-history traits. Although tropical species had lower sperm competition risk than temperate zone species for overlapping clutch sizes, the idea of a generally reduced risk of sperm competition in tropical birds was not supported by our analysis.

Effects of condition and sperm competition risk on sperm allocation and storage in neriid flies

2019 ◽  
Author(s):  
Zachariah Wylde ◽  
Angela Crean ◽  
Russell Bonduriansky
Keyword(s):  
Sperm Competition ◽  
Perceived Risk ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
The Body ◽  
Condition Dependence ◽  
Ejaculate Size ◽  
Sperm Competition Risk ◽  
High Condition ◽  
Allocation Strategies

Abstract Ejaculate traits can be sexually selected and often exhibit heightened condition-dependence. However, the influence of sperm competition risk in tandem with condition-dependent ejaculate allocation strategies is relatively unstudied. Because ejaculates are costly to produce, high-condition males may be expected to invest more in ejaculates when sperm competition risk is greater. We examined the condition-dependence of ejaculate size by manipulating nutrient concentration in the juvenile (larval) diet of the neriid fly Telostylinus angusticollis. Using a fully factorial design we also examined the effects of perceived sperm competition risk (manipulated by allowing males to mate first or second) on the quantity of ejaculate transferred and stored in the three spermathecae of the female reproductive tract. To differentiate male ejaculates, we fed males nontoxic rhodamine fluorophores (which bind to proteins in the body) prior to mating, labeling their sperm red or green. We found that high-condition males initiated mating more quickly and, when mating second, transferred more ejaculate to both of the female’s posterior spermathecae. This suggests that males allocate ejaculates strategically, with high-condition males elevating their ejaculate investment only when facing sperm competition. More broadly, our findings suggest that ejaculate allocation strategies can incorporate variation in both condition and perceived risk of sperm competition.

scholarly journals Environmental Conditions Affect Sperm Competition Risk in Japanese Beetles (Coleoptera: Scarabaeidae)

2008 ◽  
Vol 101 (6) ◽  
pp. 1154-1161 ◽  
Author(s):  
Paul V. Switzer ◽  
Patrick C. Enstrom ◽  
Carissa A. Schoenick
Keyword(s):  
Sperm Competition ◽  
Environmental Conditions ◽  
Sperm Competition Risk

scholarly journals Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 75 ◽  
Author(s):  
David Bierbach ◽  
Amber M Makowicz ◽  
Ingo Schlupp ◽  
Holger Geupel ◽  
Bruno Streit ◽  
...  
Keyword(s):  
Mate Choice ◽  
Sexual Activity ◽  
Sperm Competition ◽  
Evolutionary Significance ◽  
Behavioral Syndromes ◽  
Male Mating ◽  
Data Set ◽  
Poecilia Mexicana ◽  
Audience Effects ◽  
Sperm Competition Risk

Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect), thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR). Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations) and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation), but did not detect a correlation between aggressiveness and audience effects. Suites of correlated behavioral tendencies are termed behavioral syndromes, and our present study provides correlational evidence for the evolutionary significance of SCR in shaping a behavioral syndrome at the species level across poeciliid taxa.

scholarly journals Implications of diversity in sperm size and function for sperm competition and fertility

2008 ◽  
Vol 52 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Montserrat Gomendio ◽  
Eduardo R.S. Roldan
Keyword(s):  
Sperm Competition ◽  
And Function ◽  
Sperm Size

scholarly journals Social manipulation of sperm competition intensity reduces seminal fluid gene expression

2018 ◽  
Vol 14 (1) ◽  
pp. 20170659 ◽  
Author(s):  
Nadia S. Sloan ◽  
Maxine Lovegrove ◽  
Leigh W. Simmons
Keyword(s):  
Gene Expression ◽  
Sperm Competition ◽  
Seminal Fluid ◽  
Fertilization Success ◽  
Accessory Gland ◽  
Fluid Composition ◽  
Competition Intensity ◽  
Teleogryllus Oceanicus ◽  
Sperm Competition Risk ◽  
Considerable Body

A considerable body of evidence supports the prediction that males should increase their expenditure on the ejaculate in response to sperm competition risk. The prediction that they should reduce their expenditure with increasing sperm competition intensity is less well supported. Moreover, most studies have documented plasticity in sperm numbers. Here we show that male crickets Teleogryllus oceanicus exhibit reduced seminal fluid gene expression and accessory gland mass in response to elevated sperm competition intensity. Together with previous research, our findings suggest that strategic adjustments in seminal fluid composition contribute to competitive fertilization success in this species.

Sperm morphology of the Rattini – are the interspecific differences due to variation in intensity of intermale sperm competition?

2018 ◽  
Vol 30 (11) ◽  
pp. 1434 ◽  
Author(s):  
Tessa Pahl ◽  
Hanna J. McLennan ◽  
Yun Wang ◽  
Anang S. Achmadi ◽  
Kevin C. Rowe ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murine Rodent ◽  
Murine Rodents ◽  
Sperm Size

It is widely accepted that in mammals a causal relationship exists between postcopulatory sexual selection and relative testes mass of the species concerned, but how much it determines sperm size and shape is debatable. Here we detailed for the largest murine rodent tribe, the Rattini, the interspecific differences in relative testes mass and sperm form. We found that residual testes mass correlates with sperm head apical hook length as well as its angle, together with tail length, and that within several lineages a few species have evolved highly divergent sperm morphology with a reduced or absent apical hook and shorter tail. Although most species have a relative testes mass of 1–4%, these derived sperm traits invariably co-occur in species with much smaller relative testes mass. We therefore suggest that high levels of intermale sperm competition maintain a sperm head with a long apical hook and long tail, whereas low levels of intermale sperm competition generally result in divergent sperm heads with a short or non-existent apical hook and shorter tail. We thus conclude that sexual selection is a major selective force in driving sperm head form and tail length in this large tribe of murine rodents.

Sign in / Sign up

Export Citation Format

Share Document