Sperm Competition in Muroid Rodents

1984 ◽  
pp. 547-571 ◽  
Author(s):  
DONALD A. DEWSBURY
Keyword(s):  
Sperm Competition ◽  
Muroid Rodents

Studies of sperm competition in two species of muroid rodents

1981 ◽  
Vol 9 (2) ◽  
pp. 121-133 ◽  
Author(s):  
Donald A. Dewsbury ◽  
Denis J. Baumgardner
Keyword(s):  
Sperm Competition ◽  
Muroid Rodents

scholarly journals Sperm competition differentially affects swimming velocity and size of spermatozoa from closely related muroid rodents: head first

Reproduction ◽  
2011 ◽  
Vol 142 (6) ◽  
pp. 819-830 ◽  
Author(s):  
Laura Gómez Montoto ◽  
María Varea Sánchez ◽  
Maximiliano Tourmente ◽  
Juan Martín-Coello ◽  
Juan José Luque-Larena ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Swimming Speed ◽  
Comparative Studies ◽  
Sperm Head ◽  
Swimming Velocity ◽  
Evolutionary Changes ◽  
Muroid Rodents ◽  
Sperm Swimming Speed ◽  
Sperm Size ◽  
Head Area

Sperm competition favours an increase in sperm swimming velocity that maximises the chances that sperm will reach the ova before rival sperm and fertilise. Comparative studies have shown that the increase in sperm swimming speed is associated with an increase in total sperm size. However, it is not known which are the first evolutionary steps that lead to increases in sperm swimming velocity. Using a group of closely related muroid rodents that differ in levels of sperm competition, we here test the hypothesis that subtle changes in sperm design may represent early evolutionary changes that could make sperm swim faster. Our findings show that as sperm competition increases so does sperm swimming speed. Sperm swimming velocity is associated with the size of all sperm components. However, levels of sperm competition are only related to an increase in sperm head area. Such increase is a consequence of an increase in the length of the sperm head, and also of the presence of an apical hook in some of the species studied. These findings suggest that the presence of a hook may modify the sperm head in such a way that would help sperm swim faster and may also be advantageous if sperm with larger heads are better able to attach to the epithelial cells lining the lower isthmus of the oviduct where sperm remain quiescent before the final race to reach the site of fertilisation.

scholarly journals Sperm Competition, Sperm Numbers and Sperm Quality in Muroid Rodents

PLoS ONE ◽  
2011 ◽  
Vol 6 (3) ◽  
pp. e18173 ◽  
Author(s):  
Laura Gómez Montoto ◽  
Concepción Magaña ◽  
Maximiliano Tourmente ◽  
Juan Martín-Coello ◽  
Cristina Crespo ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Sperm Quality ◽  
Muroid Rodents

scholarly journals Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Andrew Singson ◽  
Katherine L Hill ◽  
Steven W L’Hernault
Keyword(s):  
Caenorhabditis Elegans ◽  
Sperm Competition ◽  
Sperm Function ◽  
Sperm Precedence ◽  
Wild Type ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Normal Sperm ◽  
Self Fertilization ◽  
Competition Assays

Abstract Hermaphrodite self-fertilization is the primary mode of reproduction in the nematode Caenorhabditis elegans. However, when a hermaphrodite is crossed with a male, nearly all of the oocytes are fertilized by male-derived sperm. This sperm precedence during reproduction is due to the competitive superiority of male-derived sperm and results in a functional suppression of hermaphrodite self-fertility. In this study, mutant males that inseminate fertilization-defective sperm were used to reveal that sperm competition within a hermaphrodite does not require successful fertilization. However, sperm competition does require normal sperm motility. Additionally, sperm competition is not an absolute process because oocytes not fertilized by male-derived sperm can sometimes be fertilized by hermaphrodite-derived sperm. These results indicate that outcrossed progeny result from a wild-type cross because male-derived sperm are competitively superior and hermaphrodite-derived sperm become unavailable to oocytes. The sperm competition assays described in this study will be useful in further classifying the large number of currently identified mutations that alter sperm function and development in C. elegans.

scholarly journals Functional morphology of immature mating in a widow spider

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Lenka Sentenská ◽  
Aileen Neumann ◽  
Yael Lubin ◽  
Gabriele Uhl
Keyword(s):  
Sperm Competition ◽  
Storage Conditions ◽  
Sperm Storage ◽  
Sperm Transfer ◽  
Costs And Benefits ◽  
Micro Computed Tomography ◽  
Mating Tactics ◽  
Adult Females ◽  
Storage Organs ◽  
Widow Spider

Abstract Background Mating generally occurs after individuals reach adulthood. In many arthropods including spiders, the adult stage is marked by a final moult after which the genitalia are fully developed and functional. In several widow spider species (genus Latrodectus), however, immature females may mate a few days before they moult to adulthood, i.e. in their late-subadult stage. While the “adult” mating typically results in cannibalism, males survive the “immature” mating. During both “immature” and “adult” matings, males leave parts of their paired copulatory organs within female genitalia, which may act as mating plugs. To study potential costs and benefits of the two mating tactics, we investigated female genital morphology of the brown widow spider, L. geometricus. Light microscopy, histology and micro-computed tomography of early-subadult, late-subadult and adult females were conducted to determine the overall pattern of genital maturation. We compared genitalia of mated late-subadult and adult females to reveal potential differences in the genitalic details that might indicate differential success in sperm transfer and different environments for sperm storage and sperm competition. Results We found that the paired sperm storage organs (spermathecae) and copulatory ducts are developed already in late-subadult females and host sperm after immature mating. However, the thickness of the spermathecal cuticle and the staining of the secretions inside differ significantly between the late-subadult and adult females. In late-subadult females mating plugs were found with higher probability in both spermathecae compared to adult females. Conclusions Sperm transfer in matings with late-subadult females follows the same route as in matings with adult females. The observed differences in the secretions inside the spermathecae of adult and late-subadult females likely reflect different storage conditions for the transferred sperm which may lead to a disadvantage under sperm competition if the subadult female later re-mates with another male. However, since males mating with late-subadult females typically transfer sperm to both spermathecae they might benefit from numerical sperm competition as well as from monopolizing access to the female sperm storage organs. The assessment of re-mating probability and relative paternity will clarify the costs and benefits of the two mating tactics in light of these findings.

scholarly journals Fisher vs. The Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms That Produce Them

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1793
Author(s):  
Justin Van Goor ◽  
Diane C. Shakes ◽  
Eric S. Haag
Keyword(s):  
Sex Ratio ◽  
Sperm Competition ◽  
Sex Chromosomes ◽  
Sex Ratios ◽  
Environmental Sex Determination ◽  
Fitness Advantage ◽  
Selection For ◽  
Facultative Parthenogenesis ◽  
Multicellular Organisms ◽  
Inbred Populations

Parker, Baker, and Smith provided the first robust theory explaining why anisogamy evolves in parallel in multicellular organisms. Anisogamy sets the stage for the emergence of separate sexes, and for another phenomenon with which Parker is associated: sperm competition. In outcrossing taxa with separate sexes, Fisher proposed that the sex ratio will tend towards unity in large, randomly mating populations due to a fitness advantage that accrues in individuals of the rarer sex. This creates a vast excess of sperm over that required to fertilize all available eggs, and intense competition as a result. However, small, inbred populations can experience selection for skewed sex ratios. This is widely appreciated in haplodiploid organisms, in which females can control the sex ratio behaviorally. In this review, we discuss recent research in nematodes that has characterized the mechanisms underlying highly skewed sex ratios in fully diploid systems. These include self-fertile hermaphroditism and the adaptive elimination of sperm competition factors, facultative parthenogenesis, non-Mendelian meiotic oddities involving the sex chromosomes, and environmental sex determination. By connecting sex ratio evolution and sperm biology in surprising ways, these phenomena link two “seminal” contributions of G. A. Parker. 

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.

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