Insect Sperm Competition

2016 ◽  
pp. 1-4
Author(s):  
Zenobia Lewis
Keyword(s):  
Sperm Competition ◽  
Insect Sperm

scholarly journals Sperm Viability Matters in Insect Sperm Competition

2005 ◽  
Vol 15 (3) ◽  
pp. 271-275 ◽  
Author(s):  
Francisco Garcı́a-González ◽  
Leigh W. Simmons
Keyword(s):  
Sperm Competition ◽  
Sperm Viability ◽  
Insect Sperm

Spermatogenesis in the Dragonfly with Particular Reference to the Cytoplasmic Organelles

1972 ◽  
Vol 30 ◽  
pp. 110-111
Author(s):  
Sant S. Sekhon
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Mature Sperm ◽  
Electron Microscopic ◽  
Cytoplasmic Organelles ◽  
Microscopic Studies ◽  
Insect Sperm ◽  
Large Round

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).

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. 

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