Longer Sperm Swim More Slowly in the Canary Islands Chiffchaff by Emily R. A. Cramer, Eduardo Garcia-del-Rey, Lars Erik Johannessen, Terje Laskemoen, Gunnhild Marthinsen, Arild Johnsen, Jan T. Lifjeld

“…Sperm swimming performance affects male fertilization success, particularly in species with high sperm competition. Understanding how sperm morphology impacts swimming performance is therefore important. …”
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Genotype‐by‐environment interactions for precopulatory mate guarding in a lek‐mating insect by Nikolas Vellnow, Sonja Schindler, Tim Schmoll

“…Previous studies showed the mating latency with the second female to be shorter under higher perceived sperm competition risk. We accordingly measured the mate‐guarding behavior of males from six inbred lines under either elevated perceived male–male competition risk or under control conditions allowing us to test for G × E interactions. …”
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Sexual coevolution of spermatophore envelopes and female genital traits in butterflies: Evidence of male coercion? by Víctor Sánchez, Carlos Cordero

“…According to the SAC hypothesis, males evolved thick spermatophore envelopes to delay the post-mating recovery of female sexual receptivity thus reducing sperm competition; in response, females evolved signa for breaking spermatophore envelopes faster, gaining access to the resources contained in them and reducing their intermating intervals; the evolution of signa, in turn, favored the evolution of even thicker spermatophore envelopes, and so on. …”
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Low sperm to egg ratio required for successful in vitro fertilization in a pair-spawning teleost, Senegalese sole (Solea senegalensis) by Sandra Ramos-Júdez, Wendy Ángela González-López, Jhons Huayanay Ostos, Noemí Cota Mamani, Carlos Marrero Alemán, José Beirão, Neil Duncan

“…Senegalese sole have a pair-spawning reproductive behaviour characterized by gamete fertilization in close proximity with no sperm competition. The provision of a large-scale in vitro fertilization protocol (200 µl of sperm per 100 ml of eggs) will enable the industry to operate sustainably and implement breeding programmes to improve production.…”
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Molecular evolution of mammalian genes with epistatic interactions in fertilization by Claire C. Morgan, Michael W. Hart

“…Abstract Background Genes that encode proteins associated with sperm competition, fertilization, and sexual conflicts of interest are often among the most rapidly evolving parts of animal genomes. …”
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Sexual selection and personality: individual and group-level effects on mating behaviour in red junglefowl by Roth, AM, Dingemanse, NJ, Nakagawa, S, McDonald, GC, Løvlie, H, Robledo-Ruiz, DA, Pizzari, T

“…In female-biased groups, the fastest- and slowest-exploring males experienced the highest mating success and lowest sperm competition intensity. Faster-exploring males also obtained more mates in female-biased groups when their competitors were, on average, slower-exploring, and the proportion of matings obtained by fast-exploring males decreased with the proportion of fast-exploring males in a group, consistent with negative frequency-dependent sexual selection. …”

Reproductive biology of the mice and rats (family Muridae) in New Guinea—diversity and evolution. In Papers in Honour of Ken Aplin, ed. Julien Louys, Sue O’Connor, and Kristofer M.... by William G. Breed, Chris M. Leigh, Eleanor J. Peirce

“…The findings of large relative testes mass in Pogonomys and long sperm tails in Chiruromys and Xenuromys suggest selection for high levels of intermale sperm competition and hence multimale breeding systems in these species, whereas the variation in preputial gland size suggest interspecific differences in social organization.…”

Variation in the reproductive quality of honey bee males affects their age of flight attempt by Bradley N. Metz, David R. Tarpy

“…Background Honey bee males (drones) exhibit life histories that enable a high potential for pre- or post-copulatory sperm competition. With a numerical sex ratio of ∼11,000 drones for every queen, they patrol flyways and congregate aerially to mate on the wing. …”
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Discovering novel reproductive genes in a non-model fly using de novo GridION transcriptomics by Mrinalini Walter, Nalini Puniamoorthy

“…These genes synthesize seminal fluid proteins that often affect post-copulatory sexual selection—they can mediate male-male sperm competition, ejaculate-female interactions that modify female remating and even influence reproductive incompatibilities among diverging species/populations. …”
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Genomic Insights Into the Molecular Basis of Sexual Selection in Birds by Shubham K. Jaiswal, Ankit Gupta, Aaron B. A. Shafer, Vishnu Prasoodanan P. K., Nagarjun Vijay, Vineet K. Sharma

“…Genes involved in nucleic acid binding and gene expression regulation, including a specific regulator of sex-determination known as TRA2A to be under positive selection in the species with high post-copulatory sexual selection manifested as high sperm competition. We also detected specific feather-related and immune-related gene-pairs evolving under similar selection pressures across the 11 species, including peacock (Pavo cristatus), which is consistent with the Hamilton-Zuk hypothesis. …”
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Bovine Follicular Fluid Derived Extracellular Vesicles Modulate the Viability, Capacitation and Acrosome Reaction of Bull Spermatozoa by Mohammad Mehedi Hasan, Qurat Ul Ain Reshi, Freddy Lättekivi, Janeli Viil, Kasun Godakumara, Keerthie Dissanayake, Aneta Andronowska, Ülle Jaakma, Alireza Fazeli

“…This is an important aspect of the interactions between different sexes at the earliest stages of reproduction and helps to understand molecular mechanisms modulating processes such as sperm competition and female cryptic choice.…”
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Sperm Chromatin Status and DNA Fragmentation in Mouse Species with Divergent Mating Systems by Clara Agudo-Rios, Ana Sanchez-Rodriguez, Ingrid I. D. Idrovo, Juan Ángel Laborda-Gomariz, Ana J. Soler, Maria E. Teves, Eduardo R. S. Roldan

“…The relationship between chromatin status and DNA integrity appeared to be related to levels of sperm competition among species.…”
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Mate availability does not influence mating strategies in males of the sexually cannibalistic spider Argiope bruennichi by Anna-Lena Cory, Jutta M. Schneider

“…Males of this species mutilate their genitalia during copulation, which reduces sperm competition and limits their mating rate to a maximum of two females (bigyny). …”
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Differential allocation in a gift-giving spider: males adjust their reproductive investment in response to female condition by Diego Solano-Brenes, Luiz Ernesto Costa-Schmidt, Maria Jose Albo, Glauco Machado

“…These females are more fecund and oviposit faster after copulation than females in poor body condition, which under natural field conditions probably reduces the risk of multiple matings and thus the level of sperm competition faced by the males. As a final remark, our findings indicate that the hypothesis of differential allocation also applies to species with a scramble competition mating system, in which males heavily invest in nuptial gift construction, but not in parental care.…”
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A targeted in situ hybridization screen identifies putative seminal fluid proteins in a simultaneously hermaphroditic flatworm by Michael Weber, Julia Wunderer, Birgit Lengerer, Robert Pjeta, Marcelo Rodrigues, Lukas Schärer, Peter Ladurner, Steven A. Ramm

“…Results Based on existing transcriptomic data, we selected 150 transcripts known to be (a) predominantly expressed in the tail region of the worms, where the seminal fluid-producing prostate gland cells are located, and (b) differentially expressed in social environments differing in sperm competition level, strongly implying that they represent a phenotypically plastic aspect of male reproductive allocation in this species. …”
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Evolution of nuptial gifts and its coevolutionary dynamics with male-like persistence traits of females for multiple mating by Yoshitaka Kamimura, Kazunori Yoshizawa, Charles Lienhard, Rodrigo L. Ferreira, Jun Abe

“…Nuptial gifting sometimes causes severe female-female competition for obtaining gifts (i.e., sex-role reversal in mate competition) and selection on females to increase their mating rate, changing the intensity of sperm competition and the resultant paternity gains. We built a theoretical model to simulate such coevolutionary feedbacks between nuptial gift size (male trait) and propensity for multiple mating (female trait). …”
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Group size and mating system predict sex differences in vocal fundamental frequency in anthropoid primates by Toe Aung, Alexander K. Hill, Dana Pfefferle, Edward McLester, James Fuller, Jenna M. Lawrence, Ivan Garcia-Nisa, Rachel L. Kendal, Megan Petersdorf, James P. Higham, Gérard Galat, Adriano R. Lameira, Coren L. Apicella, Claudia Barelli, Mary E. Glenn, Gabriel Ramos-Fernandez, David A. Puts

“…In a sample of vocalizations (n = 1914 recordings) across 37 anthropoid species, we investigated whether fundamental frequency dimorphism evolved in association with increased intensity of mating competition (H1), large group size (H2), multilevel social organization (H3), a trade-off against the intensity of sperm competition (H4), and/or poor acoustic habitats (H5), controlling for phylogeny and body size dimorphism. …”
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Sperm collection in Black-legged Kittiwakes and characterization of sperm velocity and morphology by Ségolène Humann-Guilleminot, Pierre Blévin, Antonin Azou-Barré, Agathe Yacoumas, Geir Wing Gabrielsen, Olivier Chastel, Fabrice Helfenstein

“…Conclusions We discuss the high percentage of abnormal sperm and high within-ejaculate variation in sperm morphology in light of sperm competition theory and conclude that these figures are likely due to relaxed post-copulatory sexual selection, kittiwakes being strictly monogamous. …”
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Spawning aggregation behavior and reproductive ecology of the giant bumphead parrotfish, Bolbometopon muricatum, in a remote marine reserve by Roldan C. Muñoz, Brian J. Zgliczynski, Bradford Z. Teer, Joseph L. Laughlin

“…Mating interference was not witnessed but we noted instances suggesting that sperm competition might occur. Densities of Bolbometopon on the aggregation site averaged 10.07(±3.24 SE) fish per hectare (ha) with maximum densities of 51.5 fish per ha. …”
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The evolution of social behaviour: the effect of mating system and social structure in the European badger Meles meles by Dugdale, H

“…Promiscuous and repeated mountings were observed, which may reduce male–male aggression and infanticide, but may also promote sperm competition, genetic diversity, and / or genetic compatibility. …”