scholarly journals Freezing ovarian fluid does not alter how it affects fish sperm swimming performance: creating a cryptic female choice ‘spice rack’ for use in split‐ejaculate experimentation

2020 ◽  
Vol 96 (3) ◽  
pp. 693-699 ◽  
Author(s):  
Craig F. Purchase ◽  
Anna C. Rooke
2019 ◽  
Vol 30 (5) ◽  
pp. 1298-1305 ◽  
Author(s):  
Federica Poli ◽  
Simone Immler ◽  
Clelia Gasparini

AbstractIn polyandrous mating systems, females maintain the opportunity to bias male fertilization success after mating in a process known as cryptic female choice. Mechanisms of cryptic female choice have been described both in internal and external fertilizers, and may affect fertilization processes at different stages before, during, and after fertilization. In internal fertilizers, females have substantial control over sperm storage and fertilization, whereas in external fertilizers, female control is limited. A key factor proposed to mediate cryptic female choice is the fluid surrounding the eggs, the ovarian fluid, as it may directly affect sperm performance. Here, we studied the role of ovarian fluid in post-mating sexual selection using the zebrafish, Danio rerio. Firstly, we assessed how ovarian fluid affects sperm swimming performance compared with freshwater. We focused on sperm motility, velocity, swimming trajectory, and longevity, all traits associated with competitive fertilization success in externally fertilizing fish. In a second step, we used a North Carolina II design to explore female, male, and female x male effects by testing sperm motility of 2 males in the ovarian fluid of 2 females in a total of 11 blocks. Our results indicate that the ovarian fluid affects sperm performance differently from freshwater. Specifically, sperm velocity, motility, and longevity were higher in the ovarian fluid than in freshwater, whereas sperm linearity and beat cross frequency showed the opposite pattern. Moreover, these effects varied according to male, female, and male x female identities, supporting the potential for cryptic female choice mediated by ovarian fluid in this species.


2017 ◽  
Vol 284 (1859) ◽  
pp. 20170853 ◽  
Author(s):  
Cornelia Geßner ◽  
Sheri L. Johnson ◽  
Paul Fisher ◽  
Shannon Clarke ◽  
Kim Rutherford ◽  
...  

In a range of taxa, the relatedness between mates influences both pre- and post-mating processes of sexual selection. However, relatively little is known about the genetic loci facilitating such a bias, with the exception of the major histocompatibility complex. Here, we performed tightly controlled replicated in vitro fertilization trials to explore the impact of relatedness on two possible mechanisms of cryptic female choice (CFC) in Chinook salmon ( Oncorhynchus tshawytscha ). We tested (i) whether relatedness of mates, assessed using 682 single nucleotide polymorphisms (SNPs) on 29 SNP-linkage groups (LGs), biases a male's sperm velocity in ovarian fluid (a parameter previously shown to predict male fertilization success), and (ii) whether relatedness of mates governs fertilization success via other mechanisms, probably via sperm–egg interactions. We found that relatedness on three LGs explained the variation in sperm velocity, and relatedness on two LGs explained fertilization success, which might indicate the presence of genes important in sperm–ovarian fluid and sperm–egg interactions in these genomic regions. Mapping of the SNPs on these LGs to the rainbow trout genome revealed two genes that affect fertility in humans and represent candidate genes for further studies. Our results thereby provide a novel contribution to the understanding of the mechanism of CFC.


2021 ◽  
Author(s):  
Tyler H. Lantiegne ◽  
Craig F. Purchase

Polyandrous mating systems result in females mating with multiple males. This includes the potential for unintended matings and subsequent sperm competition with hybridizing species, especially in the presence of alternative reproductive tactics (sneaker males). Cryptic female choice allows females to bias paternity towards preferred males under sperm competition and may include conspecific sperm preference when under hybridization threat. The potential becomes particularly important in context of invasive species that can novelly hybridize with natives. We provide the first examination of conspecific sperm preference in a system of three species with potential to hybridize: North American native Atlantic salmon (Salmo salar) and brook char (Salvelinus fontinalis), and invasive brown trout (Salmo trutta) from Europe. Using naturalized populations on the island of Newfoundland, we measured changes in sperm swimming performance, a known predictor of paternity, to determine the degree of upregulation to female cues related to conspecific sperm preference. Compared to water alone, female ovarian fluid in general had a pronounced effect and upregulated sperm motility (mean 53%) and swimming velocity (mean 30%). However, patterns in the degree of upregulation suggest there is no conspecific sperm preference in the North American populations. Furthermore, female cues from both native species tended to boost the sperm of invasive males more than their own. We conclude that cryptic female choice is too weak in this system to prevent invasive hybridization and is likely insufficient to promote or maintain reproductive isolation between the native species.


Author(s):  
Patricia L.R. Brennan ◽  
Dara N. Orbach

The field of post-copulatory sexual selection investigates how female and male adaptations have evolved to influence the fertilization of eggs while optimizing fitness during and after copulation, when females mate with multiple males. When females are polyandrous (one female mates with multiple males), they may optimize their mating rate and control the outcome of mating interactions to acquire direct and indirect benefits. Polyandry may also favor the evolution of male traits that offer an advantage in post-copulatory male-male sperm competition. Sperm competition occurs when the sperm, seminal fluid, and/or genitalia of one male directly impacts the outcome of fertilization success of a rival male. When a female mates with multiple males, she may use information from a number of traits to choose who will sire her offspring. This cryptic female choice (CFC) to bias paternity can be based on behavioral, physiological, and morphological criteria (e.g., copulatory courtship, volume and/or composition of seminal fluid, shape of grasping appendages). Because male fitness interests are rarely perfectly aligned with female fitness interests, sexual conflict over mating and fertilization commonly occur during copulatory and post-copulatory interactions. Post-copulatory interactions inherently involve close associations between female and male reproductive characteristics, which in many species potentially include sperm storage and sperm movement inside the female reproductive tract, and highlight the intricate coevolution between the sexes. This coevolution is also common in genital morphology. The great diversity of genitalia among species is attributed to sexual selection. The evolution of genital attributes that allow females to maintain reproductive autonomy over paternity via cryptic female choice or that prevent male manipulation and sexual control via sexually antagonistic coevolution have been well documented. Additionally, cases where genitalia evolve through intrasexual competition are well known. Another important area of study in post-copulatory sexual selection is the examination of trade-offs between investments in pre-copulatory and post-copulatory traits, since organisms have limited energetic resources to allocate to reproduction, and securing both mating and fertilization is essential for reproductive success.


Sign in / Sign up

Export Citation Format

Share Document