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 Concepts in sperm heterogeneity, sperm selection and sperm competition as biological foundations for laboratory tests of semen quality

Reproduction ◽  
2004 ◽  
Vol 127 (5) ◽  
pp. 527-535 ◽  
Author(s):  
William V Holt ◽  
Katrien J W Van Look
Keyword(s):  
Sperm Competition ◽  
Laboratory Tests ◽  
Semen Quality ◽  
Sea Urchins ◽  
Selection Process ◽  
Sperm Quality ◽  
Genetic Material ◽  
Mendelian Inheritance ◽  
Competition Theory ◽  
Selection Processes

Stringent selection mechanisms, in both internal and external fertilisation systems, reject all but a significant minority of the spermatozoa released at ejaculation. Sperm competition theory provides circumstantial evidence that the selection process involves mechanisms by which the quality of the fertilising spermatozoon is controlled, thereby ensuring that females and their offspring receive high quality genetic material. In this review we examine some of these selection processes to see whether they could be exploited for the improvement of laboratory tests of sperm quality. Such tests are not only required for clinical and agricultural purposes, but are increasingly needed in fields such as reproductive and environmental toxicology where the species requirement is much broader. Despite many years of research, sperm quality assessment methods continue to provide imprecise data about fertility; here we suggest that this may be a consequence of using tests that focus on the spermatozoa that would normally be unable to fertilise under natural conditions. To achieve fertilisation a spermatozoon must be capable of responding appropriately to external signalling stimuli; those involving protein kinase-regulated flagellar function seem especially influential in governing effects ranging from non-Mendelian inheritance in mammals to sperm chemotaxis in sea urchins. Examination of the elicited responses reveals considerable heterogeneity in all species. Here we propose that this level of heterogeneity is meaningful both in terms of understanding how spermatozoa from some individuals possess fertility advantages over spermatozoa from their rivals in sperm competition, and in that the heterogeneity should be exploitable in the development of more accurate laboratory tests.

scholarly journals A scientometric analysis on pre- and post-copulatory traits in Odonata

2021 ◽  
Vol 24 ◽  
pp. 215-226
Author(s):  
Gabrielle Cristina Pestana ◽  
Erick Mateus-Barros ◽  
Leandro Schlemmer Brasil ◽  
Rhainer Guillermo-Ferreira
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Quality ◽  
Large Body ◽  
Size Variation ◽  
Integrative Approach ◽  
Scientometric Analysis ◽  
Sexual Ornaments ◽  
Male Characters ◽  
Male Wing

In the last decades, studies on sexual selection in odonates have shown a relationship between mating success and costly sexual ornaments, mainly male characters. Here, we conducted a scientometric analysis to assess the state of art of studies on sexual selection in odonates, especially on the role of male ornamentation (pre-copulatory traits) and sperm competition (post-copulatory traits). We found 51 papers focused on sexual ornamentation and 34 on sperm competition. Only one study simultaneously addressed both pre- and post-copulatory traits, nevertheless without an integrative approach. Results show that calopterygids are extensively studied regarding pre-copulatory traits (i.e., male wing pigmentation), while libellulids are mostly studied in post- copulatory traits (e.g., sperm competition) focused research. These preferences seem to be related to characteristics like presence of ornamentation and territoriality, large body size, variation and complexity of sperm removal structures, respectively. For the post-copulatory traits, sperm removal is frequently addressed, but few other strategies, like the investment in sperm quality and quantity, are investigated. Finally, we demonstrate that it is necessary to conduct studies focused on addressing the relationship between pre- and post- mating sexual traits.

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.

Sperm competition and fertilization success in Atlantic cod (Gadus morhua): effect of sire size and condition factor on gamete quality

1999 ◽  
Vol 56 (12) ◽  
pp. 2315-2323 ◽  
Author(s):  
Ana Rakitin ◽  
Moira M Ferguson ◽  
Edward A Trippel
Keyword(s):  
Body Size ◽  
Sperm Competition ◽  
Gadus Morhua ◽  
Condition Factor ◽  
Atlantic Cod ◽  
Sperm Quality ◽  
Fertilization Success ◽  
Male Body ◽  
Single Female ◽  
Male Condition

Sperm competition experiments were conducted to test the null hypothesis that sperm quality is not affected by male body size in Atlantic cod (Gadus morhua). Genetic markers (allozymes) were used to determine the proportion of larvae sired by pairs of males when their sperm was combined with eggs of a single female simultaneously. Significant differences in fertilization success between males were not explained by differences in body size. Fertilization success was positively associated with male condition factor (K) and with spermatozoa density in each male's semen when equal volumes of semen from each male were used. Male K was positively associated with male fertilization success when the volume of semen used from each male was adjusted to add approximately equal numbers of spermatozoa from each male. The relative fertilization success of males varied depending on which female was the egg donor, suggesting that female "choice" at the gamete level may be occurring in cod.

scholarly journals Sperm quality and quantity evolve through different selective processes in the Phasianidae

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Wen Bo Liao ◽  
Mao Jun Zhong ◽  
Stefan Lüpold
Keyword(s):  
Body Size ◽  
Sperm Competition ◽  
Sperm Quality ◽  
Sperm Storage ◽  
Sperm Length ◽  
Sperm Number ◽  
Selective Force ◽  
Storage Duration ◽  
Selective Pressures ◽  
Multivariate Traits

AbstractSperm competition is often considered the primary selective force underlying the rapid and diversifying evolution of ejaculate traits. Yet, several recent studies have drawn attention to other forms of selection with the potential of exceeding the effects of sperm competition. Since ejaculates are complex, multivariate traits, it seems plausible that different ejaculate components vary in their responses to different selective pressures. Such information, however, is generally lacking as individual ejaculate traits tend to be studied in isolation. Here, we studied the macroevolutionary patterns of ejaculate volume, sperm number, sperm length and the proportion of viable normal sperm in response to varying levels of sperm competition, body size and the duration of female sperm storage in pheasants and allies (Phasianidae). Ejaculate volume, sperm number and sperm viability were all relatively higher in polygamous than in monogamous mating systems. However, whereas ejaculate volume additionally covaried with body size, sperm number instead increased with the female sperm-storage duration, in conjunction with a decrease in sperm length. Overall, our results revealed important details on how different forms of selection can jointly shape ejaculates as complex, composite traits.

scholarly journals Dunnock social status correlates with sperm speed, but fast sperm does not always equal high fitness

2020 ◽  
Author(s):  
Carlos Esteban Lara ◽  
Helen Taylor ◽  
Benedikt Holtmann ◽  
Sheri Johnson ◽  
Eduardo S. A. Santos ◽  
...  
Keyword(s):  
Social Status ◽  
Sperm Competition ◽  
Wild Population ◽  
Sperm Quality ◽  
Sperm Cells ◽  
Competition Theory ◽  
The Social ◽  
Statistical Support ◽  
Mating Opportunities ◽  
Low Levels

Sperm competition theory predicts that males should modulate sperm investment according to their social status. Sperm speed (one proxy of sperm quality) also influences the outcome of sperm competition because fast sperm cells may fertilize eggs before slow sperm cells. We evaluated whether the social status of males predicted their sperm speed in a wild population of dunnocks (Prunella modularis). In addition to the traditional analysis of the average speed of sperm cells per sample, we systematically evaluated ranked groups of sperm, ranging from the 5-fastest sperm cells to the 100-fastest sperm cells in a sample. We further evaluated whether fitness, defined here as the number of chicks sired per male per breeding season, relates to the sperm speed in the same population. We found that males in monogamous pairings (i.e. low levels of sperm competition), produced the slowest sperm cells whereas subordinate males in polyandrous male-male coalitions, (i.e. high levels of sperm competition), produced the fastest sperm cells. This result was consistent across all the ranked groups of sperm, but statistical support was conditional on the number of sperm cells included in the analysis. Surprisingly, we found no significant relationship between fitness and sperm speed, contrary to theory – it is possible that the differential mating opportunities across social status leveled out any possible difference. Our study also suggests that it is important to identify biologically meaningful rankings of fastest sperm and cutoffs for inclusions for assessing sperm competition via sperm speed.

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