Search results for "S.E.M."
showing 10 items of 5492 documents
Paternal age negatively affects sperm production of the progeny.
2021
International audience; Parental age has profound consequences for offspring’s phenotype. However, whether patrilineal age affects offspring sperm production remains unknown, despite the importance of sperm production for male reproductive success in species facing post-copulatory sexual selection. Using a longitudinal dataset on ejaculate attributes of the houbara bustard, we showed that offspring sired by old fathers had different age-dependent trajectories of sperm production compared to offspring sired by young fathers. Specifically, they produced less sperm (−48%) in their first year of life, and 14% less during their lifetime. Paternal age had the strongest effect, with weak evidence …
Semen characteristics and their ability to predict sperm cryopreservation potential of Atlantic cod, Gadus morhua L.
2010
There is a lack of biomarkers or indices that can be used to predict the quality of fish semen samples following the freezing and thawing cycle. In the present study, a series of semen indices were tested to assess if they could accurately forecast the cryopreservation potential of Atlantic cod (Gadus morhua) semen. Fresh and frozen-thawed sperm activity variables were compared, and relationships between frozen-thawed sperm activity and fertilization success were examined. In comparison with fresh sperm, activity variables of frozen-thawed spermatozoa were reduced. Of the 18 males examined, mean (± SEM) spermatocrit of fresh sperm was 40.72 ± 4.23%, osmolality of the seminal plasma 366.32 ±…
Post-copulatory sexual selection allows females to alleviate the fitness costs incurred when mating with senescing males.
2019
8 pages; International audience; Male senescence has detrimental effects on reproductive success and offspring fitness. When females mate with multiple males during the same reproductive bout, post-copulatory sexual selection that operates either through sperm competition or cryptic female choice might allow females to skew fertilization success towards young males and as such limit the fitness costs incurred when eggs are fertilized by senescing males. Here, we experimentally tested this hypothesis. We artificially inseminated female North African houbara bustards with sperm from dyads of males of different (young and old) or similar ages (either young or old). Then, we assessed whether si…
No inbreeding depression in sperm storage ability or offspring viability in Drosophila melanogaster females.
2013
Mating between relatives usually decreases genetic quality of progeny as deleterious recessive alleles are expressed in inbred individuals. Inbreeding degrades sperm traits but its effects on sperm storage and fate within females are currently unknown. We quantified the relationship between the degrees of inbreeding relevant to natural populations (f=0, 0.25 and 0.50) and the number of sperm inseminated and stored, sperm swimming speed, long-term sperm viability while in storage, pattern of sperm precedence, mating latency, and offspring viability of female Drosophila melanogaster. The use of transgenic flies that have either red or green fluorescent sperm heads allowed us to distinguish tw…
Postcopulatory sexual selection generates speciation phenotypes in Drosophila.
2013
Background: Identifying traits that reproductively isolate species and the selective forces underlying their divergence is a central goal of evolutionary biology and speciation research. There is growing recognition that postcopulatory sexual selection which can drive rapid diversification of interacting ejaculate and female reproductive tract traits that mediate sperm competition may be an engine of speciation. Conspecific sperm precedence (CSP) is a taxonomically widespread form of reproductive isolation but the selective causes and divergent traits responsible for CSP are poorly understood. Results: To test the hypothesis that postcopulatory sexual selection can generate reproductive iso…
Endocrine correlates of the breeding asynchrony between two Corsican populations of Blue tits (Parus caeruleus)
2004
International audience; Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the Wrst results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy diVerent oak habitats and are separated by only 25km. Despite their close proximity, they show a one-month diVerence in onset of egg laying, even after controlling for altitude. This micro-geographic diVerence in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum …
The evolution of sperm morphometry in pheasants
2007
7 pages; International audience; Post-copulatory sexual selection is thought to be a potent evolutionary force driving the diversification of sperm shape and function across species. In birds, insemination and fertilization are separated in time and sperm storage increases the duration of sperm-female interaction and hence the opportunity for sperm competition and cryptic female choice. We performed a comparative study of 24 pheasant species (Phasianidae, Galliformes) to establish the relative importance of sperm competition and the duration of sperm storage for the evolution of sperm morphometry (i.e. size of different sperm traits). We found that sperm size traits were negatively associat…
Testosterone-Mediated Effects on Fitness-Related Phenotypic Traits and Fitness
2009
International audience; The physiological and behavioral mechanisms underlying life-history trade-offs are a continued source of debate. Testosterone (T) is one physiological factor proposed to mediate the trade-off between reproduction and survival. We use phenotypic engineering and multiple laboratory and field fitness-related phenotypic traits to test the effects of elevated T between two bank vole Myodes glareolus groups: dominant and subordinate males. Males with naturally high T levels showed higher social status (laboratory dominance) and mobility (distance between capture sites) than low-T males, and the effect of T on immune response was also T group specific, suggesting that behav…
Quantitative genetics of sexual display, ejaculate quality and size in a lekking species.
2013
9 pages; International audience; The investment into extravagant sexual display and competitive sperm are two essential components of pre- and post-copulatory sexual selection. Even though the selective forces acting on sexual display and sperm characteristics have been extensively studied in recent years, the genetic architecture underlying the expression of these traits has been rarely explored. Here, we estimated the genetic variances and covariances of traits linked with ejaculate size and quality, and sexual display in the houbara bustard (Chlamydotis undulata undulata, Jacquin 1784). Using a very large pedigree-based data set, we show that sexual signalling and ejaculate size (but not…
Diet and trophic niche of the invasive signal crayfish in the first invaded Italian stream ecosystem.
2021
The occurrence of the signal crayfsh Pacifastacus leniusculus in the Valla Stream was the frst established population of this invasive species recorded in an Italian stream ecosystem. We evaluated the seasonality of diet and trophic niche of invasive signal crayfsh in order to estimate the ecological role and efects on native communities of the stream ecosystem. We studied the diferences in food source use between sexes, life stages and seasons using carbon and nitrogen stable isotope analyses. To supplement stable isotope analyses, we evaluated food source usage using traditional stomach content analysis. We tested the hypothesis that juveniles have a diferent diet, showing diferent trophi…