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Fertilization Success (fertilization + success)

Distribution by Scientific Domains

Life Sciences	81%
Earth and Environmental Science	18%

Selected Abstracts

EVOLUTIONARY REDUCTION IN TESTES SIZE AND COMPETITIVE FERTILIZATION SUCCESS IN RESPONSE TO THE EXPERIMENTAL REMOVAL OF SEXUAL SELECTION IN DUNG BEETLES

EVOLUTION, Issue 10 2008
Leigh W. Simmons
Sexual selection is thought to favor the evolution of secondary sexual traits in males that contribute to mating success. In species where females mate with more than one male, sexual selection also continues after copulation in the form of sperm competition and cryptic female choice. Theory suggests that sperm competition should favor traits such as testes size and sperm production that increase a male's competitive fertilization success. Studies of experimental evolution offer a powerful approach for assessing evolutionary responses to variation in sexual selection pressures. Here we removed sexual selection by enforcing monogamy on replicate lines of a naturally polygamous horned beetle, Onthophagus taurus, and monitoring male investment in their testes for 21 generations. Testes size decreased in monogamous lines relative to lines in which sexual selection was allowed to continue. Differences in testes size were dependent on selection history and not breeding regime. Males from polygamous lines also had a competitive fertilization advantage when in sperm competition with males from monogamous lines. Females from polygamous lines produced sons in better condition, and those from monogamous lines increased their sons condition by mating polygamously. Rather than being costly for females, multiple mating appears to provide females with direct and/or indirect benefits. Neither body size nor horn size diverged between our monogamous and polygamous lines. Our data show that sperm competition does drive the evolution of testes size in onthophagine beetles, and provide general support for sperm competition theory. [source]

The development of haddock and Atlantic cod sperm cryopreservation techniques and the effect of sperm age on cryopreservation success

JOURNAL OF FISH BIOLOGY, Issue 2 2004
R. M. Rideout
Three cryoprotectants [dimethyl sulphoxide (DMSO), propylene glycol (PG) and glycerol], two diluents (sucrose- and saline-based), two sperm collection times, two freezing rates and three times between thaw and activation (0, 30 and 60 min) were tested in order to develop a protocol for the cryopreservation of sperm of haddock Melanogrammus aeglefinus and Atlantic cod Gadus morhua. The faster freezing rate resulted in extremely low post-thaw motility in comparison to the slower freezing rate, which was successful for sperm from both gadids. In both cases, the use of PG resulted in significantly higher post-thaw sperm motility-recovery indices than with DMSO or glycerol, which did not differ significantly from one another. Diluent had no effect on post-thaw sperm motility for Atlantic cod or haddock. Sperm collected at the end of the spawning season tended to have reduced post-thaw motility compared to that collected 2 weeks after the start of spawning. A 30 min delay between thaw and activation of haddock and Atlantic cod sperm resulted in a significant decrease in sperm motility. When PG was used as cryoprotectant, sperm motility continued to decrease between 30 and 60 min post-thaw. With DMSO or glycerol as cryoprotectant, motilities were already very low after 30 min post-thaw and did not decrease any further after 60 min. Cryoprotectant, diluent and time between thaw and activation had no effect on mean or maximum sperm swimming speeds for either Atlantic cod or haddock sperm. Fertilization success for haddock eggs, like sperm motility, was higher with PG-frozen sperm than DMSO- or glycerol-frozen sperm. These results constitute the first reported successful cryopreservation of haddock sperm and improve on previous methods used to cryopreserve sperm from Atlantic cod. [source]

Male body size predicts sperm number in the mandarinfish

JOURNAL OF ZOOLOGY, Issue 3 2010
M. B. Rasotto
Abstract Theory predicts that, in species with non-resource-based mating systems, female preference for male sexual traits might be selected to ensure higher levels of fertility. Accordingly, secondary sexual traits used by females to assess males are expected to covary with ejaculate size and/or quality transferred during copulation, and female fecundity should be directly linked to mating with more attractive males. To date, direct tests of this hypothesis have been performed on internal fertilizing species, where several factors, such as for instance sperm competition, cryptic female choice, male parasite load, may affect ejaculate characteristics and female fecundity. Here, we used as a model the mandarinfish Synchiropus splendidus a small pelagic spawner where males only provide females with ejaculates and sperm competition does not occur. Males are significantly larger than females and we experimentally demonstrated that females prefer larger males. In addition, by collecting gametes from 67 natural spawning events, we attained a measure of the number of eggs and sperm released in each spawning event and the fertilization rates. The mean number of gametes produced positively correlates with body size in both sexes. Males do not regulate sperm number according to egg number and/or female body size. Fertilization success is significantly related to the mean number of sperm released but not directly to male body size. These findings, despite not fully accomplishing theoretical expectation, suggest that larger and more fecund females may suffer sperm limitation in mating with smaller males. In addition, our results have possible implications for the aquarium fishery of this species, which targets large males. [source]

Male and female effects on fertilization success and offspring viability in the Peron's tree frog, Litoria peronii

AUSTRAL ECOLOGY, Issue 3 2008
CRAIG D. H. SHERMAN
Abstract There is increasing theoretical and empirical evidence that genetic compatibility among partners is an important determinant of fertilization success and offspring viability. In amphibians, females often actively choose partners from among a variety of males and polyandry is common. Genetic compatibility among partners may therefore be an important determinant of fertilization success and offspring viability in some amphibians. Amphibians also show some of the highest levels of genetic differentiation among neighbouring populations known in vertebrates, and as such, populations may have evolved different co-adapted gene complexes. This means that offspring from among-population crosses may have reduced fitness. It is therefore essential to understand to what extent crossings between and within populations may interfere with successful fertilization and offspring viability. Here, we test whether crossing individuals within and between two different populations of the Australian Peron's tree frog (Litoria peronii) using artificial fertilizations affect fertilization success and offspring viability. Fertilization success per se is strongly influenced by male identity, which is likely to depend at least to some extent on the experimental procedure (e.g. resulting in variation in sperm number per ejaculate), whereas there was no fertilization effect of female identity. More importantly, male and female identity, independently of each other, explained significant variation in offspring viability, whereas no such effect could be linked to population of origin. Thus, our experiments suggest that crossing populations may not always be the most significant factor affecting fertilization success or offspring viability, but may be more influenced by the genetic quality or the genetic compatibility of partners. [source]

Life-cycle exposure of fathead minnows (Pimephales promelas) to an ethinylestradiol concentration below 1 ng/L reduces egg fertilization success and demasculinizes males

ENVIRONMENTAL TOXICOLOGY, Issue 2 2005
Joanne L. Parrott
Abstract Forty-eight hours after fertilization, fathead minnow (Pimephales promelas) eggs were exposed to the synthetic estrogen 17,-ethinylestradiol (EE2) at nominal concentrations of 0.32 and 0.96 ng/L and measured concentrations of 3.5, 9.6, and 23 ng/L. The fish were observed through the larval, juvenile, and adult stages. Growth, secondary sex characteristics, the liver somatic index, the gonadosomatic index, and fecundity were examined after several lengths of exposure. No significant changes were seen in fry or juvenile growth from 8 to 30 days posthatch (dph). An increase in the ovipositor index (a female secondary sex characteristic) was the most sensitive early response at 60 dph and was seen in fish exposed to EE2 concentrations , 3.5 ng/L. Continuation of the EE2 exposure until 150 dph, through maturation and reproduction, allowed measurement of two sensitive end points: decreased egg fertilization and sex ratio (skewed toward females), both of which were significantly affected at the lowest EE2 concentration tested, 0.32 ng/L. The next most sensitive end point was demasculinization (decreased male secondary sex characteristic index) of males exposed to an EE2 concentration of 0.96 ng/L. The effects of low concentrations of EE2 (0.32 and 0.96 ng/L) were manifested in male fish (decreased male sex characteristics and reduced egg fertilization success), whereas female fish showed no changes in the gonadosomatic index. Exposure to higher EE2 concentrations negatively affected females, as shown by a reduced gonadosomatic index at 150 dph in fish exposed to ,3.5 ng/L EE2. Although there were some end points that showed changes at 60 dph, the reproductive end points and external sex characteristics measured in mature fish at 150 dph were more sensitive, with response thresholds of EE2 ranging from 0.32 to 0.96 ng/L. The concentrations of EE2 that negatively affected fathead minnows were similar to or lower than those detected in many municipal wastewater effluents. In conclusion, life-cycle exposure of fathead minnows proved to be a very sensitive bioassay, and responses were seen at concentrations of less than 1 ng/L, which are environmentally relevant concentrations of EE2. © 2005 Government of Canada. Exclusive worldwide publication rights in the article have been transferred to John Wiley & Sons, Inc. Environ Toxicol 20: 131,141, 2005. [source]

Toxicity of dispersed weathered crude oil to early life stages of Atlantic herring (Clupea harengus)

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2010
Stephen McIntosh
Abstract Reports of the chronic toxicity of dispersed crude oil to early life stages of fish perpetuate uncertainty about dispersant use. However, realistic exposures to dispersed oil in the water column are thought to be much briefer than exposures associated with chronic toxicity testing. To address this issue, the toxicity of dispersed weathered oil to early life stages of Atlantic herring (Clupea harengus) was tested for short exposure durations, ranging from 1 to 144,h. Toxicity was a function of concentration and duration of exposure, as well as of the life stage exposed. Medium South American crude oil dispersed with Corexit 9500 caused blue sac disease in embryos, but not in free-swimming embryos. The age of embryos was negatively correlated with their sensitivity to oil; those freshly fertilized were most sensitive. Sensitivity increased after hatch, with free-swimming embryos showing signs of narcosis. Gametes were also tested; dispersed oil dramatically impaired fertilization success. For exposures of less than 24,h, gametes and free-swimming embryos were the most sensitive life stages. For those of more than 24,h, young embryos (<1 d old) were most sensitive. The results are presented as statistical models that could assist decisions about dispersant use in the vicinity of fish spawning habitats. Environ. Toxicol. Chem. 2010;29:1160,1167. © 2010 SETAC [source]

Bauxite manufacturing residues from Gardanne (France) and Portovesme (Italy) exert different patterns of pollution and toxicity to sea urchin embryos

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2002
Giovanni Pagano
Abstract This study was designed to investigate the composition and toxicity of solid residues from bauxite manufacturing plants. Soil and dust samples were collected in the proximity of two bauxite plants (Gardanne, France, and Portovesme, Italy). Samples were analyzed for their content of some selected inorganic contaminants by means of inductively coupled plasma optical emission spectroscopy (ICP-OES) either following acid digestion procedures or by seawater release of soluble components. Toxicity was tested by sea urchin bioassays to evaluate a set of toxicity endpoints including acute embryotoxicity, developmental defects, changes in sperm fertilization success, transmissible damage from sperm to the offspring, and cytogenetic abnormalities. Inorganic analysis showed two distinct sets of inorganic contaminants in Gardanne versus Portovesme, including Al, Cr, Cu, Fe, Mn, Pb, Ti, and Zn; sample composition (seawater-soluble cotaminants) and toxicity showed a noteworthy association. The most severe toxicity to embryogenesis and to sperm fertilization success was exerted by some Portovesme samples (0.03,0.5% w/v), with a significant association between toxicity and dose-related seawater release of Zn, Pb, and Mn. Seawater extraction of a toxic dust sample (G20) from the Gardanne factory showed increasing seawater release of Al, Fe, and Mn; the G20 sample, at the level of 0.5%, affected both developing sea urchin embryos and sperm (offspring quality). Soil samples around the Gardanne factory showed the highest frequency of toxic soil sites eastward from the factory. The present data point to solid deposition from bauxite plants as a potential subject of environmental health concern. The results suggest that extraction methods for evaluating the toxicity of complex mixtures should be based on the environmental availability of mixture components. The differences in sample toxicity among the tested sites, however, suggest possible site-to-site variability in geochemical and/or technological parameters. [source]

Reproductive and transgenerational effects of methylmercury or Aroclor 1268 on Fundulus heteroclitus

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2001
Mary Baker Matta
Abstract This research determined the potential for methylmercury or Aroclor 1268 to disrupt reproduction and sexual differentiation in Fundulus heteroclitus. The research determined whether fish that are exposed to mercury or Aroclor 1268 survive and successfully reproduce; whether offspring of exposed fish hatch, survive, produce eggs, and fertilize them; and whether the secondgeneration offspring of exposed fish hatch and survive. Fundulus heteroclitus were exposed to mercury or Aroclor 1268 via contaminated food. Endpoints evaluated included survival, growth, fecundity, fertilization success, hatch success, larval survival, sex ratios, and the prevalence of gonadal abnormalities. In general, polychlorinated biphenyls were highly bioavailable and accumulated well through feeding. The only statistically significant effect observed as a result of treatment with Aroclor 1268 was an increase in growth in the offspring of exposed fish. Mercury was accumulated in a dose-dependent fashion via food exposures. Exposure to mercury in food increased mortality in male F. heteroclitus, which possibly occurred as a result of behavioral alterations. Increased mortality was observed at body burdens of 0.2 to 0.47 ,g/g. Offspring of F. heteroclitus fed mercury-contaminated food were less able to successfully reproduce, with reduced fertilization success observed at egg concentrations of 0.01 to 0.63 ,g/g, which corresponds with parent whole-body concentrations of 1.1 to 1.2 ,g/g. Offspring of exposed fish also had altered sex ratios, with treatment at moderate concentrations producing fewer females and treatment at the highest concentration producing more females than expected. Alterations in sex ratios were observed at concentrations of less than 0.01 ,g/g in eggs or between 0.44 and 1.1 ,g/g in parents. Offspring of mercury-exposed fish also had increased growth in moderate treatments, when egg concentrations were less than 0.02 ,g/g, or when parent whole bodies contained 0.2 to 0.47 ,g/g. In summary, exposure to mercury reduced male survival, reduced the ability of offspring to successfully reproduce, and altered sex ratios in offspring. Both direct effects on exposed fish and transgenerational effects were observed. [source]

Bourgeois Males of the Peacock Blenny, Salaria pavo, Discriminate Female Mimics from Females?

ETHOLOGY, Issue 6 2005
David Gonçalves
In a Portuguese population of Salaria pavo, two types of reproductively active males occur: large bourgeois males that defend nests and have fully developed secondary sex characters (SSC) and small sneaker males that mimic the females' morphology and behaviour to approach nests and parasitize fertilizations. These two alternative reproductive tactics are sequential, as sneakers develop into bourgeois males. We investigated whether bourgeois males were able to discriminate between sneakers and females of different sizes. In a laboratory experiment bourgeois males were sequentially presented with a female and a sneaker matched for size. Complementary field observations were conducted on the interactions between females and sneakers with bourgeois males. If bourgeois males discriminated females from sneakers, we predicted that they should direct more aggressive behaviours towards sneakers and more courtship acts towards females. In general, bourgeois males courted and attacked small females and sneakers equally. However, large sneakers were courted less and attacked more than large females. Larger sneakers, beginning to develop SSC, were attacked more and courted less by the bourgeois male than smaller sneakers, and larger females were attacked less and courted more than smaller females. These results strongly suggest that only small female-mimicking males were able to deceive bourgeois males. In S. pavo, if the sneakers' fertilization success correlates with their female-mimicking ability, a fitness decrease with an increasing body size can be predicted. [source]

SPERM MORPHOLOGY AND VELOCITY ARE GENETICALLY CODETERMINED IN THE ZEBRA FINCH

EVOLUTION, Issue 10 2009
Jim Mossman
Sperm morphology (size and shape) and sperm velocity are both positively associated with fertilization success, and are expected to be under strong selection. Until recently, evidence for a link between sperm morphology and velocity was lacking, but recent comparative studies have shown that species with high levels of sperm competition have evolved long and fast sperm. It is therefore surprising that evidence for a phenotypic or genetic relationship between length and velocity within species is equivocal, even though sperm competition is played out in the intraspecific arena. Here, we first show that sperm velocity is positively phenotypically correlated with measures of sperm length in the zebra finch Taeniopygia guttata. Second, by using the quantitative genetic "animal model" on a dataset from a multigenerational-pedigreed population, we show that sperm velocity is heritable, and positively genetically correlated to a number of heritable components of sperm length. Therefore, selection for faster sperm will simultaneously lead to the evolution of longer sperm (and vice versa). Our results provide, for the first time, a clear phenotypic and genetic link between sperm length and velocity, which has broad implications for understanding how recently described macroevolutionary patterns in sperm traits have evolved. [source]

EVOLUTIONARY REDUCTION IN TESTES SIZE AND COMPETITIVE FERTILIZATION SUCCESS IN RESPONSE TO THE EXPERIMENTAL REMOVAL OF SEXUAL SELECTION IN DUNG BEETLES

GEOGRAPHIC VARIATION OF GENETIC AND BEHAVIORAL TRAITS IN NORTHERN AND SOUTHERN TÚNGARA FROGS

EVOLUTION, Issue 8 2006
Heike Pröhl
Abstract We use a combination of microsatellite marker analysis and mate-choice behavior experiments to assess patterns of reproductive isolation of the túngara frog Physalaemus pustulosus along a 550-km transect of 25 populations in Costa Rica and Panama. Earlier studies using allozymes and mitochondrial DNA defined two genetic groups of túngara frogs, one ranging from Mexico to northern Costa Rica (northern group), the second ranging from Panama to northern South America (southern group). Our more fine-scale survey also shows that the northern and southern túngara frogs are genetically different and geographically separated by a gap in the distribution in central Pacific Costa Rica. Genetic differences among populations are highly correlated with geographic distances. Temporal call parameters differed among populations as well as between genetic groups. Differences in calls were explained better by geographic distance than by genetic distance. Phonotaxis experiments showed that females preferred calls of males from their own populations over calls of males from other populations in about two-thirds to three-fourths of the contrasts tested. In mating experiments, females and males from the same group and females from the north with males from the south produced nests and tadpoles. In contrast, females from the south did not produce nests or tadpoles with males from the north. Thus, northern and southern túngara frogs have diverged both genetically and bioacoustically. There is evidence for some prezygotic isolation due to differences in mate recognition and fertilization success, but such isolation is hardly complete. Our results support the general observation that significant differences in sexual signals are often not correlated with strong genetic differentiation. [source]

PERSPECTIVE: FEMALE REMATING, OPERATIONAL SEX RATIO, AND THE ARENA OF SEXUAL SELECTION IN DROSOPHILA SPECIES

EVOLUTION, Issue 9 2002
Therese Ann Markow
Abstract., As commonly observed among closely related species within a variety of taxa, Drosophila species differ considerably in whether they exhibit sexual dimorphism in coloration or morphology. Those Drosophila species in which male external sexual characters are minimal or absent tend, instead, to have exaggerated ejaculate traits such as sperm gigantism or seminal nutrient donations. Underlying explanations for the interspecific differences in the presence of external morphological sexual dimorphism versus exaggerated ejaculate traits are addressed here by examining the opportunity for sexual selection on males to occur before versus after mating in 21 species of Drosophila. Female remating frequency, an important component of the operational sex ratio, differs widely among Drosophila species and appears to dictate whether the arena of sexual selection is prior to, as opposed to after, copulation. Infrequent female mating results in fewer mating opportunities for males and thus stronger competition for receptive females that favors the evolution of male characters that maximize mating success. On the other hand, rapid female remating results in overlapping ejaculates in the female reproductive tract, such that ejaculate traits which enhance fertilization success are favored. The strong association between female remating frequency in a given species and the presence of sexually selected external versus internal male characters indicates that the relationship be examined in other taxa as well. [source]

Aspects of the larval biology of the sea anemones Anthopleura elegantissima and A. artemisia

INVERTEBRATE BIOLOGY, Issue 3 2002
Virginia M. Weis
Abstract. We investigated several aspects of the larval biology of the anemone Anthopleura elegantissima, which harbors algal symbionts from two different taxa, and the non-symbiotic A. artemisia. From a 7-year study, we report variable spawning and fertilization success of A. elegantissima in the laboratory. We examined the dynamics of symbiosis onset in larvae of A. elegantissima. Zoochlorellae, freshly isolated from an adult host, were taken up and retained during the larval feeding process, as has been described previously for zooxanthellae. In addition, larvae infected with zooxanthellae remained more highly infected in high-light conditions, compared to larvae with zoochlorellae, which remained more highly infected in low-light conditions. These results parallel the differential distribution of the algal types observed in adult anemones in the field and their differential tolerances to light and temperature. We report on numerous failed attempts to induce settlement and metamorphosis of larvae of A. elegantissima, using a variety of substrates and chemical inducers. We also describe a novel change in morphology of some older planulae, in which large bulges, resembling tentacles, develop around the mouth. Finally, we provide the first description of planulae of A. artemisia and report on attempts to infect this non-symbiotic species with zooxanthellae and zoochlorellae. [source]

Offspring sex ratio skew in the sexually monomorphic house martin Delichon urbicum

JOURNAL OF AVIAN BIOLOGY, Issue 5 2010
Monika Zieli
Sex ratio at conception may be under selection pressure, given that male and female offspring differ in the cost of production or generate different fitness returns under specific conditions. We studied adjustments in the primary, secondary and tertiary sex ratio in house martin Delichon urbicum, which is a sexually monomorphic, socially monogamous, colonial bird. Males of this species engage in extra-pair copulations with heavy males acquiring the highest fertilization success. We analyzed variation in the sex ratio in relation to clutch size and parental characteristics including body condition, wing length, as well as length and pigmentation of the white rump patch during three breeding seasons. The only variable which significantly explained the variation in the sex ratio was wing length of the social father and mother. The proportion of sons among offspring was positively correlated to wing length of the social father and negatively correlated to mother wing length. Social father wing length positively correlated with mean brood body mass at fledging, which may suggest that females that mated with long-winged males produced sons, which acquired the highest total fertilization success. Consequently, our results indicate that house martin females may adaptively adjust offspring sex composition at egg laying in relation to the characteristics of their social mate. [source]

Does male extra-territory foray effort affect fertilization success in hooded warblers Wilsonia citrina?

JOURNAL OF AVIAN BIOLOGY, Issue 6 2005
Bridget J. M. Stutchbury
Hooded warbler Wilsonia citrina males vary greatly in the frequency and duration of their off-territory forays in search of extra-pair copulations. We used radiotracking and microsatellite parentage analysis in high and low density populations to determine if (1) high foray rate or time off-territory reduces within-pair fertilization success, and (2) if a high foray rate onto the territory of a fertile female increases the likelihood of obtaining EPFs with that female. Males who left their territory often, or for longer periods, did not have lower within-pair fertilization success. Some males repeatedly visited a neighboring fertile female, but in only 3 of 19 cases where radiotagged males visited a fertile female did the male actually sire offspring with that female. Male foray rate onto a fertile female's territory was not a good predictor of whether or not he sired extra-pair offspring with that female. We suggest that mate choice and extra-pair behavior by females may explain why male foray behavior does not correspond closely with actual fertilization success. [source]

Infrequent sporophyte production maintains a female-biased sex ratio in the unisexual clonal moss Hylocomium splendens

JOURNAL OF ECOLOGY, Issue 5 2010
Knut Rydgren
Summary 1.,Sex ratios in unisexual bryophytes are most often female biased, whereas male-biased sex ratios predominate in unisexual seed plants. This ,bryophyte paradox', i.e. that sex ratios are biased in favour of the sex associated with the highest reproductive costs, has remained unexplained. 2.,Analysis of sex-ratio patterns via the influence of sex distribution on population growth rates (,) has not previously been carried out for bryophytes. We used this method to model how variation in sex ratio and sporophyte frequency influences , in the clonal bryophyte Hylocomium splendens. We obtained , by matrix modelling of synthetic experimental populations derived from demographic field data, using a linear two-sex model. 3.,In our set of experimental populations , varied between 1.13 and 1.27 in response to variation in sex ratio and sporophyte frequency, with the highest , obtained for the combination of a very low sporophyte frequency and a slightly female-biased sex ratio. 4.,Our results explain the female-biased sex ratio of H. splendens by the slightly lower survival of and production of vegetative offspring by males than by non-sporophytic females. 5.,Synthesis. According to our models, female dominance is the predicted outcome of low to moderate fertilization success and male performance intermediate between that of sporophytic and of non-sporophytic females. Our results therefore explain how a female-biased sex ratio can be maintained despite higher costs of reproduction in females than in males. In dioecious bryophytes, males and females must grow in close contact for fertilization to take place. Better performance of male ramets than of the female ramets they fertilize also explains how male clones can expand into female clones. A similar performance hierarchy of males and females may occur in unisexual clonal seed plants, but more efficient fertilization systems by pollination prevents the selective advantage of unfertilized females from being realized. This explains why vascular plant populations tend to be male biased. We hypothesise difference in fertilization distance range between sperm and pollen as a simple explanation why ramet level sex ratios are in general male dominated in clonal seed plants and female dominated in clonal bryophytes. [source]

Direct and indirect responses to selection on pollen size in Brassica rapa L.

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2001
T. S. Sarkissian
Pollen size varies little within angiosperm species, but differs extensively between species, suggesting the action of strong selection. Nevertheless, the potential for genetic responses of pollen size to selection, as determined by additive genetic variance and genetic correlations with other floral traits, has received little attention. To assess this potential, we subjected Brassica rapa to artificial selection for large and small pollen during three generations. This selection caused significant divergence in pollen diameter, with additive genetic effects accounting for over 30% of the observed phenotypic variation in pollen size. Such heritable genetic variation suggests that natural selection could effect evolutionary change in this trait. Selection on pollen size also elicited correlated responses in pollen number (,), flower size (+), style length (+), and ovule number (+), suggesting that pollen size cannot evolve independently. The correlated responses of pollen number, flower size and ovule number probably reflect the genetically determined and physically constrained pattern of resource allocation in B. rapa. In contrast, the positive correlation between pollen size and style length may represent a widespread gametic-phase disequilibrium in angiosperms that arises from nonrandom fertilization success of large pollen in pistils with long styles. [source]

Optimization of fertilization success in Sander vitreus is influenced by the sperm : egg ratio and ova storage

JOURNAL OF FISH BIOLOGY, Issue 4 2005
J. Rinchard
Walleye Sander vitreum eggs could be stored at 7° C for up to 30 h with 60% fertilization rates. Fertilization rates at 1 and 12° C fell to 17 and 5%, respectively. At spermatozoa : egg ratios <25 000 : 1, survival to the eyed stage declined precipitously. Beyond a ratio of 25 000 : 1, survival to the eyed stage did not increase >c. , 70%. Therefore, a standard spermatozoa : egg ratio of 25 000 : 1 was established and is recommended for studies concerning fertilizing success. [source]

RECENT ADVANCES IN FERTILIZATION ECOLOGY OF MACROALGAE,

JOURNAL OF PHYCOLOGY, Issue 1 2002
Bernabé SantelicesArticle first published online: 19 FEB 200
Our understanding of natural patterns of fertilization in seaweeds has increased substantially over the last 10 years due to new approaches and methods to characterize the nature and frequency of fertilization processes in situ, to recognize the conditions and mechanisms enhancing fertilization success, and to anticipate population and community consequences of the patterns of natural fertilization. Successful reproduction in many species depends on a delicate juxtaposition of abiotic and biotic conditions. Important abiotic factors are those triggering gamete release (e.g. single or interacting effects of light quality and water movement) and those affecting gamete viability or concentrations (e.g. salinity effects on polyspermy blocks; gamete dilution due to water movement). Examples of important biotic components are synchronous gamete release, efficiency of polyspermy-blocking mechanisms, population density of sexually fertile thalli, interparent distances, and male-to-female ratios. Field data indicate fertilization frequencies of 70%,100% in broadcasting-type seaweeds (e.g. fucoids) and 30%,80% in brooding-type (red) algae. Red algal values are higher than previously thought and challenge presently accepted explanations for their complex life histories. Important population and community questions raised by the recent findings relate to the magnitude of gene flow and exchange occurring in many micropopulations that seemingly breed during periods of isolation, the physiological basis and population effects of male-to-male competition and sexual selection during fertilization of brooding seaweeds, and the effects of massive gamete release, especially in holocarpic seaweeds, on benthic and planktonic communities. Comparative studies in other algal groups are now needed to test the generality of the above patterns, to provide critical pieces of information still missing in our understanding of natural fertilization processes, and to elucidate the evolutionary consequences of the different modes of reproduction (e.g. brooders vs. broadcasters). [source]

How female reed buntings benefit from extra-pair mating behaviour: testing hypotheses through patterns of paternity in sequential broods

MOLECULAR ECOLOGY, Issue 9 2006
KAREN M. BOUWMAN
Abstract Extra-pair paternity is an important aspect of reproductive strategies in many species of birds. Given that in most species females control whether fertilization occurs, they are expected to benefit in some way from the extra-pair matings. In this study we use patterns of extra-pair paternity (EPP) in broods of individual reed buntings (Emberiza schoeniclus), both within and between seasons, to test four hypothesized female benefits: (1) assessing potential future partners and seeking (2) genetic diversity (3) good genes, or (4) compatible genes. Reed buntings are socially monogamous, multibrooded passerines with extremely high levels of extra-pair paternity. We studied a population of reed buntings in the Netherlands in 2002 and 2003; 51% of offspring in 74% of nests were extra-pair. We showed that patterns of EPP did not support the first and second hypotheses, since females did not form a pair with previous extra-pair partners, EPP was not evenly distributed among broods and more broods than expected were sired by a single male. Furthermore, there was no relation between a male's within- and extra-pair fertilization success, no consistency in EPP between breeding attempts, no effect of parental relatedness on EPP and several cases of reciprocal paternity. These patterns do not support the good genes hypothesis and are most consistent with the genetic compatibility hypothesis. However, our previous finding that older males are more successful in gaining EPP, suggests some effect of good genes. These hypotheses need not be mutually exclusive, as females may select compatible males above a certain quality threshold (e.g. old males). [source]

Analysis of a chalcone synthase mutant in Ipomoea purpurea reveals a novel function for flavonoids: amelioration of heat stress

MOLECULAR ECOLOGY, Issue 5 2003
L. C. Coberly
Abstract Flavonoids are thought to function in the plant stress response and male fertility in some, but not all, species. We examined the effects of a self-fertile chalcone synthase null allele, a, for the effects of heat and light stress on fertilization success and flower production in Ipomoea purpurea. Pollen recipients and pollen donors of both homozygous genotypes exhibit reduced fertilization success at high temperatures, indicating that high temperature acts as a stress-lowering fertilization success. Homozygous aa individuals exhibit reduced male and female fertilization success, compared to AA individuals, at high temperatures but not at low temperatures. In addition, aa individuals produce fewer flowers than AA individuals at low temperatures, but not at high temperatures. These results suggest that flavonoids alleviate heat stress on fertilization success. They also suggest that pleiotropic effects at the A locus may explain the low frequency of the a allele in natural populations. [source]

Analysis of segregation distortion and association of the bovine FGF2 with fertilization rate and early embryonic survival

ANIMAL GENETICS, Issue 5 2009
X. Wang
Summary Fibroblast growth factor 2 (FGF2) plays an important role in fertility and early embryo development. The objectives of this study were to test the association of FGF2 polymorphisms with fertilization success in cattle using an in vitro fertilization experimental system and to investigate the mechanisms leading to the presence of rare alleles of FGF2 in the Holstein population. A total of 7502 fertilizations were performed and a total of 5049 embryos were produced to collect fertilization and embryo survival records. A total of 444 ovaries, from which oocytes were aspirated and fertilized, were genotyped for two single nucleotide polymorphisms (SNPs) previously identified in FGF2 (g.23G>T and g.11646A>G). Frequency of the TT genotype of the g.23G>T SNP was low in the ovary population (5.4%) and in a different Holstein cattle population (6.6%) examined in this study. Single SNP analysis showed that both SNPs were associated with early embryonic survival rate. Two-way interaction analysis revealed significant association of epistatic interaction between the SNPs with fertilization rate. To test whether or not low frequency of allele T for the g.23G>T SNP in the population is a result of a fertilization failure of T oocytes, semen from six GG bulls was used to fertilize a total of 458 oocytes obtained from 19 GT ovaries. A significant segregation distortion was observed for 169 embryos genotyped for the g.23G>T SNP. We conclude that oocytes carrying the T allele show a reduced fertilization rate and that segregation distortion leads to rarity of the TT genotype in the population. [source]

Preliminary investigations on the effects of dietary lipid on the spawning performance and egg quality of black sea bass Centropristis striata L

AQUACULTURE RESEARCH, Issue 16 2009
Christopher D Bentley
Abstract Adult black sea bass Centropristis striata broodstock (N=162) were fed three different dietary treatments: two commercially prepared diets with 45% protein and two different lipid levels (12% and 20%) (diets 1 and 2), and a diet of frozen Atlantic silversides Menidia menidia (SS, diet 3). Broodstock were held under controlled photothermal conditions and induced to spawn with an LHRHa pellet (72 ,g kg,1 bw). Dietary lipid had pronounced effects on spawning performance and egg quality. Diet 3 (SS) produced a significantly (P<0.05) higher fertilization success (22.4%) than diets 1 (0.6%) and 2 (4.8%). The hatching success of fertilized eggs was similar in all diets (range=40,58.6%), but only two spawns from diet 1 (12% lipid) yielded viable yolk-sac larvae (YSL). Diet 3 (SS) also produced significantly more YSL per female (21.8 × 103) than the diet 1 (0.3 × 103). Eggs from diet 3 (SS) contained a significantly greater proportion of n-3 series fatty acids, with docosahexaenoic acid (DHA) as the largest fraction. Eggs from commercially prepared dietary treatments contained significantly more n-6 fatty acids. The poor spawning performance of fish fed diet 1 (12% lipid) may be related to higher levels of linoleic acid and lower levels of DHA in the diet. [source]

Comparative fatty acid composition of eggs from wild and captive black sea bass, Centropristis striata L.

AQUACULTURE RESEARCH, Issue 6 2009
Gloria T Seaborn
Abstract Lipid content, lipid class and fatty acid compositions were determined in eggs from wild and captive black sea bass, Centropristis striata L., from northern (New England) and southern (South Carolina) regions to determine the effects of diet on egg composition and fertilization success. The formulated diets fed to the northern captive (NC) fish were higher in total lipids (22%) compared with the cut fish and squid diet fed to the southern fish (SC; 3.3% lipid) and had a higher relative amount of linoleic acid (LA) and lower relative amounts of docosahexaenoic acid (DHA) and arachidonic acid (AA). These dietary differences were broadly reflected in the egg lipid composition. The LA levels were higher in all lipid classes in eggs of NC fish while AA levels were lower. The DHA was higher in the major polar lipids (PL) (phosphatidylcholine and phosphatidylethanolamine) of SC eggs compared with NC. Compared with wild fish, both captive groups produced eggs with PLs richer in LA and lower in DHA and AA. Over all fish groups, fertilization success was directly correlated with levels of DHA and AA in the PLs and was inversely correlated with LA levels. [source]

Male and female effects on fertilization success and offspring viability in the Peron's tree frog, Litoria peronii

Size-dependent mating strategies and the risk of cannibalism

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2008
MARK A. ELGAR
The role of sexual selection in determining the nature and direction of sexual size dimorphism may depend upon the timing of sexual selection, and this may also influence the variation in male size. For example, selection through sperm competition favours smaller males in the highly sexually size dimorphic orb-weaving spider Nephila edulis, whereas larger males are better able to exclude their smaller rivals from the central hub of the web where mating takes place. We investigate experimentally the role of body size and hub tenure in determining male fertilization success when males of different sizes compete for a single female over a 24-h period that includes a period of darkness. Our results confirm that small and large males obtain similar paternity share but that, in contrast with previous studies, hub tenure does not translate into greater paternity share. Unexpectedly, smaller males are at greater risk of postmating sexual cannibalism than larger males, suggesting that natural selection through sexual cannibalism may place a lower limit on male size. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 355,363. [source]

The evolution of male mate choice in insects: a synthesis of ideas and evidence

BIOLOGICAL REVIEWS, Issue 3 2001
RUSSELL BONDURIANSKY
ABSTRACT Mate choice by males has been recognized at least since Darwin's time, but its phylogenetic distribution and effect on the evolution of female phenotypes remain poorly known. Moreover, the relative importance of factors thought to underlie the evolution of male mate choice (especially parental investment and mate quality variance) is still unresolved. Here I synthesize the empirical evidence and theory pertaining to the evolution of male mate choice and sex role reversal in insects, and examine the potential for male mating p to generate sexual selection on female phenotypes. Although male mate choice has received relatively little empirical study, the available evidence suggests that it is widespread among insects (and other animals). In addition to ,precopulatory' male mate choice, some insects exhibit ,cryptic' male mate choice, varying the amount of resources allocated to mating on the basis of female mate quality. As predicted by theory, the most commonly observed male mating p are those that tend to maximize a male's expected fertilization success from each mating. Such p tend to favour female phenotypes associated with high fecundity or reduced sperm competition intensity. Among insect species there is wide variation in mechanisms used by males to assess female mate quality, some of which (e.g. probing, antennating or repeatedly mounting the female) may be difficult to distinguish from copulatory courtship. According to theory, selection for male choosiness is an increasing function of mate quality variance and those reproductive costs that reduce, with each mating, the number of subsequent matings that a male can perform (,mating investment'). Conversely, choosiness is constrained by the costs of mate search and assessment, in combination with the accuracy of assessment of potential mates and of the distribution of mate qualities. Stronger selection for male choosiness may also be expected in systems where female fitness increases with each copulation than in systems where female fitness peaks at a small number of matings. This theoretical framework is consistent with most of the empirical evidence. Furthermore, a variety of observed male mating p have the potential to exert sexual selection on female phenotypes. However, because male insects typically choose females based on phenotypic indicators of fecundity such as body size, and these are usually amenable to direct visual or tactile assessment, male mate choice often tends to reinforce stronger vectors of fecundity or viability selection, and seldom results in the evolution of female display traits. Research on orthopterans has shown that complete sex role reversal (i.e. males choosy, females competitive) can occur when male parental investment limits female fecundity and reduces the potential rate of reproduction of males sufficiently to produce a female-biased operational sex ratio. By contrast, many systems exhibiting partial sex role reversal (i.e. males choosy and competitive) are not associated with elevated levels of male parental investment, reduced male reproductive rates, or reduced male bias in the operational sex ratio. Instead, large female mate quality variance resulting from factors such as strong last-male sperm precedence or large variance in female fecundity may select for both male choosiness and competitiveness in such systems. Thus, partial and complete sex role reversal do not merely represent different points along a continuum of increasing male parental investment, but may evolve via different evolutionary pathways. [source]