共查询到20条相似文献，搜索用时 15 毫秒
1.
C. GASPARINI I. A. M. MARINO C. BOSCHETTO A. PILASTRO 《Journal of evolutionary biology》2010,23(1):124-135
Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the offspring. We tested this hypothesis in the guppy (Poecilia reticulata), a species characterized by polyandry and intense sperm competition, by investigating whether age affects post‐copulatory male traits and sperm competition success. Females did not discriminate between old and young males in a mate choice experiment. While old males produced longer and slower sperm with larger reserves of strippable sperm, compared to young males, artificial insemination did not reveal any effect of age on sperm competition success. Altogether, these results do not support the hypothesis that polyandry evolved in response to costs associated with mating with old males in the guppy. 相似文献
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Pavlína Opatová Malika Ihle Jana Albrechtová Oldřich Tomášek Bart Kempenaers Wolfgang Forstmeier Tomáš Albrecht 《Ecology and evolution》2016,6(1):295-304
Inbreeding depression, or the reduction in fitness due to mating between close relatives, is a key issue in biology today. Inbreeding negatively affects many fitness‐related traits, including survival and reproductive success. Despite this, very few studies have quantified the effects of inbreeding on vertebrate gamete traits under controlled breeding conditions using a full‐sib mating approach. Here, we provide comprehensive evidence for the negative effect of inbreeding on sperm traits in a bird, the zebra finch Taeniopygia guttata. We compared sperm characteristics of both inbred (pedigree F = 0.25) and outbred (pedigree F = 0) individuals from two captive populations, one domesticated and one recently wild‐derived, raised under standardized conditions. As normal spermatozoa morphology did not differ consistently between inbred and outbred individuals, our study confirms the hypothesis that sperm morphology is not particularly susceptible to inbreeding depression. Inbreeding did, however, lead to significantly lower sperm motility and a substantially higher percentage of abnormal spermatozoa in ejaculate. These results were consistent across both study populations, confirming the generality and reliability of our findings. 相似文献
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Arild Johnsen;Kristine Wold-Dobbe;Camilla Lo Cascio Sætre;Marie-Christine Eybert;Matthieu Marquet;Patrick Bonnet;Emily R. A. Cramer; 《Journal of avian biology》2023,2023(9-10):e03125
Individual heterozygosity may influence the expression of fitness-related traits, via genome-wide or local genetic effects. Earlier studies have shown negative relationships between heterozygosity and sperm variation, predominantly in captive, highly inbred populations. Little is known about the possible influence of variation in heterozygosity on sperm traits in wild, outbred populations. We studied two populations of the bluethroat, one from the widely distributed northern subspecies Luscinia. s. svecica and the other from the smaller, more patchily distributed subspecies breeding along the French coast of Brittany L. s. namnetum. The two subspecies differed significantly in body size, plumage colour, sperm traits and the degree of genetic diversity. However, there was no evidence that sperm traits (total length and motility) were influenced by the degree of heterozygosity at the individual level. In contrast, we found that male body size was positively related to heterozygosity across both populations, indicating a possible relationship between overall genetic diversity and general vigour or ability to obtain food. We conclude that sperm traits are unrelated to levels of heterozygosity in the studied outbred and weakly genetically depauperate bluethroat populations. 相似文献
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Mariola Słowińska Andrzej Ciereszko Trevor E. Pitcher 《Biological journal of the Linnean Society. Linnean Society of London》2013,108(1):99-108
Although alternative reproductive tactics (ARTs) are common across a range of taxa, little is known about whether the different tactics have adapted to sperm competition risk. Chinook salmon, Oncorhynchus tshawytscha, have two ARTs: large males that participate in dominance‐based hierarchies for access to spawning females, known as hooknoses, and small males that attempt to sneak fertilizations during spawning events from peripheral positions, known as jacks. Jacks continually face sperm competition risk because they always spawn in the presence of another male, whereas hooknoses face relatively low sperm competition risk because other males are not always present during spawning events. Based on the sneak‐guard model of sperm competition this asymmetry in sperm competition risk predicts that jacks ought to invest significantly more into sperm‐related traits important for sperm competition success relative to hooknoses. In the present study we report on reproductive investment patterns, sperm characteristics, and seminal plasma physiology of males that exhibit ARTs in Chinook salmon. We found that jacks invest significantly more of their somatic tissue into gonads compared with hooknoses. Sperm velocity also varied significantly between the ARTs, with jacks having significantly faster sperm than hooknoses. No significant differences in seminal plasma physiology metrics related to sperm quality were detected between the ARTs. We interpret these sperm investment patterns in light of the sneak‐guard model of sperm competition that is based on differences in sperm competition risk and alternative investment possibilities among ARTs. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??. 相似文献
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Hanna Nyborg Støstad Arild Johnsen Jan Terje Lifjeld Melissah Rowe 《Evolution; international journal of organic evolution》2018,72(9):1918-1932
Sperm exhibit extraordinary levels of morphological diversification across the animal kingdom. In songbirds, sperm have a helically shaped head incorporating a distinct acrosomal membrane or “helical keel,” the form and extent of which varies across species. The functional significance of this helical shape, however, remains unknown. Using scanning electron microscopy, we quantified inter‐ and intraspecific variation in sperm head morphology across 36 songbird species (Passeriformes: Passerida). Using phylogenetic comparative methods, we investigated the relationship between sperm head morphology and both sperm swimming speed and the frequency of extra‐pair young (EPY). We found that species whose sperm had a relatively more pronounced helical form (i.e., long acrosome, short nucleus, wide helical membrane, and a more pronounced waveform along the sperm head “core”) had faster‐swimming sperm. We found no evidence of a relationship between interspecific variation in sperm head morphology and EPY, although we did find that among‐ and within‐male variation in sperm head traits were negatively correlated with EPY. Applying principles of fluid mechanics, we discuss how the helical form of the sperm head may influence swimming speed, and suggest that further studies considering aspects of sperm morphology beyond sperm length are needed to improve our understanding of sperm structure‐function relationships. 相似文献
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DITA B. VIZOSO GUNDE RIEGER LUKAS SCHÄRER 《Biological journal of the Linnean Society. Linnean Society of London》2010,99(2):370-383
Different interests between mating partners regarding the fate of their gametes can lead to sexual conflicts in many species. Although these conflicts can sometimes be dealt with pre‐copulatorily (e.g. by choosing with which partners to mate), they often extend beyond copulation. Post‐copulatory sexual conflicts are expected to be particularly strong in simultaneous hermaphrodites because an individual may have to accept sperm in order to obtain an opportunity to donate sperm, reducing the effectiveness of pre‐copulatory conflict resolution. The present study investigates the post‐copulatory interactions between male and female sexual traits of a highly promiscuous simultaneous hermaphrodite, the free‐living flatworm Macrostomum lignano. Using light and electron microscopy, we show the different levels of complexity of the sperm and the genitalia, and derive hypotheses about how the different traits may represent evolutionary responses to such sexual conflicts. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 370–383. 相似文献
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Maximiliano Tourmente Melissah Rowe M. Mar González‐Barroso Eduardo Rial Montserrat Gomendio Eduardo R. S. Roldan 《Evolution; international journal of organic evolution》2013,67(6):1838-1846
Sperm competition often leads to increase in sperm numbers and sperm quality, and its effects on sperm function are now beginning to emerge. Rapid swimming speeds are crucial for mammalian spermatozoa, because they need to overcome physical barriers in the female tract, reach the ovum, and generate force to penetrate its vestments. Faster velocities associate with high sperm competition levels in many taxa and may be due to increases in sperm dimensions, but they may also relate to higher adenosine triphosphate (ATP) content. We examined if variation in sperm ATP levels relates to both sperm competition and sperm swimming speed in rodents. We found that sperm competition associates with variations in sperm ATP content and sperm‐size adjusted ATP concentrations, which suggests proportionally higher ATP content in response to sperm competition. Moreover, both measures were associated with sperm swimming velocities. Our findings thus support the idea that sperm competition may select for higher ATP content leading to faster sperm swimming velocity. 相似文献
9.
Sex allocation (SA) theory for simultaneous hermaphrodites predicts an influence of group size on SA. Since group size can vary within an individual's lifetime, this can favor the evolution of phenotypically plastic SA. In an emerging comparative context, we here report on SA plasticity in three closely related Macrostomum flatworm species, namely Macrostomum janickei, Macrostomum cliftonensis, and Macrostomum mirumnovem. For each species, we experimentally raised worms in three group sizes (isolated, pairs, and octets) and two enclosure sizes (small and large) in all factorial combinations and studied the effects of these factors on different estimates of SA. In addition, we also evaluated whether isolated worms engage in self‐fertilization. We found that all species have plastic SA, with M. cliftonensis being more plastic than the other two species, as assessed by comparing standardized effect sizes of (a) the presence/absence of mating partners and (b) the strength of sexual competition. Moreover, we found that sperm production rate—but not sperm morphology—is plastic in M. cliftonensis, and that only M. mirumnovem self‐fertilized during our observation period. Our study suggests that both SA and SA plasticity can diverge even between closely related species. 相似文献
10.
Evolutionary theory predicts that selection will favour sperm traits that maximize fertilization success in local fertilization environments. In externally fertilizing species, osmolality of the fertilization medium is known to play a critical role in activating sperm motility, but there remains limited evidence for adaptive responses to local osmotic environments. In this study, we used a split‐sample experimental design and computer‐assisted sperm analysis to (i) determine the optimal medium osmolality for sperm activation (% sperm motility and sperm velocity) in male common eastern froglets (Crinia signifera), (ii) test for among‐population variation in percentage sperm motility and sperm velocity at various activation‐medium osmolalities and (iii) test for among‐population covariation between sperm performance and environmental osmolality. Frogs were obtained from nine populations that differed in environmental osmolality, and sperm samples of males from different populations were subjected to a range of activation‐medium osmolalities. Percentage sperm motility was optimal between 10 and 50 mOsm kg?1, and sperm velocity was optimal between 10 and 100 mOsm kg?1, indicating that C. signifera has evolved sperm that can function across a broad range of osmolalities. As predicted, there was significant among‐population variation in sperm performance. Furthermore, there was a significant interaction between activation‐medium osmolality and environmental osmolality, indicating that frogs from populations with higher environmental osmolality produced sperm that performed better at higher osmolalities in vitro. This finding may reflect phenotypic plasticity in sperm functioning, or genetic divergence resulting from spatial variation in the strength of directional selection. Both of these explanations are consistent with evolutionary theory, providing some of the first empirical evidence that local osmotic environments can favour adaptive sperm motility responses in species that use an external mode of fertilization. 相似文献
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Sperm senescence can have important evolutionary implications due to its deleterious effects on sperm quality and offspring performance. Consequently, it has been argued that polyandry (female multiple mating) may facilitate the selection of younger, and therefore competitively superior, sperm when ejaculates from multiple males compete for fertilization. Surprisingly, however, unequivocal evidence that sperm ageing influences traits that underlie sperm competitiveness is lacking. Here, we used a paired experimental design that compares sperm quality between ‘old’ and ‘young’ ejaculates from individual male guppies (Poecilia reticulata). We show that older sperm exhibit significant reductions in sperm velocity compared with younger sperm from the same males. We found no evidence that the brightness of the male''s orange (carotenoid) spots, which are thought to signal resistance to oxidative stress (and thus age-related declines in sperm fitness), signals a male''s ability to withstand the deleterious effects of sperm ageing. Instead, polyandry may be a more effective strategy for females to minimize the likelihood of being fertilized by aged sperm. 相似文献
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W. G. Breed G. A. Cox C. M. Leigh P. Hawkins 《Molecular reproduction and development》1988,19(2):191-202
The morphology of spermatozoa from the red veld rat, Aethomys chrysophilus, of Southern Africa is described; two very different types were found, which came from animals from two separate, as-yet-undescribed, species. In individuals from South Africa the sperm head had a somewhat disc-shaped nucleus and a large acrosome with a huge apical segment that, during epididymal transit, changed in form from initially projecting anteriorly to a highly complex structure that was flexed caudad and lay alongside part of the rest of the sperm head. In addition, the chromatin generally appeared to be not fully condensed. Spermatozoa from animals collected in Malawi were very different in morphology and had a head with a typical apical hook, a perforatorium, fully condensed chromatin, and a 4-μm-long ventral spur. Its sperm tail was also significantly longer. The time of divergence of these two groups of animals from a common ancestor is not known, but the present results show that a considerable morphological change in the sperm nucleus, acrosome, and subacrosomal space can evolve even between two, presumably closely related, species. 相似文献
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Fishelson L 《Journal of morphology》2003,256(3):285-300
Testis structure, spermatogenesis, and spermatocytogenesis were compared in 13 species of cichlid fishes, belonging to the subfamilies Haplochrominae and Tilapinae. The species studied were either mouth brooders, in which fertilization occurs mostly inside the mouth of the brooding fish, or substrate brooders, whose eggs adhere to a substrate over which the sperm is ejaculated. In this study, the embryogenesis of testes anlagen and sperm production was followed in embryos and in fish up to 15 years old, as well as in hybrids of the two subfamilies. In cichlids, the testes are of the unrestricted type and primary spermatogonia develop along the entire length of the developing sperm tubule. The first primary spermatogonia are observed in the testes anlagen 2-5 days after fertilization and they continue to develop in cysts formed by the enveloping Sertoli cells and the intertubular elements. The dimensions of such primary and secondary spermatocysts are correlated with the number of spermatogonia they contain and the corresponding number of mitotic multiplications. The largest mature cysts attained 300 microm, and contained 2,200-2,400 spermatids in the mouth-brooding species and 2,600-3,200 in the substrate-brooding species. Despite the fact that in such cysts cytoplasmic bridges connect only the isogamete spermatids, the maturation of all cells and consequent spermiation is synchronized. Meristic characters distinguish the sperm of mouth brooders from those of substrate brooders, especially in the number of mitochondria and length of the flagellum. In older fish and hybrids, various changes can be seen in the gametogenic epithelium and intertubular cells. These include thickening of the connective tissue, formation of \"yellow\" groups of Leydig cells, cell apoptosis and degeneration, and, especially, formation of large spermatogonia, with large, electron-dense nucleoli, that have the cytological characteristics of oocytes. The intra- and interspecific variability of sperm dimensions in the studied cichlids poses an interesting question in the context of sperm competition. 相似文献
14.
Mai A Weerachatyanukul W Tomietto M Wayner DD Wells G Balhorn R Leader A Cyr JL Tanphaichitr N 《Molecular reproduction and development》2002,63(4):471-479
The objective of this study was to use atomic force microscopy (AFM), with submicron resolution, for morphophologic and morphometric analyses of acrosome intact and acrosome-reacted human sperm heads. A mixed population of acrosome intact and reacted sperm was produced by treating capacitated sperm with A23187, which induced the acrosome reaction in approximately 50% of total sperm population. This A23187-treated sperm suspension was then plated onto a coverslip and acrosome reacted sperm were preidentified by their specific staining with rhodamine-conjugated Concanavalin A. The sperm coverslip was then air-dried and scanned by a Nanoscope IIIa atomic force microscope, using the contact mode. Top and side view images processed through the illuminate mode revealed three dimensional sperm head contour, with the highest point situated in the head posterior in both acrosome intact and acrosome reacted sperm. Maximum height, length, and width measured in 50 acrosome intact and 50 acrosome-reacted sperm were the same in both populations. However, head length at half maximum height was significantly decreased in acrosome reacted sperm (2.99 +/- 0.24 microm vs. 3.56 +/- 0.32 microm of acrosome intact sperm), due to the sudden change of the height contour from the maximum peak to the anterior tip of acrosome-reacted sperm. Our results described here can therefore be used to differentiate acrosome intact and reacted sperm from each other. This would allow future studies on subcellular changes, related to the acrosome reaction, at the submicron resolution level under more physiological conditions, since AFM does not require fixing or staining of the samples. 相似文献
15.
L. Locatello M. B. Rasotto B. Adriaenssens A. Pilastro 《Journal of fish biology》2008,73(7):1600-1611
In the present study, the correlation between sperm number, sperm quality (speed, viability, longevity and length), sperm bundles quality (size and dissolving rate) and male body size has been tested in the eastern mosquitofish Gambusia holbrooki a poecilid species characterized by coercive mating tactics where males do not possess obvious ornaments, and the body size is the key determinant of pre‐copulatory male mating success. The results do not tally with theoretical predictions. Indeed, no correlation between male body size and either sperm or sperm‐bundle traits has been found, evidencing the lack of the theoretically expected trade‐off between the investment in characters involved in mate acquisition and the investment in ejaculate quality. An explanation for the observed pattern comes from the extremely dynamic mating system of G. holbrooki, characterized by variable size‐related male mating success and strong post‐copulatory selective pressure, with all males facing a similar high level of sperm competition. In this situation, a higher investment in growth and maintenance at the expense of ejaculate quality is not expected. These results underscore the necessity to comprehend detailed information on species’ reproductive biology and reproductive environment to understand both the evolution of ejaculate characteristics and possible deviations from theoretical predictions. 相似文献
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Cecilia S. Blengini Naretto Sergio Cardozo Gabriela Laura C. Giojalas Chiaraviglio Margarita 《Ecology and evolution》2014,4(21):4080-4092
In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize male fertilization success. We aim at elucidating the variability of sperm morphometric traits and velocity in two Tupinambis lizards in the context of sperm competition risk. Sperm traits showed substantial variation at all levels examined: between species, among males within species, and within the ejaculate of individual males. Sperm velocity was found to be positively correlated with flagellum: midpiece ratio, with relatively longer flagella associated with faster sperm. Our results document high variability in sperm form and function in lizards. 相似文献
19.
Evolutionary theory predicts that selection will favor phenotypic plasticity in sperm traits that maximize fertilization success in dynamic fertilization environments. In species with external fertilization, osmolality of the fertilization medium is known to play a critical role in activating sperm motility, but evidence for osmotic‐induced sperm plasticity is limited to euryhaline fish and marine invertebrates. Whether this capacity extends to freshwater taxa remains unknown. Here, we provide the first test for plasticity in sperm‐motility activation in response to osmotic environment in an anuran amphibian. Male common eastern froglets (Crinia signifera) were acclimated to either low (0 mOsmol kg−1) or high (50 mOsmol kg−1) environmental osmolality, and using a split‐sample experimental design, sperm were activated across a range of osmolality treatments (0, 25, 50, 75, 100, and 200 ± 2 mOsmol kg−1). Unexpectedly, there was no detectable shift in the optimal osmolality for sperm‐motility activation after approximately 13 weeks of acclimation (a period reflecting the duration of the winter breeding season). However, in both the low and high acclimation treatments, the optimal osmolality for sperm‐motility activation mirrored the osmolality at the natural breeding site, indicating a phenotypic match to the local environment. Previously it has been shown that C. signifera display among‐population covariation between environmental osmolality and sperm performance. Coupled with this finding, the results of the present study suggest that inter‐population differences reflect genetic divergence and local adaptation. We discuss the need for experimental tests of osmotic‐induced sperm plasticity in more freshwater taxa to better understand the environmental and evolutionary contexts favoring adaptive plasticity in sperm‐motility activation. 相似文献
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Selection imposed through sperm competition is commonly thought to promote the evolution of longer sperm, since sperm length is assumed to be positively associated with sperm swimming velocity. Yet, the basis for this assumption remains controversial, and there is surprisingly little intraspecific evidence demonstrating such a link between sperm form and function. Here, we show that sperm length and velocity are highly correlated in the sea urchin Heliocidaris erythrogramma, but importantly we report that failure to account for within-male variation in these sperm traits can obscure this relationship. These findings, in conjunction with the mounting evidence for extremely high levels of intra-specific variance in sperm traits, suggest that a functional link between sperm morphology and velocity may be more prevalent than what current evidence suggests. Our findings also suggest that selection for faster swimming sperm may promote the evolution of longer sperm, thereby supporting recent findings from macroevolutionary studies. 相似文献