Fertilization kinetics of sea urchin eggs

Vogel, Helmut; Czihak, G.; Chang, Patrick; Wolf, W.

doi:10.1016/0025-5564(82)90073-6

Cited by 173 publications

(223 citation statements)

References 10 publications

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“…Therefore, given that sperm from high-density animals lived longer, it is possible that the high-density sperm had a reduced velocity, which could lower collision rates and serve a similar function to reducing sperm numbers under high competition [as predicted by Bode and Marshall (3)]. Such an interpretation can only be speculative without direct measurements on sperm velocity, but it is interesting that sperm from high-density animals not only lived longer but achieved identical levels of fertilization at lower sperm concentrations-a result that would not be predicted on the basis of differences in sperm velocity alone (57). Regardless of the direct mechanism, it seems clear that S. plicata manipulate the qualities of their sperm in a way that is likely to increase their fertilization success when population densities are high and polyspermy is likely.…”

Section: Discussionmentioning

confidence: 91%

Gamete plasticity in a broadcast spawning marine invertebrate

Crean

Marshall

2008

Proc. Natl. Acad. Sci. U.S.A.

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Sperm competition has classically been thought to maintain anisogamy (large eggs and smaller sperm) because males are thought to maximize their chance of winning fertilizations by trading sperm size for number. More recently it has been recognized that sperm quality (e.g., size, velocity) can also influence sperm competition, although studies have yielded conflicting results. Because sex evolved in the sea, debate has continued over the role of sperm competition and sperm environment in determining both sperm and egg size in externally fertilizing broadcast spawners. Remarkably, however, there have been no direct tests of whether broadcast spawners change the traits of their gametes depending on the likelihood of sperm competition. We manipulated the density (and thus, sperm environment) of a broadcast spawning ascidian (Styela plicata) in the field and then determined whether the phenotype of eggs and sperm changed. We found that sperm from adults kept at high density were larger and more motile than sperm from low-density adults. In vitro fertilizations revealed that sperm from high-density adults also lived longer and induced less polyspermy. Adult density also affected egg traits: eggs from high-density adults were smaller targets for sperm overall but produced larger ovicells than eggs from low-density adults. This suggests that broadcast spawning mothers balance (potentially conflicting) pre-and postzygotic selection pressures on egg size. Overall, our results suggest that sperm competition does not represent a strong force maintaining anisogamy in broadcast spawners. Instead, sperm limitation seems to select for large eggs and smaller, more numerous sperm.anisogamy ͉ sperm competition ͉ adaptive maternal effect ͉ transgenerational plasticity T he fundamental difference between the sexes is that males produce numerous, tiny sperm, and females produce relatively fewer, large eggs (anisogamy). Classic theory suggests that anisogamy most likely evolved by, and is maintained through, sperm competition (whereby sperm from 2 or more males compete to fertilize an egg) because males producing a greater number of sperm have a competitive advantage (refs. 1 and 2; but see ref. 3 for an alternative). In species with internal fertilization, competition for fertilizations can therefore be viewed as a ''raffle,'' whereby males that have the highest representation of sperm in the pool have the greatest chance of fertilizing eggs (4, 5). More recently, however, it has been proposed that sperm quality (e.g., sperm size, velocity, and longevity) can also influence the outcome of sperm competition (6, 7). Furthermore, because a male's sperm supply is limited (8, 9) and each mating opportunity may carry a variable risk of sperm competition (10), males must make decisions on the optimal allocation of both sperm number and quality for each mating event. The optimal allocation of sperm size and number within an ejaculate remains a source of intense debate (reviewed in refs. 7 and 9).The prediction that males should increase the ...

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Section: Discussionmentioning

confidence: 91%

Gamete plasticity in a broadcast spawning marine invertebrate

Crean

Marshall

2008

Proc. Natl. Acad. Sci. U.S.A.

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“…derived by Vogel et al [7] as a plausible relationship between fertility and sperm density (see also [6]), where the constant k depends on the properties of the gametes and the fertilization process. Then we can write the mutant's marginal benefits as…”

Section: (A) Intensitymentioning

confidence: 99%

“…[5,6]) and sperm density in the surrounding medium of external fertilizers (e.g. [7]). Interest in sperm limitation (SL) has recently increased [8], and under some conditions found in nature, certain broadcast spawning invertebrates experience low levels of fertility owing to SL [9], while others show high fertility [10].…”

Section: Introductionmentioning

confidence: 99%

Gamete evolution and sperm numbers: sperm competition versus sperm limitation

Parker

Lehtonen

2014

Proc. R. Soc. B.

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Both gamete competition and gamete limitation can generate anisogamy from ancestral isogamy, and both sperm competition (SC) and sperm limitation (SL) can increase sperm numbers. Here, we compare the marginal benefits due to these two components at any given population level of sperm production using the risk and intensity models in sperm economics. We show quite generally for the intensity model (where N males compete for each set of eggs) that however severe the degree of SL, if there is at least one competitor for fertilization (N 2 1 ! 1), the marginal gains through SC exceed those for SL, provided that the relationship between the probability of fertilization (F) and increasing sperm numbers (x) is a concave function. In the risk model, as fertility F increases from 0 to 1.0, the threshold SC risk (the probability q that two males compete for fertilization) for SC to be the dominant force drops from 1.0 to 0. The gamete competition and gamete limitation theories for the evolution of anisogamy rely on very similar considerations: our results imply that gamete limitation could dominate only if ancestral reproduction took place in highly isolated, small spawning groups.

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“…Rather than simultaneously solve the three unknowns (␤, ␤ 0 , and t b ), the collision constant was estimated using known values for the crosssectional area of the egg (0.07 mm 2 from empirical measures) and the sperm velocity (0.2 mm/sec, typical marine invertebrate sperm velocity; Levitan 1995;Vogel et al 1982). The model fits to these data were not dependent on the estimated value of this collision constant.…”

Section: Details Of Gamete Age and Dilution Experimentsmentioning

confidence: 99%

Mechanisms of Reproductive Isolation Among Sympatric Broadcast-Spawning Corals of the Montastraea Annularis Species Complex

et al. 2004

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Abstract. Many coral species spawn simultaneously and have compatible gametes, leading to controversy over the nature of species boundaries and the frequency with which hybridization occurs. Three western Atlantic corals, Montastraea annularis, M. faveolata, and M. franksi, typify this controversy; they all spawn sympatrically on the same evenings after the fall full moons. Here we show, in both Panama and the Bahamas for multiple years, how a variety of mechanisms may act in concert to reproductively isolate all three species. Field studies indicate that M. franksi spawns two hours earlier than the other two species, and the eggs released during this earlier period disperse an average of 500 m by the time the other species spawn. Field measures of fertilization indicate that peak fertilization occurs when spawning synchrony is high and that corals that spawn at the tails of the spawning distributions have greatly reduced fertilization success. Laboratory studies indicate that there is a gametic incompatibility between M. faveolata and the other two species. There are regional differences in the gametic compatibility of M. franksi and M. annularis. In Panama, the two species are completely compatible, whereas in the Bahamas, M. franksi sperm can fertilize M. annularis eggs but the reciprocal cross often fails. Gamete age influences patterns of fertilization, such that very young eggs seem resistant to fertilization and old sperm lose viability after two hours. In sum, the combination of temporal differences in spawning, sperm aging, gamete dispersal and dilution, and gametic incompatibility act in various combinations among the three species, making it unlikely that hybrid fertilization would occur.

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Fertilization kinetics of sea urchin eggs

Cited by 173 publications

References 10 publications

Gamete plasticity in a broadcast spawning marine invertebrate

Gamete plasticity in a broadcast spawning marine invertebrate

Gamete evolution and sperm numbers: sperm competition versus sperm limitation

Mechanisms of Reproductive Isolation Among Sympatric Broadcast-Spawning Corals of the Montastraea Annularis Species Complex

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