Sperm investment and alternative mating tactics in bluegill sunfish (Lepomis macrochirus)

Neff, Bryan D.; Fu, Ping; Gross, Mart R.

doi:10.1093/beheco/arg032

Cited by 171 publications

(130 citation statements)

References 40 publications

Supporting

Mentioning

123

Contrasting

Order By: Relevance

“…For all ten females, this resulted in a total of 90 trials. To avoid the effects of CFC being potentially masked by sperm competition, we precautionary controlled for sperm number, a factor known to have a key role in sperm competition in the bluegill sunfish (Neff et al, 2003;Stoltz and Neff, 2006), but possibly not crucial in salmonids (Gage et al, 2004), by determining sperm densities using an improved Neubauer haemocytometer. We then added respective volumes of milt containing 1 × 10 8 of spermatozoa from each male (2.1-9.8 μl) to the given egg batch.…”

Section: Experimental Overviewmentioning

confidence: 99%

Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha)

et al. 2017

View full text Add to dashboard Cite

Cryptic female choice (CFC), a form of sexual selection during or post mating, describes processes of differential sperm utilization by females to bias fertilization outcomes towards certain males. In Chinook salmon (Oncorhynchus tshawytscha) the ovarian fluid surrounding the ova of a given female differently enhances the sperm velocity of males. Sperm velocity is a key ejaculate trait that determines fertilization success in externally fertilizing fishes, thus the differential effect on sperm velocity might bias male fertilization outcomes and represent a mechanism of CFC. Once sperm reach the oocyte, CFC could potentially be further facilitated by sperm-egg interactions, which are well understood in externally fertilizing marine invertebrates. Here, we explored the potential genetic basis of both possible mechanisms of CFC by examining whether the genotypic combinations of mates (amino-acid divergence, number of shared alleles) at the major histocompatibility complex (MHC) class I and II explain the variation in sperm velocity and/or male fertilization success that is not explained by sperm velocity, which might indicate MHC-based sperm-egg interactions. We recorded sperm velocity in ovarian fluid, employed paired-male fertilization trials and evaluated the fertilization success of each male using microsatellite-based paternity assignment. We showed that relative sperm velocity was positively correlated with fertilization success, confirming that the differential effect on sperm velocity may be a mechanism of CFC in Chinook salmon. The variation in sperm velocity was independent of MHC class I and II. However, the MHC class II divergence of mates explained fertilization success, indicating that this locus might influence sperm-egg interactions.

show abstract

Section: Experimental Overviewmentioning

confidence: 99%

Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha)

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Much of this variability may arise from the fact that sperm size may covary with velocity and longevity, and the benefits of these traits may be highly context dependent. The relationship between sperm competition and sperm longevity may be positive (21), negative (27,28), or absent (29), and fertilization success may increase for sperm that are faster (26) or longer lived (27). Hence, it remains unclear whether males should adaptively adjust sperm traits in response to changes in the risk of sperm competition.…”

mentioning

confidence: 99%

Gamete plasticity in a broadcast spawning marine invertebrate

Crean

Marshall

2008

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

View full text Add to dashboard Cite

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 ...

show abstract

“…Some males exhibit an alternative reproductive strategy in which they are known as "satellites" or "sneakers." Satellite and sneaker males mature precociously and do not build nests of their own but mimic females or use sneaking, respectively, to gain access to fertilization during oviposition (Belk and Hales Jr., 1993;Breck, 1996;Neff et al, 2003).…”

Section: Life History and Demography Of Bluegillmentioning

confidence: 99%

Modeling effects of toxin exposure in fish on long-term population size, with an application to selenium toxicity in bluegill (Lepomis macrochirus)

Gledhill

Kirk

2011

Ecological Modelling

View full text Add to dashboard Cite

MODELING EFFECTS OF TOXIN EXPOSURE IN FISH ON LONG-TERM POPULATION SIZE, WITH AN APPLICATION TO SELENIUM TOXICITY IN BLUEGILL (LEPOMIS MACROCHIRUS)Michelle Gledhill A primary goal in ecotoxicology is the prediction of population-level effects of contaminant exposure based on individual-level response. Assessment of toxicity at the population level has predominately focused on the population growth rate (PGR), but the PGR may not be a relevant toxicological endpoint for populations at equilibrium. Equilibrium population size may be a more meaningful endpoint than the PGR because a population with smaller equilibrium (i.e., long-term mean) size is more susceptible to the negative effects of environmental variability. I address the ecotoxicology individual-to-population extrapolation problem with modeling. I developed and analyzed a general model applicable to many freshwater fish species that includes density-dependent juvenile survival and additional juvenile mortality due to toxicity exposure, and I quantified its effect on equilibrium population size as a means of assessing toxicity. I then used selenium toxicity in bluegill sunfish as an example to assess the effects of environmental stochasticity on toxicity response with simulation modeling. Individual-level effects are typically greater than population-level effects until the individual effect is large, due to compensatory density-dependent relationships. These effects are sensitive to the recruitment potential of a population, in particular the low-density first-year survival rate S b . Assuming high S b could result in underestimating effects of population-level toxicity. The equilibrium size depends directly on S b , the reproductive potential, the toxin concentration at which mean mortality is 50% (LC 50 ), and iii the rate at which individual mortality increases with increasing toxin concentration. More experimental data are needed to decrease the uncertainty in estimating these parameters.Effects of environmental variability resulted in simulated extinctions at much lower toxin concentrations than predicted deterministically. iv ACKNOWLEDGEMENTS

show abstract

Sperm investment and alternative mating tactics in bluegill sunfish (Lepomis macrochirus)

Cited by 171 publications

References 40 publications

Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha)

Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha)

Gamete plasticity in a broadcast spawning marine invertebrate

Modeling effects of toxin exposure in fish on long-term population size, with an application to selenium toxicity in bluegill (Lepomis macrochirus)

Contact Info

Product

Resources

About