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Teleogryllus oceanicus

Publications filtered by: Teleogryllus oceanicus

Male-induced costs of mating for females compensated by offspring viability benefits in an insect
Garcia-Gonzalez, F. & Simmons, L. W. 2010 Male-induced costs of mating for females compensated by offspring viability benefits in an insect Journal of Evolutionary Biology, 23: 2066-2075
Sexual conflict facilitates the evolution of traits that increase the reproductive success of males at the expense of components of female fitness. Theory suggests that indirect benefits are unlikely to offset the direct costs to females from antagonistic male adaptations, but empirical studies examining the net fitness pay-offs of the interaction between the sexes are scarce. Here, we investigate whether matings with males that invest intrinsically more into accessory gland tissue undermine female lifetime reproductive success (LRS) in the cricket Teleogryllus oceanicus. We found that females incur a longevity cost of mating that is proportional to the partner’s absolute investment into the production of accessory gland products. However, male accessory gland weight positively influences embryo survival, and harmful ejaculate-induced effects are cancelled out when these are put in the context of female LRS. The direct costs of mating with males that sire offspring with higher viability are thus compensated by direct and possibly indirect genetic benefits in this species.
Paternal indirect genetic effects on offspring viability and the benefits of polyandry
Garcia-Gonzalez, F. & Simmons, L. W. 2007 Paternal indirect genetic effects on offspring viability and the benefits of polyandry Current Biology, 17: 32-36
Although females are expected to maximize their reproductive success with only one or a few matings, the females of many species mate with multiple partners. Experimental studies have found evidence for an increase in egg or embryo viability when females mate polyandrously. These studies have been interpreted in the context of genetic-benefit models that propose that multiple mating increases offspring viability because it allows females to select male genotypes that influence viability directly or because it allows females to avoid genetic incompatibility. However, no studies have examined directly the precise mechanisms by which parents influence embryo viability. Using a morphological marker that enabled us to determine paternity and survival of embryos sired by individual male crickets in both sperm competitive and -noncompetitive situations, we show that males inducing high embryo viability enhance the viability of embryos sired by inferior males. These results indicate that paternal effects and interacting phenotypes determine embryo viability. They show that a male’s reproductive success is modified by the interaction between indirect genetic effects of sperm competitors. Importantly, our findings show that the benefits accruing to offspring of multiply mated females need not be transmitted genetically.
Female crickets trade offspring viability for fecundity
Simmons, L. W. & Garcia-Gonzalez, F. 2007 Female crickets trade offspring viability for fecundity Journal of Evolutionary Biology, 20: 1617-1623
A growing number of studies are suggesting that females can improve the viability of their embryos by mating with multiple males. However, the reason why females should have low rates of embryo viability is puzzling. Here we conduct a quantitative genetic study of maternal effects on embryo viability in the field cricket Teleogryllus oceanicus. After controlling for female body size, we find significant additive genetic variance for ovary weight, a measure of fecundity, and egg hatching success, a measure of embryo viability. Moreover, we show a genetic trade-off between these traits that is predicted from life-history theory. High rates of embryo mortality in this highly fecund species might therefore be explained by selection favouring an optimum balance between fecundity and embryo viability that maximizes maternal fitness. Paternal effects on female fecundity and embryo viability are often seen as benefits driving the evolution of polyandrous behaviour. However, we raise the alternative possibility that paternal effects might shift females from their naturally selected optimum, and present some support for the notion that sexual conflict over a female’s optimal fecundity and embryo viability might generate antagonistic coevolution between the sexes.
The evolution of polyandry: intrinsic sire effects contribute to embryo viability
Garcia-Gonzalez, F. & Simmons, L. W. 2005 The evolution of polyandry: intrinsic sire effects contribute to embryo viability Journal of Evolutionary Biology, 18:1097-1103
Females typically mate with more than one male despite the costs incurred, thus questioning Bateman’s principle. A series of genetic benefits have been proposed to account for the evolution of polyandry, including the acquisition of viability genes for offspring. The ‘intrinsic male quality’ hypothesis suggests that polyandry increases the probability that females produce offspring sired by males that bestow high viability on their offspring. Heritable variation in viability is the basic requirement for the occurrence of this genetic benefit. By using a half-sib breeding design with a species of cricket in which polyandry is known to increase hatching success, we present clear experimental evidence that intrinsic male quality contributes to embryo viability. Despite recent support for the evolution of polyandry based on compatibility of genotypes between males and females, we show that hatching success is not determined by an interaction between paternal and maternal genotypes but rather that sons inherit paternal genes that influence the viability of eggs laid by their mates. Moreover, our data implicate a potential role for indirect genetic effects of male accessory gland products on embryo viability. Additive genetic contributions to embryo viability may be an important factor underlying the frequently observed benefits of polyandrous behaviour.
Sperm viability matters in insect sperm competition
Garcia-Gonzalez, F. & Simmons, L. W. 2005 Sperm viability matters in insect sperm competition Current Biology, 15: 271-275

Female promiscuity often results in the ejaculates of different males competing to fertilize a female's ova. Experimental studies in insects have shown how sperm competition can be a potent selective force acting on an array of male reproductive traits, including features of the ejaculate such as sperm numbers or sperm size. However, experimental analysis of the role of sperm quality in determining paternity in insects has been neglected, despite the fact that sperm quality has been shown to influence the outcome of sperm competition in vertebrates. A recent comparative analysis found that males of polyandrous insect species show a higher proportion of live sperm in their stores, suggesting that sperm competition has shaped the quality of insect sperm. Here we test the hypothesis that sperm viability influences paternity at the within-species level. We use the cricket Teleogryllus oceanicus to conduct sperm competition trials involving pre-screened males that differ in the viability of their sperm. We find that paternity success is determined by the proportion of live sperm in a male's ejaculate. Furthermore, we were able to predict the patterns of paternity observed on the basis of the males' relative representation of viable sperm in the female's sperm storage organ. Our findings provide the first experimental evidence for the theory that sperm competition selects for higher sperm quality in insects, and indicate that between-male variation in sperm quality needs to be considered in theoretical and experimental studies of insect sperm competition.

Variation in paternity in the field cricket Teleogryllus oceanicus: no influence of sperm numbers or sperm length
Simmons, L.W.; Wernham, J.; Garcia-Gonzalez, F. & Kamien, D. 2002 Variation in paternity in the field cricket Teleogryllus oceanicus: no influence of sperm numbers or sperm length Behavioral Ecology, 14: 539-545
Recent attention has focused on the role that sperm competition may play in the evolution of sperm morphology. Theoretical analyses predict increased sperm size, decreased sperm size, and no change in sperm size in response to sperm competition, depending on the assumptions made concerning the life history and function of sperm. However, although there is good evidence that sperm morphology varies widely within and between species, the adaptive significance of this variation has not been examined. Here we document significant intraspecific variation in sperm length in the field cricket, Teleogryllus oceanicus. Sperm length did not influence the rate of migration of sperm from the spermatophore to the female’s spermatheca. We performed sperm competition trials in which we varied the numbers of sperm transferred by each of two males that differed in the length of sperm they produced. Neither sperm length nor the number of sperm transferred influenced paternity. The same results were obtained using two different methods for assigning paternity. The distribution of paternity across a female’s mates was highly variable, with frequently one, or more in the case of females mated to four males, principal sire. There were no mating order effects on paternity. These data show that sperm do not mix randomly in the female’s spermatheca. We discuss several alternative explanations for the patterns of paternity observed.