Natural and experimental evolution of sexual conflict within Caenorhabditis nematodes

BACKGROUND: Although males and females need one another in order to reproduce, they often have different reproductive interests, which can lead to conflict between the sexes. The intensity and frequency of male-male competition for fertilization opportunities is thought to be an important contributor to this conflict. The nematode genus Caenorhabditis provides an opportunity to test this hypothesis because the frequency of males varies widely among species with different mating systems. RESULTS: We find evidence that there is strong inter- and intra-sexual conflict within C. remanei, a dioecious species composed of equal frequencies of males and females. In particular, some C. remanei males greatly reduce female lifespan following mating, and their sperm have a strong competitive advantage over the sperm of other males. In contrast, our results suggest that both types of conflict have been greatly reduced within C. elegans, which is an androdioecious species that is composed of self-fertilizing hermaphrodites and rare males. Using experimental evolution in mutant C. elegans populations in which sperm production is blocked in hermaphrodites (effectively converting them to females), we find that the consequences of sexual conflict observed within C. remanei evolve rapidly within C. elegans populations experiencing high levels of male-male competition. CONCLUSIONS: Together, these complementary data sets support the hypothesis that the intensity of intersexual conflict varies with the intensity of competition among males, and that male-induced collateral damage to mates can evolve very rapidly within populations

Data from: Natural and experimental evolution of sexual conflict within Caenorhabditis nematodes

Background: Although males and females need one another in order to reproduce, they often have different reproductive interests, which can lead to conflict between the sexes. The intensity and frequency of male-male competition for fertilization opportunities is thought to be an important contributor to this conflict. The nematode genus Caenorhabditis provides an opportunity to test this hypothesis because the frequency of males varies widely among species with different mating systems. Results: We find evidence that there is strong inter- and intra-sexual conflict within C. remanei, a dioecious species composed of equal frequencies of males and females. In particular, some C. remanei males greatly reduce female lifespan following mating, and their sperm have a strong competitive advantage over the sperm of other males. In contrast, our results suggest that both types of conflict have been greatly reduced within C. elegans, which is an androdioecious species that is composed of self-fertilizing hermaphrodites and rare males. Using experimental evolution in mutant C. elegans populations in which sperm production is blocked in hermaphrodites (effectively converting them to females), we find that the consequences of sexual conflict observed within C. remanei evolve rapidly within C. elegans populations experiencing high levels of male-male competition. Conclusions: Together, these complementary data sets support the hypothesis that the intensity of intersexual conflict varies with the intensity of competition among males, and that male-induced collateral damage to mates can evolve very rapidly within populations

Palopoli_elegans_sperm_size

Sperm size measures for C. elegans males evolved under conditions of high and low male-male competitio

Palopoli_remanei_spermcompetition

Sperm competition among three strains of C. remanei mated against three female backgrounds

Palopoli_elegans_spermcompetition

Sperm competition results for C. elegans lines evolved in the presence of high and low male-male competitio

Palopoli_elegans_hermaphroditemortality

Survival of hermaphrodites living with males evolved under conditions of high and low male-male competitio

Palopoli_elegans_spiculeinsertion

Duration of spicule insertion for C. elegans males evolved under conditions of high and low male-male competition

Palopoli_remanei_sperm_size

Sperm size measurements for three strains of C. remane

Palopoli_remanei_lifehistory

Total reproduction and lifespan (age at death) for three different stains of C. remanei mated in a series of factorial crosses. Includes lifespans for virgin females