Among-population pollen movement and skewed male fitness in a dioecious weed

AbstractNotwithstanding recent evidences, paternal environment is thought to be a potential but unlikely source of fitness variation that can affect trait evolution. Here we studied intergenerational effects of males’ exposure to varying adult density in Drosophila melanogaster laboratory populations.We held sires at normal (N), medium (M) and high (H) adult densities for two days before allowing them to mate with virgin females. This treatment did not introduce selection through differential mortality. Further, we randomly paired males and females and allowed a single round of mating between the sires and the dams. We then collected eggs from the dams and measured the egg size. Finally, we investigated the effect of the paternal treatment on juvenile and adult (male) fitness components.We found a significant treatment effect on juvenile competitive ability where the progeny sired by the H-males had higher competitive ability. Since we did not find the treatment to affect egg size, this effect is unlikely to be mediated through variation in female provisioning.Male fitness components were also found to have a significant treatment effect: M-sons had lower dry weight at eclosion, higher mating latency and lower competitive mating success.While being the first study to show both adaptive and non-adaptive effect of the paternal density in Drosophila, our results highlight the importance of considering paternal environment as important source of fitness variation.

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Sperm quality parameters are increased and asymmetric in house mouse hybrids

10.1101/666511 ◽

2019 ◽

Author(s):

Iva Martincová ◽

Ľudovít Ďureje ◽

Stuart J. E. Baird ◽

Jaroslav Piálek

Keyword(s):

Y Chromosome ◽

House Mouse ◽

Sperm Quality ◽

Quality Parameters ◽

F1 Hybrids ◽

Secondary Contact ◽

Male Fitness ◽

Cross Direction ◽

Sperm Trait ◽

The Difference

AbstractSpermatogenesis is a tuned cascade of processes producing sperm; impairment of any phase of this process can affect fitness of males. The level of impairment can be pronounced in hybrids between genetically divergent populations. To explore the effect of hybridization on sperm quality we produced F1 hybrids from 29 wild derived strains of two house mouse subspecies, M. m. musculus and M. m. domesticus, which diverged 0.5 MY ago. The measured sperm quality traits did not significantly differ between intrasubspecific crosses. Effects of intersubspecific hybridization were dependent on sperm trait and cross direction. The proportion of sperm head abnormalities was increased in F1 intersubspecific hybrids. The frequency of dissociated sperm heads was increased in the M. m. musculus × M. m. domesticus (♀×♂) F1 but decreased in M. m. domesticus × M. m. musculus (♀×♂) F1 hybrids, with the difference in medians being more than 180%. We deduce that the dissociated sperm heads trait is associated with the X chromosome and modulated by interaction with the Y chromosome; nevertheless, the high proportion of unexplained variance (55.46 %) suggests the presence of polymorphic autosomal interactions. The reported differences in sperm quality between cross types may be highly relevant to male fitness in zones of secondary contact between the two subspecies. The cross direction asymmetry in frequency of dissociated sperm heads should favour the M. m. musculus Y chromosome. This is consistent with the spread of the M. m. musculus Y chromosome in nature across the hybrid zone between these two subspecies.

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Genetic variance in fitness and its cross-sex covariance predict adaptation during experimental evolution

10.1101/2020.02.26.966119 ◽

2020 ◽

Author(s):

Eva L. Koch ◽

Sonja H. Sbilordo ◽

Frédéric Guillaume

Keyword(s):

Experimental Evolution ◽

Genetic Variance ◽

Environmental Changes ◽

Additive Genetic Variance ◽

Relative Fitness ◽

Male Fitness ◽

Adaptive Potential ◽

Genetic Covariance ◽

Flour Beetles ◽

Single Stress

AbstractIn presence of rapid environmental changes, it is of particular importance to assess the adaptive potential of populations, which is mostly determined by the additive genetic variation (VA) in fitness. In this study we used Tribolium castaneum (red flour beetles) to investigate its adaptive potential in three new environmental conditions (Dry, Hot, Hot-Dry). We tested for potential constraints that might limit adaptation, including negative genetic covariance between female and male fitness. Based on VA estimates for fitness, we expected the highest relative fitness increase in the most stressful condition Hot-Dry and similar increases in single stress conditions Dry and Hot. High adaptive potential in females in Hot was reduced by a negative covariance with male fitness. We tested adaptation to the three conditions after 20 generations of experimental evolution and found that observed adaptation mainly matched our predictions. Given that body size is commonly used as a proxy for fitness, we also tested how this trait and its genetic variance (including non-additive genetic variance) were impacted by environmental stress. In both traits, variances were sex and condition dependent, but they differed in their variance composition, cross-sex and cross-environment genetic covariances, as well as in the environmental impact on VA.

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Do metrics of sexual selection conform to Bateman's principles in a wind-pollinated plant?

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.0532 ◽

2019 ◽

Vol 286 (1905) ◽

pp. 20190532 ◽

Cited By ~ 6

Author(s):

Jeanne Tonnabel ◽

Patrice David ◽

John R. Pannell

Keyword(s):

Spatial Distribution ◽

Sexual Selection ◽

Reproductive Success ◽

Pollen Dispersal ◽

Male Fitness ◽

Female Fitness ◽

Dioecious Plant ◽

Common Gardens ◽

Mate Acquisition ◽

Mercurialis Annua

Bateman's principles posit that male fitness varies more, and relies more on mate acquisition, than female fitness. While Bateman's principles should apply to any organism producing gametes of variable sizes, their application to plants is potentially complicated by the high levels of polyandry suspected for plants, and by variation in the spatial distribution of prospective mates. Here we quantify the intensity of sexual selection by classical Bateman metrics using two common gardens of the wind-pollinated dioecious plant Mercurialis annua . Consistent with Bateman's principles, males displayed significantly positive Bateman gradients (a regression of fitness on mate number), whereas the reproductive success of females was independent of their ability to access mates. A large part of male fitness was explained by their mate number, which in turn was associated with males' abilities to disperse pollen. Our results suggest that sexual selection can act in plant species in much the same way as in many animals, increasing the number of mates through traits that promote pollen dispersal.

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