Interspecific competition between Drosophila melanogaster and D. simulans: Effects of adult

1977 ◽  
Vol 25 (4) ◽  
pp. 699 ◽  
Author(s):  
JJ Moth

The hatchability of eggs laid by D. simulans st and D. melanogaster Or-R-C in consecutive 12-hour periods was measured for the first seven days post eclosion in a replicated experiment where adult density at six levels, species frequency at two levels, and 32P tissue content at two levels were varied factorially. A similar experiment was done for D. simulans st and D. melanogaster yw. In both experiments, all unhatched eggs were classified as either dead or infertile. Least-squares analyses of variance on arcsine-transformed percentage data indicated that the three strains produced significantly different proportions of hatched, dead, and infertile eggs. Increased adult density significantly decreased the proportion of hatched eggs (and increased the proportion of dead eggs) for D. simulans st and D. melanogaster Or-R-C, but not for D. melanogaster yw. Effects of strain frequency were not significant for D. simulans st or D. melanogaster Or-R-C, but for D. melanogaster yw higher hatchability and lower proportions of infertile eggs were obtained in pure populations. Hatchability varied between periods; changes in hatchability being random (but significant) for D. melanogaster yw, and consistent (but not significant) for D. simulans st (a decrease in hatchability with time) and D. melanogaster Or-R-C (an increase with time). The competing strain of D. melanogaster did not influence the proportions of hatched, dead or infertile eggs from D. simulans st.

2018 ◽  
Author(s):  
Purbasha Dasgupta ◽  
Saubhik Sarkar ◽  
Akankshya A. Das ◽  
Tanya Verma ◽  
Bodhisatta Nandy

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.


2020 ◽  
Author(s):  
Yongzhuo Chen ◽  
Min Zhang ◽  
Wei Hu ◽  
Jing Li ◽  
Pengcheng Liu ◽  
...  

Abstract Background Drosophila suzukii is widely distributed. Research has revealed that the presence of Drosophila melanogaster can reduce the emergence and egg laying of D. suzukii. However, the reasons for these phenomena have not yet been reported. To investigate this issue, we sought to answer three questions: Can the presence of D. melanogaster reduce the longevity of D. suzukii? Does D. melanogaster dominate in larval interspecific competition with D. suzukii? Does reproductive interference occur between these species; i.e., do individuals of one species (e.g., D. suzukii) engage in reproductive activities with individuals of the other (e.g., D. melanogaster) such that the fitness of one or both species is reduced? Results The results showed that the adult offspring number of Drosophila suzukii was significantly reduced when this species was reared with Drosophila melanogaster. The larval interspecific competition had no significant effects on Drosophila suzukii longevity or population size. Surprisingly, Drosophila melanogaster imposed reproductive interference on males of Drosophila suzukii, which led to a significant decline in the rate of successful mating of the latter species. Conclusions The presence of Drosophila melanogaster causes the population size of Drosophila suzukii to decrease through reproductive interference, and the rate of successful mating in Drosophila suzukii is significantly reduced in the presence of Drosophila melanogaster.


Genetics ◽  
1979 ◽  
Vol 92 (4) ◽  
pp. 1315-1328
Author(s):  
Andrew Clark

ABSTRACT Populations of Drosophila melanogaster with a fourth-chromosome polymorphism were subjected to different levels of competition with Drosophila simulans. The dynamics of the polymorphism and the equilibrium frequencies of the sparkling allele were seen to depend on the competitive level, while the higher productivity of the competing populations was shown to be due to the initial parental density. The effects of competition on fitness components were quantified by fitting the data to both a two-stage selection model and a fertility model. Additional experiments were performed to verify that the interspecific competition caused the changes in fitness. The results are discussed in light of the importance of considering selection components in models of ecological genetics.


2022 ◽  
Author(s):  
Paresh Nath Das ◽  
Aabeer Kumar Basu ◽  
Nagaraj Guru Prasad

The density-dependent prophylaxis hypothesis predicts that risk of pathogen transmission increases with increase in population density, and in response to this, organisms mount a prophylactic immune response when exposed to high density. This prophylactic response is expected to help organisms improve their chances of survival when exposed to pathogens. Alternatively, organisms living at high densities can exhibit compromised defense against pathogens due to lack of resources and density associated physiological stress; the density stress hypothesis. We housed adult Drosophila melanogaster flies at different densities and measured the effect this has on their post-infection survival and resistance to starvation. We find that flies housed at higher densities show greater mortality after being infected with bacterial pathogens, while also exhibiting increased resistance to starvation. Our results are more in line with the density-stress hypothesis that postulates a compromised immune system when hosts are subjected to high densities.


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