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Effects of algal food quality on sexual reproduction of Daphnia magna.

Choi JY, Kim SK, La GH, Chang KH, Kim DK, Jeong KY, Park MS, Joo GJ, Kim HW, Jeong KS - Ecol Evol (2016)

Bottom Line: From the results, we found that the mating frequency and copulation duration increased in the treatment with S. hantzschii, resulting in a significant increase of hatching rates of resting eggs.In the other two repetitive mating strategies (e.g., one female vs. multiple males, and one male vs. multiple females), we found that the hatching rates of resting eggs were greater in the S. hantzschii treatment.In summary, our study manifested that diatom consumption of D. magna leads to more successful sexual reproduction.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Ecology Seo-Cheon Gun Chungcheongnam Province 325-813 Korea.

ABSTRACT
The objective of our study was to investigate sexual reproduction of Daphnia magna associated with mating behaviors and hatching rates, according to different algal food sources. Since a diatom is known to contain more abundant long-chain poly unsaturated fatty acids (PUFAs), we hypothesized that the diatom-consuming D. magna would exhibit more successful reproduction rates. Upon the hypothesis, we designed three experiments using two algal species, a green alga (Chlorella vulgaris) and a diatom (Stephanodiscus hantzschii). From the results, we found that the mating frequency and copulation duration increased in the treatment with S. hantzschii, resulting in a significant increase of hatching rates of resting eggs. In the other two repetitive mating strategies (e.g., one female vs. multiple males, and one male vs. multiple females), we found that the hatching rates of resting eggs were greater in the S. hantzschii treatment. In addition to the mating strategy, male body size significantly increased in the diatom treatment, hence average diameter of penis was also statistically different among the treatments (greater diameter in the S. hantzschii treatment). To examine the effect of algal food quality, we estimated quantity of fatty acids in the two algal species. Our result showed that S. hantzschii had a higher proportion of long-chain PUFAs than C. vulgaris. Furthermore, a stable isotope analysis revealed that carbon and nitrogen originated from S. hantzschii were more assimilated to D. magna. In summary, our study manifested that diatom consumption of D. magna leads to more successful sexual reproduction. We then discussed how the diatom consumption of zooplankton influences food web dynamics in a freshwater ecosystem.

No MeSH data available.


Results of stable isotope analysis. A, δ13C and δ15N ratio of the algal food sources and Daphnia magna in three experimental groups; B, distribution of the solutions for contribution of two resources to the diet of D. magna in the SIAR mixing model; C, estimated source proportions (0–1) of C. vulgaris and S. hantzschii for D. magna. Values were calculated using isotopic mass balance (δ13C and δ15N) for each food source. Lines and boxes indicate averages, and 50%, 75%, and 95% Bayesian credibility intervals for means.
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ece32058-fig-0007: Results of stable isotope analysis. A, δ13C and δ15N ratio of the algal food sources and Daphnia magna in three experimental groups; B, distribution of the solutions for contribution of two resources to the diet of D. magna in the SIAR mixing model; C, estimated source proportions (0–1) of C. vulgaris and S. hantzschii for D. magna. Values were calculated using isotopic mass balance (δ13C and δ15N) for each food source. Lines and boxes indicate averages, and 50%, 75%, and 95% Bayesian credibility intervals for means.

Mentions: Stable isotope analysis revealed that D. magna depended more on S. hantzschii than on C. vulgaris when they fed on a mixture of these algae (Fig. 7). The δ13C and δ15N ratio indicated the contribution of phytoplankton eaten by D. magna. Some adults fed on only one species (i.e., CHL and STE); either C. vulgaris or S. hantzschii (Fig. 7A). However, D. magna in the MIX group relied more on S. hantzschii. Between the two foods, the greater nutritional resources for D. magna were in S. hantzschii as estimated using SIAR mixing models. Figure 7B shows the model results for the MIX group as a series of stacked histograms that indicated the posterior probability density distributions predicted for the proportions of each food species. The graphic output of the distribution showed separate density distributions for the two food sources with a higher proportion of S. hantzschii. In addition, when the contribution rates of the two algal food species in the MIX group were calculated, the S. hantzschii contribution rate (ca 60%) was higher than that of C. vulgaris (ca 40%) with a narrow, 95%, credibility interval (CI) indicating a very high degree of accuracy (Fig. 7C).


Effects of algal food quality on sexual reproduction of Daphnia magna.

Choi JY, Kim SK, La GH, Chang KH, Kim DK, Jeong KY, Park MS, Joo GJ, Kim HW, Jeong KS - Ecol Evol (2016)

Results of stable isotope analysis. A, δ13C and δ15N ratio of the algal food sources and Daphnia magna in three experimental groups; B, distribution of the solutions for contribution of two resources to the diet of D. magna in the SIAR mixing model; C, estimated source proportions (0–1) of C. vulgaris and S. hantzschii for D. magna. Values were calculated using isotopic mass balance (δ13C and δ15N) for each food source. Lines and boxes indicate averages, and 50%, 75%, and 95% Bayesian credibility intervals for means.
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Related In: Results  -  Collection

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ece32058-fig-0007: Results of stable isotope analysis. A, δ13C and δ15N ratio of the algal food sources and Daphnia magna in three experimental groups; B, distribution of the solutions for contribution of two resources to the diet of D. magna in the SIAR mixing model; C, estimated source proportions (0–1) of C. vulgaris and S. hantzschii for D. magna. Values were calculated using isotopic mass balance (δ13C and δ15N) for each food source. Lines and boxes indicate averages, and 50%, 75%, and 95% Bayesian credibility intervals for means.
Mentions: Stable isotope analysis revealed that D. magna depended more on S. hantzschii than on C. vulgaris when they fed on a mixture of these algae (Fig. 7). The δ13C and δ15N ratio indicated the contribution of phytoplankton eaten by D. magna. Some adults fed on only one species (i.e., CHL and STE); either C. vulgaris or S. hantzschii (Fig. 7A). However, D. magna in the MIX group relied more on S. hantzschii. Between the two foods, the greater nutritional resources for D. magna were in S. hantzschii as estimated using SIAR mixing models. Figure 7B shows the model results for the MIX group as a series of stacked histograms that indicated the posterior probability density distributions predicted for the proportions of each food species. The graphic output of the distribution showed separate density distributions for the two food sources with a higher proportion of S. hantzschii. In addition, when the contribution rates of the two algal food species in the MIX group were calculated, the S. hantzschii contribution rate (ca 60%) was higher than that of C. vulgaris (ca 40%) with a narrow, 95%, credibility interval (CI) indicating a very high degree of accuracy (Fig. 7C).

Bottom Line: From the results, we found that the mating frequency and copulation duration increased in the treatment with S. hantzschii, resulting in a significant increase of hatching rates of resting eggs.In the other two repetitive mating strategies (e.g., one female vs. multiple males, and one male vs. multiple females), we found that the hatching rates of resting eggs were greater in the S. hantzschii treatment.In summary, our study manifested that diatom consumption of D. magna leads to more successful sexual reproduction.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Ecology Seo-Cheon Gun Chungcheongnam Province 325-813 Korea.

ABSTRACT
The objective of our study was to investigate sexual reproduction of Daphnia magna associated with mating behaviors and hatching rates, according to different algal food sources. Since a diatom is known to contain more abundant long-chain poly unsaturated fatty acids (PUFAs), we hypothesized that the diatom-consuming D. magna would exhibit more successful reproduction rates. Upon the hypothesis, we designed three experiments using two algal species, a green alga (Chlorella vulgaris) and a diatom (Stephanodiscus hantzschii). From the results, we found that the mating frequency and copulation duration increased in the treatment with S. hantzschii, resulting in a significant increase of hatching rates of resting eggs. In the other two repetitive mating strategies (e.g., one female vs. multiple males, and one male vs. multiple females), we found that the hatching rates of resting eggs were greater in the S. hantzschii treatment. In addition to the mating strategy, male body size significantly increased in the diatom treatment, hence average diameter of penis was also statistically different among the treatments (greater diameter in the S. hantzschii treatment). To examine the effect of algal food quality, we estimated quantity of fatty acids in the two algal species. Our result showed that S. hantzschii had a higher proportion of long-chain PUFAs than C. vulgaris. Furthermore, a stable isotope analysis revealed that carbon and nitrogen originated from S. hantzschii were more assimilated to D. magna. In summary, our study manifested that diatom consumption of D. magna leads to more successful sexual reproduction. We then discussed how the diatom consumption of zooplankton influences food web dynamics in a freshwater ecosystem.

No MeSH data available.