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Od trusu k prostřenému ubrusu. Molekulární analýza potravy raka signálního
ŠKRABÁNEK, Jan
This thesis aimed to determine the diet of the signal crayfish in Křesánovský brook in 2020. In addition to that, we aimed to find and test suitable markers for the diet analysis of signal crayfish, which are described in the thesis. We analyzed the crayfish diet by examining DNA from faecal pellet samples collected monthly from April to September. By using group-specific DNA markers, we targeted the main dietary groups such as Heptagenidae (markers Hpt28Sf + Hpt28Sr), Ephemeroptera (Epa28Sf + Epa28Sr), Integripalpia and Spicipalpia (Inspi18Sf + Inspi18Sr), Plecoptera (Ple-gen A269 + Ple-gen S268), Chironomidae (Chiro18Sf + Chiro18Sr), and Gammaridae (Gamae28Sf + Gamae28Sr). We also focused on representatives of macrophytes Characeae (CHA677 + CHA1681R) and Eudicotyledons (MYR152F + MYR1696R). The results showed that the crayfish's diet varied during the sampling season. Gammaridae was the most common food item, found in 54.1% of the samples of faecal pellets. Heptagenidae, Integripalpia, and Spicipalpia were also significant, present in 31.3% of the samples. Plecoptera appeared in 20.8% of the samples, while Chironomidae and Characeae were found in 10.4%. Eudicotyledons were detected in 8.3% of the samples. Ephemeroptera were the least common food group, detected only in 2.1 %. Gammaridae were the most significant component of the crayfish diet in April (found in 7 samples), while Heptagenidae were the second most abundant component. The diet was more diverse in May, but Gammaridae remained the primary food source, followed by Integripalpia and Spicipalpia (in 5 samples). In June, Gammaridae was present in all samples, while Heptagenidae and Integripalpia/Spicipalpia were significant. In July, Heptagenidae was the most common food group (found in 5 samples), with Gammaridae found in 4 samples. No food items were detected in the samples from August and October, and only one sample contained Gammaridae in September. Overall, this study provides insights into both the seasonal variations in the diet of signal crayfish and markers suitable for its analysis.
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