Ph.D. Tezi Görüntüleme

Student:	Zeliha ÇOLAK
Supervisor:	Assoc. Prof. Bilal KUTRUP
Department:	Biyoloji
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University, Turkey

Title of the Thesis:	The Effects of the Ecological Factors on the Feeding Habits of Pelophylax ridibundus Pallas, 1771 (Anura: Ranidae)
Level:	Ph.D.
Acceptance Date:	11/2/2011
Number of Pages:	98
Registration Number:	Di829

Summary:

In this study, the aim was to determine the effects of ecological factors on the feeding biology of frogs. From 6 different habitats, 636 Pelophylax ridibundus (Pallas, 1771) were flushed out between April and September. Its diet was correlated with the prey availability. It consumed not only small invertebrates but also fish and anurans. These results suggest that P. ridibundus is a generalist and opportunistic predator.

In September and April, this frog consumes larger and more aquatic preys than the others. Although the prey number was higher in July and August, prey volume was found smaller. The individulas from ponds tended to prey on smaller preys in larger numbers than from branches and rivers. The populations in high altitude (Sebinkarahisar) were, generally, found to consume smaller preys with smaller quantities and to eat more aquatic preys than those inhabiting in low altitude populations (Görele). The regression analyses obtained from PCA and CATPCA showed that, this species has shown to altered its feeding habits due to the ecological factors. Water chemical parameters affected the number and volume of prey, while regional habitat variables

affected the prey volume, total volume and the proportion of aquatic preys. Some unfavorible features such as high altitude, salinity and water flow rate and lacking of forest and grass in the environment, caused this frog to enter the stress. Therefore, it developed some feeding strategies such as reducing the prey number, increasing the prey volume and staying longer in the water. However, total stomach volume was found similar among the habitats and the variances of regressions with the ecological variables were not satisfied for it. From these results, it can be concluded that, this species could have developed some

adaptations according to ecological conditions to change its feeding habits so that it gain optimum energy needed. Moreover, 24-hour analyses showed that, this frog was more active in feeding during the day than the night.

Key Words: Pelopyhlax ridibundus, Ecological Parameters, Feeding, Adaptation, Anura