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Variabilityin egg shell pigmentation of great tit clutches
Kratochvílová, Anna ; Svobodová, Jana (advisor) ; Veronika, Veronika (referee)
Eggshell coloration in bird clutches shows a striking variability within species which has not yet been fully explained. Its character is determined by the deposition of two main pigments: blue-green biliverdin is responsible for the background colour while brown-red protoporphyrin is associated with the dark spot pattern. Considering the role and matabolism of these two pigments in the avian organism it was suggested that they might have an important impact on the oxidative stress levels and their deposition into the eggshell is therefore suggested to possibly reflect the body condition of laying females during the laying periods. This is also the basic assumption for the signalling hypothesis of eggshell coloration which predicts the eggshell appearance to reflect the female body condition and individual health status or directly indicate aenemia in birds (aenemic hypothesis). Here it was tested whether there is a relationship between parameters representing the body condition of female great tits (Parus major) and the characteristics of protoporphyrin maculation of their eggs. Female body condition was expressed by standardized body weight and the selected haematological parameters (heterophil to lymphocyte ratio and relative immature erythrocyte counts). Eggshell coloration was characterized by spot colour (hue, saturation and brightness), spot counts and the reflectance of the background colour. It was found that females with higher heterophil to lymphocyte ratio laid eggs with more spots and higher reflectance of the background colour in some nesting seasons. Eggs with more spots on its surface were also laid by females with higher immature erythrocyte counts. These results suggest that more intensive deposition of protoporfyring into the eggsell can indicate worse body condition of the laying females. On the other hand, it was also found that heavier females laid eggs with lower reflectance of the background colour. Despite this discrepancy, these results are not inconsistent with the pressumptions of the signalling hypothesis and they partially support the aenemia hypothesis. However, the above mentioned dependencies were inconsistent among the nesting seasons, indicating that further important determinants must be considered in the avian eggshell coloration.
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Variability of eggshell colouration
Bubeníčková, Kateřina ; Svobodová, Jana (advisor) ; Sládeček, Martin (referee)
Bird´s Eggs Are Specific for Big Variability in Eggshell Coloration. This Eggshell Eoloration Is Caused by Two Pigments; Biliverdin and Protoporphyrin. Biliverdin Causes Bluegreen Color of the Egg and Protoporphyrin Causes RedBrown and Black Maculas on the Surface of the Eggshell. Many Hypotheses Try to Clarify the Reason of Resultant Variability in the Eggshell Coloration. The Final Reason of the Variability in the Eggshell Coloration Has Not Been yet Explained and this Is the Reason, Why this Topic Is Subject of Scientifical Researches. In the Theoretical Part of this Thesis Are Described Individual Hypotheses, Which Describe Variability in the Eggshell Coloration. These Theses Were Focused on Structural and Signal Function of Pigment and the Anemic Hypothesis; these are Explained in Detail in the thesis, because they are the subjects of this thesis´s Research. Signal Hypothesis Works with Theory, That Egg´s Pigmentation Informs the Partner about Female´s Condition Quality. Results of Recent Published Studies, Which Are Focused on Signal Function, Say, That 60% of Results Support the Theory, That Egg Maculation Relates to Female´s Body Condition. 80% of Studies about Signal Function Made There Researches on Passerines. This Is the Main Reason, Why Signal Function of Pigment Cannot Be Applied Generaly on All Bird Species, because the Signal function Was Not Properaly or None Tested on Other Species Than Passerines (Out of Few Exceptions). Anemic Hypothesis Might Explain the Variability in the Eggshell Coloration with Theory, Protoporphyrin, Which Is Derived in Higher Concetration from Blood Due the Anaemia Causes Higher Maculation on the Surface of Eggshell. Purpose of Practical Part of this Thesis Was Finding Out, Whether Female´s Condition Quality Depends on the Character of Color Maculation in Great tit (Parus major). Futhermore if There Exist Correlation between Ratio (of Immature Red Blood Cells and Total Sum of Red Blood Cells) and Eggshell Coloration. Results of the Study Show, that the Eggshell Coloration May Depend on female´s Conditon. Specifically, Red-Brown Macules with Lower Level of Intensity and Saturation Pronounce Larger Area of Melanin Based Ventral Stripe. In Conclusion, this Thesis Supports Signal Function Thesis of Protoporhyrin and Leads to the Fact, that Final Eggshell Coloration Has an Impact on the Female´s Body Condition. Results of this Thesis Does Not Prove any Relationship Between Ratio (of Immature Red Blood Cells and Total Sum of Red Blood Cells) and Eggshell Coloration. It Leads to the Fact, that there Is No Possible Support for Correlation between Anaemia and Variability in Eggshell Coloration in our Population of Great tit.
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