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Mimicry of hoverflies (Diptera: Syrphidae) in the context of selection pressures from predators, thermoregulation and sexual selection
Daňková, Klára ; Janšta, Petr (advisor) ; Pekár, Stanislav (referee)
Thermoregulation plays an important role in organisms' lives during foraging, escaping from predators, sexual selection or overwintering. Moreover, pressure on efficient thermoregulation could affect species on an evolutionary level and was recently hypothesized to maintain imperfect mimicry in hoverflies (Diptera, Syrphidae). We set these two aims: 1) to study relationships between thermoregulation, mimicry accuracy and resembled model, 2) to closely study effect of developmental temperature in an intermediately accurate honeybee mimic, Eristalis tenax. In the first part of the project, we examined temperature excess of 566 specimens in 47 species of hoverflies in the field. We did not find significant effect of mimicry accuracy on temperature excess in our data. However, we found a strong sexual dimorphism. Females had lower temperature excess, which was very resilient to internal and external factors, whereas males had higher temperature excess, influenced by activity at time of capture (flying > sitting) and resembled model (bumblebee-mimics > honeybee- mimics > wasp-mimics > solitary bee-mimics). We suggest, that males are pushed to higher temperature excess by sexual selection within lekking. In the second part of the project, we reared E. tenax in three different temperatures in laboratory...
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UV signs in coloration of common leopard gecko (Eublepharis macularius)
Baranová, Veronika ; Frynta, Daniel (advisor) ; Veselý, Petr (referee)
The presence of ultraviolet patterns on body, as well as perception of ultraviolet spectrum by special photoreceptors, is part of sensory ecology of many animal species, including reptiles. Most current research discusses the importance of ultraviolet signs in coloration of diurnal species. The aim of our study was to find out what character have the reflective signs in ultraviolet spectrum in overall coloration of common leopard gecko (Eubplepharis macularius) through a digital photography. The reflective pattern is present in both adults and juveniles and passes as well as the rest of the coloration by significant ontogenetic changes. Another aim was to evaluate the role of ultraviolet reflecting signs in the biology of this crepuscular-nocturnal species. We expect that the pattern contributes to their antipredatory strategies during their first few months of life, and also a white reflecting surface is preserved in adulthood, especially on their tail, which is differently coloured than the rest of the body.
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Signaling function of plumage coloration in Yellowhammer males
Kauzál, Ondřej ; Petrusková, Tereza (advisor) ; Šálek, Miroslav (referee)
Sexual selection theory tries to explain evolution of apparently useless traits which mainly developed in males of numerous species. One such trait is also rich and vibrant coloration, typical for many of the bird species. These traits are difficult to be falsified, and therefore they honestly signal quality of the individual. Carotenoid coloration reflects the health condition and melanin coloration the social status, even though this traditional division might not be as strict according to the latest studies. Apart from these ways of maintaining honesty, recent studies are focusing more also on the effect of hormones, mainly two steroids: male sexual hormone - testosterone -, and the "stress" hormone - corticosterone. Both hormones could positively influence male's sexual traits such as ornamental coloration. On the other hand, elevated levels of these hormones possess risk to the organism (higher energetic expenditure, chronic stress), therefore also might potentially become costly. Using photographs of birds in standardized conditions as well as spectrophotometry I analyzed the plumage coloration of males of the Yellowhammer (Emberiza citrinella). Concentrations of testosterone and corticosterone deposited in feathers were analyzed using the LC-MS/MS. Also, for males in breeding season 2015,...
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Behavioural correlates of lizard colouration
Bauerová, Anna ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee)
The coloration is a significant animal attribute which can be examined from the view of phylogenesis, ontogenesis, ecology or life-history parameters. In this thesis the method of coloration quantification and pattern complexity was developed, with the focus on Leopard gecko (Eublepharidae) family. are one of the most commonly breeded lizards, the great part of their popularity being due to their attractive "leopard" coloration. Yet we only know a little about their "wild" coloration. They have become an important organism for many etological and physiological experiments, the distinct color pattern change during ontogenesis being especially unusual. These aspects make them an ideal subject for coloration change and affecting parameters analysis. The results of this work show clear ekological pattern for coloration. The amount of black color correlates with the humidity and abundance of vegetation in the habitat of the species. The coloration quantification was also verified using spectrophotometry, which confirmed the original assumptions for colors included in the pattern. Given the absence of UV reflectance in the Leopard gecko pattern, we can assume that the UV spectrum pattern is not an essential parameter. Therefore, the photographies can be used for quantification as well. It is apparent...
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The effect of coloration of predator on reaction of birds at the feeder.
BURŠÍKOVÁ, Markéta
I investigate the effect of coloration of predator on the willingness of birds to undergo a predation risk at the winter feeder. I presented five colour modification of a sparowhawk and a control pigeon. The experimental species of birds presented at the feeder include great, blue, marsch and willow tits and nuthatch. My results suggest that birds are able to distinguish among the models but only in some extent. The behaviour of particular bird species differed significantly and was influenced by conditions like temperature and presence of the snow cover.
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Could fur characters be a source of phylogenetic information?
VOLDŘICHOVÁ, Marie
This work analysed phylogenetic utility of several characters associated with basic coloration, moulting and whorls in Cervidae via comparison of these traits with relatively robust phylogeny of this group based on several morphological, ethological and molecular data. I was able to detect probable evolutionary history of some selected traits, their ancestral state and synapomorphies of recognized clades.
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Ontogeny of coloration patterns in Neotropical cichlids of the Tribe Heroini (TELEOSTEI: CICHLIDAE: CICHLASOMATINAE)
Muška, Milan ; Říčan, O. ; Novák, J.
We have studied the ontogeny of Cichlid fishes of the tribe Heroini, using developmental series. By observing the development of pigment patterns in larval, juvenile and adult cichlids, the homologous elements of the lateral barring pattern have been hypothesized. Although pigmentation is often disregarded as a source of characters containing historical information, the congruence of many of these characters with a recent phylogeny of heroini, suggest their utility. A common mechanism underlying pattern formation is suggested based on similarities between Neotropical and African Cichlids.
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