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Pach vítězství: role feromonů v interakcích raků
MAREŠ, Josef
Analysis of communication, hierarchy, and role of pheromones in crayfish is an interesting area that constantly brings new knowledge and can help us understand some facts that may be valid not only for crayfish but also other crustaceans. In this work, it was therefore studied how the offspring of two females behave in a one tank. After the dominance establishment in females (after a series of contacts and fights), the offspring of preferred a dominant female only, regardless of if their own or a unfamiliar mother. The dominant female, that successfully fought the fights, collected juveniles by its active movement, and they followed its movements. The subordinate female accepted her position, tried to avoid contacts, and reduced its activity. The juveniles practically ignored the subordinate mother at this stage of the experiment. Within the diploma thesis, all set goals were achieved and the newly discovered facts may be an important part of further follow-up experiments. We were able to respond positively to all primary hypotheses when: 1 / Females of marbled crayfish in one tank always established a relationship of the dominant and subordinate one, 2 / marbled crayfish juveniles always chose only one mother in a common tank, and 3 / it was in all cases the dominant one. The results show that dominance (whether communicated chemically or by visual stimuli) is a more important factor for juvenile crayfish than the specific brood pheromeone of their mother. The results bring significant knowledge to the issue of the hierarchy of various chemical and visual signals in crayfish communication. Thus, certain communication signals seem to be superior to others. The "winner odours" are probably stronger than such a strong stimulus as the brood pheromone responsible for recognizing the offspring and the mother. On the other hand, it is not possible to rule out a possible effect of the unattractiveness of the subordinate mother. How the relationships among the subordinate female, dominant female and their offspring would develop in remains opened to further research hypotheses.
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