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| Which is the Most Important in Determining Dominance in | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Melanochromis Johanni:� Residence, Size, or Gender? | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Melanochromis johanni is an aggressive fish from Africa.�� It is a good fish to test for aggressiveness and residency because it shows distinct behaviors toward other fish in the same species. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| � There are three hypotheses that are being tested in this experiment. 1) If sex determines dominance, then one sex would be the most dominant.� 2) If size determines dominance, then the larger fish could be more aggressive.� 3) If residency determines dominance, then the resident would be more dominant. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� �An intruder fish is selected to be carefully placed in a tank that has a resident fish in it.��� The tank is the resident fish?s territory, so it shows its aggressiveness to the intruder fish.�� The results show that the resident fish is clearly more dominant than the intruder fish.�� Gender, residency, and size do not determine which fish is more dominant.�� This concludes that out of gender, residency, and size, residency is the best determining factor in dominance.��� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Introduction | |||||||||||||||||||||||||||||||||||||||||||||||||||
| An organism is determined to be dominant if it controls the behavior of another and predictions can be made about the outcome of future competitive interactions between these two individuals (Basey 43).� The resulting arrangement of dominant and subordinate individuals in the group is referred to as a dominance hierarchy.� Dominance hierarchies are usually linear or despotic where all subordinate are equal (Halloran ;Basey 43).��� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| � Cichlid fish exhibit behaviors that represent territoriality and dominance, which is the fish's interaction in nature.(Halloran &Basey 44).� As far as the factors that determines dominance are concerned, we know the influence of age, or body color, of sex, or prior territoriality or dominance experiences, or individual recognition and experimental manipulations, and of body size (Nelissen 153). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Body size could be a dominance determining factor is intuitively relevant: we expect body size to be correlated with fighting capacities, and thus with dominance (Nelissen 153).� A previous study (turner & Huntngford 1986) of O. mossambicus found that the winners were generally the larger fish, and it was not possible to determine whether the behavior carried information about size.� There was no residency asymmetry ensured that some contests were won by smaller fish (Turner 656). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Sex could be a dominance-determining factor.� The male is usually is referred to as the dominant in a society of organisms.� When females have offspring, they show dominance to any individual that might threaten t he babies. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Residency could be a dominance-determining factor.� When an organism enters into the territory of another of the same species, the resident organism has the home court advantage and would fight off the other organism to get him out of their territory. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Cichlid fish shows its behaviors in several categories: aggressive, submissive, and neutral.� Here is | |||||||||||||||||||||||||||||||||||||||||||||||||||
| a description of each behavior in those categories. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aggressive Behaviors | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Pursuitone fish with its fins up, aggressively pursues another. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Lateral threat displayThe fish orients itself sideways to its opponent and spreads-out, or raises, all its fins. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Bumping, biting, or nipping one fish bumps, bites or nips (including mouth fighting) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| any part of its opponent.� Mouth fighting occurs when both fish touch each other with their open mouths.� Either or both fish may clump down on each other in a mouth lock. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Fins up-the fish holds its fins out away from the body. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Color change�brighter-part or all of the body becomes brighter, or more enhanced in color. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Submissive Behaviors | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Retreat-the fish swims away with the opponent in pursuit. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Hiding-the fish hides behind, beneath, or near an object trying to conceal itself from its opponent. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Fins down-the fish holds its fins close to the body. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Color change�duller-part or all of the body becomes duller, or less enhanced, in color. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Neutral Behaviors | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Indifference-the fish ignores the other fish; no color changes; no obvious displays of any type | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Ambivalence-the fish is uncertain what to do; appear frustrated.� It may approach and then retreat, sporadically and repeatedly.� It may act strange, such as nipping at the aquarium glass or objects in the aquarium, or it may pick up gravel in its mouth. Some fish will skim or flick objects with the lateral sides of their body; quivering may occur; circling, swimming away, repeatedly or intermittently. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| (Halloran ; Basey 46) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| There are three different hypotheses that can be applied to this experiment on the behaviors of cichlid fish.� 1) If gender is the most important determining factor of dominance, then males would be more dominant than females.� 2) If size is the most important determining factor of dominance, then the larger fish is more dominant than the smaller fish.� 3) If residency is the most important determining factor of dominance, then the resident would be more dominant than the intruder fish. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ���� Materials and Methods | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Design a set of experiments to observe territoriality and dominance among cichlid fish.� In these experiments, use a resident fish, which has resided in a tank over a period of several days, and presumably have established territories within the tank.� Also use an intruder fish, which is kept incommunity tanks with other conspecifics.� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Observe the fish in the group tank in the back of the lab.� Identify the behaviors listed in the Introduction section of the paper and try to determine how the roles of size, gender, and residence are involved in determining dominance in the group tanks.�� Divide into groups of four, discuss the observations and derive a hypothesis.�� If one desires, they can do a practice round on a fish in the group aquarium in the back of the lab. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Choose a fish out of the group tank, but be careful when it netted because the fish does not need stress on it.� Lay it flat and measure it from head to tail with a centimeter ruler.� Record the sex, length, and whether the fish is an intruder or resident.� Place the intruder fish into the resident's tank and count the number of aggressive, submissive, and neutral displays.� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Among the four students in the group, one should act as data recorder for the intruder fish, one should act as a data recorder for the resident fish, one should quietly call out behaviors for the intruder fish, and one should quietly call out behaviors for the resident fish.� The data should be quantitative, which means to count the number of times a behavior occurs, and if the behavior is continuous, try to time the behavior. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| �Caution:� Be careful to stop the experiment if one fish begins to abuse the other.� When bumping and nipping become excessive or appear harmful, stop the experiment, and record it as overtly� aggressive for the time period involved.�� The species that was used in this experiment has been selected because it is known to engage in agonistic behavior in its natural habitats, yet in laboratory settings it rarely exhibits overtly aggressive behavior.� When finished, record data of the experiment (Halloran; Basey 47-8) . | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Results | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� The results of this experiment were that the resident fish were clearly more dominant than the intruder fish.� Out of 47 different experiments in terms of resident fish vs. intruder fish, 31 of them display that the resident fish is more dominant than the intruder fish, so in 16 out of 47 experiments, the resident fish could not fight off the intruder fish.� In some of those experiments, the intruder fish was too big that the resident could not fight the fish off and gave up the fight (Figure1). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| �In the experiments that deal with gender in terms of� female resident vs. male intruder fish (11experiments), 6 tests displayed that the female resident was able to fight off the male fish.� In the other 5 tests, the male intruder was the dominant one.� In the experiments that deal with male resident vs. female intruder fish (6 experiments), two tests displayed that the female intruder fish was more dominant than the male resident fish.� In the other four experiments, the male resident was more dominant than the female intruder (Figure 1) was.� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| In the experiments that deal with size, in terms of a big intruder fish vs. a smaller resident fish | |||||||||||||||||||||||||||||||||||||||||||||||||||
| (12 experiments), in three of those tests, the small resident fish were able to fight off the big intruder fish.� In the other tests, the large intruder fish were more dominant than the small resident fish (Figure 1). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Discussion | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� In terms of gender, it does not matter which is more dominant, as in female fish vs. male fish.� In terms of residency, it does matter because the resident fish is fighting the intruder out of its territory (Figure 1).� There were no problems with the experiment and experimental design. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| �According to Wazlavek and Figler, there was no significant difference for any of the three groups between the proportions of residents versus intruders. (Groups of this experiment were: Resident-larger; Same-size; and Intruder-larger.) (239) | |||||||||||||||||||||||||||||||||||||||||||||||||||
| �In another pervious experiment, it was found all groups a linear dominance hierarchy was established. In this rank order a subordinate will never act aggressively towards a dominant fish when the hierarchy is stable.� The dominant animal will always display the dominant rank (Andries et al. 169).� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� �According to Nelissen, the body size directly or indirectly influences the capabilities to obtain a higher dominance status in a group, but is not an absolute dominance factor.�� This influence may be overruled by other determinants: sex, physiological state, experience, group factors and so on (155). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ���������������� According to another experiment done by Nelissen (89), that fish could remember which fish is the dominant one and they fled away from the fish, in other words, dominance relation remained constant, even if the partners were kept separated from one another. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Conclusion | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� This experiment with Melanochromis johanni clearly concludes that out of the three dominance determining factors, residency is the factor that determines dominance the most. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Literature Cited | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Andries, Suzanne and Nelissen, Mark H.J.� A Study of the Dominance Hierarchy in Four Mbuna- | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Species:� Melanochiromis, M. Auratus, Pseudotropheus Ornatus, and P. Lombardoi | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� (Teleostei: Cichlidae).� Zool.�� 1990.� 165-193. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Halloran, Margaret E. and Basey, John M. ?Exercise 4: Animal Behavior.� General Biology Lab II:� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Spring and Summer 1998. California: Groveland� The Robin Works.�� 1997.� 41-54. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Nelissen, Mark H.J. Does Body Size Affect the Ranking of a Cichild Fish in a Dominance Hierarchy? | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Short Communication. �1992.� 153-156. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Nelissen, Mark H.J. Structure of the Dominance Hierarchy and Dominance Determining Group Factors �� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� In Melanchocheromis Auratus (Pisces, Cichlidae).�� Behavior.� 1994.� 85-107.� | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Turner, George F.� The fighting tactics of male mouthbrooding cichlids:� the effects of size and | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Residency.�� Anim.� Behav.� 1994.� 655-662. | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Wazlavek, Bernard E. and Figler, Michael H.� Territorial Prior Residence, Size Asymmetry, and | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Escalation of Aggression in Convict Cichlids (Cichlasoma nigrofasciatum Gunther). | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ��������������� Aggressive Behavior.�� 1989.� 235-244. | |||||||||||||||||||||||||||||||||||||||||||||||||||