How female fish ornamentation influences males sexual selection

Document Type:Essay

Subject Area:Biology

Document 1

Some species of fish have extinct completely for the reason thought to be selection. Moreover, random sampling of two-spotted gobies has indicated more female than male. This implies that females now compete for mate from scarcity of male fish. There is a lot of competition among female fish during breeding. Female fish compete for male’s attention. The female realizes this and swims as well towards the same nest. On the other hand, if courtship is induced by a female, she approaches male at a close range exposing her coloured belly to attract male’s attention (Mascolino, 2016). Actually, in most cases, courtship is female-centred. It is likely to be observed that one male is surrounded by several females. Therefore due to this stiff competition, the female has to develop attractiveness that so as to be identified by the few male who are in the colony of many females (Amundsen et al, 2001).

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It is a small fish that is four to five cm long and inhabits rocky shores which have deep waters. Goby is a semi-pelagic fish that moves in shoals. It colonizes places with the algal type of vegetation. Research Question Do bright belly female fish (Gobiusculusflavescens) attract male’s attention compared to dull colored fish? Prediction It is expected that male fish will discriminate fecund females against the dull coloured fish species in sex-role-reversed fish like in the case of gobies. During spawning, malesprefer to mate with the females which have coloured bellies rather than those that have dull bellies. Permanent marker with colourless ink PVC tube 80 mm long and 14 mm in diameter Setting Aquarium Aquarium was made with a capacity of 60 liters.

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Their measurements were 74 by 23 by 35 cm. it was then divided into three compartments. The aquarium was ensured that there was a steady supply of water in and out freely. The perforated Plexiglas was used to separate each compartment as well as allowing free water transport. Movements were considered to be lateral shiver; male moving towards female or lead shivers where male moves towards the nest in the expectation that the female will follow it. Experiment: colour manipulation (1) A male fish is placed into central compartment. It is given time to establish ownership. This time may be averagely 72 hours. (2) Females are marked one with coloured marker another one with a colourless marker. 27 mm with a deviation of 1. 7mm. When paired then, t=0.

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32, P = 0. 75 while df = 14 Their masses were also measured and the following results were obtained. This is important so as to main population density of fish in water. Chemical methods should be avoided as method of obtaining fish from the water. Other environmental friendly methods like use of nets should be applied. Data presentation Below is a graph of body length in millimetre against body mass in grams combing the two types of fish. Colorful drab 0. Out of the 16 times, that observation was done, the female with bright colour was placed in the left aquarium 9 times while 7 times in the right aquarium. This placement was determined in a random way. The organisms used in this experiment were released back into their natural environment after the experiment.

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Since these responses are not independent, we carried out one sample test to test for preference for a colourful female against the expected preferences. The proportion obtained were arcsine transformed first before testing was done. The natural light did not have any impact on fish. Observation and discussion of results Male spent 43. 1% of their time with female fish. This had a deviation of 21. Fourteen out of sixteen times were towards the coloured fish. This is a binomial distribution where P=0. According to Wilcoxon signed-rank test where P=0. 78 and z=-0. 28%, it was clear that no significant difference was observed in female treatment. It was found that for the dull fish, time spent was 69. Strength It was fortunate that the time experiment corresponded breeding time of both the female fish.

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This enabled them to display their typical mating behaviors. Weakness The main weakness of this investigation was provision of the natural habitat as sea water in which the fish leaves. The Aquarium was in the open environment exposed to high light intensity. This automatically negatively affected the movement of the male fish. At the beginning, this study tried to explain this brightness. It is because of egg colour that is visible through the skin of the fish. Likewise, it is also as a result of carotenoids which the gobies assimilate into their bodies by eating the crustaceans (Etges, 2003). In any natural environment, it is always expected that male organism are ready to fertilize as many eggs as possible. However, their number if small may hinder this function.

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