Interspecific Comparion In Morphology And Swimming Performance Within Cyprinidae

The objective of this study was to1) investigate the interspecific difference inmorphology andswimming performance among Cyprinids;2) explore the relationship betweenmorphology, swimming performance and habitant characteristic;3) investigate theeffect of temperature on the swimming performance, we measure the critical swimmingspeed (Ucrit), metabolic rate(MO2)and Fast start performance of Aristichthys nobilis,Carassius auratus, Ctenopharyngodon piceus, Procypris rabaudi, Cyprinus carpio,S_pinibarbus sinensis Bleeker, Onychostoma sima, Parabramis pekinensis,Ctenopharyngodon idellus, Hypophthalmichthysmolitrix, Abbottina rivularis,S_arcocheilichys parvus Nichols, Pseudorasbora parva, Rhodeus ocellatus, Rhodeussinensis Gunther, S_chizothorax wangchiachii, Opsariichthys bidens, Zacco platypus,Hemicculter Leuciclus and Garra pingi at25℃; Carassius auratus,Cyprinus carpio,S_pinibarbus sinensis Bleeker,Onychostoma sima,Parabramis pekinensis and Procyprisrabaudi at15℃. The morphology photographs were also obtained. Then we calculated:resting metabolism (MOrest),maximum locomotory metabolism (MOactive), metabolismscope (MS₎, cost of transport (COT), optimum swimming speed (V_cot), caudalcoefficient, the ratio of caudal fin, anal fin and dorsal fin, the distance of former120ms,max linear velocity and acceleration etc.The results are as follows1. The morphological differences among fish from diverse habitantsThere was significant difference in all five morphology parameters among speciese(P<0.0001). Body ratio (H/L) and the proportion of dorsal fin square were significantlyaffected by current velocity for the wild fish (P<0.0001), and for the artificial culturedfish, the caudal fin, anal fin, dorsal fin square were also significantly affected(P<0.0001). Generally, body ratio (P<0.0001), caudal square (P=0.028), anal fin square(P=0.033), dorsal fin square (P<0.0001) were all significantly affected by the currentvelocity of the habitat.2. Effect of habitant and morphology on swimming performance and interspecificdifference in swimming capacityThere was significant difference in Ucrit(P<0.0001), MOactive(P<0.0001), MO2rest, V_max(P<0.0001), Amax(P=0.006), and S₁20ms(P<0.0001) among species. Ucritwas positivelycorrelated to V_max(P=0.004),and no significant correlation was found between Amaxand S₁20ms. The Ucrit(P<0.0001), V_max(P=0.001), V_cot(P=0.046), MOactive(P<0.004) andS₁20ms(P=0.002) of the wild fish, and Ucrit(P<0.0001), V_cot(P=0.002), S_MR (P=0.007),MOactive(P=0.038) of cultured fishes were all significantly affected by the currentvelocity. Moreover, Based on the analysis of software tpsRegr, there was significanteffect of morphology on the Ucritand the three index of Fast start (P<0.0001). 3The effect of temperature on two types of swimming performance and the trade-offsbetween themThe Ucritvaried significantly as the temperatures changed (P<0.001), Temperature andswimming speed all affected MO2significantly (P<0.001), and the effect of temperaturewere different among species (P<0.0001).The Vmax, Amaxand S₁20msvaried significantly at different temperatures (P<0.001), andthere was interactive effect of temperature and taxon on Amax(P=0.001).Q10of Ucritwas positively related to the Q10of Vmax(P=0.029), Amax(P=0.048) andS₁20ms(P=0.033).In conclusion:1. During long term natural selection, Cyprinids evolved to be adapted to the currentprofile of their living habitant in many extents, e.g., morphology, swimming capacityand metabolic traits.2. At preference temperature (25℃),there is a significantly positive correlationbetween Ucritand Vmaxof cyprinid fish.3. There are significant differences in some of the morphological, swimmingperformance and metabolic ability parameters between wild fish and cultured fish livingin different current velocities, these results suggest that artificial selection and cultureenvironment may have powerful influence on species plasticity and geneticcharacteristics.4. The effect of temperature on the two types of swimming performance andmetabolic traits of six closely related cyprinid fish in the same area are significant, andthe temperature sensitivity of the two types of swimming performance are differentamong experimental fish. S_uch evidence indicates that temperature may play animportant role in the evolution of the cyprinids.