Developmental instability in morphological characters can occur during individual development due to various environmental stresses. Fluctuating asymmetry （FA） is often used as a measurement of developmental instabi...Developmental instability in morphological characters can occur during individual development due to various environmental stresses. Fluctuating asymmetry （FA） is often used as a measurement of developmental instability, but within-environment variation （CVo） is also considered an indicator of developmental instability. Cabbage aphid （Brevicoryne brassicae） populations were reared on zinc- （Zn） or cadmium- （Cd） contaminated cabbage and radish plants. Developmental instability indicators were measured and their relations with fitness were explored. Results revealed that cabbage aphids exposed to Cd and Zn displayed considerable developmental instability, particularly fluctuating asymmetry. Differences in developmental instability between the two metals were also detected, as well as differences between the two developmental instability measurements. For almost all measured traits, FA was greater on Cd- and Zn-contaminated compared to non-contaminated host plants. In contrast, CVo of some traits was greater on non-contaminated host plants, yet for other traits CVo was greater on contaminated host plants. There were also non-significant inverse relationships between FA and fitness of cabbage aphid populations. Due to weak correlations between FA and different patterns of two developmental instability measurements, this study does not support the hypothesis that developmental instability is a useful bioindicator of environmental quality.展开更多
Biomonitoring using fish has been a popular method of assessing the toxic effects of cadmium concentrations of cadmium in water bodies and has led to bioaccumulation in fish contributing to various morphological alter...Biomonitoring using fish has been a popular method of assessing the toxic effects of cadmium concentrations of cadmium in water bodies and has led to bioaccumulation in fish contributing to various morphological alterations. Among the known effects of these alterations is developmental instability via fluctuating asymmetry (FA). The utilization of FA data is a simple yet effective method to evaluate the toxic effects of cadmium on the stability of development. This study used climbing perch (Anabas testudieneus) to assess the FA in the diameter of the eye because of low-level cadmium exposure. The left and right sides of the traits were measured once every four weeks for 16 weeks. The average measurements from both sides of the traits were used to calculate the FA value. Results found that the highest mean FA for the diameter of the eye was obtained in the highest treatment group, 0.015 mg/L. The results also indicate that increasing concentrations of cadmium exposure had a statistically significant effect on the FA of eye diameter. There was also a statistically significant interaction between the duration of exposure and treatment groups in FA of the diameter of the eye. The results from the study indicate that prolonged exposure to sub-lethal concentrations of cadmium can cause significant effects on the normal development of eyes in Anabas testudineus. This study can add to the body of research regarding fluctuating asymmetry as a tool to study developmental toxicants and assess other bilateral organs.展开更多
Development perturbations may affect the regular phenotype and are commonly measured through fluctuat-ing asymmetry (FA) levels. Short-term climatic variations, that modify the temperature, can influence chemical and ...Development perturbations may affect the regular phenotype and are commonly measured through fluctuat-ing asymmetry (FA) levels. Short-term climatic variations, that modify the temperature, can influence chemical and physical water characteristics. Fishes have been used as model organisms for studying stress-induced changes in body symmetry, since they are ectothermic, good bioindicators, easy to find and having economic relevance. Northern pike being a holoarctic, big, edible, top predator is one of the most economically important freshwater fish for recreational and commercial fisheries and freshwater ecosystems management. The isolated population of Lake Trasimeno (Central Italy)—in good health conditions and that can be considered one of the genetically best conserved of Italy—, was chosen as model. FA, seven mi-crosatellite loci and early developmental stages were investigated in order to correlate the developmental stability of this population to its genetic variability and to environmental perturbations. The results obtained underlined a positive correlation (>>0.40) between FA indexes and temperature;the non-parametric Kruskall- Wallis test showed significant differences in FA levels for some FA indexes and parameters. Over-all results underlined that FA increased in individuals grown at a temperature above 8°C as compared with those grown at 5°C or at lower temperatures. Both positive and negative correlations between FA parameters and chemical and physical water characteristics were shown. The comparison of genetic and FA data under-lined a low correlation between microsatellite and FA pairwise distances, nevertheless a positive and signifi-cant correlation emerged for some FA measurements and microsatellite data. In particular, only Elu87 locus showed a statistical significant correlation versus total FA. Finally, as expected, results indicated that the in-cubation time was temperature-dependent;the ODT was in the range 8–10°C and lower and higher tempera-tures caused drastic embryo mortality.展开更多
文摘Developmental instability in morphological characters can occur during individual development due to various environmental stresses. Fluctuating asymmetry （FA） is often used as a measurement of developmental instability, but within-environment variation （CVo） is also considered an indicator of developmental instability. Cabbage aphid （Brevicoryne brassicae） populations were reared on zinc- （Zn） or cadmium- （Cd） contaminated cabbage and radish plants. Developmental instability indicators were measured and their relations with fitness were explored. Results revealed that cabbage aphids exposed to Cd and Zn displayed considerable developmental instability, particularly fluctuating asymmetry. Differences in developmental instability between the two metals were also detected, as well as differences between the two developmental instability measurements. For almost all measured traits, FA was greater on Cd- and Zn-contaminated compared to non-contaminated host plants. In contrast, CVo of some traits was greater on non-contaminated host plants, yet for other traits CVo was greater on contaminated host plants. There were also non-significant inverse relationships between FA and fitness of cabbage aphid populations. Due to weak correlations between FA and different patterns of two developmental instability measurements, this study does not support the hypothesis that developmental instability is a useful bioindicator of environmental quality.
文摘Biomonitoring using fish has been a popular method of assessing the toxic effects of cadmium concentrations of cadmium in water bodies and has led to bioaccumulation in fish contributing to various morphological alterations. Among the known effects of these alterations is developmental instability via fluctuating asymmetry (FA). The utilization of FA data is a simple yet effective method to evaluate the toxic effects of cadmium on the stability of development. This study used climbing perch (Anabas testudieneus) to assess the FA in the diameter of the eye because of low-level cadmium exposure. The left and right sides of the traits were measured once every four weeks for 16 weeks. The average measurements from both sides of the traits were used to calculate the FA value. Results found that the highest mean FA for the diameter of the eye was obtained in the highest treatment group, 0.015 mg/L. The results also indicate that increasing concentrations of cadmium exposure had a statistically significant effect on the FA of eye diameter. There was also a statistically significant interaction between the duration of exposure and treatment groups in FA of the diameter of the eye. The results from the study indicate that prolonged exposure to sub-lethal concentrations of cadmium can cause significant effects on the normal development of eyes in Anabas testudineus. This study can add to the body of research regarding fluctuating asymmetry as a tool to study developmental toxicants and assess other bilateral organs.
文摘Development perturbations may affect the regular phenotype and are commonly measured through fluctuat-ing asymmetry (FA) levels. Short-term climatic variations, that modify the temperature, can influence chemical and physical water characteristics. Fishes have been used as model organisms for studying stress-induced changes in body symmetry, since they are ectothermic, good bioindicators, easy to find and having economic relevance. Northern pike being a holoarctic, big, edible, top predator is one of the most economically important freshwater fish for recreational and commercial fisheries and freshwater ecosystems management. The isolated population of Lake Trasimeno (Central Italy)—in good health conditions and that can be considered one of the genetically best conserved of Italy—, was chosen as model. FA, seven mi-crosatellite loci and early developmental stages were investigated in order to correlate the developmental stability of this population to its genetic variability and to environmental perturbations. The results obtained underlined a positive correlation (>>0.40) between FA indexes and temperature;the non-parametric Kruskall- Wallis test showed significant differences in FA levels for some FA indexes and parameters. Over-all results underlined that FA increased in individuals grown at a temperature above 8°C as compared with those grown at 5°C or at lower temperatures. Both positive and negative correlations between FA parameters and chemical and physical water characteristics were shown. The comparison of genetic and FA data under-lined a low correlation between microsatellite and FA pairwise distances, nevertheless a positive and signifi-cant correlation emerged for some FA measurements and microsatellite data. In particular, only Elu87 locus showed a statistical significant correlation versus total FA. Finally, as expected, results indicated that the in-cubation time was temperature-dependent;the ODT was in the range 8–10°C and lower and higher tempera-tures caused drastic embryo mortality.
