Individual variability of Polyphemus pediculus (Cladocera, Onychopoda) in a local population (Yaroslavl region, Russia)
Butorina, L. G.
published: Oct 1, 2014
ArtNo. ESP141018502005, Price: 29.00 €
A study of nine quantitative, twelve meristic features and one qualitative feature was conducted on 774 individuals of Polyphemus pediculus (Linnaeus, 1761) of different age and sex from a local population, whose location in the water body was permanent in the course of the open-water period. Experimental data were treated statistically employing the ANOVA analyses. Feature discrimination, their accuracy and the impact strength of environmental conditions were assessed by the ratio of sizes of different features, the variation of coefficient values, the mean level of variation, Student's test and Fisher's exact test. The studied features were unstable and subject to continuous variability. All types of individual variability were interrelated, proceeded in the population simultaneously and continuously, and affected the same quantitative and meristic features. Environmental conditions impact the strength, degree of variability and the number of simultaneously varying features, the level of variability of individuals varying within the population in accordance with changes of habitat conditions, the age and sex of the population members. Quantitative features were more variable than meristic ones. Their mean values equaled 25.4 % and 15.3 %, respectively. The qualitative feature was the most stable. Seasonal variability was the highest and age-specific variability was higher than sex-related variability. The highest variability was characteristic to immature specimens (20.8–15.9 %) and males (18.5–15.4 %), and the lowest to parthenogenetic females (16.7–10.5 %). Immature individuals were the most variable in spring, parthenogenetic females in summer and heterosexual individuals in autumn. All individuals of the population differed reliably (95–99.9 %) from each other in the majority of studied features. P. pediculus is characterized by plasticity of its phenotype and phenotypic development.
age-specific • certainty of differences • mean level of variability • meristic features • polyphemus pediculus • qualitative features • quantitative features • seasonal variability • sex-related • variation coefficients