Final thermal preference in parthenogenetic females of Daphnia magna straus (Crustacea: Cladocera) acclimated to various temperatures

The final thermal preference FTP) range in parthenogenetic females of cladoceran Daphnia magna was assessed by “acute” and “chronic” methods. The first method included 4-month acclimation to different temperatures in the range of 14.2 ± 0.7 to 27.1 ± 0.3°C; the “chronic” method was characterized by long-term acclimation to +20°C. Two ranges of FTP were found for D. magna, 13.3–15.4°C and 20.2–26.2°C. The thermal preference of daphnids and the temperature of acclimation were correspondingly linearly. The range of FTP was independent of the season. The searching activity of D. magna rose in April, when the FTP range increased, and the FTP was less pronounced.     

Marker Analysis of Quantitative Traits in Maize by ISSR–PCR

The segregating maize population (GK26 × Mo17)F₂ has been used for identification of ISSR markers able to reveal a significant difference between alleles by a quantitative index. Confidence ranges have been determined for variation in 17 quantitative traits. Variations in the traits under study correlate with the inheritance of 16 marker loci have been found. The nature of these correlations and the possibility of chromosomal mapping of genetic markers are discussed.     

The influence of various temperature regimes on the abundance dynamics and thermal tolerance of cladoceran Ceriodaphnia quadrangula (O.F. Müller, 1785)

Experimental studies on the abundance dynamics and thermal tolerance of cladoceran Ceriodaphnia quadrangula (O.F. Müller, 1785) as they depend on the value and action pattern of a thermal factor, as well as field observations and mathematical calculations were carried out. Based upon the results of these studies, the values of the temperature zone of normal vital functions (17.0–25.0°C) and of the zones of temperature “static” optimum (21.4–25.0°C) were determined for C. quadrangula. It was shown using experimental populations of C. quadrangula as an example that it is necessary not only to keep the range of the factor optimal values within the tolerance scale (i.e., the static optimum) but also to maintain the optimal parameters of dynamic factor changes (or “dynamic optimum”) in order to form optimal conditions for their growth and development. For C. quadrangula this dynamic temperature optimum is 24.0 ± 1.1°C, with non-periodical (graded) warming to 24.7–25.3°C over five to eight days.     

Thermal resistance,preferred and avoidance temperatures of <Emphasis Type="Italic">Cyclops strenuus</Emphasis> Fischer, 1851, and their relation to optimal,pessimal, and tolerant temperatures

Ranges of preferred and avoidance temperatures in Cyclops strenuus Fischer, 1851 were determined based on the results of its experimental testing in the thermal gradient device. It is established that the process of temperature selection occurs with an overshoot. It is noted that copepods started to select the final preferred temperatures on the 8th day (temperatures above 26°C were avoided; the avoidance of low temperatures was not recorded). The average value of the critical thermal maximum for the season was determined. It is found that optimal, pessimal, and tolerant temperatures can be calculated on the scale of the species tolerance according to values of preferred and avoidance temperatures as well as according to values of the temperature range of regulation of the critical thermal maximum.     

Population dynamics of <Emphasis Type="Italic">Daphnia longispina</Emphasis> (O.F. Müller, 1785) and <Emphasis Type="Italic">Diaphanosoma brachyurum</Emphasis> (Lievin, 1848) (Crustacea,Cladocera) under stable and graded temperature regimes

Laboratory experiments have been performed to study the effects of different temperature regimes—constant (16.3±0.8, 20.3±0.8, and 24.6±0.7°C) and graded, with temperatures changing at intervals of 4.4 or 8.8°C within the range of 15.1–25.4°C—on the population dynamics of two dominant species of littoral zooplankton, Daphnia longispina and Diaphanosoma brachyurum. The results show that aperiodic stepwise changes in temperature within the ranges of 16.3–20.4, 20.4–25.1, and 16.3–25.1°C, which may take place in water bodies of the temperate zone in the summer period, can exert either stimulating (direct or delayed) or inhibitory effect on the natural development of D. longispina populations. The development of D. brachyurum, a more stenothermic thermophile, is stimulated only by a stable elevated temperature (24.5±0.9°C). All temperature changes within the above range, except for rapid heating from 16.3 to 25.1°C, either inhibit the development of D. brachyurum populations or have no significant effect on them.     

Thermal preference and avoidance in cladoceran <Emphasis Type="Italic">Daphnia magna</Emphasis> strauss (crustacea,cladocera) acclimated to constant temperature

The final preferable temperature (FPT) and avoidance temperature (AT) were determined in parthenogenetic females of the crustacean Daphnia magna Strauss. The animals were preliminary acclimated to constant temperature of 23.4°C followed by keeping them in a thermo-gradient device for 24 days. It was revealed that daphnia select FPT with overshoot. In the first four days, daphnia selected temperatures 0.6–1.6°C higher than the acclimation temperature and 4–7.4°C higher than FPT. Two zones of FPT are revealed: the first zone by the time of 5–13 days (17.6 ± 1.2°C); the second, by 16–24 days (20 ± 1.5°C). The dynamics of AT diapason followed the dynamics of FPT. Two zones of the AT plateau were observed: over five to 17 days (temperatures <14°C and >25.8°C were avoided) and for 21–24 days (<8.5°C and >26°C).     

Multimetric statistical analysis of behavior in mice selected for high and low levels of isolation-induced male aggression

Behavioral observations as a matrix of probabilistic changes of postures and acts are multiple measurements that could introduce variability to statistical analysis. We propose the multimetric statistical algorithm that supplements the linear analysis of variance by pair correlation, factor and discriminant function analyses. Although these methods were utilized mostly in behavioral studies, the combined use in frame of one behavioral test was not done before. In present study statistical techniques were applied to analyze social behavior in Turku aggressive (TA) and Turku non-aggressive (TNA) mouse lines, bidirectional selected for offensive aggression towards an unknown male. Each statistical technique amplified new details of mouse behavioral profiles that give possibility to describe TA and TNA subjects in terms of Cloninger's model of personality. Also, it was identified that TA mice displayed fighting-biting aggression while TNA mice demonstrated immobile defensive strategy. Hypothetical discriminant formula was found for each mouse behavioral genotype that might be used to identify behavioral profile and line affiliation of unknown subjects.     

The dynamics of abundance of <Emphasis Type="Italic">Simocephalus vetulus</Emphasis> (O.F. Müller, 1776) (Crustacea,Cladocera) under acyclic stepwise changes in temperature

This experimental study examines the influence that acyclic stepwise temperature regimes with 4.4 and 8.8°C increments in a range of 14.8 to 25.5°C have on the dynamics of the number of Simocephalus vetulus (O.F. Müller). It is revealed that an increase in the number of this dominant species of littoral zooplankton may be stimulated by differently directed acyclic stepwise changes in temperature. However, the maximal development of the population is registered after a decrease in water temperature from 24.3 ± 0.7 to 20.4 ± 0.5°C and from 19.9 ± 0.8 to 15.5 ± 0.4°C. Under the same temperature conditions, a prolonged stimulating effect is observed. Our results confirm the assumption put forward earlier that, in order to define the real ecological optimum for a species by a specific environmental factor, it is necessary to consider not only the limits of the optimal values of the factor, but also the dynamics of their changes and the possibility of after-effects of the factor (prolonged and delayed effects).