Development of aquatic insect eggs in relation to temperature and strategies for dealing with different thermal environments

Abstract

Average reaction norms relating number of day-degrees required to complete egg development to temperature are described for 95 species (1 15 populations) of Plecoptera, Odonata, Ephemeroptera, and Diptera (mainly Culicidae, with some Tipulidae and Sciomyzidae). The slope of the average reaction norm is used as an index of adaptation, with positive slopes indicating cold-adapted species, negative slopes indicating warm-adapted species, and slopes around zero indicating generalist species; 57% of the between-taxon variation in slope is associated with differences between orders, 14% among families, 7% among genera, 14% among species, and 8% among populations. Significant differences between congeneric species are found in only 4 of 92 possible comparisons. Only Plecoptera show much coldadaptation, with 40% of the species having significantly positive slope. However, 26% of the species (mainly in the Systellognatha) have significantly negative slope, suggesting adaptation to warmer waters than those in which the order is believed to have originated. The other orders probably originated in warm water and have generally maintained this adaptation. All Odonata, 7 1 O h of the Diptera and 81 % of the Ephemeroptera have significantly negative slopes. Diapause is a common alternative to metabolic adaptation to deal with unfavourable thermal environments. We suggest that it occurs widely in eggs of Plecoptera and in the mayfly Rhihgcna h y o b , cold-adapted species that may use diapause to survive periods of high temperature.

Influence of the temperature regime on the composition of the macrozoobenthos community in a thermal brook in Serbia

“…At the same time, the greatest diversity in cold waters is exhibited by larvae of insect groups, which together with specimens of Gammaridae, are also dominant in terms of abundance. This can be attributed to the fact that most macrozoobenthos insect groups (with the exception of Odonata) originated from cold lotic waters, and even though some of them adapted to warm lentic waters in the course of evolution, the majority remained better adapted to cold rather than warm aquatic habitats (Ward & Stanford, 1982;Pritchard et al, 1996).…”

“…• C (Pritchard et al, 1996). An important characteristic of the Termalni brook's benthocoenosis is the complete absence of Ephemeroptera larvae, even at site Tb 4 , where insect groups dominate.…”

The influence of temperature on the development of Baltic Sea sprat (Sprattus sprattus) eggs and yolk sac larvae

“…The index of thermal sensitivity for Baltic sprat eggs was calculated to be 0.63, (Parameter b of power Function- slope of reaction norm, Table 2), which reflected coldadaptation according to the gradient of the slope (Pritchard et al 1996). Similarly, the temperature-dependent time-tohatch data (50% hatch) reported by Nissling (2004) were used, fitted to the power function to obtain 0.83 for the parameter b (Table 2), which also reflected cold-adaptation.…”

“…Consequently, differences in thermal environments during life history evolution could lead to a change in the optimal set of phenotypes expressed by a genotype (i.e. reaction norm: Pritchard et al 1996; and references therein). In a study on the effect of temperature on the development of aquatic insect eggs, the slope of the average reaction norm was used as an index of adaptation, with positive slopes indicating cold-adapted species, negative slopes indicating warm-adapted species, and slopes around 0 indicating generalist species (Pritchard et al 1996).…”

“…reaction norm: Pritchard et al 1996; and references therein). In a study on the effect of temperature on the development of aquatic insect eggs, the slope of the average reaction norm was used as an index of adaptation, with positive slopes indicating cold-adapted species, negative slopes indicating warm-adapted species, and slopes around 0 indicating generalist species (Pritchard et al 1996). The slope of this reaction norm can be taken as an indicator of thermal sensitivity.…”