![]() Only the selections that progressed to the next round are shown. At each round of selection a range of stability pressures were tested. The variations in selected temperature for the different developmental stages presumably reflect changing physiological requirements and modes of environmental optimization during maturation. (C) Stability selection conditions used for EPO and G-CSF. Temperature appears to play an important role in tadpole distribution. In contrast, little difference was found between the two acclimation groups in late metamorphic tadpoles. In premetamorphic and metamorphic tadpoles, the CA groups selected lower temperatures than the corresponding WA group. Temperature selection in tadpoles acclimated to 7 C (CA) was compared with that of tadpoles acclimated to 21 C (WA). This type of selection occurs in populations where environmental conditions remain constant for long periods. Stabilising selection selects for the average phenotypes and against more extreme phenotypes. ![]() In the laboratory, studies in a temperature gradient showed that (1) premetamorphic tadpoles had high selected temperatures (27.3 ± 0.6 C) (2) early metamorphic tadpoles selected the warmest temperatures (28.8 ± 0.4 C) and had the lowest level of activity and (3) late metamorphic tadpoles (19.0 ± 0.6 C), froglets (14.5 ± 0.4 C), and 2-yr-old adults (16.0 ± 0.6 C) selected much lower temperatures. There are three main types of selection: stabilising, directional, and disruptive. Tadpoles formed dense aggregations in the warmer portions of the pond during the afternoon and night and always selected the warmer portions of the pond. In a mountain pond, temperatures spanned 8-30 C in the late afternoon and 5-12 C during the early morning. Temperature selection in Rana cascadae tadpoles and adults was studied in the field and in the laboratory. ![]()
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