Evolutionary Relationship between Diapause and Cold Hardiness in the House Spider, Achaearanea tepidariorum (Araneae: Theridiidae).
The relationship between diapause and cold hardiness of the house spider, Achaearanea tepidariorum, differed geographically. In a cool-temperate population, enhanced chilling tolerance and supercooling ability were observed in diapause individuals, whereas a subtropical population showed only chilling tolerance. Because this spider is considered to be of tropical origin, it would follow that the ancestral diapause of this spider was equipped with chilling tolerance, but not with an increased supercooling ability. It seems that the ability to lower the supercooling point evolved through natural selection in the course of expansion of this species to the northern climates. Copyright 1997 Elsevier Science Ltd. All rights reserved
TANAKA
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Zoological Section, Institute of Low Temperature Science, Hokkaido University, Sapporo 060, Japan