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 spid er, Achaearanea tepidariorum, differed geographically. In a cool-tempe rate population, enhanced chilling tolerance and supercooling ability were observed in diapause individuals, whereas a subtropical populatio n 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 inc reased supercooling ability, It seems that the ability to Lower the su percooling point evolved through natural selection in the course of ex pansion of this species to the northern climates. (C) 1997 Elsevier Sc ience Ltd.