The induction of sexual reproduction in Daphnia magna : genetic differences between arctic and temperate populations

• Published in: Canadian Journal of Zoology
• Main Authors: Ferrari, Denise C., Hebert, Paul D. N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1982
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Arctic; Canada
• Online Access: http://dx.doi.org/10.1139/z82-274; http://www.nrcresearchpress.com/doi/pdf/10.1139/z82-274

Even when provided with abundant food and grown in isolation, Daphnia magna from arctic Canada responds to declining photoperiods by producing male and then ephippial offspring. In contrast, clones of English origin do not alter their reproductive behaviour when exposed to photoperiod shifts. Hybrid clones show an intermediate response in terms of ephippial egg production, but a variable response in male production. The results indicate that variation exists at gene loci controlling sexual behaviour in local populations as well as between distant populations. The significance of this variation is discussed in relation to the environmental heterogeneity encountered by D. magna over its extensive range.