Ecological genomics: steps towards unraveling the genetic basis of inducible defenses in Daphnia

Abstract

Little is known about the genetic mechanisms underlying inducible defenses. Recently, the genome of Daphnia pulex, a model organism for defense studies, has been sequenced. Building on the genome information, recent preliminary studies in BMC Developmental Biology and BMC Molecular Biology have assessed gene response profiles in Daphnia under predation pressure. We review the significance of the findings and highlight future research perspectives.

Figure 1

Schematical representation of the current knowledge on inducible defenses in Daphnia pulex. (a) Daphnia pulex forms defenses in response to chemical cues (kairomones) released by predators. Even tiny 'neckteeth', morphological changes, are protective. (b) Whereas different phenotypic defenses (adaptive changes in morphology, life-history and/or behaviour) in response to predation pressure are reported from ecological studies, little is known about the genetic mechanisms underlying these phenotypic changes. (c) Preliminary evidence for an involvement of several genes in inducible defenses exists (IS, insulin signaling; JH, juvenile hormone; UBC, ubiquitin-conjugating enzyme). (d) Concerted multidisciplinary efforts are required in the future to address and answer the question about the genetic basis of inducible defenses. QTL, quantitative trait loci; RNAi, RNA interference.