It is argued in this paper that the diversity of plant life histories in the Arctic is much greater than indicated by general descriptions in the literature. Three basic types of life cycle are suggested as a fundamental trait-based framework for exploring the diversity of plant life histories in the Arctic: (i) annual, (ii) non-clonal perennial and (iii) clonal perennial. An overview of current understanding of traits of arctic plant life histories is provided within this framework. Based on the overview it is concluded that (i) there is a substantial diversity of plant life histories in the Arctic, and (ii) there is no single life-history trait that is specific for arctic plants. Furthermore, it is proposed that because arctic environments differ in many respects from other environments, unique combinations of life-history traits are selected among arctic plants. Consequently, arctic plants should express a unique spectrum of life histories. It is also recognized that there are large gaps in the knowledge on arctic plant life-history traits and that fine-tuned trait–habitat relationships may be offset by historical, biogeographical or ecological factors, which may hamper analyses of life history–habitat relationships. On the other hand, it may be rewarding in terms of an improved understanding of functional and evolutionary responses of arctic plants to climate and other environmental changes to identify potential life history syndromes (strategies) among them.
The water strider Aquarius paludum inhabits the surfaces of a wide variety of freshwater habitats both temporary and permanent. It can also live on the surface brackish-water around river mouths. Exposure to a brackish rather than freshwater environment may affect a range of adult and offspring life-history traits. In a two-stage experiment A. paludum offspring from fresh- (F) and brackish-water (B) populations were obtained and their offspring reared in either a fresh- or brackish-water (0.45% NaCl) environments. The four offspring treatment groups (F-F, F-B, B-F, B-B) varied in terms of the parental and offspring rearing environments. The effect of parental and offspring rearing environment on longevity, fecundity and flight was assessed. Offspring reared in a brackish environment throughout their larval and adult stages had a reduced longevity and egg production. The flight activity of the offspring originated from the brackish-water population was maintained when they were reared in a brackish environment, but inhibited when they were exposed to freshwater. Our results suggest that the life-history strategies depend critically on the degree of salinity in both the current environment and that of their parents.