Effects of neonate size and food concentration on the life history responses of a clone of the hybrid
            Daphnia hyalina × galeata
            to fish kairomones

Phenotypic plasticity is the ability of a genotype to produce different phenotypes depending on the environment. It has an influence on the adaptive potential to environmental change and the capability to adapt locally. Adaptation to environmental change happens at the population level, thereby contributing to genotypic and phenotypic variation within a species. Predation is an important ecological factor structuring communities and maintaining species diversity. Prey developed different strategies to reduce their vulnerability to predators by changing their behaviour, their morphology or their life history. Predator-induced life history responses inDaphniahave been investigated for decades, but intra-and inter-population variability was rarely addressed explicitly. We addressed this issue by conducting a common garden experiment with 24 clonal lines of EuropeanDaphnia galeataoriginating from four populations, each represented by six clonal lines. We recorded life history traits in the absence and presence of fish kairomones. Additionally, we looked at the shape of experimental individuals by conducting a geometric morphometric analysis, thus assessing predator-induced morphometric changes. Our data revealed high intraspecific phenotypic variation within and between fourD. galeatapopulations, the potential to locally adapt to a vertebrate predator regime as well as an effect of the fish kairomones on morphology ofD. galeata.

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A review of the life cycles and life-history adaptations of pelagic tunicates to environmental conditions

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr159 ◽

2011 ◽

Vol 69 (3) ◽

pp. 358-369 ◽

Cited By ~ 33

Author(s):

Don Deibel ◽

Ben Lowen

Keyword(s):

Life History ◽

Environmental Conditions ◽

Generation Time ◽

Egg Production ◽

Food Concentration ◽

Life Cycles ◽

Population Doubling ◽

Event Scale ◽

Generation Times ◽

Doubling Times

Abstract Deibel, D., and Lowen, B. 2012. A review of the life cycles and life-history adaptations of pelagic tunicates to environmental conditions. – ICES Journal of Marine Science, 69: 358–369. Phylogeny, life cycles, and life-history adaptations of pelagic tunicates to temperature and food concentration are reviewed. Using literature data on lifetime egg production and generation time of appendicularians, salps, and doliolids, rmax, the maximum rate of lifetime reproductive fitness, is calculated as a common metric of adaptation to environmental conditions. The rmax values are high for all three groups, ranging from ∼0.1 to 1.9 d−1, so population doubling times range from ∼8 h to 1 week. These high values of rmax are attributable primarily to short generation times, ranging from 2 to 50 d. Clearly, pelagic tunicates are adapted to event-scale (i.e. days to weeks) rather than seasonal-scale changes in environmental conditions. Although they are not closely related phylogenetically, all three groups have a unique life-history adaptation promoting high lifetime fitness. Appendicularians have late oocyte selection, salps are viviparous, and doliolids possess a polymorphic asexual phase. There has been little research on hermaphroditic appendicularians, on large oceanic salps, and on doliolids generally. Research is needed on factors regulating generation time, on the heritability of life-history traits, and on age- and size-specific rates of mortality.

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