Abstract
1. Recent theory suggests that compensation or even overcompensation in stage-specific biomass
can arise in response to increased mortality. Which stage that will show compensation depends on
whether maturation or reproduction is the more limiting process in the population. Size-structured
theory also provides a strong link between the type of regulation and the expected population
dynamics as both depend on size / stage-specific competitive ability.
2. We imposed a size-independent mortality on a consumer-resource system with Daphnia pulex
feeding on Scenedesmus obtusiusculus to asses the compensatory responses in Daphnia populations.
We also extended an existing stage-structured biomass model by including several juvenile stages
to test whether this extension affected the qualitative results of the existing model.
3. We found complete compensation in juvenile biomass and total population fecundity in
response to harvesting. The compensation in fecundity was caused by both a higher proportion of
fecund females and a larger clutch size under increased mortality. We did not detect any difference
in resource levels between treatments.
4. The model results showed that both stages of juveniles have to be superior to adults in terms of
resource competition for the compensatory response to take place in juvenile biomass.
5. The results are all in correspondence with that the regulating process within the population was
reproduction. From this, we also conclude that juveniles were superior competitors to adults,
which has implications for population dynamics and the kind of cohort cycles seen in Daphnia populations.
6. The compensatory responses demonstrated in this experiment have major implications for community
dynamics and are potentially present in any organisms with food-dependent growth or
development.
Original language | English |
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Pages (from-to) | 871-878 |
Journal | Journal of Animal Ecology |
Volume | 79 |
DOIs | |
Publication status | Published - 2010 |
Keywords
- amplitude cycles
- body-size
- populations
- prey
- growth
- reproduction
- variability
- plants
- model