Offspring size, fecundity, and reproduction effort had significantly changed after 11 years (Reznick and Ghalambor 2005).
Overall, our results suggest a population expansion strategy of the studied Pacific oyster Danish population, potentially relying on a females-biased sex-ratio, a greater reproduction effort and gamete quality, noticeable on molecular signatures.
Timing of reproduction and breeding effort are expected to be direct drivers of an individual's fitness, but can also affect subsequent survival and/or future reproduction (Faaborg et al. 2010).
In addition to resource-dependent trade-offs, life-history theory predicts that in iteroparous organisms an increase in extrinsic mortality selects for optimal life history that shifts towards earlier reproduction, and higher reproductive effort [8].
Additionally, when raised in a common environment, individuals from an invasive Spartina alterniflora population that had recently taken over open habitat on the west coast had earlier reproduction and higher reproductive effort, but also earlier mortality, than individuals from high-density native east coast populations (Davis 2005).
Trade-offs between current reproductive effort and future reproduction and survival are fundamental to the evolutionary biology of ageing.
This is consistent with the positive pleiotropy between male and female reproduction: good genes for reproductive effort are expressed in both sexes and at all ages.
For example, age at first reproduction influenced the amount of reproductive effort invested in offspring production and defense in Sockeye salmon, Oncorhynchus nerka[ 25- 27].
Under conditions where normal semelparous reproduction may result in lost reproductive effort, deferral of reproductive effort to a second reproductive bout can realize fitness gains [ 11, 19, 22, 23, 30, 31].
Thus, greater adult mortality should select for less growth and a greater reproductive effort (proportional allocation to current reproduction).
