4.5 | Conclusions
We found evidence for different selective pressures for POP YOY across
two different years that had very different environmental conditions.
These results provide evidence that long-lived marine species such as
POP may be resilient to natural environmental variability by maintaining
a portfolio of adaptive alleles resulting from selection encountered by
each cohort during their most vulnerable life stage from parturition to
settlement. However, this resilience may be limited to the environmental
conditions that prevailed in the last few centuries. The “selective
sieve” framework may provide valuable insights into other species
employing similar life history strategies. Hoffman and Sgro (2011) note
that species facing strong but fluctuating selection pressures, such as
YOY POP during the pelagic life stage, will have a difficult time
adapting. Here, we demonstrated an exception where due to the way POP
are able to maintain these selected alleles may allow them to be
especially adaptable under fluctuating environmental conditions. POP
have proven to be an ideal model species for investigating portfolio
effects. By examining relative strengths of selection among discrete
populations and adult cohorts, it allows us to jointly examine spatial
and temporal portfolio effects. In the future, we plan to sample across
adult populations to link genetic variation to larval cohorts and adult
habitat/geographic population structure.