A marked inflection point in age versus elevation data at ca. 25 Ma defines the bottom of the exhumed post-Oligocene He partial retention zone (He-PRZ).
This limitation in quantifying radiation damage (and hence crystal retentivity) introduces non-uniqueness to interpreting time temperature paths in rocks that resided in the apatite helium partial retention zone for long durations.
In the case of populations under mean advection, however, the upstream retention zone will represent a heritable component of reproductive success for any larvae spawned there because a small fraction of these larvae retain their parents' geographic reproductive advantage.
This suggests that the population at the upstream edge will increase until, due to density dependent effects, the average of Nallele over the upstream retention zone is reduced until it just satisfies eq. (1).
He called for the creation of retail retention zones to protect small businesses threatened by national chains, with incentives offered to landlords in return for low rents; a moratorium on the rezoning of 1,800 acres of manufacturing space, to promote the expansion of existing companies; and the creation of a new mayoral office to coordinate work force development programs throughout the city.
Ultimately, the importance of each reserve's contribution to network persistence will depend on rockfish density, age structure, and fine-scale patterns of dispersal caused by oceanographic currents and features such as retention zones (e.g. White et al. 2010).
In addition to mean dispersal, reserve design should take into account retention zones, oceanographic conditions, and major currents to maximize biological exchange among reserves (Murray et al. 1999; Botsford et al. 2003).
The criteria for reserve siting may include any of the following: representation of biogeographic regions, maximization of species diversity, maximization of habitat heterogeneity (including adult versus nursery habitats), and the representation of retention zones (Botsford et al. 2003).
However, heterogeneity in abiotic (i.e. oceanography, temperature, salinity) as well as biotic (i.e. physiological responses) factors that result in an interruption or severe reduction of larval transport from upstream may lead to the formation of additional retention zones within a species' geographic range that harbor additional diversity [ 12, 13].
In rockfishes, connectivity and gene flow has been shown to be influenced by possible barriers to dispersal such as retention zones and mesoscale eddies that entrain planktonic larvae (Parrish et al. 1981; Morgan and Botsford 1998; Wing et al. 1998; Hyde and Vetter 2009; Hess et al. 2011).
As a third and related reason for reduced dispersal, Cape Blanco is a geographical headland along the coast, and such promontories are known to cause retention zones that entrain rockfish larvae and may form discrete barriers to gene flow (Morgan and Botsford 1998; Wing et al. 1998).
