Appendix 1 Hypothetical relationships between juvenile densities (y axis) and adult densities (x
axis), and the underlying processes that may be responsible for each relationship (assuming
overlap in habitat use between age classes occurs). The type of settlement pattern required for
each process is described as (i) selective – settling larvae display habitat preferences and are able
to choose settlement habitats, (ii) passive – settling larvae are unable to select specific settlement
habitats and settle randomly, or (iii) either- the process can occur regardless of whether or not
settlement is selective or passive. In addition, the possibility that a particular process could lead
to intercohort density dependence (DD) is indicated by a yes (Y) or a no (N). In some cases
(marked with an *), density dependence could only occur if (i) settlement is selective and (ii)
there is lower survival in the selected habitat. The authors acknowledge that this is not an
exhaustive list of potential hypotheses, but rather a list of observed processes in the literature
Expected relationship
Passive or
selective
settlement
DD
Literature
No effect of adult conspecifics
Either
N
Levin 1993
Passive (non-selective) settlement
of settlers across habitats
Passive
N
Forrester 1999
Sub-lethal effects of adults on
settler growth and maturity
Either
N
Jones 1987,
Tupper and
Boutilier 1995
Settlers use resident adults as
settlement cues
Selective
N
Hunt 2011,
Stamps and
Krishnan 2005
Juvenile recruitment success
predicts future adult distributions
(i.e. densities are correlated within
habitat patches from year to year)
Either
N
Gutiérrez 1998
Co-variation of settler habitat
quality and adult density
Either
Y
(cryptic
DD) /N
Shima and
Osenberg 2003
Competitive exclusion from habitats
by adults
Either
Y
Samhouri 2009,
Webster 2004
Cannibalism
Either
Y
Bjørnstad 1999
Settlers shift habitat preferences as
adult density increases to avoid
settling near adults
Selective
Y*/ N
Ayllón 2012
Combination of facilitation by prior
residents or co-variation in habitat
quality (positive) combined with
competition/cannibalism (negative)
Either
Y
Adam 2011
Facilitation by prior residents or covariation in habitat quality
(positive) combined with
differential habitat selection by
settlers at high adult densities
Selective
Y*/ N
-
Potential processes
References
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