More complex models of selection

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More complex models of selection Spatial
variation Temporal variation Frequency-depende
nce
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temporal heterogeneity in selection
-- random fluctuations -- long-term change --
regular oscillations
A1A1 A1A2 A2A2 wet 1 1 1-s dry
1-t 1 1
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frequency-dependent selection
frequency-dependent predation
random predation
fitness advantage when rare disadvantage
when common
frequency eaten output
frequency in array input
common
rare
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at equilibrium allele frequencies, all genotypes
can have the same fitness w is not
necessarily maximized at equilibrium
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frequency dependent selection in the
cichlid Peridossus microlepis
(Hori 1993)
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explanation prey fish learn which side to
protect, depending on which morph of P.
microlepis is common null hypothesis no
learning response by prey, success by the two
morphs of P. microlepis is either equal or
proportional to their frequency alternate
hypothesis the common morph will have lower
success than the rare morph test by measuring
success rates at times when each morph is common
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frequency-dependent selection may be
widespread self-incompatibility alleles in
plants apostatic selection by
predators mimicry complexes (negative f-d when
the mimic is palatable positive f-d when the
mimic is distasteful sexual reproduction and
parasites sexual selection sex determination
in haplodiploids
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spatial heterogeneity can maintain a genetic
polymorphism - relative frequency of patch
types - relative strength of selection within
patch types - dispersal capabilities of the
organism temporal heterogeneity will maintain
genetic variation under certain
conditions - random fluctuations or (slow)
long-term change in selection pressures
promote genetic polymorphisms - regular
oscillations (i.e., seasonality) in selection
tend to eliminate all but one allele from the
population frequency-dependent selection -
negative frequency-dependent selection will
maintain a polymorphism with dynamic (vs.
stable) allele frequencies - frequency-dependent
selection may be widespread in nature